My 99 Jimmy 4x4 blows heat thru the vents under hard acceleration. I've read in another post that this could be due to faulty transfer case input seal leaking fluid into the vac system. How can you tell if the t-case input seal is faulty?

With 80k miles on this 10 year old vehicle I'm thinking of changing rear & front diff lubes and transfer case lube.
A couple questions on that... do these components use special lubes?
And,near the fill/drain plugs are stickers that say special thread sealer is supposed to be used so the plugs won't sieze.
What is that exactly>

 

If you pull out the fill plug on the back of the transfer case and fluid pours out, the input seal is bad. Simple as that.

As far as special lubes... That depends on if you have the Auto4wd option. If you do, use GM Autotrak 2 fluid only. If not, then transmission fluid is fine.

As far as thread sealer goes... Never seen that. You could use a regular paste pipe dope and it should seal it up and prevent it from seizing.

 

if it pours out... minepours out... so that mean it bad

 

I guess I will repeat myself...

If you removed the fill (upper) plug, and fluid poured out, yes, that means that your input seal is bad.

To add to this so that everyone is clear on which plug is the fill plug and which is the drain plug. There will be two plugs on the back of the transfer case. One will be down quite low on the back of the transfer case. The other will be above that. The upper one is the fill port. Lower, drain.

 

thread sealer is a made by loctite and probably other brands it is in the same type of tube as thread locker but it says thread sealer on it it seals of the threads like gasket maker but it is also an anti size and will not lock up the bolt, so it wont leak and will come out easy. great stuff