Tow Vehicle Getting a Little Hot in Summer

bbrown · 09-08-2014, 03:08 PM

As you can probably see from my signature, I've got an aging TV (2001 Silverado 2500HD) but I've taken very good care of it and only rolled about 165K miles so far. I've also customized almost every inch of it myself including but not limited to: upgraded trans cooler, new engine heads and valves, upgraded alternator, stereo upgrades, rhino liner, nerf bars, HID headlights with projectors, all LED bulbs, Amsoil in almost everything (yes even break fluid but not the anti-freeze) the list is longer..you get the idea. The last RV trip we took was to the OBX here in NC and the weather was very warm (high 90s). My TV works hard but tows our 8500 lbs 5er through this mostly flat land with ease for the most part until the temps get up in the high 90s...then I start seeing my coolant and trans temps soar up. On the way back from the OBX, I saw my engine coolant go to 230 on some of the longer slopes and trans temps were hovering at 200. My TV came stock with both a trans cooler and oil cooler. I've upgraded the trans cooler to a Hayden HD with an electric fan w/thermostat and the tranny is running Amsoil fluid so I'm not worried about the it so much. But the engine has upgraded HP mods (headers, intake, programmer, heads, valvetrain) and even tough I've never put it on a dyno...I can estimate there's another 60-75 HP on the crank. That power increase has resulted in more heat and even though GM says towing temps are normal up to 260...I don't even like seeing 230. Has anyone else seen things this hot. I just recently added the Amsoil Dominator coolant boost to the system but I've not towed with it yet...looking for anybody who might have had a similar experience.

wwsmith111 · 09-08-2014, 03:52 PM

Radiators get plugged up over time. I would put a new one (or reman) with a new thermostat in it.

Grumpy · 09-08-2014, 03:58 PM

I'd be more worried about EGT getting too high. Your fan may be getting a little weak also.

bbrown · 09-09-2014, 07:32 AM

Quote:

Originally Posted by wwsmith111

Radiators get plugged up over time. I would put a new one (or reman) with a new thermostat in it.

Yeah, radiators can get plugged on the inside with scale and the outside with bugs and road dirt. Although, I'm pretty sure that is not my issue...I've flushed my radiator with super flush at the recommended intervals, replaced the water pump recently, and every season I blow out the fins with compressed air and dig out any lodged debris. I do think one of my e-fans is weak...although the fans don't contribute much at 65 mph. But, on the other hand, if I did replace the radiator...I'd want to install an upgraded one to handle the increased heat output. Has anyone done that? I know the 8.1L V8
has a larger radiator core...just don't know if it would fit in the front mount.

DocBrown · 09-09-2014, 07:59 AM

Both temps you are seeing are perfectly normal and nothing to get worried about. You only have to worry about trans temps when they are over 220 for extended periods. Short bursts over 220 are not a problem.

There isn't really a lot you can do about it.

Jagiven · 09-09-2014, 08:09 AM

I am no expert in this area. But last year I thought my radiator temp was a bit higher than I liked on a long trip during hot summer days. The radiator looked fairly clean, but I stopped into a do it yourself carwash a couple days into the trip, and power washed the exterior of the radiator (be careful not to damage the radiator). I saw a lot of dirt come off. After that the engine temp stayed very stable, even pulling through steep mountain grades.

lx22f/c · 09-09-2014, 09:07 AM

First have your Radiator checked out.
Another reason could be a restricted exhaust. I had to have my cat converters replaced about at the same mileage. A good exhaust man can tell you by looking into them with a camera or by a back pressure test. Hope it is something simple. My truck never hits 200 degrees even with 100 degrees Texas heat and towing through the hill country.

Plowtoy · 09-09-2014, 09:21 AM

As an ASE certified mechanic and working at a GM dealership when your truck came out, and seeing many with the same complaint, I will put money on your coolant fan clutch is warn out. When this happens, the fan cannot get up to speed to cool the antifreese in the radiator enough to bring temps down to "normal". The aftermarket (napa, autozone, advance) all sell regular and heavy duty coolant fan clutches. You see this alot in the winter (here in Michigan) where a guy running around with his snow plow up overheats because the clutch didn't engauge and pull the cool air through the radiator because the plow was blocking the normal air flow.
I'm not saying you couldn't be having some of the other problems listed above, but it is pretty common for those clutches to fail.
Be prepared! When you put a new clutch on, you most likely will notice your fuel mileage go down. Again, this is normal because when the clutch is working correctly, you are putting more "drag" on the engine therefor consuming a bit more fuel. There are kits out there to convert from a mechanical fan, to electric fans. That may be something to check into if you are worried about fuel mileage...

