Transmission fluid cooler overheating

[100acre]

I had my mechanic put on some new belts and install a trans fluid cooler in my M1008. Before that it was running around 210* which is about normal I was told. He also put in a flex fan and fan spacer. He sistered the trans cooler up against the main radiator and now the temp maxes out. It says 250 but if the after market gauge could go higher I think it would. That's the other thing, of the 3 gauges now the oil one doesn't work and water temp gauge is higher than normal too. Is there a possibility that either the flex fan isn't blowing enough air or is the problem because of the two radiators are now sistered together? He also installed a steering column I got from another SS member. Now the turn signal I have to hold in both directions. It is also leaking power steering fluid. Main question is trans fluid overheating and why.

 

[doghead]

Reinstall the OEM fan and see if that cures the problem. I hope the fan shroud is still in place.

 

[100acre]

Thanks, there was the other thing it now seems like my whole radiator is loose. Yes the shroud is still in place.

 

[markg]

where are you measuring the trans temp? water temp is supposed to run at 195, with a good thermostat. getting rid of the factory fan clutch will make the bad fuel milage even worse, not counting the constant roaring noise. i think you might have another problem. trans temp should be the same as the radiator if your not pulling a load. i have a cooler on one of my 6.2's that bypasses the radiator and on the hottest days here in texas never gets above 190. make sure the trans lines are flowing , and the vent on the housing is clear.

 

[Warthog]

It could be that the fan is installed backwards. Pushing air into the radiator instead of pulling.

 

[DieselBob]

I was thinking the same thing. Some people try to interchange 88+ parts to a earlier year not thinking that the later serpentine belt style pumps and fans run reverse from the 87 and earlier years. A good factory fan and clutch assembly will be far superior to a fixed fan anyway.

 

[100acre]

where are you measuring the trans temp? water temp is supposed to run at 195, with a good thermostat. getting rid of the factory fan clutch will make the bad fuel milage even worse, not counting the constant roaring noise. i think you might have another problem. trans temp should be the same as the radiator if your not pulling a load. i have a cooler on one of my 6.2's that bypasses the radiator and on the hottest days here in texas never gets above 190. make sure the trans lines are flowing , and the vent on the housing is clear.

Temps are being read on after market gauges prior own put in. Water temps were 240+. Where is vent on housing? Might need to replace thermostat, did that once before. Is your cooler mounted on radiator or separate for more airflow? Tanks

 

[100acre]

I will definitely put the OEM fan back on. I had them switched because when the frame flexed my fan hit the radiator. I did not know that later parts didn't work as well as stock. Tanks y'all, I'll see how this turns out. It'll have to be after this weekend as we have a big tent surplus sale this weekend at Old Grouches in Clyde. Gotta make some more money to throw into the big green pit.

 

[MarcusOReallyus]

I'd check those temps with another instrument you can trust.

Along with that, I have never understood the logic of dumping the trans heat straight into the radiator the way most do. Put the cooler somewhere else where it can get air, and better yet, put it BEFORE the built-in trans cooler, so you dump any excess heat to the air instead of your engine coolant.

 

[markg]

Along with that, I have never understood the logic of dumping the trans heat straight into the radiator the way most do.

the logic was that in cold weather it would warm up to radiator temp and remain constant. gm finally figured out in 94-95 that if you were going to tow you needed a way to air cool the trans temp and increase capacity by adding a cooler in front of the a/c condensor. btw i measure my trans temp with a probe mounted in the pan.

vent for the transmission case can become plugged not allowing it to breath, wich can cause overheating. you can see it from underneath. looks like rubber fuel line. while you are under there check your front and rear axle vents, they look very similar.

check or have someone check your fan clutch, they do go bad. there should be resistance when you try to spin it. if your coolant temp reads over 250 then you should see hot fluid coming out the cap. you will hear all kinds of strange noises coming from the radiator. when cold make sure radiator is full, and that the overflow has fluid in it. and that you have a good 15lbs cap. thanks. mark. ps, these pics are from my civilian 87 6.2 1/2 ton 4x4. first one is the cooler mounted under the air dam, behind bumper, second is the probe mounted in the pan, btw this is a 700, not a 400. third is the gage.

