Rear diff fluid
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Joined: Oct 2000
Posts: 97
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From: Austin, TX
I'm swapping all of the fluids on my '96 6 speed and changed the oil, tranny fluid, but I'm stumped on changing the diff fluid... has GM heard of a drain plug? My '95 suburban doesn't have one either.
How do you empty the old diff fluid?
How do you empty the old diff fluid?
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
There is no drain plug on the differentials. You will have to siphon out the fluid with a suction pump. There was an article awhile back in Corvette Fever on installing a drain plug. It involved drilling and tapping a hole at the bottom rear of the carrier just to the right of the centerline. Some here have done it, but I would rather just suck out the old fluid with a pump.
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Joined: Mar 1999
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From: At the beach in little Rhody
I use a miti-vac with a fluid transfer kit to get it out and put it in. The miti-vac and kit can be bought at Eastwood if you are interested. I don't like the drain plug idea either.
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Joined: Oct 2000
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From: Austin, TX
great, I have both a vaccuum pump and a mityvac. I have a pretty good sized kit for my mityvac, so I'll see if I can use it to transfer fluid... Thanks for the hints...
The wierd part about this is that although, the rear diff fluid is a normal maintenance item, neither my factory manual or my haynes manual, mentions anything at all about changing the fluid.
The wierd part about this is that although, the rear diff fluid is a normal maintenance item, neither my factory manual or my haynes manual, mentions anything at all about changing the fluid.
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
I am not sure that they consider it a normal maintenance item. I don't remember seeing it in the maintenance chart. However, from everything I have read, overheating a rear differential is as bad as overheating the tranny fluid. I try to keep it maintained (changed) in both my rear wheel drive cars, the Vette and the Suburban.
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Joined: Oct 2000
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From: Austin, TX
Just to complete the topic, I changed the fluid using a suction pump (even with that it was a hassle to get the fluid out, I then put about 1/2 a quart of new synthetic fluid in, sucked that out also and then filled with Mobil 1 gear lube and limited slip fluid.
Filling was easy, because a long time ago I ought a half gallon of gear lube in a container with a pump on top. That's what I use to put fluid in transmissions and diffs. Since I use different stuff, I usually flush it with a little bit of fluid before I put it in whatever I'm filling, but it works great, for instance, filling my transmission with motor oil took literally 2 minutes, instead of the 20 it would have taken using my suction pump.
John S.
Filling was easy, because a long time ago I ought a half gallon of gear lube in a container with a pump on top. That's what I use to put fluid in transmissions and diffs. Since I use different stuff, I usually flush it with a little bit of fluid before I put it in whatever I'm filling, but it works great, for instance, filling my transmission with motor oil took literally 2 minutes, instead of the 20 it would have taken using my suction pump.
John S.
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Joined: Jun 2001
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From: LAKE BROWNWOOD, TEXAS, USA
STECZ, On my 87 the plug is a 3/8 hex. I used a pump called a MR GOODPUMP which I found at a boating supply. It makes short work out of any fluid transfer. To refill I used a pump from the set you use to fill the lower unit on a outboard. I mixed the limited slip additive in with the first mix and then filled it up. I agree with you about changing all fluids so that you know the condition. regards, Jim L
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