3'senough · 09-09-2014, 09:53 AM

I will just add this for comparison. This summer in mid to upper 80's I was pulling down I-81, I-77 and I-40 through some steep 6-8% climbs and decends like I-40 in Ashville and my engine hit 238 on the coolant and 235 on the oil. But on the downside it cooled 30 degrees in 3-4 miles and while on the flats it would hover around 200 with it being mostly in the 190's. When on a climb my engine would push 2800 and temps would slowly increase. Did you get fluctuations and rapid ones at that? If your fan and radiator are working you should see rapid changes over 210 when on the flats and cruise speeds.

Now mine is another manufacturer, but just to give you some indication of how my temps fluctuate. My tranny never goes over 190 and hovers in the 165 range, but I understand GMs run hotter and it could be as simple as where the guage is located too.

I would invest in Plowtoys suggestion first then see where it takes you as it seems you are on top of your fluids maintenance pretty well. Also it's possible that your thermostat is sticking. Maybe put a 185 in there.

Arefbee · 09-09-2014, 10:05 AM

Quote:

Originally Posted by 3'senough

Also it's possible that your thermostat is sticking. Maybe put a 185 in there.

X2 - looking at your apparent skill level, probably not necessary to suggest this, but sometimes the simplest things get over looked.

Iraqvet05 · 09-09-2014, 10:18 AM

I've seen multiple posts on GM forums about the fan clutches on the early 2500's going bad. While mine seems to cool OK at higher temps, the a/c won't blow cold air at idle and a few people claim a bad fan clutch also causes this...I've been looking at replacing mine with a Hayen clutch.

clubhouse · 09-09-2014, 10:55 AM

This might seem a bit obvious, but in your list mods did you do anything like add a billet insert in the stock grill for aesthetics?

If so maybe the slight reduction in airflow is catching up to the radiator/transmission cooler when that truck is working on hot days.

DocBrown · 09-09-2014, 12:15 PM

Quote:

Originally Posted by 3'senough

Also it's possible that your thermostat is sticking. Maybe put a 185 in there.

No! Don't put in a 185! That may work fine while towing but it will be the death of your catalytic convertor in normal driving. Running cool will cause the PCM to run the engine rich and eventually melt the insides of the CATs. It doesn't necessarily throw a code when all this is happening either. I know, been there, done that.

wwsmith111 · 09-09-2014, 04:08 PM

I am an ASE cert. tech. Like I said before. Radiators get plugged up over time. Have it checked out. One easy way to tell is to measure the temperatures of the radiator from top to bottom with a infrared laser thermometer. Usually one or more coils will be colder than the rest. This indicates that it is all or partially blocked by sediment and corrosion. It sounds like you didn't notice a problem until the engine started putting out more heat due to your performance upgrades. If you do replace the radiator it wouldn't hurt to upgrade to a slightly larger model if you can find one that will fit. Always change out the thermostat when you do a radiator job. It is a cheap part. You may also be able to send the radiator out for service if it isn't to bad. Like everyone has pointed out, there are many possibilities. What I am suggesting is the most probable due to the age of the vehicle assuming everything else is working properly.

bbrown · 09-10-2014, 07:05 AM

Thanks for all the responses guys...I don't mind the simple suggestions. The t-stat is new along with the water pump and I'm running electric fans. I looked last night and it appears that there are plenty of bug guts building up so I'm gonna buy a can of coil cleaner and clean it out again. I also found a quick way to dump some of the heat build up quickly after those long hills...dial the interior heating up to about 1/2 with the windows slightly open. I did that when I saw the temp hit 230 and within 45 secs the temps dropped to 213...of course this is a little uncomfortable for a few minutes but it works in a pinch.

