I have a 2003 F-250 V10 auto with 36,200 miles. The other morning I started up the truck and within 30 seconds or so there was a ringing sound comming from the engine compartment. It varied in frequencies. This lasted for about 1-2 minutes and went away. That morning it was about -5 below zero. Drove to work (about 30 miles) and everything was fine. Started it up after sitting at work for 9-10 hours and everything fine. By this time the temps made it to about 15 or so. We had a few mornings that were in the 20's and no ringing sound. This morning with temps below zero again, the ringing was back. Not at startup and idle but while driving with foot in the throttle. It was slight but noticable. Letting off the throttle made it stop. This only happened while the engine was cold. The water temp. guage was still not reading any water temp. As soon as the water started getting anykind of heat....around 5 minutes of driving the ringing sounds was gone.

Now this sound only happens when the engine is stone cold. Of course I am at 36,200 miles and out of warranty. What the heck is it? I do have the banks power pack exhaust kit.....It does not seem to be comming from any of those components.....I think it is in the engine compartment some place.

Any Ideas?

I posted this thread originally in the V10 forum but I think it is not a V10 problem.

OK, I narrowed it down to the front of the engine.......one of the accessories are making this noise......the best was to describe it is to whistle and hum at the same time and you got the sounds exactly. Could it be a pulley? the fan? a bearing ina water pump? I have worked and many mechanical engines and have never heard anythink like it.

 

Sounds to me like an alternator. Just my .02 cents. Kinda hard to diagnose without being there, but at least keep an eye on it.

 

There is a rubber tube that comes off the throttle body and down to the PCV. It makes a 90 degree turn and I know that sometimes these rubber hoses wear through creating a whistle. This past summer, I had a whistle in my engine compartment and the truck was running funny. I found this 90 degree elbow tube had split.

Nate

99 Reg Cab V10