# 1995 Chevy Blazer Internal Coolant Leak



## How Do I (Feb 11, 2008)

Picked up a *1995 Chevy Blazer 4.3L* (very cheap, thankfully) with a possible blown head gasket and/or head/block crack. (Been through this once before :lookout Last time I just replaced whole engine to be done with it. May be my best option this time, but am wondering, besides stripping down the whole engine and having heads and block magnafluxed and heads checked for warping, what are the chances that it was just the head gasket and not something more serious. I don't have a history of the Blazer so can't provide any more info there. This looks to be my midsummer project now. Here's what I've noticed so far just by inspecting it today: Was a little low on coolant, Oil looked only very slightly milky on dipstick, no froth on dipstick, PCV valve had some water hanging from it when I pulled it, had a little froth adhering right inside the oil fill tube, light rust dust on exterior left side of engine and front of engine (last time I saw something like that it was a cracked block), no external coolant leaks I can notice so far, when I was adding antifreeze at idle with the radiator cap off coolant mix came shooting out of the filler hole (heard that that indicates internal leak; head gasket or worse?). I've seen it bubble out before when burping, but this shot out halfway across the battery. Tried to drive it off the lot, thinking I may be able to get it to the garage. Starts right up like new. Had a bit of stuttering, hesitation when taking off and driving. One mile or less down the road it started overheating quickly, little over 210. Shut it down and let it sit and called for a tow. Now it's sitting there waiting for me to make the decision. The last engine I pulled was from a boat, so this may be my first for SUV. My common sense says to just try another engine. So what would you do? Take a chance with another used engine or see if this one is worthy? I can possibly get a decent used for around $150. Head gasket kit is around $70 and water pump around $30. WWYD?


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## james dilley (Mar 21, 2004)

Why not try thr $3.00 fix??? Aluma-seal. Its A grey powder in A tube try one. It can't hurt. Also theres one thats Bronze! Both can stop leaks. And easy to use!


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## agmantoo (May 23, 2003)

I would go buy 2 each large bottles of Barr's leak and follow the directions. I would then see how the engine ran.


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## How Do I (Feb 11, 2008)

I guess I'm not really looking for a cure in a bottle on this one... I'm just trying to figure, what are the chances that more damage than the head gasket itself occurred. I've scanned through sites and forums everywhere about *blown head gasket* and have even had family members and friends that have had head gaskets that blew and just installing a new head gasket fixed the problem. How would you honestly know if more damage was not done? The boat I had, I could clearly see that there was a crack on the engine exterior, thus the new engine. Is it more common for a gasket to go before a crack somewhere on the motor or vice versa. I have *the worst* of luck in these types of situations. I'm expecting the worst and hoping for the best. I'm thinking I could pull the heads and check the gaskets and I could see one or both of the gaskets bad and replace, but if more damage is done, I've wasted the time and money. Or I could pull the whole dang thing out and replace with another used engine and it may be on its last leg. So, that's more of what I wanted to know I guess. If you had to choose between the two, what would you take your chances on?


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## Beeman (Dec 29, 2002)

It's late and I'm tired but I'll try and make tyhis make sense.

I'm guessing this is a pig in a poke with no idea if it really has a problem or if someone has been working on it.

Let the truck sit for a day and remove the oil drain plug and just drain out a little. Coolant/water will sink to the bottom if there is any. The coolant shooting out happens on some vehicles just before the thermostat opens which is why it's frustrating on many to fill the cooling system. I used a coolant machine that pulled a vacum on the system and then allowed the coolant to flow in with no air pockets. If you suspact a head gasket because of pressure in the system try this. Remove the fan belt, fill the cooling system, crank the engine without starting and observe the coolant. if it raises or blows out of the neck you have problems. If it doesn't do anything but you still suspect a head or gasket do this. Remove the thermostat, leave the belt off, and fill the block thru the therm hole. start the engine and observe the coolant for bubbles. A blown gasket will push air bubbles which rise to the highest point, you can even see which side it comes from.

What fuel injection system does this have? Is it the newer style centerport injection with the plastic plenum on the intake? They have problems with intake gaskets leaking internally which would show up in the first test of water in coolant.


