# 1995 Chevy Blazer - Head Gasket?



## How Do I (Feb 11, 2008)

On the way to Louisville this morning, I noticed that the temp gauge was reading about 200 for most of the trip. Usually hangs around 180-185 after warming up. On my way back I pulled into a gas station. As I pulled away, I noticed that when I accelerated around the parking lot, as soon as I did, I could immediately hear gurgling sounds from behind the dash. Tried this several times in the parking lot and every time, right after pressing down on the accelerator, I would hear the gurgling behind the dash. Couldn't really hear the sound as I was driving the rest of the way home, but heard it again after I pulled into the drive. Is this most likely the head gasket- exhaust/compression leaking into coolant? Haven't really noticed any large loss of coolant, oil looks perfectly fine. I knew I had a pin hole in the heater core, so I attributed the small loss of coolant to that over many months. One thing I have noticed is that when warming up in the morning, I hear a light knocking noise, about 20 seconds in length. Didn't know if this had to do with the external oil filter issue or not or maybe small amount of coolant leaking back into cylinder and causing the knocking until it burned off. I'm guessing someone is going to ask me if I've performed a compression test yet?? Not yet, I just got home. Hope this makes some amount of sense. Been a very long day.........


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## Ray (Dec 5, 2002)

if you can hear gurgling sounds in the firewall, did you open the hood and look and listen? when it was hot and making the noise with the hood open you might be able to fine the gurgle sound. some engines can get an airlock in them after loosing a certain amount of coolant. It can get so bad the water pump cant even pump water through the system. some of these have a bolt type release in the top of the water jacket manifold, for when you have to drain the coolant all the way out or you loose too much to bleed the sys. with, some none. if it is a head gasket you might have been able to locate it if it was making that mush noise, wgen it gets warm and makes those noises have someone else work the gas and have them pull up and back up a couple times whole you watch. I could hear the gurgling sounds when my bravada was low on coolant and hot enough the coolant was boiling under the pressure of the radiator system. If your engine does get HOT its best to have it running while adding coolant to keep from cracking the block. it also sounds like it just might have lost enough coolant that it was getting hot and with a pinhole in the heater core you could hear it real well. remember with a blown head gasket it can leak oil to coolant, coolant to oil, maybe neither, but you should loose some compression on at least one cylinder, and maybe 2, leaking into each other, but you should feel the power loss under a blown head gasket, I would think, but nothing is carved in stone, best wishes ray


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## How Do I (Feb 11, 2008)

Thanks Ray! I guess that does make sense now that you mention it. i DID notice the smell of coolant MUCH MORE than usual on the way out this morning and the windows fogged up which they never have before. Didn't even remember THAT until you mentioned it. See if I can bleed the air out tomorrow and see if that makes any difference. Ugh, and guess I'll DEFINITELY have to get that heater core replaced since that's probably the culprit. GN........


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## Ross (May 9, 2002)

4.3 vortec? I have two in 95 Astro/Safari and the updated vortec in a 98 Jimmy. They definately gurgle when low on coolant and they're hard to bleed all the air out. Sounds like your heater core let too much coolant out all right.


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## Wis Bang 2 (Jan 12, 2010)

Fog on the windows is the heater core. The 4.3L vortec is well know to have issues w/ trapped air and gurgle sounds. If you are leaking coolant into a combustion cly, it produces dense white smoke out the exhaust and will make the engine miss. If you don't feel any change in the engines power, if it isn't running rough due to a miss, it is your heater core...

Most of your dash has to come out [I watched the guy changing the A/C evap & heater core in my '93 Jimmy] and it is a labor intensive process...consider changing the a/c evaporator too since the heater/blower area will be uncovered...

My 88 S10 didn't have A/C and it was possible to just loosen the right side and pull the dash back to change the heater core...still took me 3.5 hours the first time...I left out one bolt in the heater cover and the second time was under two hours!

You'll find the matting under the carpet on the right side is soaked w/ coolant too!


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## Beeman (Dec 29, 2002)

Light knocking noise on start up?
That's not a good thing. On those with the remote oil filter they have an anti drainback valve built in the filter. If you use a cheap filter or the improper filter it woill allow oil to drain back out of the filter causing an oil starvation problem on start up. The sound you hear is the metal to metal banging of the bearings before the oil pressure builds and fills the clearance so the crank and rods ride on the film of oil. That knocking is shortening your engines life. Also be sure you are usiang the correct grade and viscosity of oil. If memory serves me it's probably 5w-30 or 10w-30 in that truck.


