Well, I| finally got to tow my travel trailer for the first time and I have mixed feelings about it. I towd my trailer from Lake Powell UT to Riverside Ca. I really have some mixed feelings about my truck right now.


First of all, the power was great!!! My truck had 3000 miles on it when I began my trip and I only pull a 6000lb trailer. I figured I would have no problems at all.

Second: I had no overheating issues at all which was a good thing. The temp outside was arround 90-100 the whole time.

Now for the bad news:

The stupid fan would run for 5-10 minutes at a time then stop for two minutes only to turn back on for another 5-10 minutes!!! This really pissed me off. The temp gauge never moved from 210 degrees though!!

As a result of the fan running my milage was at 9.5mpg until I had a forty mile downhill run from Victorville which brought the average up to 11.4 mpg. What can I do to keep the fan from running all of the time? Will the stack sealing mod fix this? Any help would be appreciated.

FYI, My truck averaged 17.4 mpg from California to St George Ut to pick up my trailer and my truck is getting 14 mpg on average city driving.

First, Lake Powell is a little slice of heaven. Second, yes the stack sealing and shrouds will improve fan actuation. I hear mine when climbing or occasionally on very hot days towing the 5ver, rarely ever unloaded. Check out the overheat solutions, stack sealing and shroud threads for more intel. JJ

Thanks for the info and yes, I too now love Lake Powell!!
I will be visiting that lake for many years to come.

I have had my 05 for about 3 months. I use it almost exclusively with my 24 foot enclosed car hauler. (8 to 9,000 I am guessing). Here in Texas us almost always 90+ with not many real hills. Have never heard the fan with out the trailer, and only very seldom with the trailer. First time I heard it scared the bejesus out of me till I figured it out.

I get about 10.5 to 11.5 with the trailer at about 70. Last 500 mile trip I slowed down to 60 to 65 (not much freeway driving) and I actually got 12.3. Guages run like yours with absolutely no indication of heating whether the fan is on or not.

Is there a programming difference or some other physical parts regional difference in these trucks that we are unaware of? It is awefully hot here in Texas and many people tow heavy, even RDL proved you don't need the altitude or the hills to run one hot, and we have some nasty hill country as well, yet you never seem to hear of a Texas truck that gets hot at all. What Doug is saying seems to be the norm down here, we only hear the fan just seldom with even a trailer and next to never without it, where other areas say they get the fan always even in just traffic.


Is there a difference in South and East and North and West Dmaxes???????

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Tx... The 500 mile trip I described was from East Texas (East of Dallas) to Houston and return. And I want to tell you it was HOT..DAMN HOT in Houston...

You may be onto something with the regionality.. Did you know the "employee pricing discounts" were different depending on what region you were in??

No I wasn't aware of the employee pricing differences. I know in the past they have had different regional discount programs, but unless you really get around you would never know it. The employee thing was pitched as a national thing but who knows that could be the impression given via localized advertising.

I snapped a pic last week of 105* on the outside temp measurement in the dash of my Accord Hybrid, and that was travelling 65mph down I-10 from Katy to Houston. So yeah, it gets hot here too, and stays consistently hot a good while. I just don't get why I can't find an overheating truck within even 500 miles of me but when you get out west they are common, as well as more to the north. California emissions? Trucks calibrated for more severe winter operation perhaps? I dunno. Could be nothing, just seems odd.

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We all know how "heat index" makes us feel as compared to the outside temperature. So after spending a weekend in Houston with Heat indexes that were 10 to 14 degrees above the actual temperature, I was wondering if the high dew points that cause them would have any effect on our cooling system in the truck? Probably not. Any thoughts?

Guys,

I forgot to mention that I almost never hear my fan unloaded, even in 100 + degree temps. I sure hope sealing will at the very least cut my fan time in half. Also, my fan 98% of the time came on when I would start going down hill no matter how long the climb was.

On my new 05 I never hear the fan unloaded... Today I just returned from a short 200 mile pull with the 13000 lb 5er and the fan was on 75% of the time...

I was hooked up and left the house with a cool engine. Within 5 blocks the fan came on! This was with OAT of 92 and just going 30 MPH!

My water temp never moved over 210, it never has with even 102 OAT and 70 mph. The Tranny temp moves 20 to 40 degrees and hangs around 190 but has gone to 220 pulling the 5er, BUT with only slow speeds and an easy foot...

My 01 never did run the fan and the 4.5 ran it only 10 to 15% of the time pulling my 11000 lb 5er in the hot part of the summer in the hills of Tenn...

I found a place here in houston that sold me the rubber belt material for the nose shroud and I am almost finished making the parts...

This is a "Houston" truck as have the other two I have owned.. I don't think it will get very hot but it does get hot enough to make the fan run!

Steve

Guys,

I forgot to mention that I almost never hear my fan unloaded, even in 100 + degree temps. I sure hope sealing will at the very least cut my fan time in half. Also, my fan 98% of the time came on when I would start going down hill no matter how long the climb was.