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## Madsaw (Feb 26, 2008)

Well I will make this simple. I have not had much time working on vehicles. My main thing is diesel tractors.
So, lets list what we know so far:
Milky oil
Low coolant
Pressurized coolant system when running from engine compression
Fast overheating


Here is a couple of quick checks:
Compression test on all 6 cylinders will show a low compression on leaking cylinder
Or a cylinder leak down test. Do this with the rad cap off and full. Make sure valves are closed on the cylinder being checked and pressurize it with a air compressor. A bad gasket or head will alow the air to escape to the rad and bubble out.
From past experince with tractors, if its blowing water that hard and heating up that fast. There is nothing in a bottle thats going to work. Possible problem head gasket or warped head causeing the head gaske tto leak. I came to this because, if it was a cracked head there would most of the time not be coolant in the oil (99 % of the time). When you pull the heads off you will see the gaskets burnt to where its leaking.
Bob


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## How Do I (Feb 11, 2008)

After more reading and suggestions, I guess I'll run through some tests to try and figure the best plan of action here. I'll update when I find out more. Thanks guys!!


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## Hammer4 (Oct 13, 2005)

That is an unlikely engine to have a cracked block, I would bet money it's a head gasket. 

Check the compression as mentioned above, pulling the spark plugs may well show one that is wet with antifreeze or looks black from coolant getting in.

Changing the head gasket and having the head checked by a machine shop to make sure its flat is the least cost and effort fix I would think.


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## Janis Sauncy (Apr 11, 2006)

I'm having the same problem with my S-15 (also 4.3). 

The coolant is going _somewhere_ but I don't know where. I talked to my mechanic and he suggested we change the thermostat first, since it's a cheap and easy fix and is the place to start. He only charged me $15.00, and that included the part.

It seemed to help somewhat, in that I didn't seem to be losing as much coolant as fast. It did overheat the other day after running errands. I had stopped at the post office and it was fine, until I turned off the engine. It then started gurgling and boiling over at the overfill.

A guy who was there said it sounded/looked like the water wasn't circulating. He looked at the radiator cap, which he said was really corroded and was possibly the problem. He cleaned that up as best he could with his knife and the next day I went and bought a new radiator cap. The guy at the parts store said I might also want to try flushing the radiator and told me how to do it.

I've made a couple of short trips since then and checked the coolant each time and I'm still losing small amounts.

I've asked my mechanic about fixing it if it is the head gasket and his feeling is it's too much to spend on this truck.

It's an '89, but the engine is newer (possibly a '95).

What do you all think? How much should it cost to have the head gasket replaced (my mechanic's shop rate is $60.00 p/h)?

Or is it possible the Barr's Leak might do the trick?

Janis


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## Windy in Kansas (Jun 16, 2002)

Several ways to diagnose and most have been given already.

One other way is to place an air chuck and air pressure in the sparkplug hole of each cylinder. If air winds up bubbling in the oil pan and you can hear it in the oil fill hole you can expect a cracked block. If the air leak sound comes through the carburetor it is probably a cracked head. If it comes into the radiator it is probably a head gasket.

Old diagnosing tricks that I've not tried so don't know if they would work on modern engines or not. 

Any peppery smell to the exhaust?


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## idahodave (Jan 20, 2005)

There's a history of intake manifold gaskets leaking on these motors. Coolant runs into the valley and down to the oil pan. 

Might not be as bad as you think.


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## How Do I (Feb 11, 2008)

> There's a history of intake manifold gaskets leaking on these motors.


And after doing some research, this may be one of the reasons why:http://www.girardgibbs.com/dexcool.html

I've been wondering why the radiator interior looked like it had such a rusty looking coating. Maybe that was it.

Unfortunately, my "helper" wasn't available today to give me assistance with the Blazer. A few other things I may have failed to mention before that I just remembered: Could smell no antifreeze from the exhaust. Right at the front of the intake I could hear bubbling or maybe boiling water after I turned the engine off. No fluid either entering or exiting the reserve tank. There was a little puddle of antifreeze sitting in one of the dips atop the front of the intake manifold, but I swiped it up before driving off and no more has gathered there since. The only thing that bothers me is that hesitation and roughish feel coming from the motor while driving. Would something related to water/coolant in the oil cause that? Now I'm thinking, what's going to be good enough to flush that Dex-cool crap, if that's what it is, out of the radiator and galleys if this thing is repairable? I'm also thinking, with my limited knowledge, could I do a compression test and if that comes up in normal range on all cylinders and I check the intake gasket and find the fault there that there would be no need to go further on down to the head gasket replacement?


