I'm gonna keep going with my new owner questions. I just got my truck back from having the head gaskets replaced and noticed that there is a high pitch whistle coming from the engine when it's at low RPM. It goes away when the RPMs are higher but it doesn't matter if it's cold or hot. Is this possibly water pump bearings or alternator? It's hard to pinpoint where it's coming from.

 

Might be best to pop off your serpentine belt, and spin everything and listen.
Lol if I haaaaad to guess I bet the tensioner arm is it.

 

Ok, I'll take a closer look at it with that info. If it's something quick like tensioner adjustment I can prob handle that. If not, back to the mechanic. Thanks for the response.

 

Just a thought but could you have a vacuum leak? Manifold vacuum is at idle and goes away as soon as the throttle body opens which might explain the disappearance above idle. Easiest way to check would be carb cleaner lightly sprayed in the direction of the whistle to see if it changes the idle. If it does, could be a vacuum leak...good luck.

 

There is no throttle body on your motor and there definitely isn't a carburetor. You have an injection pump that controls how much fuels gets injected into the cylinders. There is no butterfly valve either. These are parts to a gasoline motor. Diesel motors do not create vacuum because the turbo is forcing air into the cylinders as the intake valve opens. That's why you have a vacuum pump on the front of the motor. You need to get under the hood and poke around a little and try to locate the area the noise is coming from. The mechanic may have not installed all the vacuum lines properly. I cant say for sure if this would make this noise because I have never dealt with that before. I have seen on larger motors where the turbo plumbing wasn't sealed properly and the "whistle" was actually the forced air being pushed out of the plumbing. You may have to pull the doghouse off to make sure the turbo and intake plenum are all sealed up. If it is a chirping type of whistle, it may be a head gasket leaking.

 

Sorry, I was assuming yours is a 6.5TD as most are. If it isn't, then disregard my previous post. Sorry about that.

 

No problem, it is a 6.5TD. I just had the head gaskets replaced and this noise was there when I got it back. It's at the shop again now to have them check it out and do inspection. I'll let you know what the problem is just in case you come across it again. As I get more hands on with this truck you guys are invaluable with the info, thanks.