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## How Do I (Feb 11, 2008)

Update: I went ahead and bled the system and it was running fine...until today. :awh: 'Nother trip to Louisville, went fine. Stopped for lunch before errands. Started it up after lunch and it started running rough. Coolant in reserve had dropped a bit since this morning. Drove less than a mile and the engine temperature warmed up, but kept on going up to 230 so I shut it down and let it cool off. Started it back up in the parking lot after cooling off and it started running rough and blowing white steam out the tailpipe along with dripping. Got a friend to tow it home for gas money, thankfully. I was truly hoping my luck would hold out for at least another month, but... After a nice chunk of change for taxes this month, plus money for a water meter installed and water lines to the house and now all of this. Welcome to Brokeville. LOL I've been through and through the intake so many times I could probably disassemble and reassemble in my sleep, but I haven't been down to removing the heads before on one of these so I may pop back in here for any tips or questions from time to time in the next few days.

@Beeman - Since I'll be changing the oil in this process, what brand filter would you or others recommend? I've been using 5W-30 since I purchased and it is what manufacturer recommends.

@Wis Bang 2 - I used to have a 93 Jimmy and had to replace the heater core on it also. It was a whole lot easier than the book makes this procedure to look like. The whole dash to replace a heater core?? I mean seriously, who designed these things?


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## Beeman (Dec 29, 2002)

GM vehicle, AC Delco oil filter. It's good enough for the factory, it's good enough for me. Wix would be the aftermarket choice or NAPA gold which is Wix also. 

93 Jimmy would be older body style, easy to replace heater core. 95 newer body style, not so easy to replace heater core, look at where the hoses attach and you'll see why.


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## Wis Bang 2 (Jan 12, 2010)

With the intake off there isn't that much more to do the heads. 4.3's need new head bolts and removing the exhause can be a it of a hassle. You need to have the heads check to make sure they are not warped. Might be easier to swap them for a re-maned set, you don't want to do this again!

The first gen heater core w/ A/C required loosening the whole dash to allow room, my neighbor works full time as a tech and he took the dash out instead of just pulling it back enough to get in there...

My new to me 05 silverado has dual temp controls, I wonder what that is like when the time comes.....


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## How Do I (Feb 11, 2008)

what now? i just had this all apart i think two years ago and I had gas in the intake manifold last time from a leaking fuel pressure regulator. Now I have *oil*...(pic is hyper-linked to a larger pic) and I swear it looks like and smells like that left hand side of the intake is being washed out with fuel again.



I replaced that fuel pressure regulator last time I was in there. Both sides were as clean as (much cleaner actually) the left, minus the oil and gas...


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## Beeman (Dec 29, 2002)

Either turn the key on and let the fuel pump run or jumper the fuel pump circuit and build pressure while observing. Any leaks will be easy to see. The feed and return lines are bad to crack on those also and should be replaced. Don't try to start it with the plenum off. The EGR valves are also bad to get hung open with carbon on those also.


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## How Do I (Feb 11, 2008)

I pressurized the lines before I tore it all down and couldn't find any gas leaking around the regulator or lines. Fuel lines are already removed from intake manifold. Will take another look at it once I start reassembling. Should have it finished tore down in the morning. Trying to get the heads into the machine shop Monday morning. Got hung up today with finding a pulley puller for the PS pump. Think the oil is from blowby? I haven't had a problem with oil puddling in the intake before. 273,000+ miles, so some wear wouldn't be surprising.


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## HermitJohn (May 10, 2002)

The oil filter buisiness has turned into some goofy high profit marketing game where your guess is as good as anybody elses what filter is made by who at any particular time and what quality of it is. AC filters used to be quality and good buy. But GM quit oil filter manufacturing and the AC filters now are Champion Labs "ecore" design for several years. I dont know, but looks and feels lot cheaper than the old GM made AC filters.

From what I have read WIX, Purolator Pure One, Baldwin, and Donaldson are the best you will find without the hype. Motorcraft is a relabled Purolator Pure One. In other words they arent playing marketing games. Fram seems to be the one to totally avoid. http://minimopar.knizefamily.net/oilfilters/reference.html At one time decades ago under different ownership, Fram used to be quality, now it seems its mostly hype based on that old reputation.

Saying all that, I imagine if you change your oil and filter say 3000 miles, it really matters little what filter you use as long as said filter doesnt cause your engine to make strange noises on startup.


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## Beeman (Dec 29, 2002)

How Do I said:


> I pressurized the lines before I tore it all down and couldn't find any gas leaking around the regulator or lines. Fuel lines are already removed from intake manifold. Will take another look at it once I start reassembling. Should have it finished tore down in the morning. Trying to get the heads into the machine shop Monday morning. Got hung up today with finding a pulley puller for the PS pump. Think the oil is from blowby? I haven't had a problem with oil puddling in the intake before. 273,000+ miles, so some wear wouldn't be surprising.


