My GMC Serria 2500HD overheated and the power cut-out last week towing 12,000lbs over the WV mountains. Changed the thermostat and it fixed the overheating but now it seems I lost a lot of power and fuel mileage dropped. Dealer just checked it out and says there is nothing wrong??? Did any of you ever run into this?? Thanks for your help

Go to "user cp" in the upper right corner and fill in your signature so that we can see what type of vehicle you have.

Sorry, here is more info. 2008 GMC 2500HD LMM 6.6 Duramax, Crewcab Shortbed SLE Z71. Thanks

I know that in the automotive world a stuck closed thermostat is a possible failure, but I have never heard of one with this engine. So playing the odds, I will say that I doubt that this overheated due to a thermostat problem. This means that there is still a problem with this truck that has not been repaired.

I understand that you went into power limiting (which can be for a lot of different reasons), but why do you think it was due to overheating and why do you think it was a thromostat that was the cause? With more detail maybe we can help with the loss of power.

I understand that you went into power limiting (which can be for a lot of different reasons), but why do you think it was due to overheating and why do you think it was a thromostat that was the cause? With more detail maybe we can help with the loss of power.[/quote]

I have noticed it was running hotter than normal for a few weeks now and my dealer just kept saying there is nothing wrong. So when pulling 12,000 lbs over the WV mountains it went into power limiting when the temp hit 230. That is the reason I changed the thermostat. (The truck gauge showed I was getting 9 mpg but when I calculated the mileage on a tank of fuel I was only getting around 4 mpg.) It doesn't run hot any more but I don't have the power I used to have and my fuel mileage dropped. The dealer just keeps saying as long as the Check Engine light doesn't come on there is nothing he can do.

Is the fill/overflow tank full when truck is cold? Have you added any coolant? Reason I ask is a few here have had issues with the EGR leaking and losing coolant. If the tank is low/empty when cold, could be leaking, causing some issues. Chris

Is the fill/overflow tank full when truck is cold? Have you added any coolant? Reason I ask is a few here have had issues with the EGR leaking and losing coolant. If the tank is low/empty when cold, could be leaking, causing some issues. Chris

That is the first thing I checked. Only had to add a little once in the last year. Thanks

The dealer just keeps saying as long as the Check Engine light doesn't come on there is nothing he can do.


My personal opinion is to take it to another dealer. Even if you have to go out of your way to get it to them.


Bigfeet

Do you happen to know what codes were pulled?

I will make a guess and say that you are having a problem with the cooling fan system. At times it is coming on too often (poor fuel economy and loss of power) and at times it is not turning fast enough (elevated coolant temperature).

Did the fan come on? Were you wooping that bad boy hard? Few LBZ and LMM trucks overheat, suppose anything is possible and I also suppose if you dawg anything hard enough then anything would overheat.

You also overheated in pretty cool weather unless you were towing those weeks that were in the 80's and maybe 90 degrees. Anyhow our trucks will get hot and i myself see the trans get up then the engine gets hot but the fan will come on an cool it quickly. the trans however has a habit of staying hotter longer.

wich thermostat did you change?

230 is actually 210. The 210 that it normally shows is 180 on a hand-held OBDII tester. 230 is not overheating anyway.


So, that temp is normal. That is why they are saying nothing is wrong.

The reduction in power was most likely the DPF full of soot. Pulling, especially if you leave it in 6th, makes a ton of soot - even with stock programming. My theory is; the DPF can't get into regen and burn off the soot fast enough. So, the pull continues and the soot keeps backing up. Eventually it has no choice other than cutting the fuel/boost back to let the DPF catch up. I've known several here and there that have been limping at 5mph on the shoulder for the remainder of the hill due to this.

I dropped mine before it could happen to me.

I am a newbie. Could some one please tell me what you mean by DPF?

I am a newbie. Could some one please tell me what you mean by DPF?

Diesel Particulate Filter. Part of the new emissions crap!

Diesel particulate filter, part of the lmm emissions system. Be aware if you remove it you will void your warranty.

230 is actually 210. The 210 that it normally shows is 180 on a hand-held OBDII tester. 230 is not overheating anyway.


So, that temp is normal. That is why they are saying nothing is wrong.

The reduction in power was most likely the DPF full of soot. Pulling, especially if you leave it in 6th, makes a ton of soot - even with stock programming. My theory is; the DPF can't get into regen and burn off the soot fast enough. So, the pull continues and the soot keeps backing up. Eventually it has no choice other than cutting the fuel/boost back to let the DPF catch up. I've known several here and there that have been limping at 5mph on the shoulder for the remainder of the hill due to this.

