transmission heat concerns

[justinsturg]

We're only a couple months away from the start of camping season, and I want to do a couple things with my tax return. Last year, with sustained towing of the TT uphill, there were a couple times I would see the trans temp gauge creep up to around 250 before I would pull over and let things cool again.

I have done the TCC lockup mod, and that helps when I can keep up speed, but on some of the steep, twist mountain roads here in Idaho, keeping speed can be a challenge. I have noticed that when i crest a hill, it seems to take quite a while for the trans temp to drop back down to normal (much longer that for engine temp to drop back down).

I installed a deep, cast trans pan with a new filter and fluid last year. Although people have talked about how the tcc will cause a shudder at very low speed if the tcc lockup is engaged, I have never had that happen. I remember testing it to see if the lockup was working, and still never noticed it. But I do know the lockup is working, because if I am driving at speed with the lockup engaged, and take my foot of the accelerator, engine RPM remains steady and only slowly falls as the truck slows.

I have been thinking of upgrading to 1/2 inch lines like I saw on a post here a while back, but i'm not sure if that will help. I don't know of a way to check trans pressure to ensure that fluid is flowing adequately, but I do not have any codes, so I assume so. I have the stock routing of trans lines -Trans to radiator to stock cooler in front of the cooling stack, and back to the trans. I dont have any problems with shifting or anything, but have considered dropping the pan back out and replacing the shift solenoids, epc and lockup solenoids, pressure manifold switch, and internal wiring. The kit is not terribly expensive, but I don't know if it would make any difference at all.

Any thoughts on what I can do to get the best performance and reliability out of my 4l80e would be welcome.
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[WarWagon]

Welcome!

What is your engine running at? The 6.5 diesel should not be taken over 210 period! It likes to crack over 210. Lots of cooling upgrades available. HO water pump, fans, fan clutches including low temp clutches. If the engine is hot the trans oil can't be cooled in the radiator... Air to oil coolers only do so much if it gets reheated in the radiator.

The 4L80E is known to run hot, 220 towing at the pressure test port where I have the sender put in.
Over 230 you have issues. I would start with pulling the oil coolers away from the condenser and cleaning the mat that builds up there. Clean the condenser. Scrubbing bubbles works. Pull the radiator and clean it out. Take it to a radiator shop or replace it depending on condition. Then look at a cooling fan upgrade if you still have a garbage 6 blade fan. they have a 9 blade steel on newer years. Fan clutches last 5 years tops.

If the cooling system is in good shape you are slipping something in the trans or not getting the TCC locked. Check codes as only emissions codes will turn on the SES light. You may have a code that is putting the trans in protection mode - and they run hot in that mode.

Another way to get power and keep heat down is to upgrade the turbo.

 

[justinsturg]

Thanks for the reply Warwagon. I have done all the cooling mods with the updated HO water pump, 9 blade fan and fan clutch from Kennedy. Last spring, I cleaned the cooling stack including hot tanked the radiator, and it did not seem to help much. I don't let the coolant get over 210, but I do notice that as trans temps increase, it seems to push that coolant temp up too. I pull over when coolant temps start to pass the 210 mark. It's odd to me that it can take 2-3 minutes or more to cool the trans temp to normal after cresting a hill, when coolant temps drop back to 180 within less than a minute. I would anticipate a more linear drop in both temps, especially as the trans oil is running thru the radiator. I will double check for codes with the TD scan, but did not show any codes last time I checked.

Turbo upgrade is definitely on my agenda this spring with income tax return. I should have updated my signature with modifications of thing I have done. I'll do that now. That would have saved you some time. sorry

 

[justinsturg]

signature updated

 

[tanman_2006]

Obviously you know your basics on these rigs and kennedy sells quality parts.

Sounds like WW could be onto something with the tranny slip idea. Maybe the TC or pump is weak? I'm not a tranny expert just throwing out ideas.

I will say a bigger turbo is a god send and a good chip is also just as important when towing.

EDIT: Just saw your sig and you have passed the basics level with the innercooler add on :thumbsup:. Sounds like you should have a nice rig but 280K is alot of miles on a 4l80E. My 95's tranny runs hot too and has almost the exact same miles and alot of the same mods, besides the innercooler. I just quit towing with the truck to solve the issue lol.

 

[THEFERMANATOR]

The deep trans pan is probably what is causing it to take so long to cool down. Does this truck have any tuning in it? There are ALOT of variables that can play into the trans running hot right down to the trans tuning itself if it is modified. Adding a deep trans pan only makes it take longer to heat up it does not lower trans temps(more fluid means you have more fluid to heat up thus making it take longer to get hot). On the opposite end though, that extra capacity makes it take longer to cool off as you have all that extra fluid to cool down now. Something as simple as overfilling it on fluid can cause trans temps to run to high. When you overfill it the fluid will get into the rotating parts of the trans while its running, and this causes the fluid to foam and aerate which makes the fluid run hotter(when it gets compressed those air bubbles actually pop and create heat). And it isn't hard to upgrade your trans cooler. Since you said you had the radiator hot tanked, are you sure something didn't get into the radiator trans cooler in the process? Take the line off at the trans coming from the cooler and have somebody start the truck for a few seconds while you watch to see how much fluid it pumps out. If the cooler circuit is good it should shoot fluid out in a hurry. There alot of things that need to be checked to see what is causing your issue.

 

[racedaymechanic]

I had some similar issues with my 6.5 and did a Thread on my upgrades http://www.thetruckstop.us/forum/showthread.php?36158-Trans-Cooling-Upgrade

 

[justinsturg]

The deep trans pan is probably what is causing it to take so long to cool down. Does this truck have any tuning in it? There are ALOT of variables that can play into the trans running hot right down to the trans tuning itself if it is modified. Adding a deep trans pan only makes it take longer to heat up it does not lower trans temps(more fluid means you have more fluid to heat up thus making it take longer to get hot). On the opposite end though, that extra capacity makes it take longer to cool off as you have all that extra fluid to cool down now. Something as simple as overfilling it on fluid can cause trans temps to run to high. When you overfill it the fluid will get into the rotating parts of the trans while its running, and this causes the fluid to foam and aerate which makes the fluid run hotter(when it gets compressed those air bubbles actually pop and create heat). And it isn't hard to upgrade your trans cooler. Since you said you had the radiator hot tanked, are you sure something didn't get into the radiator trans cooler in the process? Take the line off at the trans coming from the cooler and have somebody start the truck for a few seconds while you watch to see how much fluid it pumps out. If the cooler circuit is good it should shoot fluid out in a hurry. There alot of things that need to be checked to see what is causing your issue.

Sorry for letting things die here lately. I appreciate the feedback. Your reply totally makes sense with more fluid in the trans pan. I do have a Kennedy chip. I have not had a chance to take the line off and check flow, but I will do that shortly. I am going to get a different (and larger) cooler, and mount it a side ways to make sure there is no air getting trapped causing limited flow. I think I will upgrade the lines to 3/8 as well while I'm at it. I'll leave the internals in the trans alone for now. I have the old oil cooler that i took out when I upgraded my oil cooler lines to stainless. any thoughts on whether i should or should not use that cooler (if I can find the right fittings for it)?