Timing chain noise ? ?

[fmarinelli]

Hi, The car is a 1973.5 911T with 2.4 engine and CIS. Engine has 106,000 miles. Had a top-end rebuild by previous owner at 84,000 miles. At that time, the timing chain tensioners were replaced with the oil type. In the last six months, I've begun to hear a rhythmatic clicking that may be coming from one of the timing chain compartments. It is only evident at idle. I want to determine if this click happens once per round trip of the timing chain. For this car, can anyone tell me the number of teeth on the crankshaft sprocket and the number of links on the timing chain. I can then compute the frequency of each round trip of the chain in relation to the engine rpm. How's that for today's math problem? Fred

[T77911S]

you are over engineering troubleshooting.
bad tensioners usually make noise only at idle.
put a screwdriver on it to listen or
pull the cover off and inspect it.

the chain rattles because the tensioner has lost pressure and the chain is lose.
I had one go bad on a trip in my 2.7. sounded like an exhaust leak at idle it was so loud. driving it was quiet. yes, had to drive 250 miles to get home.

don't over think it

[Trackrash]

We mechanics don't use much math.

I would put a stethoscope on the motor to isolate the noise. Compare each side. A failed tensioner will give the sound on one side.

You could also post a video with your motor running. The gurus here will be able to identify the sound.

[proporsche]

like to boys said..never mind counting the teeth post here a video of the noise;-)

Ivan

[boyt911sc]

Originally Posted by fmarinelli

Hi, The car is a 1973.5 911T with 2.4 engine and CIS. Engine has 106,000 miles. Had a top-end rebuild by previous owner at 84,000 miles. At that time, the timing chain tensioners were replaced with the oil type. In the last six months, I've begun to hear a rhythmatic clicking that may be coming from one of the timing chain compartments. It is only evident at idle. I want to determine if this click happens once per round trip of the timing chain. For this car, can anyone tell me the number of teeth on the crankshaft sprocket and the number of links on the timing chain. I can then compute the frequency of each round trip of the chain in relation to the engine rpm. How's that for today's math problem? Fred

Fred,

Save your MATHEMATICS for other calculations. Your main objective is identifying the source of the clicking noise. I could provide you the number of teeth (cam sprocket) and number of links on the timing chains to satisfy your obsession. You are are over doing a simple mechanical diagnostic test. Just my two-cents.

Tony