The downhill fan is caused because of the letup in throttle which directly coincides with less water pump flow and a heat spike that results because of that.

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On my new 05 I never hear the fan unloaded... Today I just returned from a short 200 mile pull with the 13000 lb 5er and the fan was on 75% of the time...

I was hooked up and left the house with a cool engine. Within 5 blocks the fan came on! This was with OAT of 92 and just going 30 MPH!

My water temp never moved over 210, it never has with even 102 OAT and 70 mph. The Tranny temp moves 20 to 40 degrees and hangs around 190 but has gone to 220 pulling the 5er, BUT with only slow speeds and an easy foot...

My 01 never did run the fan and the 4.5 ran it only 10 to 15% of the time pulling my 11000 lb 5er in the hot part of the summer in the hills of Tenn...

I found a place here in houston that sold me the rubber belt material for the nose shroud and I am almost finished making the parts...

This is a "Houston" truck as have the other two I have owned.. I don't think it will get very hot but it does get hot enough to make the fan run!

Steve

My TN 05 truck is simalar to yours. My 01 a GA truck was similar to your 01.

My 01 3500 Crew Cab dooley Duramax alllison was the best truck I ever owned. My 05 Crew Cab dooley 4x4 duramax allison is the sorriest excuse for a truck I have ever owned.:mad: I wish I would have never traded the 01 for the 05.

I just got back from the Dealer Monday for the second time for problems with poor mpg, poor power, fan always running, and a first of engine temp hiting 225.Censored

I pulled a skid steer on a flat bed trailer for a total weight of just under 7000 pounds for the dealer. Out side temp was 88. The had the tech 2 hooked up and a service technition in the truck. We pulled 135 miles, mostley interstate. Fan came on 12 miles from the dealer than ran more then 60% of the time. (this is new replacement fan) Engine temp hit 225. Truck down shifted for the slightest of of hill. Biggest hill, maybe 1/2 mile truck could not maintain 70mph even down shifting. Service guy said everything is ok according to the tech 2. Service guy says something is wrong though, they just do not know what. They did a few snap shots with the tech 2 and are sending to GMC for analysis. MPg average pulling 7000 pound was 9.1:eek:

Just for referance the hill the 05 cant pull at 70 with the 7000 pound trailer, my 01 routinely pulled a 12500 pound RV up at 70 mph in OD! My 01 averaged 11.7 pulling 12500 pounds. 01 engine temp never got over 215 pulling 12500 up a 6.5% grade in 98 degree weather and fan almost never ran.

This 05 is my 7th straight GM 1 ton truck. In fact I have only bought 1 new vehicle in my life that was not a GM. If they do not fix it it will be my last GM truck and most likely my last GM anything.

This 05 is my 7th straight GM 1 ton truck. In fact I have only bought 1 new vehicle in my life that was not a GM. If they do not fix it it will be my last GM truck and most likely my last GM anything.[/quote]

You think you got problems now, get yourself a ford or dodge, then your troubles will really start.....

This 05 is my 7th straight GM 1 ton truck. In fact I have only bought 1 new vehicle in my life that was not a GM. If they do not fix it it will be my last GM truck and most likely my last GM anything.

You think you got problems now, get yourself a ford or dodge, then your troubles will really start.....[/quote]

Maybe, however my neighbors 05 Dodge with the 5.9 TD and straight drive pulls the 7000 pound trailer I used to pull for the dealer every day. He averages 14 plus mpg pulling it. He has no cooling fan running all the time. It does not over heat. In other words it can be used to work like a truck.

FLSTFI Dave, I don't want to hijack this thread but there are things you can do to help. GM should have resolved this problem over a year ago. They did not, so we have to. 225 degrees is not that hot, but combined with the other things you mention lead me to believe the "stack seal/oem valance/air box/chip" mods would fix it, or at least help it drastically. TX is also working on some stuff that might help.

I love my GM trucks and will not likely switch. All brands have their problems. The fact that the LLY is hit or miss makes it harder to pin down their problems.

I had a long talk about this with GM customer service, and after she said she has NEVER heard of these problems ( which a lot of us including me have) she did say EVERY time I take it to the dealaer make sure they put these problems on the work order so they can "code" them. She said even if I take it in for an oil change make them put the info on the work order.
It amazes me that a lot of our trucks run exactly the same way, get hot, fan runs ALWAYS, poor milage, and they have the huevos to call it NORMAL !!!!!!

It is definately hit or miss. The fan rarely runs on my 05. If I'm running hard through traffic with the Edge on 5, constantly stopping and starting, it will come on for about 30 seconds when pulling away from a light, after that nada. Pulling around town I have never had it come on, even pulling a 10000 lb boat through the middle of a June heat wave (low 90s with 90% hummidity). For some reason though, it runs when I first start the truck in the morning for about 1-2 minutes, usually going off by the time I hit the end of my street.

