JBL930

Hi all
My car has always made this particular noise to some degree but I’m sure lately it's a bit louder and was just wondering what and where it's coming from.
You know when you gently pull away in first gear (or any gear), up to about 1500rpm or so the engine makes a sort of gentle metallic "clack clack clack" sound that then disappears into the normal mechanical whine that these flat six's make, can anyone enlighten me as to why, where, what this noise is and why (if it is) is it getting louder and the possible implications
Cheers all

nathanUK '81 930 G50

Isn't that just chatter from gearbox ? The cars were sold with rubber centered clutches but most people use the 930 3.0 spring type.

JBL930

Is that what it is? I have given my clutch some abuse lately, I had a new one fitted about two years ago before I had the mods done so it was a standard rubber centred one, do you think the clutch is shot and that’s why I’m hearing more noise?

nathanUK '81 930 G50

I bet they didn't fit the rubber one. Can you find out ?

I think the rubber is quiet, then it just breaks. Hopefully someone here knows.

JBL930

The rubber had broken on my previous clutch, it was perished and old it may even have been the original, when you went on and off the throttle there was a metallic clunk I assume the rubber is there to buffer that. This is not the noise that I am explaining though, what I am talking about is similar to what the old VW beetles sound like when they pull away, a sort of muffled slap or clack with the revs until after 1500rpm or so and then it goes away, does anyone know what I mean?

JBL930

There is another noise I’ve been trying to locate, totally unrelated to the above, it sounds like it's coming from behind the dash or footwell, it's like a cat meowing, like a small motor opening and then shutting something, I’ve tried turning all the fans off and moving the heater controls around to see if it goes away but it's still there, any ideas?

nathanUK '81 930 G50

Is the engine noise related to oil pressure ? Timing chain, valvetrain, pinking or piston slap maybe.

The other noise, it's not the heating control unit between the seats ?

goldminer

Could be the fuel pump letting you know it's on it's way out.

PorschePhD

Either that or the int shaft and chains. Most have updated to a spring disc rather than a rubber center. The dampening is not there so the noise will run through the drive train. It is normal on take off and lugging the car around.

JBL930

Nathan
It looks like you were spot on with your first reply with what Stephen said, the noise has always been there to some degree so it makes sense that it's gearbox/drive train noise at really low RPM under load.
The other noise isn't coming from the heater control between the seats, it sounds like it's coming from either the passenger (driver in the US) footwell or under the dash, it's like a faint asthmatic mechanical cat or the noise a remote control toy car makes when you hold it in your hand and move the steering left, right, left, right, does that make sense?

Goldminer
The fuel pumps are new front and back, keep the guesses coming though

Stephen
Thanks for the explanation I’m glad it's normal, when I go EFI next year I’ll go for an uprated clutch. BTW what are the int shaft and chains?

38D

int shaft = Intermediate Shaft. It's the part that connects the crank to the oil pump. If the gear is worn, you can get chatter.

chains = Timing Chains. If the chains are worn, they will slap inside the case.

JBL930

Thanks for the explanation Colin, do you have any idea what the other noise might be? I'm stumped! Everything is working so it's not like there is a malfunction that would point to it being anything specific, although I do get constant warm air through the footwell, all the heater controls are cable operated and not electrical right? Except the fans of course

nathanUK '81 930 G50

The noise you explain like a radio car, is it exactly like the servo motor between the seats when it is trying to adjust temperature correctly ?

Also yes the heater flaps are operated by cable, but it is a electric servo motor (between the seats) that moves the cables.

Might be an alarm or immobiliser tucked away ?

nathanUK '81 930 G50

That gearbox chatter noise is kinda racy IMO. Did you hear Geoffreys recently built car in that video he posted ? It has solid engine/gearbox mounts.

Strange thing is I don't seem to recall my 3.2 carrera chattering, just my 930 which has less low rpm torque. Maybe the 3.2 gets out of low rpm so quickly I don't notice it unlike the low compression 930 which feels rather dull when off boost.