Noise from Engine when it warms up.

[Bigrich51]

Hello,

I just got a 1981 Porsche 911SC Targa that has been sitting for over a year. I was able to get it started and heard a squeal or constant whistle (as in rhythm with the motor turning) from the left side of the engine once it got warm. I checked the oil and have the proper amount of oil as I did check once it was warm. I removed the fan belt and it continued to make the noise once it warmed up again as it does not do it cold. When I started it up the first time it started great then after about 3 min once it started to warm up it started to make the noise. It does not sound to me like a mechanical tap/knock but I am not sure. I have never had a Porsche or worked on one of the motors. I am hoping someone might have an idea of what it might be.

Also when I shut it down and tried to restart it, it would not fire back up. I found that if I gave it a constant little gas it would fire back up any thoughts on this as well? I am thinking maybe just the fuel pump or even the throtle needs slight adjusting as once it did get warm would not idle.

This is going to be a project and am not expacting it to be complete for a while however would like to get it running soon. The carpets were wet from some mosture and had some mildew so will be redoing the interior. I am looking forward to having this as a project and getting it finished. Thanks for your help.

[ossiblue]

You might have an air leak that opens when the parts expand, causing the whistling sound. The fact that you cannot restart the car when it's warm, also points to an air leak of some kind. CIS has many areas that can cause havoc if a small crack opens up. What you might try is to use a stethoscope or rubber tube to try to pinpoint from where the whistling emanates.

Keep us up to date on anything else you can add to this situation.

[pub911]

I had a whistle after changing the CIS airbox boots on my 78 SC and found that I forgotten to tighten a few of the boot clamps. Once tightened, the engine idled back in spec, ran smoother and happily, no longer whistled.

I can't explain your squeal, but If it's in sync with the engine revs, you may want to listen close to your alternator. Good luck.

[Bigrich51]

Ok I have Monday and Tuesday off so am going to get out there and look at it. Where would I be looking for the air leak typically?

[kodioneill]

Around the intake area, also check the pop off valve in the air cleaner box.
I use a two foot long piece of vacuum hose to locate the leak by placing one end my ear then sweep the hose around the suspected area.