I'm new to diesels, but was looking forward to towing my toybox to the river this weekend. My toybox only weighs 7k and the truck has 2k miles of break-in complete. The truck is a 2005 Chevy Crew Cab, 4x4 Duramax, LT. As I left San Diego through the grade, the fan kept kicking on and slowing me down to around 45 mph, it was so loud I had to raise my voice to my wife for her to hear me, this could be a good thing too, as I had a hard time hearing her back :) once on the flats in the desert, same problem, the fan almost never stopped. Not only is this irritating, it is un-nerving, as I purchased this truck to tow, now I wonder if it's reliable? Any suggestions? The temp was 220-230, the tranny stayed around 200, the only mod I have done is 285 tires and I drive like a grandma going to church! Do you guys think I'm going to have overheating problems in the future?

I am very sorry I think there is a major problem with all the GM a buddy of mine just told me his new 05 GMC is running hot. If I were you I would take it into the shop ASAP.

the clutch fan coming on when the weather is hot is nothing to worry about, hell, here in sac i can be running without towing and have it come on at times when temps are high and im in traffic with a/c going - and on flat ground towing it comes on as well like you mentioned - i wouldnt worry about it honestly. i service my truck religously and i agree that the clutch fan seems to come on too much but other than it being on i dont see it as being a problem at all

I appreciate the reassurance, but I'm going to the dealer tomorrow, I traded my perfect Silverado 1500 for this thing for one reason, Towing, it sill has not meet my expectations. I'm bummed!

the clutch fan will come on with conditions like you are mentioning, there is no way around it and its not a problem - the engine temp WILL rise above normal when pulling a grade but SHOULD settle back down after that - it shouldnt stay above normal too long if its running correctly. Now if it is staying above normal and you are not pulling a grade or hammering it then you might have a problem. Same thing goes with the tranny temp, it will go up but will go back down if all is well with the truck. Hope this helps and good luck

...the engine temp WILL rise above normal when pulling a grade but SHOULD settle back down after that...

This has been my experience. Since reading all of the posts from guys that are having overheating problems I've been kinda paranoid about the temperature of my d-max. However, yesterday I was pulling up a 7% hill that is about 2.5 miles long with my 9000# camper and all of the kids' !@#$ in the back. Temperature in the rear view was 97 degrees. At the bottom of the hill I was going 30 mph and I had reached 55 mph at the top. The engine temperature was 3 little tick marks above its normal 210 and my Allison hardly budged above its typical 200-ish. As soon as I backed out of the throttle at the top of the hill the engine temperature came right back down to 210. I purposly went up that hill loaded during the hottest part of the day intent on working my truck extra hard. I was not disappointed.

:blahblah:

An active fan clutch is a good fan clutch. You could have GM replace it like some are, but then you run the risk of joining the overheat crowd...

I appreciate all the response, TBone, you are right, I called three different dealers and heard the exact same thing from all of them. I guess I'm just a newbie that's a little freaked out after reading all the overheating issues people are having.

my clutch fan use to run 75 percent of the time regardless if i was pulling something or not. i hated it for it was so loud you have have to yell to talk.the dealership replaced it and it almost never comes on now. it makes driving the truck alot more enjoyable. it now only comes on when towing something or if its very hot outside.

This seems to have become a very debatable topic, outside this thread. I am aware of the conventional wisdom, loud fan, good cooling, etc. I never really bought into it, and in trying to help in OH remedies, that fan always stuck out in it's operation, as something that was trying to tell us something.

The whole thing that started this for me, was the crazy hatched notion that hearing the fan comme on at 70 mph, running mt was somehow normal. Didn't work for me. Pressing the issue, we have conclusively measured airflow through the stack and discovered

1.) the chevy had about zero speed induced airflow across the cooling stack
2.) the GMC has marginally better flow

Neither is enough

and we are talking flow with the fan disengaged. So naturally, with the fan about the only source of air movement over the stack (in some vehicles) then it is going to be a nuisance, and cooling will be sub par, as we know it to be (overheating would suggest poor cooling as a possible cause)

Exploring further, we found a number of deficiencies in the stack design that are easily improved. I won't bore you with that here. They have been hashed out tin the various OH threads. The simple answer is that the fan is not very effective unless it is pulling air over the heat exchangers it was meant to assist, keyword assist. Much of the air coming over the fan, never goes through the rad, and some of the air that does, originates in the engine bay, as hot 220 degree air. It dilutes ambient air with higher energy air that does not cool as effectively.


I'll leave you with that thought, hope it peaked curiosity. If you think something isn't right, maybe it isn't. Just because someone says "always been that way" don't sit still. That is our biggest impediment to progress, the reluctance to buck conventional wisdom.

Mechanical fan noise sucks!

