Anyone out there have an after market tranny cooler they can suggest. My tranny fluid temp showed almost 200 deg while on my last outing. Is it true that when the temp hover around 200 the fluid breaks down and varnishes the inside to the tranny?

 

I've never seen a tranny cooler for the H2. not to say there is not one in exsistance..

.but is this happening under load or normal driving???

if your normally driving on good grade road- you may have a rather big problem (tranny rebuild)

under load or mountain driving ..tranny service (flush) and replace with a higher quality fluid...I use AMSOIL.....

OEM fluid should not breakdown at only 200.....that happens at 300 plus,,but your tranny would BLOW first...

Good luck,,

 

I spoke with a local Hummer dealer and he said the tranny fluid cooler is run inside the bottom of the radiator. I asked about the high temperature thermostat and he said it was needed to have a better temp for the air/fuel mixture for teh LS1, 6.0 L enigne. I just run down to Portland or up to Vancouver, BC and after about a hour into the trip it goes up to just under 200 degrees, probably just the fluid heating up because of it running inside the bottom of the radiator. I looked at a cooler from TCI and it looks promising. Have to check with them about the aditional capacity.

 

What should the tranny temp be?????? Mine runs at just under 200 all the time.

 

I guess the question that needs to be asked is at what temperature does tranny fluid start to breakdown and start depositing varnish on the tranny innards. All I could get out of the dealer was the tranny fluid cooler runs through the radiator. The thermostat is set to open at 195 degrees and that could be the reason for the 200 degree temp I would think. One other note, B & M has 2 coolers running in the $100 range beside the TCI unit. I guess I'm reading too much into this 200 degrees on tranny fluid temperature. Any thoughts...

 

Mine runs a little under 200, also, even when it is 115 here. I'd say that is its normal operating temperature. I don't worry about it.

 

OK, thanks VegasGuy.

 

This is the info I found:



Most automatic transmissions fail due to a breakdown of the transmission fluid caused by overheating. This chart provides a graphic display of heats contribution to transmission failure. The effect is also cumulative. Short term exposure to high heat levels (or even prolonged exposure to moderate heat) can break down the fluid to the point where even very short episodes of overheating will lead to failure.