Trans cooler

[94GMC2500]

Hello, The trans in my 95 k3500 runs border line hot when towing, about 240. My water temp gets up there too, ordered a radiator today. It has all the 2000 6.5 cooling stuff on it with a new fan clutch.

I noticed that there is a trans cooler right behind the grille, looks factory, but trans oil don't go into cooler in radiator. Is that the normal setup?

I bought a cooling fan that is made to go in front of condenser on left side, but the trans cooler is mounted there so no place for the fan.

Engine oil cooler is on the right side, also no engine oil cooler in radiator.


My thinking is the hot trans oil in radiator cooler would make the engine cooling more of a problem. I am thinking of adding another trans cooler.

Tom

[a5150nut]

Is there any dirt and trash between the stack?

[More Power]

Generally, electric auxiliary cooling fans do more harm than good by blocking airflow. And, they aren't needed if everything else is OK.

Remove the top half of the fan shroud, and look between the radiator and A/C condenser. See any accumulation of leaves or airflow blocking stuff?

Does your fan-clutch ever engage. The roar is unmistakable. Should happen between stoplights in town on a hot day, or anytime engine coolant temp exceeds 210.

If your radiator is original to the truck, it likely needs to be replaced or at least serviced (cleaned and flushed on the inside and outside). The plastic end-tanks are removed/replaced during a service.

Jim

[Robyn]

The oil cooler that is divorced from the radiator is a standard set up on some rigs

[94GMC2500]

I have the new radiator in. I washed out the condenser and oil coolers. They were pretty clean anyway. I need to hook it to my trailer to see if its better, hot and muggy here so it will be a good test.

[94GMC2500]

New radiator helped. Trans temp still goes way up. I got a new filter for trans today, have not changed it yet though.


On a 95 will hi trans temps cause it do defuel?

[DmaxMaverick]

High trans temp will not cause a "defuel". Maximum trans temp will (260+), and cause limp mode (SES will be on). Yours is too hot for normal duty. You shouldn't see it that hot unless towing a long grade in very hot weather. Make sure the torque converter is locking. If it isn't, it will heat up high and quick under moderate to heavy loads.

[JohnC]

My recollection is there is an air to oil cooler as well as the water to oil cooler, at least on mine with the tow package. Is that the case here?

https://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=3966&d=1530279230

(Of course, have you confirmed the accuracy of the gauge?)

[94GMC2500]

The trans goes to a good sized cooler in front of radiator but not connected to the radiator trans cooler. I put new filter in this morning pan was spotless inside so I assume someone else has had the pan of not to many years ago.

I went for a easy 20 mile ride not towing anything and trans temp said a little over 200, in 85 degree muggy weather. Trans temp gauge sender is in test port on side of trans.

I held a thermometer on a stick on the bottom of pan and it said 185 just sitting there idling in park for about 15 minutes.

The images show the normal water temp driving it easy and the trans temp from this mornings easy drive.

Do the factory coolers plug easily? The inside I mean.

[JohnC]

Mine was definitely connected to both.

[94GMC2500]

I drove truck again to day, just a normal drive, not towing anything, 94 and humid out.

Trans temp said 210, I crawled under with a temperature gun and checked side of trans, 202 degrees, side of pan 185, hot side of cooler in front was 185, cool side of cooler was 176.

The sender is in the test port, is it better to have it in the pan or test port?

[DmaxMaverick]

What does the IR temp sensor say about the location of the test port? The sender could be indicating non-fluid heat, which is OK. Part of the fluid's job is to remove heat, which it appears to be doing.

It is better in the pan or the outlet to the cooler, but doesn't matter where you put the sender. NONE of the temp data is good for anything other than tracking trends. Senders and gages are notoriously inaccurate, but should be linear with actual. As long as the value is linear with actual conditions, assign that as "normal", and track the trend from there. Or move the sender and feel better about it.

[94GMC2500]

I am going to add another cooler since I have one laying here and move sensor to the pan and it is what it is I guess.

[DmaxMaverick]

I would suggest doing one at a time. First, move the sender. See what you really have. Then, add the additional cooler to maximize the cooling ability. Doing both will not tell you what was the problem, if there was a problem.

[Robyn]

In past years when I was towing I had a gauge reading the fluid temp at the inlet of the cooler and a second gauge reading the temp at the tranny return port.

Temp of the fluid in the converter is the important issue.

If the converter is COOKING the fluid to 220-250 F but your cooler is bringing the temp down to under 200 F the cooler is working, but the fluid is still being fried....

Are you sure the converter lockup is functioning ???


Snap a piccy of the tranny cooler that's there now and post it please.

The test port is just that...A pressure test port.... and it is the end of a passage.

You need the temp sender in an area that sees fluid flow and not a place that is surrounded by metal in close proximity (Port passageway)


Get your setup so the gauge sender is in moving fluid...

The pan is nice....but as I mentioned having data on what the temp is pre cooler and post cooler is a good thing...

[94GMC2500]

When I am driving along at 60 mph without the cruise on and I touch the brake pedal the rpm goes up so I assume the converter is locking up.

I don't think I can get a decent pic of the cooler without removing the grille but I will try. It looks like the factory cooler to me. Cooler is about 11x6 inches.


The second cooler is the other one I have, 14x7.5 inches.

