bradler

Ok, maybe not that bad, but i have noticed a squeeling sound coming from under the hood, most noticable at idle. It seems to come and go, kinda figured it was just the serp belt or a pully somewhere going out (mine has always done the belt chirp on shutdown) but i popped the hood the other day and listend closely and it really sounds like it is coming from in the vicinity of the injectors, by the intake manifold. I can't think of anything there that would make a high pitched squeel? Never heard of bad injectors or valves making this kind of noise. Anyone have any idea what this could be? Truck seems to run fine other than maybe blowing a little more black smoke than usual.

Thanks, Ryan

SOhappy

Paddle faster, I hear banjo music!

bradler

Problem is it sounds like me trying to play banjo, more like stranggling cats than music at this point....

Any other ideas?

Hawglip

Mine is doing the same thing lately. I asked the dealer and they said it probably is the serp belt. Says not too much else that will do it.

BigIron70

Check hose clamps on boost hose, also bolts on top of intake make sure they are tight and not missing any bolts. Check exhaust bolts make sure they are tight and not missing any. Good Luck

Totallyrad

Most likely the belt. The cheapest way I know to check that is to buy a small can of belt dressing and apply a little. If the squeal goes away, you've got your answer. I'm guessing the belt is original. If you end up changing the belt be sure to spin all the pulleys and check for bad bearings while the belt is off, especially the tensioner.

ThatGuy34

mine was doing the same thing, and the belt dressing stopped it

bradler

Going to try some belt dressing and check for loose/missing bolts. Serp belt is fairly new, had to replace it after the old belt jumped a few ribs off the front and came apart wrapping aroud the fan hub (real fun to remove). New belt then began wearing along the front edge to where you could see the cord within 50 miles. Flipped the belt around the other way and painted the pullies to see where it was rubbing, now it seems ok. All pullies seemed fine but the one on the steering gear box seemed to have some play in it....

Does anyone remember a TSB for an over running pully to help w/ serp belt problems?

bradler

So i applied some belt dressing and checked all intake manifold/ exhaust bolts/clamps and nothing. Took it to the best diesel shop in town while it was squeeling and they have never heard such a noise before. The tech agreed with me that the sound is coming from in the vicinity of the rail/ intake manifold. It only happens at lower rpm and indle, goes away with higher rpms. Sounds like a vacuum leak whistle/hiss almost. So we came up with a list of likely suspects;

-Intake manifold gaskets, i think there are two or three, could have a small leak? No boost gauge so i can't tell if i'm loosing boost.

-That releif valve on the rail that pops if rail pressure is too high. Could it be letting a little fuel by, causing the whislte?

-How about the crankcase breather valve on the valve cover, could that whistle if clogged/malfunctioning?

Any other idea?

Thanks, Ryan

Totallyrad

Get an engine stethoscope then you should be able to narrow it down. You can pick one up cheap at most auto parts stores. http://www.northerntool.com/webapp/w...le&cm_ite=auto