What's Clattering?

[Alan Lindquist]

I'm hearing a metal/metal clattering noise from the drive train. It's not constant but I've nailed down a few possibilities and will have to look into it this weekend or soon. It's not getting worrisome, but it's not normal. 1980 911SC

1. At about 3,000 RPM, it sounds like valve clatter. I adjusted the valves last November (9,000 miles ago) and thought I got it right, but it's possible that I have a few a bit loose. Checking this will require $30 for the gaskets and nylocks.
2. This 210,000 mile transmission has been "repaired" several times, never properly rebuilt. The PO tried to show his son how to speed shift without the clutch, and lost second and fifth gear at about the 100,000 mile mark. At 190,000 miles, I lost first and second gear. The offended parts were replaced, but the whole (915) transmission has never (to my knowledge) been properly overhauled. Does the 915 make clattering noises at some RPMs? When I lost first and second, I pulled it and replaced it after repair and it came back to me dry. I can't recall what trans oil I put in there, but it wasn't Swepco.
3. The 210,000 mile motor (to my knowledge) has never been cracked open. The motor has the chain tension upgrade and the pop-off valve done. Could I be hearing a warn timing chain assembly?

There is no clatter at start-up cold, and no clatter at idle when hot.
There is no clatter below 3,000 RPM.
There is no clatter above 3300 RPM.
I cruise whatever gear I'm in at about 3000 RPM so that is a constant engine speed.
There is no clatter when pulling with torque from 2K RPM through 5K shift
There is no clatter when using about 75% throttle and rowing through the gears that I can hear - but I'm running a cat bypass and a stainless muffler with an 84mm single exit, so the hard exhaust noise may be hiding the clatter.

I can use a hollow pipe and listen to the valve covers and the valve chain covers to try to locate the noise, but it's tough to replicate it with hand throttle.

Any ideas?

[James Brown]

Might be the chain guides. valve clatter is more constant.

[DRACO A5OG]

Post a video with sound.

What brand of oil are you using in the engine?

[T77911S]

how many miles on the engine?

valve guides
chain tensionor
piston slap

[Alan Lindquist]

Originally Posted by DRACO A5OG

Post a video with sound.

What brand of oil are you using in the engine?

I doubt that the video recording will hear it. It's not drastic, but I've never heard it in the previous five years and 100,000 miles I've put on the car. It's been showing up for the last 10K miles.

I just switched to Valvoline 20/50. I had been using Castrol 20/50. No difference but I do FEEL better about switching.

[Alan Lindquist]

Originally Posted by T77911S

how many miles on the engine?

valve guides
chain tensionor
piston slap

215,000 or thereabouts. It's time for a different (younger) motor. I'm not going to put much into this to fix it because it's going to be one of those "while you're in there" $10K experiences. I'd rather find a good 3.2 and sell my 3.0 as a rebuild candidate. But I need a few more months out of the motor. It runs well, I just want to understand if I'm hearing the beginning of the end. Most mechanical things will talk to you when they are suffering. At this point, it's more like a whisper.

[steve911T]

I had roughly the same problem on a 3.2. The noise was from 2500 rpm to 3000 rpm. Ended up being a problem in the timing chain, right side. Never really sure what it was because it was fixed by the mechanic. If you can isolate the sound (using a stethoscope, Autozone $10) like I did and then remove muffler, sheet metal, lower motor, AC compressor and finally the timing chain cover, you can run it and visually inspect what is going on, of course with a small loss of oil. Good luck Steve