 This engine has 273k mi? I've never had any long term success doing just heads on a very high mileage engine. Always seems not long after you are done the bottom end blows out. You've already stated a rattling on cold start up which is the bearings making noise. I believe I would have pulled the motor and either rebuilt it, replaced with a lower mileage used or purchased a rebuilt engine.


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## How Do I (Feb 11, 2008)

Beeman said:


> This engine has 273k mi? I've never had any long term success doing just heads on a very high mileage engine. Always seems not long after you are done the bottom end blows out. You've already stated a rattling on cold start up which is the bearings making noise. I believe I would have pulled the motor and either rebuilt it, replaced with a lower mileage used or purchased a rebuilt engine.


Well, I guess I have to do what money allows for the Blazer right now. The noise I hear in _Winter only_ at start up , I'm just thinking/hoping might be the cheap oil filter. I don't hear that noise in the warmer months. I've been using the STP brand so I'll try a better one and cross my fingers. I got the heads off yesterday and took in to the machine shop this AM. Pretty sure he said to wash-check-magnaflux, $7.50 per cylinder. Of course the price would go up with any repairs needed to be made. The _heads are cast iron_. He said those had a tendency to crack. Never heard that before.:shrug: Just glancing at them, he said everything looked OK but said he wouldn't know for sure until he went further.

I had a miss and if you put a dollar bill up to the tailpipe it would suck it in and pop it out. Real faint miss, but I knew it was there. Heard that could be a burnt valve, but nothing you could see with the heads pulled.

Also, when pulling the exhaust manifolds, three bolts broke off. Two on one, One on the other. The machine shop wanted $22.00 to remove EACH bolt and if one or all required heli-coil inserts, an additional $15.00 EACH. Needless to say, I passed on that offer. Guess I'll have to dig those out myself. (personal reminder - I need to go into the bolt removing business)

Had one head bolt break off in the block with a nub sticking out (in the rear of the motor, of all places), but an extractor set backed it out like butter. Was thinking about going ahead and pulling the timing chain cover to check its condition before re-assembling all of the brackets. I'd still need to pull the water pump too to get to it... What do you think?

All cylinder walls smooth as a shiny button - not much carbon buildup at all on the rims or pistons, had some coolant in the left rear cylinder. Didn't look like it had been there long so I can't say whether it was there for sure before the head was loosened or afterward. Cleaned some of the oxidation off of one of the "freeze plugs" on the front of the engine with a small stainless steel brush. Walked away and came back about 5 minutes later and there was a small puddle of coolant on the rim of the plug. Wiped it away and it filled back up. Those will be replaced too. If you can think of anything else I can do, (besides pulling the engine and overhaul  ) I'd appreciate more ideas what to check for while it's broke down.


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## Wis Bang 2 (Jan 12, 2010)

At that mileage a timing set would be worth it & so would a new water pump...


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## calliemoonbeam (Aug 7, 2007)

I don't have any advice to offer, but will be watching this thread with interest. I have a 97 Blazer with sort of the same problem. Mine has never overheated, in fact, it always runs very cool, but I have the gurgling problem, which comes and goes. If you look on the internet, you'll find the Blazers are notorious for this problem, but people have found several different reasons. (I don't have the rattling problem or the missing you mentioned, just the gurgle).

We replaced my heater core, and it was better for a few months, then the gurgling started again, and yes they did have to remove the entire dash, it was a huge job, lol. It was better for a few months, but then started again.

Others on the internet have said it was an intake manifold gasket that blew out, and still others said there was air in the air conditioning system that needed to be bled out. I kind of think this might be my problem, as the whole thing started just a couple of months after I had the AC system serviced. They said it needed charging, but the system was too full, so it needed to be "decompressed" before they could do that, which they said involved blowing the system out under pressure and then refilling it. 

This was done at a Jiffy Lube, and when I started having the problems I took it back to them, and guess what, they don't handle anything except that service, so gave me the name of a mechanic to go to. He was going to charge me $800 just to change out the manifold gasket...without even checking the AC issue, even though I told him I read about lots of people on the internet with an identical problem. Even if I wanted to, I couldn't afford that and might (probably I think) still have the problem, because I really don't think it's the gasket!

So I'm still driving it as is, although I don't drive much, maybe only 200-300 miles per month, hoping I can save up enough money to take it somewhere and have it worked on. My son and his friends did the heater core, but they don't know anything about or have the right tools to do this kind of stuff, so I'm just stuck. I'm not losing fluids of any kind anywhere, and my floor mats aren't wet, so I really do think it's air in the system. Just don't know how to find a mechanic who won't rip me off...being a woman I get taken pretty much every time I put it in the shop. :sigh: 

Sorry this is so long, but maybe it will help you in some way. Good luck! I'll be following this.


