When I started my truck (93 W250 auto AC) there was a squeal coming from the engine. Sounded like a water pump so I pulled the serpentine belt and checked puleys AC, tensioner, fan, alternator and water pump. the water pump seemed to have a rough spot so I changed it out.
Not the problem, still have the squeal.
this leaves me with 2 options either the power steering or the turbo.
When I shut the engine off the squeal does not die instantly but tapers off. I am leaning towards the turbo, any thoughts.
I will get a stethoscope from one of the mechanics where I work and see if I can narrow it down.
Any help greatly appreciated

 

Spray the belt with a little water when it's running. If the noise changes or goes away then that will help narrow down places to look.
Or pull the intake tube off and see if the impeller is hitting the turbo housing.

 

You don't need a stethescope to hear a noise, hold the handle of a long screwdriver against your ear and probe the bearings of the turbo and other suspects with the opposite end, any sounds will be conducted through your ear drum.

Just be careful around the fan and other rotating parts.

I do this all the time even though I have an ultrasonic probe.

Jim

 

93flatbed I should have thought of that myself
Jim Lane I can check the turbo that way and will, I don't have a long enough screwdriver for the ps pump.
Thanks to both for the prompt response

 

Take the Serpentine belt off and start the truck and see if it squeals. I did that to mine and it didn't squeal anymore. Mine turned out to be the A/C Condenser.

 

It doesn't need to be a screwdriver, anything even a broom handle will do although metal is better for higher frequencies the trick is to have the butt end firmly against your head so the vibrations can conduct into your ear.

I use this trick to check motor bearings on pumps even while they are submerged.

Jim

 

I use the screw driver trick all the time.

If it tapers off after you kill it I would suspect issues with the turbo also.

 

Not to hi jack this thread but I'm in the same boat. Did the broomhandle thing and swear it was the water pump!!! Changed it out and thought it went away but it came back and is squealing again. Doesn't do it with the belt off so its not the turbo

 

Using the most common cause method that I was taught years ago, suspect the idler pulley. It is the most common cause of front motor squeal, besides the belt it'self IMHO...Mark

 

Fan clutch? aside from the turbo it`s the only thing that doesn't shudder to an INSTANT halt when the the key is turned.

 

Took the intake hose off and there is no end play and minimal if any sideplay on the inlet end.
Will pull the serpentine belt off again and run without for minimal time check for squeal without.

 

Thanks for all the sugestions, turned out to be the simplest solution removed the serpentine belt and no squeal. Word of advice, don't use belt dressing. Took me 1/2 an hour to clean the residue off the pulleys etc scrubbing with laquer thinner then wiping that off with methyl hydrate before putting the new belt on.
I now have a new water pump with what is probably a perfectly good spare needing only a new o-ring to reuse.
What i thought was a tight spot on the water pump must have been residue from teh belt dressing as well because it now spins freely with no play.
Moral of the story fix the simple stuff first.

 

So, Did you fix the actual problem?

 

rather than belt dressing try out armorall seems to work great and haven't found any side efects yet.

 

Sorry should have been clearer.
Yes the squeal is fixed. When there was no squeal running without the belt i cleaned as indicated above and put on a new belt still no squeal so the problem was the belt