Did the "thermostate" that is part of the fan change between 01-03 and 04-05s?

Are the actual fan components the same PN as 01-03 on the llys?
Same diameter, same number of fins?

Is it possible a design change in the fan has changed the amount of air flowing through the radiator, across the engine in a "natural no load fan spin"?

FLSTFI Dave, I don't want to hijack this thread but there are things you can do to help. GM should have resolved this problem over a year ago. They did not, so we have to. 225 degrees is not that hot, but combined with the other things you mention lead me to believe the "stack seal/oem valance/air box/chip" mods would fix it, or at least help it drastically. TX is also working on some stuff that might help.

I love my GM trucks and will not likely switch. All brands have their problems. The fact that the LLY is hit or miss makes it harder to pin down their problems.

The Technician at my Local GM dealer says I am by no means the first to complain about the Fan / engine temp / or poor mpg. They have at least 10 other customers at this dealership complaining. One is working the lemon law and a buy back.

So GM customer service center knows full well of the problems with them. They just refuse to accknowldge it.

Why don't you push for another truck? You might be luckey and get one that works a lot better. If it's the same you haven't really lost anything...well you would have to prove that is has a problem too, but that wouldn't be hard.

Give it a try. You paid for it - you are the customer and have the right to get a properly working product.

The cooling mods are a good thing, but only do them if you want to keep this truck. I don't think GM will fix your truck though. So unless you sell it, do the mods. They seem to be working very well. Good work guys BTW!

I have had my 05 for about 3 months. I use it almost exclusively with my 24 foot enclosed car hauler. (8 to 9,000 I am guessing). Here in Texas us almost always 90+ with not many real hills. Have never heard the fan with out the trailer, and only very seldom with the trailer. First time I heard it scared the bejesus out of me till I figured it out.

I get about 10.5 to 11.5 with the trailer at about 70. Last 500 mile trip I slowed down to 60 to 65 (not much freeway driving) and I actually got 12.3. Guages run like yours with absolutely no indication of heating whether the fan is on or not.
Lol! What a difference towing in UT or the Rockies vs. the flatlands of Tx. I have towed my toyhauler (typically with 3 quads, 100 gallons of water and 25 gallons of gas) to just about all the trails where one can play on in this beautiful state. I am used to the fan running and being obnoxious. I seldom let off the gas pedal and the most challenging summit I have had to climb, I believe was 11K feet tall but the truck never skipped a beat and took at 65 mph. BTW, I have not chipped or piped it yet. I am looking forward to my Edge Juice coming soon!

Anyone who is getting under 11 mpg hiway, would do well to just do a simple flow mod or 2. You can easily reap 2 mpg in extreme tow conditions. The fan is something you don't have to listen to any more (empty), the work has been done for you already, just follow the DIY threads.

I bought my 05 Durmax this summer and I pulled a 13,000LB 5'er this summer from Lake Tahoe to Bend Oregon. The fan ran most of the time Engine and Trans Temps where OK Trans 200 Water 210 until I pulled my Final grade on the way home from Carson City to Lake Tahoe. This is about a 7 mile 6to 7% grade.Trans was in 3rd gear RPM @3100 Water Temp 230+ Trans Temp 240. Outside Temp 90 Truck is stock. I traded in a 1999 Ford 7.3 Powerstroke for this truck. I pulled the same trailer with the Ford and the fan only came on when pulling grades. Love the 05 ride and comfort bur hate the fan noise. I complained to the dealer and got the typical response this is normal.:mad:

Why don't you push for another truck? You might be luckey and get one that works a lot better. If it's the same you haven't really lost anything...well you would have to prove that is has a problem too, but that wouldn't be hard.

Give it a try. You paid for it - you are the customer and have the right to get a properly working product.

The cooling mods are a good thing, but only do them if you want to keep this truck. I don't think GM will fix your truck though. So unless you sell it, do the mods. They seem to be working very well. Good work guys BTW!

I am pushing GMC customer service and the Dealership real hard to fix the truck. I have three documented complaints with the dealer for Fan / engine and trans heat / low power not able to hold od and poor mpg. I also have two certified letters with GMC customer service and phone calls.

I will keep pushing the dealer hard until the spring. Then if they have not fixed my truck I will do the mods. I just feel a truck with an MSRP of 50,000 should need no repairs done by the owner to perform its designed function. It's also not like I am pulling 16,000 with it like it is rated to do. So far 7000 is the biggest load and that stressed the cooling system, killed the mpg and could not hold od on slight hills. The 01 could pull the 12500 up the same route in od, with better mpg and no cooling fan running.

The ther thing is I am working 55 hours a week at my job, then I am finishing up the log home I am building. So I do not have free time at the moment to fix my truck. Nor should I have to, but I know ultimately I will end up having to.