Can A Transmission Run To Cool

96chevy7.4L · March 25, 2009

Hi guys I have a 99 Chevrolet C3500 crew cab. It has the 7.4L vortec and 4L80E transmission 4.10 rear gear w/ the G80 locking rear. I do quite a bit of heavy towing. 30 foot gooseneck with a 8000 pound tractor. The truck runs awesome with the superchips programmer on tow mode. I have a K&N filter also nothing major. I have the B&M 24,000GVW super cooler and the Derale Cooling tube pan which holds 3 extra quarts of fluid. Fully loaded the truck runs 160-170 transmission temps down here in FL in the heat. Sitting in traffic it might see 170 tops. Buy itself the transmission temp rarely goes above 150. Is this too cool. I know the engine has a 180 thremostat and I have an auxillary SPAL fan out front that I have on a swtich in the cab just in case. Let me knwo your thoughts as I would like your opinions. Thanks

Zembonez · March 25, 2009

Mine rarely gets over 150. Anything over about 75 degrees should have the fluid working as it was engineered to do. Mine has never been over 170 even in summer except when I was towing... and even then it wasn't much above that.

I'd say you are doing just fine.

alaska511 · March 25, 2009

Mine rarely gets over 150. Anything over about 75 degrees should have the fluid working as it was engineered to do. Mine has never been over 170 even in summer except when I was towing... and even then it wasn't much above that.

I'd say you are doing just fine.

+1

If you lived in a colder climate, I would say you might have an issue in the colder months of the year. You will be just fine

C & A s Dad · March 25, 2009

I agree with what has been said. I researched this a great deal before upgrading my aux trans cooler. I talked with two qualified Trans techs with one of them being the owner of a Coleman Taylor trans shop. I also talked with one of the engineers from the company who supplies us with our Reman Transmissions and an Engineer from Hayden. All said the same thing Jim has already said. The fluid simply has to get warm enough to flow properly. They said around 100 degrees is good. They did say if you lived in a really cold climate and had a large very efficient cooler, the fluid could remain too cool and would never flow as designed.

The thing that throws some people off is the fact that an engine has to heat up to run efficiently and to burn off the impurities in the oil. ie. moisture, by products from combustion etc. There is no combustion going on in a trans so these impurities do not exist.

Mine runs in the 160 range towing a 6500 lb camper in 95+ degree heat and 140s or so when not towing.

jvmorgan · March 25, 2009

I have heard that the GM-Tranny cooler kit that dealerships sell leak at the connections from poor manufacturing (ie. cheap fittings). Is this true or is it just because of expansion and contraction from heat that would cause this? I am looking at getting one from my dealership and have them install it on my truck but after hear/reading (cannot remember long time ago). Or is there an aftermarket one that you all have installed and had good luck with such as B&M universal, BeCool Cooler ect.?

Thanks

Justin

C & A s Dad · March 25, 2009

Justin, I do not want to take anything away from the OE kit. However, adding an aftermarket cooler is a piece of cake and there is no need to run new lines from the trans. You simply cut the line coming from the internall trans cooler which is located in the radiator and use a good quality trans rubber line to move the fluid to the cooler and back to the line going back to the trans.

Only 2 things you have to watch for. Don't bend the rubber line until it crimps and make sure it is not rubbing against something sharp. A few cable ties and you will have no issue. I have installed at least 8 or 10 of these on my vehicles and never once had a leak or an issue.

I used one of our (CARQUEST) Ultra Performance stacked plate coolers by Hayden. Our #s do not match Hayden's #s but here they are:

11" x 7.5" x 3/4" is a 77421 This is almost identical to the size of the OE cooler.

11" x 9.5" x 3/4" is a 77422

11" x 11.5 x 3/4" is a 77423

You can get Hayden's part #s from their website. I think they call their premium series Ultra-Cool.

Here is a picture of mine installed. I had an OE cooler so this was just an upgrade. I used the lines that were already routed to the cooler and simply connected using rubber trans line.

Outbacker · March 25, 2009

Your temps are fine. The other guys are making good points, but one point I wanted to make is what type of oil are you running in the tranny? Maybe switching to a synthetic tranny fluid will help with cooler temperatures (such as winter) will help with the viscosity. I had a tranny cooler installed from Tru-Cool and it had a cold oil bypass feature where if the oil was too thick, it would bypass the tubes and go right back to the tranny.

MikeInCtown · March 25, 2009

Sorry to but in to the post but had a quick question. I've read of the stock trans lines having a corrosion problem that allowed them to leak on some of the mid 00 vehicles. My 04 has started leaking. Would it be a-ok to just cut the metal tube somewhere clean and fasten new hose to the lines? That would be a $5 fix vs either buying or bending all new trans lines.

C. Charles Hahn · March 26, 2009

If you lived in a colder climate, I would say you might have an issue in the colder months of the year. You will be just fine

Agreed. There were a few times this past winter that my truck would read a trans temp of -1 or 0 degrees, and it would shift harder/more firmly until it warmed up to about 50 degrees. As long as you're not hammering on the throttle or trying to pull something while the transmission is way below operating temp, you'll be just fine.

C & A s Dad · March 26, 2009

Sorry to but in to the post but had a quick question. I've read of the stock trans lines having a corrosion problem that allowed them to leak on some of the mid 00 vehicles. My 04 has started leaking. Would it be a-ok to just cut the metal tube somewhere clean and fasten new hose to the lines? That would be a $5 fix vs either buying or bending all new trans lines.

Mike, I would not be comfortable with replacing the metal lines with rubber trans hose but I would have no problem in removing a bad spot from a metal line and splicing it with a good rubber trans hose. Just remember, no major bends with the rubber hose and make sure they are not rubbing against anything sharp.

As I have said before, many FWD vehicles come from the factory with several inches of rubber line connecting the trans lines to the internal cooler.