Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) UltraDork
7/9/24 3:26 p.m.

Have an 05 2500hd 6.0 gasser that gets hotter than I'd like during a regular tow I do over the pa foothills. Trailer is an enclosed about 8k lbs. Once the trans is hot it will overheat on my way home if I have the ac on. 
Thinking I can throw a bigger trans cooler on but that temp seems reasonable. Any suggestions for uprated radiators? I see some alum ones for the diesels but spendy. Not seeing much for the gassers. Fine to change to elect fans etc. 

Dusterbd13-michael
Dusterbd13-michael MegaDork
7/9/24 3:34 p.m.

Subbed

spacecadet (Forum Supporter)
spacecadet (Forum Supporter) UltraDork
7/9/24 4:03 p.m.

What you're talking about doesn't totally make sense to me.

If the trans is getting hot and overheating I'm assuming here that the truck lacks an auxilary Trans Cooler and just routes the trans fluid through the radiator. 

If that's the case, putting an auxiliary cooler on it should help solve your issue. Just as long as it's mounted up in front of the radiator and  AC condenser

I wouldn't throw money at a new radiator if the issue isn't with the Motor's cooling system.

From my research, Trans coolers integrated into the radiator are more about getting the trans up to temp sooner for MPGs than they are about properly cooling the trans in heavy use. 

Am I totally off base here and missing something from your post?

buzzboy
buzzboy UltraDork
7/9/24 6:16 p.m.

Is the trans overheating or is the exta trans heat overheating the engine?

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) UltraDork
7/9/24 11:22 p.m.

Sorry for not being clear. Trans temp is holding decent. But engine temp is fine unless trans is on the warmer side. I'd have to look at the gauge but it doesn't go much past half on the trans temp. Which is why I was thinking a bigger aux trans cooler wouldnt do much. Rad has built in trans and oil coolers in addition to aux trans and ps coolers, all stock. 

No Time
No Time UberDork
7/9/24 11:51 p.m.

Does the trans fluid run through the radiator or aux cooler first?

If it's radiator first, then I wonder if you might alleviate some of the issue by routing to the aux cooler first, then the radiator. Let the air pull out excess heat first through the aux cooler, so less  heat gets dumped into the radiator.

I'm sure others have more experience and can say if that could work.

 

gearheadE30
gearheadE30 Dork
7/10/24 11:51 a.m.

I wouldn't expect to have any overheating issues if everything is working right. First suspect would be the fan clutch. They can kind of half work but get weak as they leak over time. The AC delco ones are the best - every aftermarket clutch I've seen engages earlier than stock, which generally just means worse gas mileage. But it would help keep things a bit cooler. 

8.1 trucks have a bigger radiator than 6.0. I'm not sure if the trans connections or anything else is different, though. 

Lots of people install a Tru Cool 40k cooler on the GMT800s. I've not needed that on mine, but my enclosed is only 5500 ish lbs.

What temps are you getting to? Trans shouldn't be getting much over 200, if it gets to 200 at all on the gauge. Coolant should be 210 or a tick above on the gauge. 

Is the converter locking properly? Should pretty much be locked all the time in 3rd or 4th, and in 2nd if you're at or near WOT. If it's not locked, that will generate a ton of extra heat. 

I would not make the jump to electric fans, they are more efficient but generally move less air than the mechanical fans if the fan is coming on at highway speeds.

No Time
No Time UberDork
7/10/24 12:25 p.m.

In reply to gearheadE30 :

Your post reminded me, the fan clutches can be tweaked to engage earlier by bending the tang on the spring. That could be a way for the OP to try to fine tune the clutch fan engagement to come in earlier, but not too early to hurt unloaded mpgs. 

81cpcamaro
81cpcamaro SuperDork
7/10/24 1:32 p.m.

What Gearhead said, try the 8.1 radiator, but use one from a 2500 Suburban/Avalance. They used the 4L85E trans while the pickup use the Allison transmission, which has larger diameter transmission cooling lines, Diesels also use the large cooling lines.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) UltraDork
7/10/24 4:24 p.m.

Fan clutch being bad is an interesting thought. Most of my hills are backroad speed (30-35) but steep so the fan may be more in play than I first thought. Not sure on trans cooler routing but will check. Thanks!

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) UltraDork
8/19/24 10:31 p.m.

Pretty sure its the fan. This weekend with 90deg temps it got grumpy with the ac on at lower speeds and up hills. Need to test stills. 

Byrneon27
Byrneon27 HalfDork
8/28/24 10:55 a.m.

Mishimoto big rad for a Duramax. 40k trans cooler of your choice, ultimately get the ac condensor, intercooler, and rad support from a Duramax so that when the fun starts you dont have to take the grille out again. Primo time to add E fans aswell. 

gearheadE30
gearheadE30 Dork
8/29/24 9:55 a.m.

Personally I would not go E fans for towing. I know the 6.0 fan is different than my 8.1, but at least on mine, the amount of air that thing moves when the clutch is locked is incredible. I love electric fans for light duty applications, but when loads and engine speed are high, it's hard to beat a mechanical fan until you get into some of the 24-48 volt electric stuff. 

BTW I just towed a 7K lb enclosed/toy hauler through the PA/NY hills in the heat. No temperature issues at all with the 2500 Suburban, I would expect your truck to be able to do it just fine if everything is working right. Fan clutch was locked on by the time I got to the top of several of the hills, but even with the stock cooler, trans temp was below 200 and coolant temp never went above its usual half way point. Towing around 75 mph. Trans temp did go up some when I got off the highway and the converter wasn't locked as much, but only a tick over 200f. 

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) UltraDork
9/3/24 2:54 p.m.

I can spin the fan by hand after driving it 2hr. Time to change the clutch. 

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