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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 10/1/2005 5:56:58 AM EDT
I just drained my gear oil on a GM rear differential. Unfortunately, this is the type without a drain plug, so you have to remove the cover and replace. I used blue RTV as a sealant on the gasket and flanges, but have not yet refilled it.

My question is: Can I just put new oil in and go, or must I wait a certain amount of time before it cures? My concern is that the new oil and vibrations will keep it from curing properly.

The package says it cures in 24 hours, but it does not say that the parts must be left alone in that time frame. It's a zero pressure application, so perhaps it will cure during use well enough.
Link Posted: 10/1/2005 6:13:09 AM EDT
btt
Link Posted: 10/1/2005 6:14:40 AM EDT
You are supposed to wait 24 hours. I have just popped the cover back on and filled, but I didn't drive it the same day.
Link Posted: 10/1/2005 6:16:08 AM EDT
Go ahead, tighten your bolts on the diff cover and fill her up.

This is not a "positive pressure" type application, in fact, your diff probabably has some type of vent hose comming from it!

You'll be fine
Link Posted: 10/1/2005 6:23:15 AM EDT
I would definitely wait at least 24 hours.

With all of the various valve cover gaskets I've replaced,
the only ones that didn't leak on me were the ones that I allowed to
cure overnight before starting the engine. I'm pretty sure that
getting the stuff hot and coated with oil before it was cured led to
it's failure. (on engines with breathers, so they were not under
positive pressure either)

After going to all of the hassle of a differential, if it were me,
and if I could live without the vehicle, I would let it set for as long as
possible.

One question, did you manage to clean the inside of the housing
enough that oil won't run down and get onto your new Permatex?

I need to change the diff on my car, and have wondered how to clean
things enough to not compromise my gasket.

Link Posted: 10/1/2005 6:37:15 AM EDT
I guess I'll wait. This is my second vehicle, so I'll just take the primary. I try to avoid using the primary for runs to the dump, etc.., but oh well...

I wiped the metal mating surfaces with acetone. But did nothing to protect the surfaces from getting drained on further, except letting gravity do its best for about 45 minutes before wiping the flanges. Futher drips did not appear to make it onto the surface before I replaced the cover. Shops do this type of thing in hours, and give it back to the owner to drive away, so I'm probably just splitting hairs here, but perfection is better than less than perfection. I don't think a little drip on a curing sealant will cause much harm, after all you are trying to prevent oil from getting between the steel and the sealant, not the sealant and the empty void to be filled with oil. I suspect the chemistry of the sealant can weather a drop or two without degrading.
Link Posted: 10/1/2005 6:51:01 AM EDT
[Last Edit: 10/1/2005 6:57:01 AM EDT by Dragracer_Art]
Just goop it back together and fill it with oil.
I've done more of them than I could ever dream of counting. I've never waited more than 10 minutes before dumping oil in them.
Some of them saw more than 1200 horsepower put through them.
Never had one leak.

Edit to add:
If you are "waiting it out" expecting the oil to finish draining, you will have a long wait.
Just stick your hand in there and scoop out as much oil as you can. THEN you can wipe the gasket surface clean and... it will stay clean.
Link Posted: 10/1/2005 7:13:54 AM EDT
I've done a few hundred of these, no need to wait. Permatex Ultra Blue requires very little time before fill. Normally it's a bolt together process, maybee wait 15 minutes before fill and you can drive away.

What I like to do is clean and dry the cover first, then apply the Ultra Blue sealant to the cover and set it aside while I clean the housing. This takes a few minutes and it's enough time to allow the sealant to gel a little more. Then you can bolt on the cover, fill the differential, and test drive immediately.


Obviously waiting longer won't hurt, but it's certainly not required.
Link Posted: 10/1/2005 7:16:26 AM EDT

Originally Posted By Dragracer_Art:
Just goop it back together and fill it with oil.
I've done more of them than I could ever dream of counting. I've never waited more than 10 minutes before dumping oil in them.
Some of them saw more than 1200 horsepower put through them.
Never had one leak.

Edit to add:
If you are "waiting it out" expecting the oil to finish draining, you will have a long wait.
Just stick your hand in there and scoop out as much oil as you can. THEN you can wipe the gasket surface clean and... it will stay clean.





Dragracer_Art IS the voice of experience here.
Link Posted: 10/3/2005 6:21:48 PM EDT
Thanks Dudes...
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