 

[dependable]

I had them switched because when the frame flexed my fan hit the radiator. Gotta make some more money to throw into the big green pit.

Like markg said, check the fan clutch. If the bearing went it could let fan hit radiator. Is the 'frame flex' problem fixed? Might want to look at big picture before you throw too much money that truck.

 

[glassk]

are the lines reversed,..??

 

[MarcusOReallyus]

the logic was that in cold weather it would warm up to radiator temp and remain constant.

That happens when you run the air cooler BEFORE the radiator cooler. You dump the excess heat, then run it past the nicely regulated radiator to make sure the trans fluid is at the optimal operating temp, not too hot, not too cold. If it's too cool, it will pick up heat (thus helping to cool your engine), if it's still too hot, it will shed heat into your radiator.

 

[100acre]

More

I think I just found one of the trans fluid lines with a plug jammed into it. Something they did when installing the cooler. Is the trans cooler sistered up to the radiator on inside between radiator and radiator fan cowling the right place for it?

Sorry no pix Apple and FedEx lost my replacement iPad mini and this one's external camera is nonfunctional. Been a tough week!

 

[MarcusOReallyus]

Sorry no pix Apple and FedEx lost my replacement iPad mini and this one's external camera is nonfunctional. Been a tough week!

That's a real First World tragedy!

 

[dependable]

Is the trans cooler sistered up to the radiator on inside between radiator and radiator fan cowling the right place for it? !

I may be misunderstanding your question, but the aluminum lines behind the radiator are motor oil coolant lines. The stock transmission cooler lines(3/8 in steel) go into and out of the drivers side of radiator. If your 'mechanic' was unfamiliar with 6.2, could he have hooked up aftermarket tranny cooler to oil line?

There is not a 'correct' place for aftermarket cooler unless it is in the cooler's instructions. Most of the ones I have seen were mounted outside the radiator, but I am sure there are other ways to do it.

If they left a plug in the line, that would go a ways toward explaining your problem.

 

[Skinny]

Junk that fan and put the stock one back on. I have yet to run into someone with a good experience from a flex fan.

 

[100acre]

where are you measuring the trans temp? water temp is supposed to run at 195, with a good thermostat. getting rid of the factory fan clutch will make the bad fuel milage even worse, not counting the constant roaring noise. i think you might have another problem. trans temp should be the same as the radiator if your not pulling a load. i have a cooler on one of my 6.2's that bypasses the radiator and on the hottest days here in texas never gets above 190. make sure the trans lines are flowing , and the vent on the housing is clear.

Where might the vent on the housing be?

 

[100acre]

I had them put the stock fan and clutch back on. They didn't seem to have time to take it for a test run so I did, and within the 2nd mile my water temp was running at 210 and by mile six it was 240 degrees and then the trans fluid temp rose up to 240. These guys have totally pissed me off. Not only have they had my truck for 7 weeks and $700 dollars later it runs worse than when I brought it in. They also broke my oil pressure gauge line and charged me for replacing it.
One mechanic said all those old 6.2 get their heads cracked. Is this another ploy to suck more money from me. I want to give up! I got a camera now so I will take pix tomorrow after I go pick up the anchor(truck)/ money pit.
Should trans fluid cooler lines run independently and not into the radiator like they have them, should it be run into the trans fluid cooler only? Or maybe a failed thermostat? How do I tell if I have a cracked head? Please help. Waaaaaaaa!

 

[dependable]

Have had a lot of 6.2s, including some civy ones with high mileage. Have had never had a cracked head, not that that can't happen if truck is over heated. Just saying you should change mechanics. If motor is not overheating, then thermostat is ok. It is ok for transmission lines to go into radiator as well as transmission oil cooler. This modification seems to be causing you a lot of worry. You don't need an extra cooler at all unless you plan to do a lot of towing, (or some kind of performance application, which is not a good idea with these trucks unless you are your own mechanic.)