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## How Do I (Feb 11, 2008)

OK. Here's what I have after today. I pulled all of the plugs (none looked fouled, no sign of any moisture) and did a compression test.

Looking at the engine, I have from front to rear of engine 2-4-6 on the left side and 1-3-5 on the right side. Here's what I got from the test.

---------------------------
F 2 - 175 4 - 180 6 - 175 
R 
O
N 
T 1 - 180 3 - 180 5 - 180
---------------------------
Got to talk to the original owner of the vehicle. He said the vehicle was kept up to maintenance at _every_ interval. He sold it to his daughter and she drove it up until the last 30,000 miles at which time it was sold to a guy around three years ago. This vehicle has 244,000+ miles on it. My manual doesn't give an acceptable compression reading, just says minimum 100 and that the lowest shouldn't be less than 70% of the highest reading. So what do I suspect now? Does this pretty much rule out a head gasket, head, block? What about that manifold gasket? I did some real close looking today with a flashlight and noticed a small external leak from the intake. This was just like a tear drop amount after running the vehicle for about 5 minutes until the temp got close to 210. Any ideas where to go from here?


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## Beeman (Dec 29, 2002)

Compression is great for an engine with that mileage.


Let's start from the beginning. Is it overheating? What are we trying to fix, diagnose? 210 on a factory worn out gauge isn't telling us much. Very common to not get cooling system completely full and air being trapped causing bubbling noises and high readings/false readings on gauges. 
Were any of the spark plugs extremely clean? A cylinder with coolant getting in will steam clean the spark plug or in some cases tint it the color of the antifreeze.


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## agmantoo (May 23, 2003)

I was unclear with my post above. I never intended to have an overhaul out of a bottle. My suggestion was to get the leak temporarily sealed to determine the overall condition of a recently purchased bargain vehicle. As Beeman stated the compression is great and there is not an obviously cracked head or heavy leaking head gasket. I guess that I am still "hung up" on my initial suggestion. Two bottles of Barr's Leak and a radiator cap left loose should temporarily stop a leak. If the engine ran fine then I would consider what options I had for a more permanent fix. Personally I have known engines to run for years with this simple bandaid. Then again, I would not do this to a cross country vehicle and maybe I would carry a can of water for local trips.


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## How Do I (Feb 11, 2008)

None of the spark plugs were "extremely clean". When you look at the "Common Spark Plug Conditions", found on the back page of most manuals (Haynes), the ones that came out of this engine looked like the "normal" one, save for one (Number 4) which had a little gas that you could see and smell. My neighbor seems to agree the vehicle has a slight miss and I don't know if its maybe this cylinder (Number 4) that's not firing or what. I'll have to check that wire and make sure it's getting spark. The plugs will be changed shortly too. That plug was the only one that broke in half coming out, so I'm thinking it was already cracked to begin with. Hopefully that will cure the miss...hopefully. I realize the Temperature Sensor may be faulty. The whole area around the water pump is covered in a dusty rust-like stain. The guy that originally owned the vehicle volunteered last night that he couldn't remember if he ever had the water pump replaced or not. The inside of the radiator looks nasty, covered in some light rusty coating of something, but the fluid itself is clean. The thermostat looks like it was replaced recently, maybe to try to rectify the overheating problem?? My guess is to test that thermostat and then refill-burp and see where that leaves me standing.

_agmantoo_ - I was just looking find the source of the problem. If the stuff did work, then I would have really been stumped trying to find the root cause. As little water as I believe is getting down to the oil pan, the stuff probably would work. Thanks for the suggestion though!


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## zant (Dec 1, 2005)

As Beeman said-4.3 have problems with the intake gasket leaking both internally and externally.I took mine to dealer and they installed new updated gasket and sealant-now it leaks around hose fitting on manifold-I'm wondering if Dexcool is the problem-chemical reaction with gaskets,etc??Gonna change to old green..


