2004 4l80e hot trans on hills

My guess is at 3200 rpm and 40 mph you ARE in second gear AND no lockup.
This would make lots of heat.

At 3200rpm and 40 mph your torque converter isn't locked up and is slipping. Use second gear for the mechanical advantage and you should see your temps drop.

I have had seen this spike on temps long before the PS leak. I was driving an interstate 6% grade last year and saw the trans reach 220F and it alarmed me mentally.

currently, I climb the 15% grades at 3200 rpm. Once I got home it was over 230, brakes were super pressurized, PS pump roaring ect. The PS pump was not low, just super hot!

the trans fluid is dex3. ps fluid whatever: prestone, stp, lucas oil.

How many of us need a diesel for the closest 5 miles to your house? i have 15% grades in every direction, switchback roads, and 2 dammed resovoirs to navigate around.

the truck is in the shop. 2 issues: leaking/sweating trans cooler lines, and power steering super leak. I temporarily cured by chemicals the power steering leak, and the trans line job will open up the cooler can of worms. I was monitoring the trans fluid ensuring that it was not low or actually leaking. The PS leak dripped one quart until cured by chemicals.

I am also having a sensor issue: mass air flow, left bank , and iirc knock sensor. I prior threw $300 into that CIL issue with new plugs, and injection clean out bandaid.
older tv woes.

Ok so i put a lot of faith in my mechanic mr google but fact was as soon as the hrdolic lines busted on the output of the pump the engine and tranny temp dropped literally like a rock to normal. I saw the lines they where rusted completely and the pump blew, according to the mechanic, due to rust getting into the pump, plus lack of fluid(it was spraying all over the inside of the engine compartment) caused it to seize it. The coolant for the pump was not there they added an after market one. SO he said the coolent was being overheated by the hydrolic pump. Well that's what i remember. Since they did their work truck has been great except since it had a new pump with better pressure the rotten brake lines blew too. I do wish i had that 8.1l would make pulling my camper so much easier.

On GM full sized +8.6K GVWR will have hydro-booster instead of vacuum booster
for power brakes

Uses the steering pump as HIGH PSI source and is plumbed to it's own
external cooler on the left side of all other external coolers

This picture is of my front end while at the shop fixing the front
right fender and busted right steering knuckle from smacking a LandRover
which jumped a stop sign (I was through traffic, so no stop sign for me)






Tough to see, but it is on the drivers side and is vertical tube fin


Mine also gets VERY hot off roading, but not like Burbman in the sand.
I move boulders out of the way with the wheels...nudge up to them with
the tire just to one side and turn the steering wheel

Burbman, check your front end joints...and stay away from MOOG. Junk
now that they sold out and the new owner has them made in China

I've go NAPA HD in there now and waiting to see how they perform...

Back on topic...I don't see how the power steering and hydro-booster
system is tied in with the engine coolant system. Even the ATF in tank
is isolated and would have to spring a leak (it is inside the cold
tank of the main radiator)

The power steering/hydro-booster system is completely isolated from
both the engine coolant system and ATF system

tekman741 wrote:
The power steering and brake go thru a hydrolic booster which is on the main pully system. You'll notice that there is no brake booster behind the brake master cyclinder and to help with steering it goes thru a booster same as the brake google it.(2004 k3500 hydrolic booster)=ehow
The brake hydro booster on your vehicle provides additional braking power to help reduce the amount of effort needed on your part to slow down your vehicle. The booster works on hydraulic pressure generated by the power steering pump. When you press on the brake pedal, the booster creates additional force on the braking system. That, along with the hydraulic fluid in the brake lines, creates a tremendous amount of force on the brake calipers and pads.

If that pump starts to over heat then your coolant temp goes up and the first to be effected(explained to me by a mechanic) is your tranny temp. It's been a year since my repair and all is "cool" It's what worked for me Hope I helped?

Read more: http://www.ehow.com/how_5969469_troubleshoot-brake-hydro-booster.html#ixzz2zc0VBBPu

Well, I guess anything is possible....I know I worked the steering so hard backing the trailer into this spot that I sheared the pump shaft clean off, killing both power steering and power brakes. Wasn't bad driving back to pavement but had to be flat-bedded from there.



I have never heard of the PS pump causing the engine to overheat and in turn causing the trans to overheat, but like I said I guess anything is possible...makes me wonder if your mechanic was making it up as he went along....

BurbMan wrote:
tekman, not sure what the power steering pump has to do with trans temp, there is no collant circulating in the PS pump.

PA, normal temps should be 150, 175 when towing and 190-200 on a steep hill with the trailer. What I would suggest is having the cooler lines disconnected from the tans and power flushed separately to remove any debris.

Not sure about the 6.0 but on my 8.1 there are two coolers in series. the trans fluid goes from the 4L80E into the right side of the radiator, then from there into the aux cooler as pictured above, then back to the transmission. The radiator helps bring the trans fluid up to temp in winter since the coolant is hotter than the trans fluid and helps to warm it. The aux cooler on the front then helps to moderate temps.

The power steering and brake go thru a hydrolic booster which is on the main pully system. You'll notice that there is no brake booster behind the brake master cyclinder and to help with steering it goes thru a booster same as the brake google it.(2004 k3500 hydrolic booster)=ehow
The brake hydro booster on your vehicle provides additional braking power to help reduce the amount of effort needed on your part to slow down your vehicle. The booster works on hydraulic pressure generated by the power steering pump. When you press on the brake pedal, the booster creates additional force on the braking system. That, along with the hydraulic fluid in the brake lines, creates a tremendous amount of force on the brake calipers and pads.

If that pump starts to over heat then your coolant temp goes up and the first to be effected(explained to me by a mechanic) is your tranny temp. It's been a year since my repair and all is "cool" It's what worked for me Hope I helped?

Read more: http://www.ehow.com/how_5969469_troubleshoot-brake-hydro-booster.html#ixzz2zc0VBBPu

There is a difference between the old style "flush" and the new fluid replacement. The reverse flush is what put junk where it shouldn't be. Fluid replacement just pushes new fluid thru the same paths that your trans does all the time. Replace or really flush the cooler, it is a major cause of failures. I notice the OP hasn't responded to the secondary check of temps question unless I missed it.