'79 911 Turbo Noise

Germaneighter · 11-04-2002, 06:43 AM

I just aquired a '79 Turbo with 63K miles. (I am new to Turbo ownership but have owned (3) other 911s.)
I have a couple questions/concerns:

1.) When the turbo seems to start kicking in, (around 3500RPM), there is a knocking noise. It is somewhat intermitant and sounds like an exhaust pipe banging against something. I have not had the chance to keep my foot in it for very long but it seems to diminish somewhere past 4500 RPM. I checked the exhaust system and all seemed tight. Is this a common noise? I have read about the "Y" in the exhaust pipe cracking and needing welded often. Mine looks as if it has been welded.

2.) The boost gauge does not work. I was told it needs a new sender. What and where is it and how does it work? Mechanical or electric impulse???

3.) Every time I have started this car after it has set for 24 hours, I get a puff of oil smoke. Re-starting when warm does not produce this. Is this common?

4.) Compared to my '79 SC, the brake pedal is very stiff....almost like the power assist is not working. Brakes seem OK when I bare down hard on the pedal. It has cross drilled rotors. Are these stock? Any comment on brake feel?

I would appreciate any feedback.

DL Geer

silverc4s · silverc4s's Garage

DL,
You DID have a PPI done on this car before you plunked your money down, right?
These are very appropriate questions for the wrench that certified the car for you, as part of your learning process, and his back up of his inspection...

Germaneighter · 11-04-2002, 07:32 AM

Actually, the deal is not done. I am getting this car from a freind that, unlike myself, does not have to worry too much about finances. If there is a major problem, I am not stuck. Thanks for the concern.

Now, having said this, any technical advise would be greatly appreciated.

DLG

silverc4s · silverc4s's Garage

I would say that ANY TIME a Porsche changes hands, there should be a independent mechanic in the picture. ESPECIALLY if buying from a friend....
Get a wrench to look the car over & evaluate that noise right away, before you guys disagree on WHEN it started making that noise.....

ps. I, personally - KNOW NOTHING - about turbo motors, first hand..

930fan · 11-04-2002, 07:52 AM

Welcome to the turbo club. You will find it as rewarding as it is expensive!!

1) This is not good news. Have it checked by an experienced mechanic immediately as knocking noises can have very expensive consequences very quickly. From your description, it doesn't sound like detonation or pinging but don't take the chance.

2) The sender is electric. Try Pelican for a new one.

3) Yes its common and perfectly normal. If it doesn't go away after start up then it becomes abnormal.

4) That is normal too. The level of assist is quite low in the turbo. You will appreciate it after a while because it provides good feel for lock up and makes heel and toe-ing easier. The brakes tend to be a bit useless when cold too.

Good luck with your new purchase.