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## Beeman (Dec 29, 2002)

How Do I said:


> None of the spark plugs were "extremely clean". When you look at the "Common Spark Plug Conditions", found on the back page of most manuals (Haynes), the ones that came out of this engine looked like the "normal" one, save for one (Number 4) which had a little gas that you could see and smell. My neighbor seems to agree the vehicle has a slight miss and I don't know if its maybe this cylinder (Number 4) that's not firing or what. I'll have to check that wire and make sure it's getting spark. The plugs will be changed shortly too. That plug was the only one that broke in half coming out, so I'm thinking it was already cracked to begin with. Hopefully that will cure the miss...hopefully. I realize the Temperature Sensor may be faulty. The whole area around the water pump is covered in a dusty rust-like stain. The guy that originally owned the vehicle volunteered last night that he couldn't remember if he ever had the water pump replaced or not. The inside of the radiator looks nasty, covered in some light rusty coating of something, but the fluid itself is clean. The thermostat looks like it was replaced recently, maybe to try to rectify the overheating problem?? My guess is to test that thermostat and then refill-burp and see where that leaves me standing.
> 
> _agmantoo_ - I was just looking find the source of the problem. If the stuff did work, then I would have really been stumped trying to find the root cause. As little water as I believe is getting down to the oil pan, the stuff probably would work. Thanks for the suggestion though!


 Leave the thermostat out and fill the block thru the therm opening, this assures no air trapped in block. You could then do the head gasket/cracked head check I suggested. I'm still wanting to know what we're diagnosing. A cracked head/bad head gasket might not allow coolant into the cyl as coolant is only pressurized to 15lbs and you have 180 lbs of compression. Also a cracked head might only show up when hot as the metal expands.


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## How Do I (Feb 11, 2008)

Well, I went and changed the spark plugs today, checked Number 4 wire (Good Spark) and then put the Blazer on an incline and burped it again. Didn't "shoot" coolant out this time, but rather overflowed the radiator fill a few times (with me refilling quickly) and it finally quit burping but the temp stayed right at 210 and didn't waiver from there while idling (could see no coolant flowing). Put on a new radiator cap. Drove it less than a quarter mile down the road and it got up to 230F so I shut it down and let it cool off. Still no fluid exchange in the overflow. Still has a stuttering feel to the engine while under acceleration and at idle. Don't know whether to suspect bad thermostat, water pump or both. I plan on yanking it all apart and replacing the water pump and thermostat this coming week followed by coolant flush. I guess if I can get the coolant system under control I'll go ahead and pull the intake and replace that gasket.


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## bugeye (May 28, 2008)

as others have stated, its your intake manifold gaskets, I was doing 2-3 reseals a day when I worked for chevy on their 4.3L V-6 engines, Replace the intake gaskets before you do the water pump, if not you will have the same problem you do now and since you have to take out the dist. get a new oring for that too


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## How Do I (Feb 11, 2008)

> I'm still wanting to know what we're diagnosing.


Overheating and water in the oil??


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## Beeman (Dec 29, 2002)

Water in oil, how much and where? Did you pull the drain plug and find coolant or just a foam on the PCV valve and dipstick. 
Overheat? You said it went to 210 and then 230, is that actual degrees or what the 13 yo gauge said? 
Once the coolant stopped pushing out of the radiator you should have been able to tell if the thermostat opened by the upper hose getting hot, the radiator getting hot and the air the fan was blowing getting hot. At that point you should have been able to see the coolant flowing thru the upper tubes of the radiator as you ran and revved the engine. At that point you could use a mechanical thermometer like a meat thermometer to check the coolant temp.

What fuel injection system does this have? If it is individual injectors for each cyl. you might have a bad fuel injector causing your miss.


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## RACCOON (Dec 13, 2005)

Last year I had my dodge caravan blowed a head gasket.Van had 200.000 and was in bad shape ,I didn't want to put alot of money in her. 
Friend told me to put some Red Devil in her ,80$ a bottle
So I tried it!! today it's still running going on 250,000miles.


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## blufford (Nov 23, 2004)

Does your heater work?


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## bugeye (May 28, 2008)

its not a blown head gasket according to the psi you posted for each cylinder, what is happening is the coolant is leaking from the intake manifold into the valley under it, which is why you have water in your oil and the car is overheating


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## How Do I (Feb 11, 2008)

Pulled the intake manifold today. Looks like plenty of coolant has entered the engine. Didn't look like any leaks from the manifold gasket itself (but still a possibility I guess...I'm not an expert). Can a machine shop test/magnaflux intake manifolds? If they do, should I remove the spider before taking it in? I know for sure this intake has an external leak now. First time I looked, I thought it was at the gasket, but now can see it is leaking externally from the "mold line". Since it has the external leak would you just trash it? I could pick up a used intake for about $25. Would I be better off doing that?


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## idahodave (Jan 20, 2005)

Buy the used one. And while the coolants out, take the radiator to a shop and have it rebuilt.