I dropped mine before it could happen to me.

Don't think I subscribe to that theory. You have a hot engine when pulling so why does pulling in 6th, (hottest) create more soot.

I just got an appointment at another dealer for next week. I will let you know what he finds. Thanks

Don't think I subscribe to that theory. You have a hot engine when pulling so why does pulling in 6th, (hottest) create more soot.
If you see one without DPF, pulling in 6th - at say 1600 or so, UPHILL (I should have specified) smoke will roll out of the pipe. Even with a stock tune. Again, this is during an uphill pull. I usually tap down to 5th to lighten up the smoke and make it easier on the equipment in general.

It's a viscious cycle, actually. The truck WANTS to pull 6th gear uphill (even with a load). But, it pushes smoke - hindering the DPF.

[quote=JimmyDel;3287023]Do you happen to know what codes were pulled?

P0087

if dealer says nothing is wrong with it, is it possible to take it to a dyno shop and get numbers to prove reduced power?

if dealer says nothing is wrong with it, is it possible to take it to a dyno shop and get numbers to prove reduced power?

Great idea. I might have to try that. Thanks

P0087 is a very well understood code on tis site. Nothing to do with temperatures (unless you are running bio fuel and it is cold outside). This code means that you had a lower than expected fuel rail pressure. Tylically this is due to a fuel filter restriction, but can also occur for other reasons like kinked fuel lines or a gulp of air.

Most likely your fuel filter needs replaced. Ran fine until you towed in the mountains when the fuel system demanded a higher volume of fuel through the filter. When not enough fuel could pass through the restricted filter, you set a P0087 low fuel pressure code (and your service fuel filter message probably came on).

Replace that filter and if it has less than 15,000 miles on it, change where you buy your fuel from.

P0087 is a very well understood code on tis site. Nothing to do with temperatures (unless you are running bio fuel and it is cold outside). This code means that you had a lower than expected fuel rail pressure. Tylically this is due to a fuel filter restriction, but can also occur for other reasons like kinked fuel lines or a gulp of air.

Most likely your fuel filter needs replaced. Ran fine until you towed in the mountains when the fuel system demanded a higher volume of fuel through the filter. When not enough fuel could pass through the restricted filter, you set a P0087 low fuel pressure code (and your service fuel filter message probably came on).

Replace that filter and if it has less than 15,000 miles on it, change where you buy your fuel from.

That is the first thing I did when I got that code. Changed the fuel filter good for 90 miles than same problem.

If it helped for 90 miles, maybe you have water or trash in your fuel. ?????

If it helped for 90 miles, maybe you have water or trash in your fuel. ?????

I went though 5 or 6 tanks of fuel since I changed the filter. I don't get the error code but I only get 7 mpg when towing and I don't have the power I used to have.

sounds like a bad fprv valve if your getting p0087

Just a quick update. I took it to dealer # 2. He recalibrated the computer and now it works like a charm. Thanks to all of you for your help.

Just a quick update. I took it to dealer # 2. He recalibrated the computer and now it works like a charm. Thanks to all of you for your help.

I was just wondering if you know what the dealer did to recalibrate the computer, or what they recalibrated it to do. Just curious to know, thanks.

This thread is flawed. We fixed a truck that wasn't overheating by replaceing a thermostat that wasn't defective. Then we fixed low power and fuel economy by reflashing the ECM with a cal that doesn't affect any of those things. Not saying anything against you Trucker-Dan, just saying that you are not getting the straight story and I am afraid that this is going to confuse more people than it will help.

I have seen a few problems like this. called gm and was advised to install a revised air box they had avialable. found it was better to install a cold air intake on these trucks and seems to work fine. also might want to try installing a ram air kit onto your hood to help cool off engine while driving.

This thread is flawed. We fixed a truck that wasn't overheating by replaceing a thermostat that wasn't defective. Then we fixed low power and fuel economy by reflashing the ECM with a cal that doesn't affect any of those things. Not saying anything against you Trucker-Dan, just saying that you are not getting the straight story and I am afraid that this is going to confuse more people than it will help.


x2

but the cal that they put in hi truck i bet has p0087 of or the timer eorr changed. as there was tech billtin for this issue

reflashing the computer works about 90 percent of the time it corrects alot of issues.

