2500 Overheating when towing

[02Yukon2500]

I recently tried towing my tractor with my 2002 Yukon XL 2500 (6.0). Total weight was around 7000 lbs with the trailer. Temp was 92 deg outside, high humidity. I was running 70 MPH over rolling hills. This was the first time I've towed anything substantial since I got the truck, so I was watching things closely... Within 10 miles, both trans and engine temps were almost to the orange, so I took it back home (slowly). It seemed like the trans temp was the driver, pushing up the engine temp too, but it's hard to be sure.

I've had a ~4000 lb enclossd trailer behind the Yukon in 108 deg heat since then with no issues. With the enclosed trailer, engine temp was 195, and the trans temp was 200.

When running in that heat with no trailer, engine temp is 195 and the trans is also about 195. As a side note, the AC gets hot pretty quickly when I'm stopped too.

I'm thinking I probably need to improve radiator cooling first. I've seen where some have gone to the 05/06 electric fans, or is there another option I should look at? Should I upgrade to a new radiator too, or is the stock as good/better than the aftermarket?

Any upgrades anyone has done for the trans cooling? That's my biggest worry...

Other thoughts?

I've got an 06 GMC 3500 Duramax for my serious towing needs, but I'd like to give my Yukon as much capability as possible...

Thanks,

Danny

 

[rockola1971]

Do you haver a trans cooler? Towing in 4th (OD)? If so then 2-4 band could be slipping and causing excess heat. If that is it then you will know soon when 2nd and 4th go bye bye. Check your fluid to see if it is burnt. Smell burnt? Should be pink to reddish. Not brown to orangish.
Recommend corvette servo for the extra holding power in 4th(OD). If tranny is high miles since last rebuild then I recommend it being built for towing. If the sunshell is OEM then dont even think about backing up with a trailer and doglegging it!

 

[Sam Harris]

I can’t speak from experience, but I was under the impression the clutch fan was the better option for towing rigs. It may need some attention / new clutch? The tru-cool 40k is our go-to trans cooler, and it does great work. I’m assuming your 2500 came with the 34” radiator, so that should be correct. I’ve heard of quite a few guys being disappointed when going to aftermarket from OEM on radiators. Last time the cooling system was flushed?
Other than adding the tru-cool, I believe your best bet is to maintain / replace OEM with OEM as needed.

 

[rockola1971]

Absolutely! Adding a watter wetter to the coolant improves thermal conduction and lowers coolant temps. This is especially needed for addtional thermal load such as towing!

 

[02Yukon2500]

I had tow/haul mode on. Truck is completely stock with 140k miles. 99% sure the tyranny hasn't ever been rebuilt. No signs of burnt fluid.

Danny

 

[swathdiver]

I had tow/haul mode on. Truck is completely stock with 140k miles. 99% sure the tyranny hasn't ever been rebuilt. No signs of burnt fluid.

Danny

At 20 years old the clutch fan, radiator core, transmission cooler core are all probably due for replacement to maintain peak operating proficiency. Fresh fluids are your friend as well.

 

[rockola1971]

Radiator has been probably filled/topped off with tap water and pasages are plugging up with mineralization. Could also be plugged up by broken down Dexpuke. Check front of radiator and condenser for bugs and dirt blocking airways. Missing any airdams from under vehicle?

 

[S33k3r]

The first time I had this issue (2005 Suburban 2500) was when the clutch fan was failing. That was within 10k or so of your mileage (over). The next time this happened, I was in bumper-to-bumper traffic, and it blew the transmission within minutes -- so I don't know what killed it. In order of replacement cost:

1) Check your coolant. Purge the system if you can find a competent shop, or a place that will take used coolant.

2) Check the fan clutch. It may need to be replaced.

3) Clean the transmission cooler. Replace with TRuCool40 if it checks out.

4) Have someone check your transmission. May want to do this anyway, since you already ran hot.

5) Check fir a custom tune on your rig that doesn't have the transmission set up correctly.

 

[Mudsport96]

Do you haver a trans cooler? Towing in 4th (OD)? If so then 2-4 band could be slipping and causing excess heat. If that is it then you will know soon when 2nd and 4th go bye bye. Check your fluid to see if it is burnt. Smell burnt? Should be pink to reddish. Not brown to orangish.
Recommend corvette servo for the extra holding power in 4th(OD). If tranny is high miles since last rebuild then I recommend it being built for towing. If the sunshell is OEM then dont even think about backing up with a trailer and doglegging it!

The 2500 SHOULD have a 4L80e. So the Corvette servo wont do any good.
A 40k trucool should be all he needs for an 80e to survive anything that a 2500 burb can LEGALLY tow.

 

[rockola1971]

The 2500 SHOULD have a 4L80e. So the Corvette servo wont do any good.
A 40k trucool should be all he needs for an 80e to survive anything that a 2500 burb can LEGALLY tow.

They make a 4L80E equivalent of the Corvette 4L60E 2-4 apply servo for the 4L80E FWD band. The 4L80E will suffer from the same exact problem of the 4L60E when towing in 4th with oem parts.

 

[S33k3r]

It came from the factory with a 4L80e, can confirm.

