Wanked_FC

iTrader: (1)

I get a strange sound when the engine is over 4k rpm's. I think it could be the alternator or the turbo scraping against the housing. I have a little video of the engine revving and the sound. ANy ideas?

Video is about 4mb, please download rather than stream =).

Video

White 87 13B

EEWWW That's horrible...I don't know...Hmm...do you have a boost guage hooked up? If so, do your readings change at high RPM?

As far as the Alternator...try connecting a voltmeter to the battery to see what happens when you rev it up...does the meter bounce around? This is what we did in school the other day...the Alternator was making a bizaar noise at 4500 RPM on a Fire Bird and the voltmeter was bouncing around...

Take a stethoscope...like the one the docs use...put the ear pieces in and then take a cloth...place it over the alternator, do not obstruct the pulley, hold the end on the alternator and rev...then, do the same with the turbo...that is a good way to isolate the issue! Hope this helps.

WAYNE88N/A

Take the alt belt off, and crank it up again, see if ya get the same noise, that'll rule it in/out...Just don't let it run too long without the batt charging...Do the same with the air pump, if it's not the alt...

Wanked_FC

iTrader: (1)

not to mention the waterpump wouldnt be turning

deltr0n`

sounds like the belts to me... are they old? replace them, or try to tighten the alt slack and see if it still happens.

Sesshoumaru

iTrader: (1)

clutch fan is suppose to kick out about there IIRC.

might wan to try to remove that fast (only 4 10mm bolts)

speedholes

It does sound like a belt... but have you done any work on the secondary fuel rail or injectors recently?

gildardo

sound metallic to me.

Kenteth

It sounded to me like that belt screech happened at teh same time the clutch fan tried to engage. Engaging means putting a **** load of load on the waterpump pulley. The waterpump pulley has two belts, one might be slightly less tight causing it to slip.

I had the same problem when I ditched the Ps/AC/ and air pump. the dual alt belts worked great accept one groove allowed for a belt to slip because the other groove was slightly larger. This meant one belt will slip./

Remove that clutch fan to take the extra rotating weight off. The slip won't happen.

I had a constant screeching no matter how much I got those belts tight. I used a crowbar to make sure i got them snug. Still screeched. I reinstalled my efan, problem went away instantly...

SureShot

I agree - the fan pulley is slipping.

Possible causes:
1) loose alternator belt
2) worn alt belt (riding in the bottom of the pulley groove)

The fan clutch may or may not be an issue, but you didn't rev it so high that even a locked fan clutch should slip the belt.

Wanked_FC

iTrader: (1)

It was revved to about 4500rpm in the vid, I'll double check all my belts today after work. I think my alternator belt was loose.

spdfrk50

My Bronco did the same thing . I thought it was the belts and I changed them just to find out the clutch on the fan was bad.The bearing in the clutch would only squeel above 3500 rpm.