spode134

I have a 79 SC with 170,000 miles. It came with service records that do not mention any work on the cam chain tensioner and it does not have the turbo upgrades.
I get a noise at startup in particular that is alot like a muffler that the baffle has come loose and is rattling inside. It diminishes as the car warms up but never totally goes away. The weird thing is, when I am driving and corner to the right it rattles worse.
I have checked the heat shield on the cat and had a pretty good look at every thing external and can;t find any thing that is loose, I do get a slight resonance when I tap the cat on the outside that kind of sounds like the rattle.
The only reason i am not convinced it is cam chain noise is that it is not rpm sensitive- meaning the pitch does'nt change as I rev the engine.
I have read that when the chain guides and tensioners are worn it sounds like marbles in a can, but should'nt it change with engine rpm's.

Darrin
1979 911 sc
1980 928 racecar

Steve Weiner-Rennsport Systems

Darrin:

The very first thing you should do is stop driving the car until this is resolved.

I would pull the cam chain covers and inspect the chains, ramps and tensioners to see what is going on.

theiceman

It won't take long to pull the tinwork off to get to the chain covers and se if any of ther chains are loose. But if you have gone that far it is time for a carrera tensioner upgrade.

or you could remove the cat and start it . it will sound like hell but will know for sure if the cat is causing your noise, and since the cat is off anyway , you install your bypass. Or take the whole thing to a muffler shop and say " cut this noisy piece out and out a piece of pipe in ( cheapest bypass you will find ) .

Then go home and do said tensioner upgrade...

Peter Zimmermann

Steve's correct, the car shouldn't be driven while all the valves are still intact. For future reference you an take a very long, very skinny screwdriver, place its tip against the tensioner housing cover, listen at the handle end, and hear a noisy tensioner clearly, almost as good as a stethoscope.

spode134

Pete, i used your technique and have determined that I have a non-problem. All I hear is whirring and ticking [valves].
I did not mean to sound like a rookie with the dumb questions it's just that my experience with flat sixes is nil [ask me a 928 question!]. So I guess I just got paranoid and first thing that came to mind was tensioners failing.
The 911 is my car to just drive and really don't want to wrench on it if it doesn't need it... it's an absolutely mint car.
I wish I could figure out a way to link a movie file I took of the engine running today but as I don't have a website it's kind of tough.
Thanks for the responses all.

Darrin[IMG]911 resize[/IMG]

spode134

P.S. can anyone explain how to paste an image in a posting?

Darrin.

theiceman

hit post reply ( not quick reply )

scroll down to manage atachments, atach pic from your files and upload

You may need to resiize using irfanview or some other program to not exceed file size.

get an account with "my space" for example and post video like the one of my oil sender.

http://vids.myspace.com/index.cfm?fu...oid=1202081427


good luck

spode134

iceman, thanks i'll check it out.
D.

Droops83

I assumed that this would go without saying, but if you do find a chain tensioner problem and decide to upgrade the tensioners, REPLACE THE CHAINS! We have had a couple cars come in the past couple months with the Carrera tensioners, but with nasty chain rattle. Pulled the chain covers to find the pistons in the tensioners almost completely popped out since old, stretched out chains were not replaced when the upgrade was done. I assumed that most people replace the chains when they do the update, we always do, but I guess not. Good luck and let us know what you find.

---Chris A.

theiceman

Now theorheticaly would new chains require cam timing since the overall length of a new chain is shorter,,,hmmm,,,

r911

listen at the handle end,... by touching it to the bone near the ear

Peter Zimmermann

Chris: Tell us more!!! Marc recently did a complete overhaul on a one-owner '86 Carrera that Red Line's serviced since new (yes, even through its warranty period). It had 270K miles on it and the chains were good enough to re-use, obviously they were replaced! This was a Kendall GT-1 20w/50 car from birth, and saw a fair amount of city use. We've done a lot of top end jobs on high oil consumers, but rarely saw a problem with stretched chains (yes, we have replaced a few, but it's a pretty small percentage). Were the cars you've done used on the track, or canyon racers? Were your cars super high mileage, total including since the tensioner conversion? I've always wondered if those tensioners would impact chains somewhere down the road, because they run tight enough, just after installation, that they do "sing" a little. But they also settle in pretty quickly.

Droops83

Pete,

Both were cars previously unknown to us, one was a 73.5 one was a 2.7, a 74 or 75. Both were pretty high mileage, rough cars with unknown histories. So much was suspect about them besides just timing chains. I actually didn't personally work on either, I just saw the tensioners w/ the pistons popped out! I will ask Joe and Henry their experience w/ stretched chains; to me it just seems to be one of those no-brainer things to replace when you are updating the tensioners and ramps, but maybe I'm wrong . . . .

As a side note on the same subject I replaced the tensioners once on an '84 Carrera where they were getting noisy. Of course this car had them since new and ths is the oldest a set of hydraulic tensioners could possibly be, so it is understandable that they can get noisy and probably eventually fail.

---Chris A.

spode134

Thanks for all the feedback, what I have determined is that it's not timing chain noise. I will be removing the cat and air pump when I get a chance. I have collector plates on the car now so no need for it to pass emmisions testing and a pretty sure it's the air pump rattling.
Darrin.