Plowtoy · 09-10-2014, 07:56 AM

Quote:

Originally Posted by wwsmith111

I am an ASE cert. tech. Like I said before. Radiators get plugged up over time. Have it checked out. One easy way to tell is to measure the temperatures of the radiator from top to bottom with a infrared laser thermometer. Usually one or more coils will be colder than the rest. This indicates that it is all or partially blocked by sediment and corrosion. It sounds like you didn't notice a problem until the engine started putting out more heat due to your performance upgrades. If you do replace the radiator it wouldn't hurt to upgrade to a slightly larger model if you can find one that will fit. Always change out the thermostat when you do a radiator job. It is a cheap part. You may also be able to send the radiator out for service if it isn't to bad. Like everyone has pointed out, there are many possibilities. What I am suggesting is the most probable due to the age of the vehicle assuming everything else is working properly.

I've seen many with well over 200,000 miles still have the OE radiator. It wasn't so common, IMO, for the trucks to plug up. A 3.1, 3.8, 4.3, and 5.7you could plan on it, espicially if it still had "deathcool" in it, but not the new gen. Fan clutches were far more a problem from my experiance, however, knowing what we know now, that does not apply to this problem and you may be onto something...

Quote:

Originally Posted by bbrown

Thanks for all the responses guys...I don't mind the simple suggestions. The t-stat is new along with the water pump and I'm running electric fans. I looked last night and it appears that there are plenty of bug guts building up so I'm gonna buy a can of coil cleaner and clean it out again. I also found a quick way to dump some of the heat build up quickly after those long hills...dial the interior heating up to about 1/2 with the windows slightly open. I did that when I saw the temp hit 230 and within 45 secs the temps dropped to 213...of course this is a little uncomfortable for a few minutes but it works in a pinch.

I wondered if you had already upgraded. I saw you had an electric fan on the trans cooler, but you didn't say one way or the other until this post about the electric radiator fans. Are they turning on when their supposed to? I think you are on the right path with cleaning the exterior of the radiator (its not going to hurt it any), but you may be looking at a replacement as said above. Again, its not real common in that generation truck IMO, but possible it is getting plugged up, espicially if when you changed the heads, you disrupted build up in the coolant passages of the block and it made it back to the radiator.

bbrown · 09-10-2014, 08:15 AM

Quote:

Originally Posted by clubhouse

This might seem a bit obvious, but in your list mods did you do anything like add a billet insert in the stock grill for aesthetics?

If so maybe the slight reduction in airflow is catching up to the radiator/transmission cooler when that truck is working on hot days.

No billet grille insert...but the larger trans cooler does put more heat into the radiator/AC condenser. No way to avoid that unless I move it. I'm also using the 4 air inlet slots in the bumper to scoop intake air whereas before (stock) that air was deflected up to the cooler/radiator. Yes, I did build a custom CAI with a ram affect using the bumper slots all ducted to the air cleaner box and sealed to build pressure.

bbrown · 09-10-2014, 11:56 AM

[QUOTE=Plowtoy;232572]As an ASE certified mechanic and working at a GM dealership when your truck came out, and seeing many with the same complaint, I will put money on your coolant fan clutch is warn out. When this happens, the fan cannot get up to speed to cool the antifreese in the radiator enough to bring temps down to "normal". QUOTE]

I read this and dismissed it at first since I have electric fans now...but 2 years ago I got rid of the belt driven fan for this exact reason.

bbrown · 09-10-2014, 12:07 PM

I'm interested in seeing how the Amsoil coolant boost works out...but I'm thinking of upgrading e-fans also.

Plowtoy · 09-10-2014, 01:35 PM

[QUOTE=bbrown;232943]

Quote:

Originally Posted by Plowtoy

As an ASE certified mechanic and working at a GM dealership when your truck came out, and seeing many with the same complaint, I will put money on your coolant fan clutch is warn out. When this happens, the fan cannot get up to speed to cool the antifreese in the radiator enough to bring temps down to "normal". QUOTE]

I read this and dismissed it at first since I have electric fans now...but 2 years ago I got rid of the belt driven fan for this exact reason.

I really struggle with adding aftermarket performance stuff to any vehicle. In fact, both of our vehicles drivetrains are bone stock. Vehicle manufactures spend lots and lots of money on R&D to get these things right, then some aftermarket company think they can make it better. Although many times they do deliver on their promise of more ponies, it comes with more than just the cost up front to the consumer, which I think you are starting to experiance... I hope it all works out for you. Again, I think you are on the right path by cleaning the radiator, but if that doesn't take care of it, most likely you will be replacing it or pulling your hair out trying to figure out the higher temps.

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