Transmission leak

[TwoStates]

Just got my M1038 and noticed that the transmission pan seems to be leaking and probably needs a new gasket. In the mean time is there any problem adding Dexron III to it if it has Dexron II now? I have no idea if it has Dexron II or III in it now.

also, is there a particular brand I should buy?

 

[jerry v]

just bite the bullit enpty all the fluid and fix the gasket then you will have no worrys about damage caused by wromg trans fluid

 

[TwoStates]

Thanks, but that wasn't the question.

 

[gcbennet]

My assumption would be Dextron III is already in the tranny since it replaced Dextron II in MV's many years ago. From what I know both are compatable anyway.

For what it's worth, I switched over to synthetic when I got my truck a few years ago. Good stuff but much more expensive. It also leaks. I discovered it shrank the O-ring where the modulator goes into the tranny and always left puddles in my driveway. That said, I switched back to normal Dextron III, replaced the O-ring, and the leaking has stopped. Food for thought for those who may be thinking of switching to synthetic.

 

[tage]

Thanks, but that wasn't the question.

Hahaha that's funny...
I'm pretty sure it says it on the side of the bottles when you go to Wal-Mart to buy the oil... "Compatible with xXxX"

The real question is why are you going to mess around with a leak when you have a drain plug and easy access? Prolly 20 mins if you don't fiddle with the gasket too much...

 

[Retiredwarhorses]

Th400 leaks from 4 spots

trans pan "not that often"
modulator o-ring "most common"
shift shaft seal "50% of the time"
pump seal or torque converter seal "common"

you will have to clean it all up to find the source first...if it's weeping from the converter cover weep hole, it's most likely one or both of the last 2.
Dexron III is what is used for ATF....or equivelent.

 

[juanprado]

all flavors of dexron II,III,IV can be mixed with no problems. same basic stuff with slight modifications to the additive package.

As stated, I would think the o ring for the modulator is hard and lost elasticity. Simple o ring that can easily be found. If you drop the pan, replace with filter kit that has a rubber gasket not cork is my .02

Some times, grease monkeys way over tighten the pan bolts and slightly distort the pan causing headaches. Permatex makes a specially formulated silicone specifically for ATF use. Not universal stuff but a formula ok to use on trannys which was a no no with the universal red, blues, blacks etc.

 

[hummer4x4guy]

For gaskets check out www.lubelocker.com. I have one for my new trans pan. When I do my swap.


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