Chattering noise from engine?

TerryBPP · 07-07-2003, 04:47 AM

I have this annoying ticking coming from my engine. Thinking it was a loose lifter I did a valve adjustment. I also checked for loose head studs and everything was perfect. It sounds like a valve but there is no smoke and it runs excellent. Is it possible that it is coming from the CIS. I can't pin-point where its coming form. Any suggestions?

BTW: 1976 911S 2.7

CHILI · CHILI's Garage

I had the same thing at one point. It sounded like a valve adjustment was needed, so I too did one. Come to find out it was an exhaust leak. Right at the stud. It really sounded like a ticking from the right side of the motor, I guess because it was so small. In about a day it was more obvious it was an exhaust leak. But for a while it sure didn't. Easy fix, though. Try putting your hand down below to see if you feel puffs of air coming from places they shouldn't. Just a thought.

1fastredsc · 07-07-2003, 10:56 AM

It's also mildly possible that you have a bad valve guide. Any play with the valve and noise will be the first sign.

Superman · 07-07-2003, 11:04 AM

Exhaust leaks making ticking noises, and they tend to get quieter as the engine gets hotter. If your valves are adjusted, and you have a noticeable, non-subtle ticking noise that gets softer as the engine warms up, my guess is exhaust leak. If all this is true but the noise gets louder after warmup, you probably do have a valve that is loose in its guide. If the noise is not particularly pronounced, your engine is probably just normal.

Here's something that I think needs to be said: Valve train ticking noises, at least subtle ones, are not unnatural for our engines. They do not necessarily mean something is wrong, or even that something is misadjusted.

justinbaldwin · 07-07-2003, 11:53 AM

i don't know what chain tensioners you have but when i bought my SC i was told it had hydraulic ones. within two weeks of buying the car i started hearing a ticking noise which developed into a much louder noise, one of the tensioners went. (they weren't hydaulic!)

anyway, it was interesting watching the mechanic identify the problem. he got a two foot long screw driver, placed the handle on his ear then touched the other end on various bits of the engine from which he was able to identify the problem.

apparently with the engine running, it is much easier to isolate noises this way.

hope this helps.

TerryBPP · 07-07-2003, 12:17 PM

I suspected it was an exhaust leak aswell. I have the Carrera chains so thats not it. If it is a valve guide how do I find out which cylinder its in? Compression test? Thanks for the help, as always.

Superman · 07-07-2003, 12:58 PM

Yes, the stick (or screwdriver) against the suspected part with the other end AGAINST your ear trick, enables you to hear all kinds of internal noises, and isolate the source of the noise.

Again, it has been my experience that exhaust leak noises get quieter with engine warmup, while valves get noisier. This has been the case even with my rebuilt heads. I'll also repeat that a little ticking is normal. If what you're chasing down is a single, loud ticking noise, my guess is exhaust leak.

CHILI · CHILI's Garage

Yep, exhaust leak if it gets quieter. I forgot to mention that mine did get quieter when the car warmed up. But then one day it was very loud. The exhaust stud was simply loose! I just dropped the headers and replaced the gaskets (along with one stud that came out of the case instead of the nut coming off). Quiet as a mouse! Well, maybe not, but that's the way I like it