Engine Squeal?

vesnyder · vesnyder's Garage

Took my '83 911 out today - it was unusually sunny here in NE Ohio!

At idle when I revved the engine I hear a squeak/squeal coming from the engine? Sounds like fan belt squeaking. How taught should the belt be? The fan belt moves in slightly (~1/2") and is not as tight as the AC belt.

Superman · 01-18-2002, 10:17 AM

Don't make it too tight, but be sure it is tight enough. Squealing means it is not tight enough.

dhaines · 01-18-2002, 10:21 AM

Looks OK for adjustment. May need a new one....

ronb · 01-18-2002, 10:22 AM

How tight is tight enough? I also have a(n engine) squeal which only happens with quick acceleration or when downshifting and matching engine speed (ie the throttle blip) - doesn't always happen...I have tried the belt to varying degrees of tightness, maybe I'm not tightening it enough? And should I be carrying a spare belt? and what others?

boyo · 01-18-2002, 10:34 AM

My A/C squeals a bit a low idle - was it that sunny there?

-Boyo

nhromyak · nhromyak's Garage

You should be carrying a spare.

I thought the belt should be loose where you can push it in with your thumb ~ 1/4"-3/8".

I could be wrong, but this is where mine is, and I think mine is loose!

KTL · 01-18-2002, 10:49 AM

Make sure you've got all the shims, they're the right thickness and placed properly. Refresh your memory with the tech. article.

http://www.pelicanparts.com/techarticles/911_fan_belt/911_fan_belt.htm

I'd have at least six (I know the Pelican article only mentions five, but the last picture shows six and mine works), better to have more than less. Belt defl'n. @ midpoint should be 1/2 to 3/4 in.

Craig · 01-18-2002, 11:33 AM

I had this same problem, with the same specs on my 77. There was about 1/2 " deflection, and it was squealing. The 1/2" was in spec, but not tight enough. I think I switched out one shim from the back of the pulley to the front and that took care of it. Now deflects between 1/4" to 3/8", no squeal.

Craig

cary · 01-18-2002, 11:47 AM

I've been struggling with the same thing.
I/you can't find the correct size. It is spec'd for a 9.5mm wide belt. All I can find is a 10mm. I've ordered a couple and both were subbed with a 10mm. wide. I've also replaced the pulley.

Still sounds like a supercharger wind up. But it bugs the s*** out of me. Warmer weather, it isn't quite as bad. But I'm paranoid about over tightening it.

Jdub · 01-18-2002, 11:48 AM

The fan belt is just tight enough when you can turn the pulley nut and the fan belt turns as well. If the belt does NOT turn, pull a shim from the center and put it outside.

By the way, a squeal from the engine *can* be a broken stud as well, esp. on hard acceleration, so it dupes the symptom but may not be the cause. Hope I am wrong here obviously!

John

Jim Sims · 01-18-2002, 12:25 PM

There's also the opinion that in order to maximize accessory bearing life v-belts should be on the verge of squealing. Tight enough not to squeal under normal operation but loose enough to squeal under extreme acceleration or during cold operation. This will wear the belt sooner and polish the pulley groove but supposedly prolong bearing life. My 76's (updated to 11 blade) fan belt started to squeal whenever vigorous acceleration occurred. Very irritating; so a shim was moved from the inside to the outside.

Jim

stuttgart · stuttgart's Garage

Where at in NE Ohio are ya?

vesnyder · vesnyder's Garage

Stuttgart - I live on the west side of Cleveland, in Lakewood.

Despite the sun, it was very cold. I am going to wait until it warms a little before I adjust the belt. Probably take out one shim.

Thanks for your input!

911pcars · 01-19-2002, 05:25 PM

When a drive belt squeaks, it's usually because it's slipping. If the rubbing surface of the belt is glazed (shiny), it will tend to slip (and squeal) even though it has enough tension. Take a look at the belt. A replacement (cheap) might be the cure.

Sherwood Lee
http://members.rennlist.org/911pcars

Superman · 01-19-2002, 09:25 PM

You can get belts too tight, and this is hard on the bearings. If it squeals, it is either not tight enough or the belt should be renewed. I've come to believe that the belt shoudl be tight enough to turn the engine by turning hte alternator, OR ALMOST SO. In other words, the belt may be tight enough if it does not turn the engine. Sometimes I have to push on the belt to give it a little bit more traction, in order to turn the engine. And the belt is still tight enough.