82 SC engine noise....

brol · brol's Garage

Ok so I have read all the posts that popped up regarding Anything remotely close to what I have experienced. Unfortunately I feel even more confused than before!

The issue:

My SC (engine was rebuilt alittle over 15k ago, prior to my caretaking including updated tensioners) has been making almost a rhythmatic thumping noise that appears to be coming from the left side, when seated in the drivers seat. Now, this only occurs once the car has warmed up and been run for 10-15 minutes, no unusual noises or sound prior to this. I have not experienced any loss of power, exhaust smoking (other than the occasional on start up when it has sat for a while) or any other telltale signs of engine issues.

Any ideas? Thanks Brian

jimbauman · 02-06-2011, 05:09 PM

Does this occur at all RPMs, and does the frequency of the thumping increase and decrease with a change in engine speed? Do you hear it whether stationary or in motion? Can you feel it or just hear it?

JB

brol · brol's Garage

Quote:

Does this occur at all RPMs, and does the frequency of the thumping increase and decrease with a change in engine speed? Do you hear it whether stationary or in motion? Can you feel it or just hear it?

JB

Sorry, I had completely forgotten to mention any of that!

The only time I can say I absolutely can hear it, is when the car is stationary at idle. I have considered it may also be when the car is rev'd however I have not been able to pick it up on accel/decel, and I have definitely not heard it in motion either.
Thanks

jimbauman · 02-06-2011, 05:45 PM

Hmmm... at idle, does the noise seem worse when the clutch is in or out? Or no difference?

brol · brol's Garage

Quote:

Hmmm... at idle, does the noise seem worse when the clutch is in or out? Or no difference?

I have not noticed a difference. I believe it occurs clutch in/out. I can confirm in a day or two.

Thanks

brol · brol's Garage

Quote:

Originally Posted by brol

I have not noticed a difference. I believe it occurs clutch in/out. I can confirm in a day or two.

Thanks

Warmed the car up good today and got in to do some testing, the noise is present when the car is idling, and regardless of in or out of gear/ same goes for clutch engaged or disengaged. Upon rev it does not get any louder or become more evident. I do not know if the engine is drowning it out or the noise stops.

Again any help appreciated!

Thanks Brian

tcar · 02:05 PM

When idling and the rear deck open can you pinpoint the source more closely?

FWIW, the Carrera tensioners can and do fail. Is it coming from the left chain case?

(Get a 2' long piece of garden hose; one end to your ear, move the other end around the engine.)
Voila', a stethoscope.

brol · brol's Garage

Will do, thanks! I will report back in a few days and hopefully have more to work with.....

felix83 · felix83's Garage

I too can sometimes hear a slight thumping noise from my engine ('82 Euro SC). Usually barely audible, but I can hear it at low RPMs when driving next to an object which allows the sound to reverb (for instance a wall). It can also be heard on the overrun. Since this is my first 911, I was puzzled and somewhat worried the first time I heard it, but when I'd calmed down a bit I began thinking logically about it.

In my case, the sound isn't very intrusive, it's not a harsh, metallic sound (such as a chain rattling) and it hasn't gotten worse over the months I've had the car. The engine pulls strongly, too.

I'm not sure as to how used you are to old air-cooled 911s, but there is quite a bit to get used to, not least sound-wise. This has to do with a few things, mainly that the engine is in the rear (duh!), making the exhaust system relatively short. Also, the engine is air-cooled (double duh!), which means that there is no water running around the engine, which in a normal car serves as sound insulation.

So it's possible the sound we're hearing (given it's the same sound) is perfectly normal, and that the people who've been involved in 911s for donkeys years are so used to it that they simply can't hear it any more. It's just part of the car's charm.
Having said that, if the sound becomes worse and/or the engine starts to act strangely, it's a cause for further inspection.

Just my proverbial $.02

Drisump · Drisump's Garage

As felix said, these are not quiet/ smooth engines at idle, is it possible you are not used to the sound of a 911 at idle? To most non Porsche people, my car at idle doesn't sound wonderful.... lot's of character however. When I hear other 911's at idle though, they're all quite similar. Maybe you should do a sound check with another in your area. Cheers

brol · brol's Garage

Thanks, I had a friend listen to it the other day, He said he thinks its a valve that needs adjustment. I would never had placed it as that being the sound I am hearing, but taking into consideration the above posts it make sense

Thanks!

yelcab1 · 02-11-2011, 06:41 AM

at 15k miles after the engine rebuild, it is time for a valve adjusment ...

brol · brol's Garage

Quote:

Originally Posted by yelcab1

at 15k miles after the engine rebuild, it is time for a valve adjusment ...

The PO stated he had recently done one prior to my purchasing it. However I cant verify it was done (or right for that matter). SO its now on the list! Thanks for the input.