I Am A Newbie To This Website But Have Been A Proud Owner Of A 02 Chevy Extended Cab 3/4 Ton Duramax Truck. I Have Now Purchased A 07.5 Crew Cab Dually With Of Course The Duramax Motor. This Past Weekend We Pulled Our 28 Ft Toy Hauler Loaded To Appx 12,500 And Had Overheating Problems. This Truck I Purchased Used With 20,000 Miles On It And Now Has 22,000 On It. I Purchased The Truck For The Sole Purpose Of Pulling This Trailer. I Have An Edge Juice With Attitude And Still Retain The P.o.s. Dpf. The Attitude Reading Went All The Way To 244 Degrees & I Guess It Has An Alarm That Sounds When It Gets To 240 Degrees In Which It Did. I Never Had A Problem 1 With My 02 Ext Cab & Now This One Is Letting Me Down .
Any Help Would Be Appreciated ! !
I Was Following 2 Other Truck & Trailers Around 70 Mph In Which Neither Of Them Got HOT. Both Of Them Where 2000 Model Ford Duallys ( I Hate That F Word )

I used a PPE tune that was copied to EFI live. THe PPE tune ran to lean and my temps got warm under a load from time to time. I switched to another tune that somebody made on EFI live and I have not had any temp issues.

I Am A Newbie To This Website But Have Been A Proud Owner Of A 02 Chevy Extended Cab 3/4 Ton Duramax Truck. I Have Now Purchased A 07.5 Crew Cab Dually With Of Course The Duramax Motor. This Past Weekend We Pulled Our 28 Ft Toy Hauler Loaded To Appx 12,500 And Had Overheating Problems. This Truck I Purchased Used With 20,000 Miles On It And Now Has 22,000 On It. I Purchased The Truck For The Sole Purpose Of Pulling This Trailer. I Have An Edge Juice With Attitude And Still Retain The P.o.s. Dpf. The Attitude Reading Went All The Way To 244 Degrees & I Guess It Has An Alarm That Sounds When It Gets To 240 Degrees In Which It Did. I Never Had A Problem 1 With My 02 Ext Cab & Now This One Is Letting Me Down .
Any Help Would Be Appreciated ! !
I Was Following 2 Other Truck & Trailers Around 70 Mph In Which Neither Of Them Got HOT. Both Of Them Where 2000 Model Ford Duallys ( I Hate That F Word )

did the fan come on? Didn't it quickly start to cool the engine? Did you back out if it didn't start to cool it? at 12,500 air is thin, you loose power and I think the fan usually looses efficiency. Got to start with the fan.

He was loaded to 12,500lbs...Mine will heat up if I push it in 5th and 6th...Running 4th gear and 3/4 throttle cools it down.

Thanks for the reply guys !
coolbreeze - Yes the fan did come on (heard the roar) around the 230 degrees. Yes I did have it down in 5th gear and sometimes I did put it in 4th ( manual mode ). Yes the weight was appx 12,500 lbs. Once you crest an incline & are able to decelerate the temp would cool off. I used my edge juice with attitude in the #2 setting (tow) & it got to 244 degrees. I switched it to stock on the way back home & it still got to 238 degrees. I still have my 02 duramax in which I have made the same trip with & it never got HOT but I wanted this Dually for more sabilization. I know the DPF should be removed but would this for sure void the warranty. I know the dealership guys here in town but I bought this truck to pull & who knows where I will be if it breaks down. I am just disappointed in the truck for this reason other than that I really like this truck.

I have an 01 and last week it was a pooch. No lights either. I changed the fuel filter as it was last summer when it was changed. There was no results. Hooked up my Predator and ran codes. Fluel temp too high. I looked at the cooler under the truck and it was covered in mud and grass. Cleaned it out and will see if this helps. Cleared the soft code and my power is back.

Chad

I am having similar problems as this post started -

2008 GMC 2500HD Duramax LTZ Crew 4x4

Typical fuel mileage unloaded: 16-17 mpg
Typical Towing 9900 5th Wheel: 11-12mpg

Recently started loud blower noise while towing, sometimes when running up hill, sometimes when slowing down, sometimes when on flat ground. Can't figure out yet what triggers it to start.

Just picked up 5th wheel from repair shop, drove 81 miles and burned 14 gallons of diesel. Just under 6mpg which is awful.

Leaving Wednesday for 5000 mile cross country trip for a couple weeks.

Just had fuel filter, oil change, transfer case, front/rear axle, and transmission flush last week at 65k miles.

Going to dealer first thing Monday with 5er hooked up to demonstrate problem.

Tranny temp running 192-201 per in dash gauge.

Lastly when the fan/blower - whatever the hell noise comes on I lose power pretty bad. Hit the pedal, RPMs scream, noise increases, and feels like the tranny is not getting the message and going no where.