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## fixer1958 (Dec 12, 2005)

How Do I said:


> Pulled the intake manifold today. Looks like plenty of coolant has entered the engine. Didn't look like any leaks from the manifold gasket itself (but still a possibility I guess...I'm not an expert). Can a machine shop test/magnaflux intake manifolds? If they do, should I remove the spider before taking it in? I know for sure this intake has an external leak now. First time I looked, I thought it was at the gasket, but now can see it is leaking externally from the "mold line". Since it has the external leak would you just trash it? I could pick up a used intake for about $25. Would I be better off doing that?


I have changed probably 200 intake gaskets on the 4.3 and have never seen a bad intake manifold. Not saying it can't happen unless you got it so smoking hot that it cracked it. If you did, the heads are trashed also.

I would go with Felpro gaskets the are a rubber compound and metal instead of the OE plastic and rubber looking BS that it came with. GM may have went with the newer gaskets, but I'm not for sure.

Seems to me you are sweating over something that isn't a major factor unless you pegged the temp guage alot of times. 4.3 engines are pretty tough.
Scrap the contact surfaces with a razor (don't buff it) and suck the remaining junk out with a shop vac and you are good to go.
Change the oil before you start it.
Should start and run like you never did anything to it.
My Opinion.


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## How Do I (Feb 11, 2008)

Where I am right now: New Felpro intake gaskets installed. Had intake checked at machine shop. No warpage. Shop insisted no way would it leak where I was indicating. OK, so I take their word for it and just replace the intake gasket. Intake reinstalled - Plenum is reinstalled. Dropped distributor, changed out oil and filter and checked it this afternoon. Fired right up. Shut it off immediately. Pulled the water pump and looks like original. Took off the backplate and when turning the pulley, the pump blades just sat there inside, not moving. Spins freely on shaft. So I bought another water pump and went to install it and noticed the new one doesn't have studs like the old one, so I guess I need to find some bolts tomorrow to finish it up and flush the radiator. Let ya know what happens, hopefully in the next day or so.


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## Beeman (Dec 29, 2002)

Remove the studs from the old water pump, they just screw out, double nut them to remove. 
Did you torque the intake bolts to the spec? Easy to crush and ruin the new gasket as they take very low torque. Did you put sealer on the intake bolts?


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## How Do I (Feb 11, 2008)

Thanks for mentioning about the studs Beeman. I double-checked today and noticed they _were_ threaded. At first glance, looked like they were pressed in. Went ahead and got some new studs today as the old ones were pretty sorry looking. Yeah, I did everything by the book. Running a little rough. I checked the timing and its off 0 degrees by a few inches. Hoping I got the distributor back in through the right gear. Which brings me to another question. I'm having trouble getting to the distributor nut to adjust the timing, because of the plenum. I could have sworn I used a 14mm wrench to loosen the distributor nut. I even have the old wrench I bent in the vice to prove it. But I can't seem to find a 14 mm distributor wrench. One auto parts store I called (Auto Zone) said they only had standard and that GM's are standard. So all the other bolts on this truck have been metric and only the distributor nut is standard?? The other auto parts store I called (Advance), the guy never heard of a distributor wrench. So maybe someone here can tell me for sure what size the nut is so I can find a distributor wrench tomorrow? That would sure help me some! I'll probably have to have NAPA order it, but so be it.


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## Beeman (Dec 29, 2002)

I'm guessing you have a Vortec V-6 with the aluminum plenum and the large spider type injector. I'm guessing you has the aluminum intake with standard style gaskets and not the plastic/silicon gaskets.
From Memory dist is 9/16 bolt. To set timing you should have to unplug the bypass wire which allows the computer to control timing so you are setting base timing.


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## How Do I (Feb 11, 2008)

Beeman said:


> I'm guessing you have a Vortec V-6 with the aluminum plenum and the large spider type injector. I'm guessing you has the aluminum intake with standard style gaskets and not the plastic/silicon gaskets.
> From Memory dist is 9/16 bolt. To set timing you should have to unplug the bypass wire which allows the computer to control timing so you are setting base timing.