I live in Arizona and we have had several days above 110 degrees this summer. I only have 800 miles on my 05 and noticed how often the clutch is engaged on the mechanical fan. It is the loudest noise in the cab of the truck by far. I was thinking of going with the Flex-a-lite dual 15" fans. I have used them on my Supercharged Z-71 for a year and had great luck with them and there is no noise in the cab at all. Anyone out there that has tried Dual electric fans on thier Duramax Diesel please chime in with your opinions. Thanks

Regards,

I'm new to diesels, but was looking forward to towing my toybox to the river this weekend. My toybox only weighs 7k and the truck has 2k miles of break-in complete. As I left San Diego through the grade, the fan kept kicking on and slowing me down to around 45 mph, once on the flats in the desert, same problem, the fan almost never stopped. Not only is this irritating, it is un-nerving, as I purchased this truck to tow, now I wonder if it's reliable? Any suggestions? The temp was 220-230, the tranny stayed around 200, the only mod I have done is 285 tires and I drive like a grandma going to church! Do you guys think I'm going to have overheating problems in the future?

What kind of Truck, help us out.

Idahofox

Mechanical fan noise sucks!

I live in Arizona and we have had several days above 110 degrees this summer. I only have 800 miles on my 05 and noticed how often the clutch is engaged on the mechanical fan. It is the loudest noise in the cab of the truck by far. I was thinking of going with the Flex-a-lite dual 15" fans. I have used them on my Supercharged Z-71 for a year and had great luck with them and there is no noise in the cab at all. Anyone out there that has tried Dual electric fans on thier Duramax Diesel please chime in with your opinions. Thanks

Regards,

Rather Hear It than Smell It.

MHO.

Idahofox

the clutch fan will come on with conditions like you are mentioning, there is no way around it and its not a problem - the engine temp WILL rise above normal when pulling a grade but SHOULD settle back down after that - it shouldnt stay above normal too long if its running correctly. Now if it is staying above normal and you are not pulling a grade or hammering it then you might have a problem. Same thing goes with the tranny temp, it will go up but will go back down if all is well with the truck. Hope this helps and good luck

yeah, but he is seeing 220-230 temps.. way too hot in my opinion. My 03 rarely goes over 205 in dead hot summer (Mohave Desert well into the 115 range pulling 11000 up a grade..) Fan could be barely heard, temp in the 205 range (attitude monitor).

Somethings not right with the 05's. Over 50-60 mph you shouldn't even really even need a fan to engage..

sorry Idahofox, the truck is a 2005 duramax 4x4, LT crew cab. The truck runs great in town and all over without towing a load/trailer, but once weighted down in the heat the fan almost never stops.

sorry Idahofox, the truck is a 2005 duramax 4x4, LT crew cab. The truck runs great in town and all over without towing a load/trailer, but once weighted down in the heat the fan almost never stops.

If you have read the Over Heating threads, you may notice that the Chevys have more air flow problems than the Jimmys. We have a feeling about what is wrong. Follow with us.

230° is realy not To hot, this is a diesel and they are different.

The '03 is a different Horse, that's what I have.

Idahofox

Is the 03 grille worse or better than the 05 grille (Chevys)?

I towed 7000#'s at 75-80+ in 95-105F for 1300 miles a couple of weeks ago with only a couple thousand miles on my stock 05 Chevy Crew Cab 2500HD. My clutch fan NEVER engaged on the highway, only engaged leaving a gas station or right off a stop light for a few seconds, even going up the hills in Kentucky, etc. at high speed. Trans temp never above 200F, water temp 195-210F. I was pleasantly surprised as I had read about the overheating problems before making the trip.

I realize 7K#'s behind me is not what a lot of you guys tow, nor, the hills from MI to TX I saw is not exactly the Rockies, etc., but I was a bit concerned after reading some of the posts. I am not saying people don't have problems, just reiterating what I experienced. Take care. Dave

My fan noise comes on even when it is 30 out side. It comes on when ever it feels like it when it is snowing or butt hot. Something is not right.

230 sounds too hot to me, especially only pulling 7K

Supercharged,
I tried dual electric fans on a pickup once. Worked fine until I hitched a load to the truck. Absolutely couldn't begin to cool it. Electrics can't pull nearly the CFMs to cool when it's working hard. All I can say is, if you put the electrics on, carry your shroud and clutchfan with you so that you can put them back on when you start to cook with a load.

I just got a new '05 crew, LT with great expectations of towing. The fan literally blew me away (being a first time diesel owner). I was also annoyed by the loss of horsepower. I have had similar experiences as most other owners. How hard can you push the truck while the fan is on without damaging the truck?

I just got a new '05 crew, LT with great expectations of towing. The fan literally blew me away (being a first time diesel owner). I was also annoyed by the loss of horsepower. I have had similar experiences as most other owners. How hard can you push the truck while the fan is on without damaging the truck?

you can floor it for 30 minutes, trouble is the coolant will be behind you. There are improvements though. Some report, no fan ops after a simple stack sealing and splash guard removal.

the fan is a shocker to a newbie, was to me.

you can floor it for 30 minutes, trouble is the coolant will be behind you. There are improvements though. Some report, no fan ops after a simple stack sealing and splash guard removal.

the fan is a shocker to a newbie, was to me.

I have an '05 4x4 (no skid plates) and I have not had issues towing in summer heat, but I have not pulled mountain grades either. I also do not have the fan noise. I have added the lower air dam (light duty part #) to the front bumper for improved aerdynamics. (it is supposed to be worth a 1/4 mpg on the light duty)

What splash guard are you talking about? The simple stack sealing?

my fan came on while pulling out of the driveway after sitting for 14hrs
Mike