# Differential Cover , No Drain so Drill and Tap for drain Plug?



## fordy (Sep 13, 2003)

...............003 Chevy dually has 49k miles , diff cover has NO drain plug so i'll have too remove cover and replace , a pain ! I was thinking of simply of drilling a hole and tapping for a standard type pipe plug ! Is there anything here I should look out for , or be aware of ? I'm going too replace the gear oil with Synthetic fluid which means I won't need too do this again until 100k miles , maybe not worth the drill and tap effort and expense . , thanks , fordy:shrug:


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## Darren (May 10, 2002)

You may be creating a problem for yourself. How many threads are you going to be able to cut? In other words, how thick is the cover? You might be better off buying an aftermarket cover with a drain plug.

I think it's better to remove the cover to drain the diff. You get a chance to look at things then. Do you have brakes shoes on the rear or disk brakes?


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## fordy (Sep 13, 2003)

Darren said:


> You may be creating a problem for yourself. How many threads are you going to be able to cut? In other words, how thick is the cover? You might be better off buying an aftermarket cover with a drain plug.
> 
> I think it's better to remove the cover to drain the diff. You get a chance to look at things then. Do you have brakes shoes on the rear or disk brakes?



.........................I have disc brakes ! Don't know how thick the cover plate is but I believe I'll look into an after market cover with a drain plug installed . , thanks , fordy:shrug:


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## ninny (Dec 12, 2005)

How do you check/add fluid if there's no drain/filler plug?

.


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## OkieDavid (Jan 15, 2007)

There will be a fill plug, just no drain plug. I have never understood that about GM products (don't know about others).... I guess they want you to take the cover off to have a look see. Same thing with automatic transmissions where they don't give you a drain plug because they want you to change the filter as well as the oil. Still would be a LOT easier and cleaner if they gave me a drain plug.


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## ninny (Dec 12, 2005)

OkieDavid said:


> There will be a fill plug, just no drain plug. I have never understood that about GM products (don't know about others).... I guess they want you to take the cover off to have a look see. Same thing with automatic transmissions where they don't give you a drain plug because they want you to change the filter as well as the oil. Still would be a LOT easier and cleaner if they gave me a drain plug.


There's suction devices that remove the diffential fluid. If a drain is added/tapped into the differential it might very well void the warranty.

.


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## unioncreek (Jun 18, 2002)

If your planning on keep the truck for a while I would weld a drain bung in. I change my differential fluid every other year and more if I'm in a lot of water. 

Bobg


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## HermitJohn (May 10, 2002)

I agree with Unioncreek. Need to weld in a bung for plug. This can be simple as using a pipe fitting or part of a pipe fitting that a pipe plug will screw into if you cant find an aftermarket bung. 

I hate differentials where they expect you to add fluid though the little vent hole. Makes you want to dope slap the engineer who came up with the idea. Differentials and transmissions should have a drain plug and a filler plug. You dont want to fill any gearbox to top with fluid. The fill plug should be half way up. 

Vacuum gizmos to remove old fluid are fine for a shop that works on cars. Why should home mechanic have to buy one just cause manufacturer was too cheap to install a 10 cent plug?


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## Beeman (Dec 29, 2002)

Why bother with a drain plug? Remove the cover and drain fluid install synthetic fluid. Be sure to clean the magnet and if there is none install one. Metal particles are the enemy in a rear and they will be picked up by the magnet. If you put a drain plug in the cover it won't be low enough to fully drain the rear and get the stuff that settles in the sump of the rear.


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## plowjockey (Aug 18, 2008)

I'd use a lube pump and keep it simple.

You can get a pump, that looks like the body of a grease gun, with a plastic hose on the end, at many auto parts stores, for less than $13. It will suck out the old and put in the new(if you need it to).

Differentials and trasmsissions are a lot "different" than the old days, at least in built-in-Japan Nissans.

Most of the time the old lube I drain out, looks EXACTLY like the new stuff, I'm paying big money to replace.


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## Bluecometk (Jun 20, 2009)

If memory serves,If you take out the bottom bolts of the cover the diff will drain as the two bottom bolts are cast /drilled through the case and into the sump of the diff case. 

If you get the truck hot before you do this it will take less time. This could take a while to drain down to a drip.

Don&#8217;t forget to remove the fill plug to help it drain better and you may need to use a piece of wire or awl to clear the debris from the hole.

When you put the bolts back in put a little thread sealant on it. Fill it up with your diff lube and go have a beer.

Just my opinions

Bluecometk


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## Ky-Jeeper (Sep 5, 2010)

It's a waste of time and money for a drain plug. The only reason for one it may be alittle less messy. Magnet like someone mentioned is a very good prevention against wear. So pull that cover and wipe out that bottom area and inspect for problems.


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## fordy (Sep 13, 2003)

............OK , just wanted too followup and thank you'll collectively for your excellent suggestions . Loosening the bottom bolts seems like the easiest way too drain the fluid so I'll go that route . Laying on the ground with those rocks in yer back takes the fun out of maintenance but I have some thick cardboard . I don't trust these quick oil change type shops and they charge too much for what they do , anyway . , thanks , fordy


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