Good guessing!:bow: It took me about two hours to locate that timing bypass wire. I searched far and wide on the internet trying to locate where that wire might be located. And then the same throughout the vehicle. Every web page I saw kept saying, "its under the carpet on the passenger's side". That was my first check. Pulled the computer out from under the dash on the passenger's side and saw the tan wire with black stripe and was just minutes from getting ready to make my own new disconnect, when I happened to look *way* up under the dash on the firewall and saw the disconnect coming off of the main wiring harness. Finally got it disconnected and went to proceed with the timing procedure. Got it timed to 0 degrees and the engine kept slowly revving up and down, acting like it was going to die and then smoothing out. Sat there for a second and just listened. Heard a tick-tick-tick-tick. Glanced over on the passenger side of the engine and saw that a spark plug boot was sparking at the exhaust manifold. Pulled the boot and it had a rip almost down to the bottom. Too late for another auto parts run, so just to check the timing, I wrapped the lower part of the boot with electrical tape and then reinstalled. Timing straightened right out. I did end up getting the distributor wrench yesterday (9/16) and it did help out tremendously. Although I also again tried the 14 and guess it would do in a pinch. 

Alright, so the timing temporarily set & distributor bolted in, I took it for a test drive to the local gas station. It has a slight stumble to it both when idling and while accelerating. I did notice that the passenger side bank of the plenum interior was minutely lighter color than driver side when disassembled, so I'm thinking the fuel pressure regulator may possibly be faulty, but I'm going to go ahead and try a distributor cap, rotor and wire set before going any further. That will have to wait until next week though. The coolant is now flowing in the radiator. Temp hits _approximately_ 195 and then drops back down to where it should. So I believe that problem is now solved. Seeing no leaks on the exterior of the intake, so that's good... I'm keeping an eye on the oil and haven't noticed a rise in level...yet. (Can't you hear the pessimist in me coming out?) One other little symptom I get is when turning the key off, the mouth of the intake makes a sucking sounds, like its taking one last gulp of air. Maybe that would help narrow it down. This is my first time pulling a distributor by myself and the thought still lingers in the back of my head, did I drop the distributor in off one gear? I've heard some say you'll most likely get a no-start, while others saying it will start, but run poorly. Do you think I can rule out this being a problem with the poor idling and stumbling feel of the engine while accelerating? I had everything marked and it seemed to drop back in perfectly. Just want to rule that out, is all. 

Two last problems with the Chevy Blazer that I'm working on right now:

Two lights on in the cab. One, the *ABS light was on* and the Air Bag light is on. I pulled the tire off the driver side last night and found the ABS sensor wire had been worn in half. Temporarily fixed it with some wire connectors and electrical tape and started the Blazer back up and no more ABS light. It's really not in a good place for wire connectors to be and I don't really expect it to last long at all, with the poor location at the control arm, but at least the problem was found.

One of the air bag sensors on the bumper is covered from oil or transmission fluid (haven't checked to see which line it is yet) that is leaking. I don't know if oil got inside and screwed the sensor up or not. I'll have to work on that one. I've got the info on disabling the (SIR) air bag system.


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## Beeman (Dec 29, 2002)

I asked a ways back what engine you had, unfortunately it would have been better to know before you put everything back together. The fuel injector assy. has a bad habit of leaking on those. This would have been very easy to check with the plenum off. All you had to do was cycle the key and run up fuel pressure and you would see if there was a a leak. A clean spot in the plenum usually is leaking gas from the injector assy. They used to only service the whole assy. 
Water pump and intake bolts all required sealer on the threads.
Truck most likely wouldn't start and you wouldn't have been able to swing the dist. enough to get the timing set if you were off a tooth. Is the body of the dist in the same position as when you removed it and no wires stretched due to mispositioned dist?

Another common problem is carbon in the EGR valve holding the valve open causing poor idle.

What did you use to clean the old intake gaskets off of the manifold and heads?

Sucking sound? If I remember correctly the boot on the frt. can be tough to get on and might be kinked, also there is a breather tube that pushes in that boot. Is there an air filter in the air filter box?


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## How Do I (Feb 11, 2008)

Sorry about the confusion over the engine Beeman. I thought I had posted way early in the thread in reference to your question that is was CPI...must have went to post it and it didn't go through. I've read up on that unit being prone to leaking and dumping fuel inside the passenger side of the plenum. I planned to do a fuel pressure test this coming week. I wouldn't have been able to afford a new unit or even just a fuel pressure regulator before the end of this month regardless. Just wanted to get her running and not leaking or overheating to see if she was worth keeping before sinking any more money into her.

