Porsche 912 - Engine tapping noise, what could it be?

tjbates · Post by **tjbates** » Fri Jun 24, 2016 4:03 pm

Hello,

I am trying to get to the bottom of what this noise could be?

https://youtu.be/gEYKqjbyPMw

You can hear it between 0:10sec - 0:14sec.

My Porsche 912 runs great except it has this 'tapping' noise during acceleration whilst under load.

I've checked the compression, timing (28degrees @ 3500RPM), valve gaps, float levels on my Solex 40s.....

Could it be a knock/ping, associated to lean mixture? I'm no mechanic and would really appreciate some guidance.

Thanks.

Tom

neilbardsley · Post by **neilbardsley** » Sat Jun 25, 2016 10:25 am

Does occur when accelerating or slowing or all the time? How about if the car isn't moving and you rev the engine?

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tjbates · Post by **tjbates** » Sun Jun 26, 2016 11:05 am

Hi Neil,

It only occurs when the engine is under load during acceleration.

I can rev the engine without a problem whist the car is stationary. During declaration I get a slight burble/backfire (which I think is normal?).

Tom

Nige · Post by **Nige** » Sun Jun 26, 2016 12:15 pm

Difficult to tell, sure it's not the gearshift linkage or something rattling as the drivetrain moves under load? Essentially are you sure the noise is from the engine.

cubist · Post by **cubist** » Sun Jun 26, 2016 12:22 pm

Backfire? Lose silencer jointing or heat exchanger? Rock the tips up and down for excessive movement... when it's cold.

neilbardsley · Post by **neilbardsley** » Sun Jun 26, 2016 3:52 pm

What max advance do you have?

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Winston Teague · Post by **Winston Teague** » Mon Jun 27, 2016 6:46 pm

Leaking exhaust flange gasket?

cubist · Post by **cubist** » Mon Jun 27, 2016 8:22 pm

This ^^^^^^^^

tjbates · Post by **tjbates** » Mon Jun 27, 2016 9:05 pm

Nige, i'm pretty confidant it's from the engine as I've ran with 2 different transmissions (4-speed & 5-speed) and the noise is there with both.

Cubist & Winston Teague, i'll check my flange gasket. I'm not sure why i find the word flange funny

Neil, i've got 28 degrees at 3500+ RPM...

Winston Teague · Post by **Winston Teague** » Wed Jun 29, 2016 9:08 pm

[quote][
Cubist & Winston Teague, i'll check my flange gasket. I'm not sure why i find the word flange funny

/quote]

Well Master Bates, it's all about mating surfaces. The flange around the opening, or port must be in good condition or leakage will occur. A leaking flange is rarely good news........

DDK - Die Deutschen Klassiker

Porsche 912 - Engine tapping noise, what could it be?

Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?

Re: Porsche 912 - Engine tapping noise, what could it be?