I volunteer my time and truck to pull one of the local high schools 30' enclosed band trailers. I have had two times where my truck has started to run hot pulling steep or long grades. I would have figured this truck could handle it. I'm guessing the weight to be 10-12k lbs. Again that is a guess but the other night running home from Seattle I had to pull over put my secondary fans on including my heat to get the motor to cool down. Once I crested the hill or was on a flat things were fine. If I am pulling my 5th wheel I haven't noticed this being an issue. I'm running about 900 on the pyro and pulling about 25-30lbs of boost. Am I just pushing the motor too hard? Do I need to upgrade the HP? I see no signs of water in the oil and it doesn't give me any issues otherwise. The other thought is that I'm running the wrong gearing and maybe with the loads running it as 2200rpm in OD isn't good. I certainly want to figure out a solution as next year I probably will want to go to a cab-over camper and pulling the same trailer. I'm starting to wonder if my desire to have a dually and the 12v was the wrong way to go. Any suggestions would be appreciated. Thanks.

 

manual or auto trans?

 

Automatic trans with a Gear Vendor overdrive unit on it. I was originally told it was a 700r4 but I think that was not correct as that tranny has OD on it. I don't know exactly which trans is in it. I was also told it has an Allison Torque Converter if that matters. I was told the transmission was rebuilt by the previous owners trans guy that did his drag car. This is in a heavy dually 6-pac Chevy pickup

 

How is the transmission cooling set up? The EGT and boost numbers don't jive. Where is your pyro probe installed?

 

I am in the Seattle area and can check things out for you if needed...

 

CHECK your coolant system. Your trans is not going to cause an overheating problem! And a 700R4 is a 4 speed trans. You need to be looking at the cooling system NOT the trans. You engine should run at full load without over heating ALL day everyday if your cooling system is working properly. Manual or auto trans plays no part in that... And for everyone that is going to start up bull about and auto creating more heat then a manual trans SHUT UP. I'm not saying an auto isn't hotter but if your overheat you have a insufficient cooling.

I've pulled 30,000 lbs with my auto NO overheating problem. with EGT's at 1300. As long as I don't go higher on the EGT's the engine coolant temp staying normal. temp outside those days were high 90's and last day was in the 100's towing that load.

 

Since you mentioned Chevy, does your truck have the big 4 core radiator in it? The 4 core radiator only came if the truck originally had a 6.2L diesel in it. Otherwise, it might have a 2 core radiator.

Also, check your fan clutch if it has one. Is it locking up when it's suppose too?

The 700r4 does have an overdrive. If your truck in fact has a 700r4 transmission which I can't hardly imagine, you'll be looking for another transmission real soon. They're not strong enough even behind a 130hp 6.2L GM diesel. This transmission works great behind V6's but they fall apart quickly under lots of low rpm torque. Best thing to do right now would be to refrain from using OD with this transmission and use your Gear Vendors for gear reduction instead.

 

Snoot I was coming back from Everett to the Tri-Cities and just got to the East Summit Exit and had to pull off. I'm talking not even 1/4 from the summit but I didn't dare take it any further it was at nearly 260. As soon as I pulled off and let it sit for a couple minutes it came right back down.

I don't know where my pyrometer is positioned I didn't build this truck however I have see EGT as has as 1100 before however it was about 40 degrees outside and I don't believe I was in that range. Normal driving and normal pulling I don't seem to have an issue but this brick I'm pulling loaded has caused this to happen a couple of times. I will check the cooling system and may even have the radiator rod/cored and cleaned to make sure it's in tip top shape, replace the thermostat and go from there. Question does everyone run a 195 thermostat?

Also do they make oversized radiators for these rigs or are the rad's sufficient enough to keep things cool? Again pulling my 5th wheel I haven't seen an issue before. I might just hook up the trailer haul to one of the big hills and see if it gives me an issue like the car trailer that way I can pay attention to the EGT, the RPM's etc and get a better look at things. Thanks for all of the input.

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I do not think it's a 700R4 otherwise they wouldn't have put in the gear-vendor. Good question about the radiator as I know they had to extend the front grill out for all of the coolers. The truck originally had a 454 bb in it. That I do know. Previous owner used to pull his race trailer loaded and swears it never over heated on him and he's very prominent in the area and I suspect that what he says is very accurate just think something has changed.

 

If your truck has the coolant to trans fluid cooler, yes the trans will affect engine temps!
And the trans runs much much hotter than 160, could be close to 300 with that load

 

I always thought you pumped the transmission fluid through the cooler in front of the radiator not coolant through the trans cooler unless it has dual cooling capacity. I have never heard the coolant to trans fluid cooler. Am I missing something here? I will look tonight but can someone tell me the typical setup for this? Thanks