I have a 96 with a 305. It has 270k on it. I replaced the injector spyder about 5k ago and it has been running great. But...Last nite it developed a whistleing noise. Sounds like a turbo spooling up(very faint) when I press on the gas and goes away when I let up. I also have a bit of pre-ign. I suspect some sort of vaccuum leak but have been unable to find it as ir only seems to do it under load. The whistleing is not present or detectable with the truck in the driveway running with me looking under the hood.

This is the only vehicle I own and my daily so I've gotta get it fixed.

Thanks,

Junk

 

Guess I'm on my own...

Regards

 

There is not much here to go on. The only answer can be if you get a check engine light. That will tell you the problem.

 

I suspect vacuum leak also. Use starting fluid, with it running, and hit suspect areas i.e. intake manifold, hoses. If you have one that will find it for you. What it sounds like is intake manifold leaking when cold. You also might retorque the manifold bolts, following that correct procedure.

 

if you rev it in the driveway in gear do you hear it?

 

Already tried the spray trick...no noise detectable when reved in thr driveway...no check engine light...retorqed the upper and lower intake...??? only symptoms are the noise and a bit of pre-ign. when you take off from a stop. It does it hot of cold???

Regards

 

It only makes this noise when it is moving?

 

yes,at about 2k rpm and above and it stops when I lift off the gas pedal. It's a very faint noise and I notice it because I'm aware of what goes on with this truck as I drive it every day.It's a new noise and so is the slight pre-ign when the gas is first depressed. It only does it when being driven and will not present when sitting still and revving the engine. I'm at a total loss for what this could be.

 

Still making the noise...I have exhausted all the ideas in my brain as to what this could be...Anybody??

 

Is it a mechanical clutch fan (radiator)?