sanchez

Recently, my engine has begun to make what sounds like a rod knock. It begins when I let the clutch out in first gear. (under "load" might be a better description) Once I past 2000 rpm, the sound goes away. I'm new to 911 engines, so every strange sound scares me! The engine runs well otherwise. (4 bar oil pressure at 5000 RPM) Am I hearing a REALLY noisy valvetrain? Transmission? Chain tensioners? (the car was converted to hydraulic" Any ideas?

Todd
911SC

David Porter

My experience with rod knocks is that they are most pronounced when the crank is not under load, i.e. when you lift off the gas.

Brian911

Todd,

I just had a problem similar to yours in my SC. First the bad news, it will probably be expensive. With that said, from what info you gave it sounds like your chain tensioners. To me the noise in my SC sounded like a rod knock or a spun rod bearing but it was the tensioners. Don't drive it at all is my first advice. Being new to the 911's also I only offer this as an opinion based only on my experience.
Just like your car I had heard a slight knock and then it was like someone was inside my engine beating it with a hammer. The car ran like a stallion otherwise and the noise regressed as the rpm's got higher. If it does turn out to be the tensioners, get the upgrade of course.
Good luck and keep us updated.

rfuerst

A buddy of mine just had the same thing on his 1974-911S and it was the tensioners,don't drive it till you have it fixed.

sanchez

Thanks guys. I feel better already. I can deal with tensioners (if that is what it turns out to be). An engine rebuild is a whole other story.

My car was converted to Carrera hydraulic tensioners some time before my purchase, so I'm a bit confused while they would fail. I'll let you know when I find the true cause.