High Pitch Squealing Noise Coming From Engine

[williampeyton]

1997 PORSCHE BOXSTER 2.5 H6 ENGINE 5SPEED

Hello, how is everyone doing I have a 97 porsche boxster, my car makes a high pitch squealing noise. In fact it makes the noise around 900-3500 RPM and it only makes that noise after the engine is running at normal engine temp. While the engine is cold it will not make the noise. I first thought it was the water pump and had it changed out and the noise still persits. my mechanic stated that its the alternator: cause for my model year (97) they did not make a free spinnning pulley alternator which came much later. My mechanic said because the lights are on and radio is on it puts a load on the alternator during idleing speed or the problem is the two pulleys. I changed out the belt and tensioner, because it was makeing a sqeaky noise when I first turned on the vehicle and the engine was cold. this was at 101,000 miles now the car is 111,000 miles and this noise is annoying. the two pulleys or on back order and I will not recieve them until april so when I change them out I will let everyone know the outcome. Since my mechanic cant pinpoint the noise Im going to change out the pulleys first, thus its cheaper than the alternator. if anyone else has this same problem, please let me know so that I dont have to pay for something that does not need to be done or at least done now, thank you

[RFM]

Why not leave the engine idle for a couple of seconds without the belt, if the squeal is gone you know for sure it's related to the attributes driven by the belt, if not the engine/clutch assembly should be suspected. You should not have to be a mechanic to do that.

[wvicary]

One other thing to check is the AOS. Remove the oil fill cap with the engine running and if the noise stops your AOS has failed.

[williampeyton]

Thank You, I will try that I prey to God that it has nothing to do with the engine. I changed my clutch and fly wheel assembly 2000 miles ago, so I think that is good. I will try that and let you know

Thank You, for the reply I tried that. The noise still remained I even gunned the engine a little and like before as soon as the engine is below 4000 RPM the noise comes back and is louder than the engine at idle speed. I did notice that takeing the oil fill cap off made my engine run harder in idle speed, in fact the idle speed flectuated from 800 - 1000 RPM as if someone was gunning my engine. the exhaust even came out faster. But as soon as I capped it the gunning and fast exhaust stopped. So its not the AOS.

[williampeyton]

Hello, I found out the true problem why my belt was squealing, my radiator fluid resvior was leaking right on the belt. As soon as i got a new resvior and changed the belt again, no more squeal so check to see if your resvior is leaking. my mechanic checked my pulleys and belt tensiors, plus he even checked the timing belt tensiors too. So if your radiator fluid is constantly low and you have to refill it every once and a while. It may be leaking, my leake was a very slow leak and it leaked directly on to the belt.