 

[Mudsport96]

They make a 4L80E equivalent of the Corvette 4L60E 2-4 apply servo for the 4L80E FWD band. The 4L80E will suffer from the same exact problem of the 4L60E when towing in 4th with oem parts.

Odd never had an 80 fail towing in 4th. Not saying it isnt possible, just never had it happen to me or anyone i know with even a stock 80e. And i drug a 93 fox back from san Diego to Peoria il on a car hauler at 80-85 in 4th.

 

[02Yukon2500]

Radiator was flushed a couple months back when I bought the truck. I always do all fluids and filters when I buy something to be safe.

All the air dams are in place and both the trans cooler and radiator fins are clean.

I've started collecting the parts to upgrade the trans cooler. I'll look into the valve upgrade.

I don't see anything obviously wrong with the fan clutch, but it could be dying... Trying to decide if I want to just replace it or switch to electric. Leaning toward going electric as I think it will help a lot with the AC getting hot when stopped.

Thanks,

Danny

 

[rockola1971]

Odd never had an 80 fail towing in 4th. Not saying it isnt possible, just never had it happen to me or anyone i know with even a stock 80e. And i drug a 93 fox back from san Diego to Peoria il on a car hauler at 80-85 in 4th.

It doesnt fail the first time you tow like that. It takes wear and tear (miles) on the tranny and/or subtantial weight being towed (not neccessarily overweight). Just like a 4L60E wont fail the first time you tow with it...usually....unless its worn and has the right amount of weight combined with right amount of wear on the 2-4 band. 700r4/4l60/4L60E are way more prone to do it. While the 4L80E is a totally different design and can handle alot more HP and weight....it isnt bulletproof. If the 4L80E was such a keeper GM wouldnt have stopped making it in 2013.

 

[Sam Harris]

Radiator was flushed a couple months back when I bought the truck. I always do all fluids and filters when I buy something to be safe.

All the air dams are in place and both the trans cooler and radiator fins are clean.

I've started collecting the parts to upgrade the trans cooler. I'll look into the valve upgrade.

I don't see anything obviously wrong with the fan clutch, but it could be dying... Trying to decide if I want to just replace it or switch to electric. Leaning toward going electric as I think it will help a lot with the AC getting hot when stopped.

Thanks,

Danny

The e-fans will absolutely help with the A/C. It’s a night and day difference. However, I don’t think they work quite as well as an un-worn clutch fan for towing. I could be mistaken though.

 

[S33k3r]

The e-fans will absolutely help with the A/C. It’s a night and day difference. However, I don’t think they work quite as well as an un-worn clutch fan for towing. I could be mistaken though.

It depends on the efans you get. Specifically, you look at the max volume a clutch fan blows, then get efans rated for the same amount. You only really get into trouble trying to do things on the cheap, just like anything else. The OEM efans will flow less air vs. the clutch fans, at higher RPM, but I'd have to compare specifications to give specifics. On the other hand, how often will your engine be at those high RPMs?

 

[rockola1971]

On the other hand, how often will your engine be at those high RPMs?

When im towing and a sly copper saw me go by at 85MPH+ and the next thing I know im wanted dead or alive with 8 smokeys on my tail and my 2-4 band is slipping like a F chassis on 2" of ice!

 

[02Yukon2500]

The OEM efans will flow less air vs. the clutch fans, at higher RPM, but I'd have to compare specifications to give specifics.

I'm skeptical of that. I would bet most of the airflow at speed is being driven by air pressure on the front of the vehicle, not the fan. When running down the highway, the RPMs are low most of the time. As a result, the fan isn't "pulling" much. Sure, you can't put a fan on there that will hinder flow, but I doubt the OEM fan will. If I'm right, the flow at speed should be about the same, but vastly improved when stopped or at slow speeds.

But I'm hoping those that have done the conversion will chime in with real world feedback...

Danny

 

[S33k3r]

I'm skeptical of that. I would bet most of the airflow at speed is being driven by air pressure on the front of the vehicle, not the fan. When running down the highway, the RPMs are low most of the time. As a result, the fan isn't "pulling" much. Sure, you can't put a fan on there that will hinder flow, but I doubt the OEM fan will. If I'm right, the flow at speed should be about the same, but vastly improved when stopped or at slow speeds.

But I'm hoping those that have done the conversion will chime in with real world feedback...

Danny

I'm a member of several 2500 groups, and they point out 1) GM kept putting clutch fans on the 2500 and 3500s. And 2) you will be hitting those upper rpms under load (towing, inclines, etc.); so you'll have more cooling at low speed in those conditions. And if you tow a lot, you are likely to be in slow speed, high load conditions regularly.

 

[rockola1971]

The highest airflow wins. If the fan clutch or efan has a lower cfm than the incoming air from driving forward then incoming air wins and vice versa. So if you are moving forward at 55mph and at that speed there is 2000cfm of air coming in across the radiator and the fan(s) put out 850cfm of air then there is no air moved forward from the fan(s) because the 2000cfm of incoming air overcomes the 850cfm. The fan(s) take care of business at idle and lower vehicle speeds.