My 914 developed this awful tapping sound when engine is revving and it can only be heard from inside the cabin. I have tried to hear it from up top and only hear a strong revving engine. I appreciate any suggestions as to what it could be.

How about from under the car? Could be an exhaust leak or the heads could leak.


PS:

I will check it out. Thanks for the suggestions. Thanks, great forum.

Head leak will be more of a squeaking sound.
Adjust you valves.
Check your timing.

If the tapping/banging sound is getting progressively louder then that's a bad sign, as in rod.

. Rod about to go. Exhaust will not make a tapping noise.
Good luck

How long have you owned the car? Do you know the history or is this something you just bought?

There are some basic things to check before you panic. If someone at one time put a jack under the exhaust it's possible to cause an exhaust leak. Exhaust studs will pull out. Another thing to check is the fan. I had one come loose once and it made a weird knocking sound. With the car in gear reach over the housing and check to see if you can rock the fan. And of course the rockers need to be checked.

Another think is the cam gear rivets hitting the oil pump shaft. Can happen as the oil pump fails. That was what my engine with a "broken rod" turned out to have. Unfortunately they decided it was too expensive to fix and left it out in the rain. You can do the fix with the engine in the car.

Work it through by process of elimination. Good luck

Good one, I did have a friend who forgot to shift into 4th (loud music, real loud) and the cam rivet holes ovaled, making a lot of noise and weird sounds because the cam timing was changing by about 20+ degrees.

Well, I have owned the car for a long time, 1990 and bought it from original owner as a pretty clean running project/toy that I have always wanted. Then life happens and it was put on the back burner and never used much. Been using the car more over the last couple of years and i remember when it happened over the summer. Pulling out onto the highway after fueling up (not taching out), something let go and started this tapping which I can only hear inside the cabin. My (hope ) thought is something to do with the fan slopping around so I needless to say am glad you mention that. IF so can that be addressed with the engine in??

It's unusual for the fan to come loose. Usually it happens if it is improperly tightened after a rebuild, failed to install the big washer on the crank bolt or someone before you had the engine out and fan off and failed to get it tightened properly. As long as you have had this car I'd say that's not likely the issue. To answer your question yes you can tighten the fan bolt by reaching over the housing. If it just happened, you noticed the noise and tightened it up promptly it could be fine. But I would watch it close after that. The fan can damage the taper on the crank.

Stuff can fall down into the fan as well. At this point I'm not convinced that the issue.

...something is definitely banging around in there. Sounds like something came loose.
Plenty of stuff that could considering ’76 smog stuff somewhat removed, and AC installed.
Not that it's messy from up top, but the tin being cut up and stuff relocated (ECU), I “think” something is just loose.

The engine sounds great from up top and the exhaust sound nice too.

Probably easier to tell from bottom, once Mark gets some heat in his garage or he drives to my heated garage,
We’ll get it up in the air and investigate further.

Ray, I am not invited to the party?

Buy a cheap stethescope and start touching it to different parts of the engine.

of course you will be....Len wants to do some general maintenance and Mark want to find his gremlin. I'll try to coordinate a weekend day, hopefully you could make the drive.

...it actually sounds like a piece of tin is knocking on the firewall, so don't think it should be tough to find once looking from underneath.

Party? When?


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Egads

Bet ya she's 'tons of fun'

...oh well....can't open this thread at the office any more...or at home for that fact....

Great job Joe.