Just bought my new 2500HD D/A and have taken it on a trip in the midwest. This thing is just plain phenomenal. One thing I noticed though is that the engine fan always seems to be on, even when I started the motor on a cold morning. Fan just starts up, regardless of the temp. Is this normal? Anyone experience this? I'll be calling a dealership here where I'm staying in the morning, but I thought i would check with the real experts here first. Sorry if this topic has been covered, but I am paying for internet access at a kiosk in the motel and don't have time to look through all the threads. Thanks for any feedback.

It's normal for the fan to be on for a mile or two on a cold morning when the fluid is still thick, but once it's warmed up, it should not be on during normal driving.

Thanks. That makes sense. I wish I could tell if it's running while I'm driving. I've only observed the fan being on while parked.

You can tell if it's on for sure, you will hear it , I just got a new LBZ the fan is a little quieter and sound different but you will Know , I promise you!

Ya... the fan will always APPEAR to be running, but if you were to (have the cojones to) hold the fan while the engine is at idle "cold but warmed up" and compare it to "hot, pushing overheating" there would be a definite difference in resistance.

When hot, the fan locks up and runs at full speed.... sounds like a hurricane under there :)
When it's not "hot", the fan spins, but the resistance of the air behind the shroud is enough to keep it from spinning full speed and drawing a ton of power from the engine.

Interesting. I am brand new to the diesel world, and just picked up my LBZ over the weekend. I am hearing what sounds like the engine fan almost all the time. If it is not the fan, it is something that sounds like it is moving a lot of air.

At this point I figure I ask the dealer in a week or so when I get the oil changed.

Interesting. I am brand new to the diesel world, and just picked up my LBZ over the weekend. I am hearing what sounds like the engine fan almost all the time. If it is not the fan, it is something that sounds like it is moving a lot of air.

At this point I figure I ask the dealer in a week or so when I get the oil changed.

Turbo whistle perhaps? one of the best sounds in the world...:ro)

I would not worry about it for right now just enjoy your trip if you are concerned just pay a visit to your local GM dealer and ask the service manager to come out and give you his opinion. He should be glad to do this for you. Generally, when the fan is on it will roar and may be even give a slight vibration.

have a nice trip,
mark

Turbo whistle perhaps? one of the best sounds in the world...:ro)

I don't think so. I can definately hear the high pitch of the turbo. This is a much lower pitch. My engine fan is moving awful fast at idle to not be engaged. My Jeep would make the same noise with the engine fan but it would shut off in a block or two. The Dmax seems to do it all the time.

Having said that, this is my first truck and first diesel. I could just be hearing things.

I do love that whistle though!

Can you tape it and post the soundbyte?
The Allison forward pump makes a kind of "grindy" whine that you can hear over the engine up to about 40mph or so when wind noise masks it.

The fan is really noticeable when it's locked up. If it were locked up 24-7, I think you'd see a major fuel economy hit.

I took mine to the dealer for this, and just picked it back up today. They told me I had a faulty cooling se3nsor, and replaced it. I didn't check it when I picked it up, but I Just went out and started it, and it is doing the same thing! I'll see what it is doing tomarrow, and go talk to the dealer again.

I wouldn't worry about it until you get home.

I know what you are talking about with the noise. I hear it as well.

I took mine to the dealer for this, and just picked it back up today. They told me I had a faulty cooling se3nsor, and replaced it. I didn't check it when I picked it up, but I Just went out and started it, and it is doing the same thing! I'll see what it is doing tomarrow, and go talk to the dealer again.

I wouldn't worry about it until you get home.

I know what you are talking about with the noise. I hear it as well.

Let us know what the dealer tells you. I know my engine fan is moving quite a bit of air because I can feel the suction at idle if I put my hand on the grill.

The only other noise that I can think of that is similar would be air going throught the intake.

At this point I am not too worried about it. This is my first truck and first diesel so all these noises sound odd to me.

Dave

Ya... the fan will always APPEAR to be running, but if you were to (have the cojones to) hold the fan while the engine is at idle "cold but warmed up" and compare it to "hot, pushing overheating" there would be a definite difference in resistance.

When hot, the fan locks up and runs at full speed.... sounds like a hurricane under there :)
When it's not "hot", the fan spins, but the resistance of the air behind the shroud is enough to keep it from spinning full speed and drawing a ton of power from the engine.

Indeed you would need some serious "conjones" to hold the fan connected to a running Duramax. I can imagine some poor guy with his arms twisted into a pretzel shape muttering, "yep..that sumbichin fan does have more resistance when it's all warmed up". "Hey, can somebody get me a beer?" :muahaha:

didn't get a chance today, hopefully tomarrow.

I took mine to the dealer for this, and just picked it back up today. They told me I had a faulty cooling se3nsor, and replaced it. I didn't check it when I picked it up, but I Just went out and started it, and it is doing the same thing! I'll see what it is doing tomarrow, and go talk to the dealer again.

I wouldn't worry about it until you get home.

I know what you are talking about with the noise. I hear it as well.


There is no cooling sensor related to the fan , there is a fan clutch , perhaps they replaced it?? this fan does run at a reduced lockup all the time , most will run for a short time in the AM on first start , this is normal , you will know when the fan is locked and pulling air it is very loud. I think your dealer is confused .