[94GMC2500]

We do garden tractor pulling and I pull a 28 ft pace trailer. I wish I could get this truck so I can just go pulling and not have to worry about it over heating or if the trans is really getting to hot. I ordered a couple 180 T stats from SSDiesel, I figured it cant hurt.


I dread going up a good sized hill in hot weather, truck heats up and has no power in warm to hot weather, some times 45 mph is all it will do on hills with the trailer.


It has 4.10 gears, new diamond eye 4 inch exhaust, walking J computer chip, manual boost control, all the late model 6.5 cooling stuff, new radiator, HD fan clutch, newer lift pump.

On a hill with it floored at about 12 lbs of boost on a hot day I get no smoke out the exhaust at all, but EGT pre turbo will go to 1250 if banks gauge is right.


I am thinking of trying a holley red pump for a lift pump to get more fuel pressure going into injection pump.


The engine might be tired and don't know how good the pump and injectors are.


I have done diesel work on tractors, rebuilt a 8.3 cummins last winter, rebuilt many older IH and JD diesel engines, so I am some what up on diesels, I don't think the engine in my truck sounds to bad yet, more blow by than I would like though.


I am just venting a little I guess.


Tom W

[Robyn]

What is the gross weight of the complete outfit (T&T) and the loaded trailer weight ???


The 1250 F EGT number makes me waaaaaay nervous.

1000 F is about the max safe number to run a 6.5

Is the Pyro in the exhaust PRE or POST turbo

Pre turbo should see no more than 1000 F on a hard pull...

I have never heard of the Chip maker you spoke of..

[94GMC2500]

Pre turbo, probe is in exhaust manifold under the turbo. KOJO tune chip. I don't know what the total weight of truck and trailer is. A guess on trailer weight is 8500/9000 lbs. Trailer pulls hard in my opinion. Maybe ex temp gauge is way off, no idea on how to check it.

[Robyn]

Copy on the weight.

That flat front trailer is like pulling a barn.

Huge frontal area.

8000# on a grade behind the Burb is going to be a hard pull.

The Burb is 6000 to 7000 #

Close to 15K COMBO

Given the engine is likely in the 250 HP range and then add the heat issue...

It takes serious HP to yard that kind of weight around..

What sort of grade percent ???? 5% or greater ??

[Yukon6.2]

Hi
One of the reasons that it pulls hard may be the tire size.
It looks like 15" rubber by the pic. Make sure you have the tires at max pressure and see if that makes a difference.
I have a car hauler with 16" rubber,my buddies trailer is built lighter with 15" rubber and it pulls harder loaded.
Rolling resistance of a smaller tire that has a bigger contact patch because of lower air pressure.
Thomas

[94GMC2500]

Correct on 15 inch tires. It had D rated tires on it when I got it. I have replaced three tires recently with E rated. I run 65 in the old D rated tire and 75 in the other 3 tires.


If I get another trailer I would never get one this big again.


I can get 1000 degree exhaust temp just by flooring it passing a car without towing anything.

[Yukon6.2]

Correct on 15 inch tires. It had D rated tires on it when I got it. I have replaced three tires recently with E rated. I run 65 in the old D rated tire and 75 in the other 3 tires.


If I get another trailer I would never get one this big again.


I can get 1000 degree exhaust temp just by flooring it passing a car without towing anything.
Is the soot trap still in the exhaust?

[94GMC2500]

Nope, it has a diamond eye 4 inch without a muffler.

[Yukon6.2]

That would have been too easy...
Is the crossover stock? There have been cases of the crossover having issues.

[Robyn]

Another question ????
When was the TDC offset done last.

Get it checked and get it in the -1.5 to -1.9 degree range. NO MORE

Will be a tad more rattle cold, but these numbers work well.

[94GMC2500]

Looks like stock cross over.


Never had TDC offset checked since I have had it. Don't know anyone with a scanner to check it.

[94GMC2500]

Well I think I have most of my problems fixed. When I put the late model HD cooling stuff on my truck a couple years ago I got a new so called HD fan clutch that was claimed to engage earlier than the original.

The other day I took the fan clutch off and re bent the coil so the fan engages at a lower temp, It might be engaging a little early now. But anyways I can hear the fan roar now where it had to be like 220 on temp gauge to hear the fan and it didn't last long like it was.


I put a second trans cooler on and with the fan doing something the trans temp dropped about 75 degrees and the water temp stays at where the thermostats open, about 180.


We have a pull this Saturday so I will find out for sure how much the fan running helps when I hook the big trailer on. I have a feeling its going to be way better. I guess never assume anything with new parts these days.

[arveetek]

The other day I took the fan clutch off and re bent the coil so the fan engages at a lower temp, It might be engaging a little early now. But anyways I can hear the fan roar now where it had to be like 220 on temp gauge to hear the fan and it didn't last long like it was.


I did the same mod on my stock fan clutch a few years ago. Definitely one of the best things I did for cooling capabilities!

Casey

[Yukon6.2]

Hi All
Any chance of a bit of direction on how to do the modification of the spring for others that would like to try it?
Thanks Thomas

[94GMC2500]

Truck ran awesome today, New PMD and a fan clutch that works helps a lot lol.

Water temp never made it to 210 pulling trailer today, Trans temp and EGT were way down too. I backed my waste gate down a bunch and it would still pull 13 lbs on a hard pull. EGT would go to 1250 on a hard pull before, today on a long hill it was 1050.


But it sucked fuel like mad today. A little over 3/4 of a tank in 158 miles.