Believe it or not, the EGR valve looked halfway clean. Very little carbon film. We used to have a 1993 GMC Jimmy years ago, so I'm also familiar with _that_ problem on these vehicles. I used a gasket scraper to clean the gaskets. I've took it out for several test drives now and I'm seeing no change in water or oil level or external leaks either. All looks good in that department so far. The distributor dropped right back in like I took it out. I even marked the position of the rotor after the distributor came out for reference when dropping back in. I was just wondering *how rough* it might run if it were a tooth off. Never experienced that situation before. Timing marks line up perfectly under the light and distributor is in original position as before disassembly. It idles pretty decently, just you can tell, something is just not quite right. You know, by the sound? And when you go to accelerate, you get the buh, buh, buh, buh, in the lower RPM range of each gear. Like it might be struggling to get air or fuel? None of the air passageways blocked or kinked and everything hooked back up fine. There is an air filter (but ready for a new one), but it's making the sucking sound with or without the breather on. I mentioned earlier that the number 4 spark plug had a little gas on the plug and after noticing the short to the exhaust, I'm just guessing that was why. I was reading about people having problems with the regulator leaking and that one symptom was 2-4-6 spark plugs being carbon fouled from the extra gas being dumped. The plugs on this vehicle, save for 4, all looked exactly the same. One of the reasons I originally ruled out the fuel pressure regulator. But I guess a pressure test should help better diagnose if it's a fuel delivery problem. If I had no problems there, I was going to go ahead and change out the plug wires, cap and rotor. I did have some carbon tracking on the electrodes inside the cap when I took it off. I just lightly cleaned them off and replaced for the time being until the beginning of the month. I guess I'll just have to wait a few days, give it a good tuneup and pressure test and see where I am. Should help me rule out some things anyhow. Let me know if you or anyone else has any other ideas and if you think I'm on the right track!


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## How Do I (Feb 11, 2008)

You know Beeman, come to think about it, I did do a leak test on the fuel system before reassembling the plenum. I remember now that the book called for putting pressure on the system before reassembling the plenum and to check for leaks. And I _do_ remember doing that now and in particular checking around the injector assembly. Man this getting old stuff is for the birds. And I _swear_ I'm not blond. Well, just thought I should add this and make myself look like a fool even further. Regardless, I'll still go ahead and proceed with a fuel pressure test in the coming days.


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## How Do I (Feb 11, 2008)

Update: Fuel pressure readings were OK. I pulled the plenum once again and checked for any leaks inside. It was bone dry and as clean as when it was when the intake was reinstalled. While I was in there, I went ahead and put in a new fuel pressure regulator since these seem to be a problem in the Blazers. Reinstalled the plenum and took it for a test drive. Noticed that the exhaust was blowing out chunks of the catalytic converter. Parked it in the garage running and bits and pieces of the cat were shooting out of the exhaust. Removed the exhaust past the catalytic converter and revved it up to about 1500 rpms for a few minutes. The whole floor underneath of the Blazer was covered with cat pieces and chunks. Went and bought a new catalytic converter to install. Finally got it on today and took it for a test drive. Still had the hesitation in lower rpms while accelerating. Got about 5 miles down the road and saw smoke coming from the back underneath of the vehicle. I stopped and looked under to see that the catalytic converter was cherry red, the muffler had a hole blown in it and there was plastic flowing from over top the muffler and landing on it causing the smoke. My first guess was a clogged muffler. I'm still getting no check engine light. I don't know what else to suspect. The muffler needed to be replaced anyhow, so I guess I'll check it for blockage and put a new one on tomorrow. Any other guesses as to what would have caused this so I can check it tomorrow?


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## How Do I (Feb 11, 2008)

I was finally able to get some codes read from this thing. It gave me codes:

22 - Throttle Position Sensor out of adjustment

34 - Manifold Absolute Pressure sensor signal voltage low

I got a new muffler on and the cat looked good from the back side when I put the new muffler on. Its still dumping fuel for some reason. I checked all the plugs tonight right after taking another pressure test and the 3 & 5 cylinders look like they are getting too much fuel (washed, not carboned) for some reason. All of the other plugs looked normal. I'm still not seeing any leaks inside the plenum. I even put on another used CPI unit and EGR and getting most exactly the same symptoms. I didn't get a chance to check those sensors above yet. Was checking resistance on the IAC valve and went to put it back on and the head popped off the screw. So that left me with a disabled engine to work with until I get that screw out. Sounds like maybe one of the sensors may be causing the running rich condition. I could really use some advice on what else to check here.


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