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## How Do I (Feb 11, 2008)

Got the call today about the cast iron heads. No cracks. Slight warping. "Couple of valves weak?" They recommended milling the surface and valve job. Total comes out to $201.00/labor. Why do I feel like saying, "Thank you sir, may I have another?" They suggested if I were going to buy the head gasket set, to drop the valve stem seals off before Monday to save on parts... Their head guy won't be in until Monday, so he gave me a time estimate of middle of next week. Sound reasonable? Any questions you would ask?


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## How Do I (Feb 11, 2008)

Heads were done yesterday evening. I picked them up this morning. They look good. They just pitched the rockers in a box with nuts and bolts. I was under the impression you were supposed to keep the rockers, pushrods, etc. in their original positions if reinstalling. The guy at the machine shop said it would be fine; "just make sure the pushrods aren't bent and the holes are clear". That sound kosher? I don't want to start reassembling and learn different later. 

I'm dealing with a broken stud off the exhaust manifold w/ Easy Out snapped off in said hole. Tried drilling around it, but the bugger doesn't want to come out. Machine shop said that I wouldn't find one in town that could drill out an Easy Out. Several calls to exhaust shops gave me similar answers. They said they could blow it out with a torch, but couldn't guarantee anything that way and still want to charge about $50. So I'm looking around for a used left side exhaust at the moment.


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## haypoint (Oct 4, 2006)

The GM V6 2.8, 3.1 and 3.4 are known to have head gasket troubles.
Fogged windshield is always a failed heater core. White exaust (steam) is blown head gasket.
From what I've read, I imagine the heater core failed, coolant got low, the engine over heated and the head warped just enough for the head gasket to fail, allowing coolant into a cylinder. 

I agree that a overhaul on the top half of an engine often leads to lower end failures. Think about it. Freshly ground valves and seats increases cylinder pressure. On an older engine this means more exhaust blowby past the old rings and worn cylinders. If your EGR valve dumps into your intake manifold, you'll get a build up of oil there.

How'd we get almost to the second page of this discussion before the specific engine was mentioned?


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## Beeman (Dec 29, 2002)

Part of the problem of engine failure after working on a high mileage engine is the trash you send thru it while working on it. Small amounts of antifreeze get into the cyl and crncase. Abrasive grit from cleaning the gaskets and such. And then we have the curse of the silicon goo that everyone insists on using which braks loose internally and clogs oil passages and the oil screen. Also diturbing the built up gunk lets it break loose and clog the oil screen and the rest go through the bearings.

DO NOT USE ANY ABRASIVE CLEANING MATERIAL TO CLEAN GASKETS ON AN OPEN ENGINE! Those nice little Scotchbrite pads and discs will clean everything up but will destroy the sealing surface and then proceed to grind your bearings and oil pump to dust. You can't keep the microscopic residue they leave as they wear down from getting in the engine.
When installing the rockers be sure to generously lubricate the rockers and balls with at least motor oil or they will gall on startup as they will have no lube. I wouldn't worry too much about them being mixed up, just check them for excessive wear and the rockers for cracks. Roll the pushrods on a sheet of glass or a known flat piece of metal to check straightness. I squirt motor oil in the pushrod as I assemble to prime them so it takes less time to get oil to the rockers. Do you know how to adjust the valves?, they are adjustable and aren't just tightened down. Be sure to install a thread sealing compound on each hed bolt as the head bolts thread into the water jacket and the coolant will go right up the threads and into the oil if not. Chase the head bolts holes with a thread chaser, not a cutting tap. Place a drop of oil under the head bolt head as you install to get a proper torque reading. Also check intake manifold bolts and their holes and if they require sealer. If the holes pass thru the head then a sealer is required as oil will wick up the threads and pool at the bolt.


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## How Do I (Feb 11, 2008)

I've got the thread sealer for all of the required bolts, new head bolts, assembly lube for the pushrods, valve stem ends, etc. I think I tracked down where the oil in the intake was coming from. This is the 4.3L Vortec. I couldn't find the last thread when I was working on this engine before, looks like it was culled. But this engine had decent compression readings last time for its mileage. Right at 180, 190 on all cylinders. I understand the worry over rebuilding the top and not the bottom, I really do. Even I have some regret at not being able to pull the engine and go through it with a fine tooth comb. But there is a serious money issue right now and hopefully I'll have time to save more to have it done right before it goes or find something else. Now was just a really bad time for this to happen. And knowing my luck, when the bottom falls out, it will be the same.

I'm told these are the positive stop rocker studs and that there is no adjusting after torque @ 18 ft lbs. Here's a pic if it helps any.


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## Wis Bang 2 (Jan 12, 2010)

You could treat it like a new engine and pull the distributor and spin the oil pump drive to pump the system full of oil b/4 startup.


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