Overfilled Transfer Case on Suburban

[willyswagon]

I changed the fluid in the transfer case on my 89 Suburban tonight, removed the top fill plug and an quart of ATF came out.

How did it get overfilled? Any damage from overfilling?

It seemed to leak on the exhaust when I used 4wd which wasn't often, was this over fill related?

 

[c_rossman]

No I dont think you hurt anything. The only thing I can see is you may have filled the case with the truck at a different angle. I have noticed this before. Make sure the truck is flat on the ground.

 

[c_rossman]

You may want to check the seal between the tranny and the transfercase to make sure its not fluid from the transmission.

 

[BlazerLT]

I had this happen to to my 1995 4x4 S10 Blazer.

Had the transfer case fluid changed and the lube guy said it was really overfilled.

Maybe GM does this from the factory?

 

[crashz]

My F150 was like that when I changed out the factory fill. They probably all over fill them.

 

[willyswagon]

Checked the transmission and it was down 1 and half quarts.........so it appears the overfill came from the transmission.

Is this normal?

If so then when doing a transmission fluid change, need to do the transfer case at the same time.

 

[drm7]

I don't think the trans & xfer case have any fluid in common. At least I've never heard of such a design. There would have to be some plumbing going between them for this to happen.

 

[c_rossman]

The transmission and transfercase are joined together. But both seals would have to be bad for the transmission fluid to get into the transfercase.

 

[willyswagon]

So what kind of a problem do I have. The evidence is showing that the transmission fluid is getting into the transfer case.

do I fix it or let it go?

 

[Gary Allan]

Naturally get it fixed if you can afford to. This isn't cheap unless you're doing it yourself.

Obviously you've gotten by so far with the leak from the trans witout too much of a problem. You just gotta keep an eye on your trans level. Your t-case surely has a vent ..so I imagine that the levels are reaching some kind of equalibrium when it sits and the trans level is highest.

Can we assume that your t-case indeed takes ATF (like my NV231)??

 

[Arup]

One of the biggest bummers in over-filling your tranny or transfer case is seal breakage. It is a pain when that happens and in some cases the whole transfer case or tranny needs to be opened up to remedy it.

Better to be on a little low side than over-fill.

 

[willyswagon]

Thanks for the info gents

......slowly putting the puzzle together.

Am I safe to assume that it is the rear transmission seal that is the problem?

My manual shows the rear seal replacment instructions as follows:

....
5. Using a long screwdriver, pry the old seal out of the end of the transmission
6. Compare the new seal with the old one to make sure they are the same.
7. Drive the new seal into position using a large socket or piece of pipe which is the same diameter as the seal
8. Once in position, coat the lips of the new seal with automatic transmission fluid.
.......

Doesn't sound too difficult if this is it. First thought was that the whole tranny had to come apart.

 

[Gary Allan]

quote:

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Am I safe to assume that it is the rear transmission seal that is the problem?

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Yes, this would be my first item to look at.

quote:

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Doesn't sound too difficult if this is it. First thought was that the whole tranny had to come apart.

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No, as long as you also assumed that you're gonna divorce and pull the t-case. If that's in your plans ..then it is that simple.

 

[BlazerLT]

quote:

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Originally posted by willyswagon:
So what kind of a problem do I have. The evidence is showing that the transmission fluid is getting into the transfer case.

do I fix it or let it go?

---

Just because you have a low tranny fluid level doesn't mean it transferred to the transfer case.

Poor logic.

Also, you sure the fluid is leaking out of the rear seal?