"Grinding" sound at idle and low RPM.

[Hans]

Hi there,
my 79 V8 (5.0) Mustang is noisy.
At low RPM a mechanical noise can be heard.

Any ideas?
Timing?
Cam shaft and lifters? (They need some time when cold before they stop ticking).


Thanks,
Hans.

[gregpro50]

throwout bearing?

[Hans]

Greg,

it has a C4. Does it have such a bearing?

Thanks,
Hans.

[gregpro50]

Nope. Nevermind then.

Where is the noise coming from?

[Hans]

Seems to be coming from the front of engine or center of the engine. Can't tell more acurate.

FYI;
replaced the belt recently, all driven parts like water-, air- ,steer pump, alternator, tensioner wheel turned smoothly and silent when powered by hand.

Are there known areas that wear over time? Could it be the timing chain not being tensioned enough?

(It runs great though. No big issues like with the bottom end likely).

Hans.

[JACook]

Are there known areas that wear over time? Could it be the timing chain not being tensioned enough?

It could, especially if you've still got the nylon-tooth cam sprocket in there. I've
seen timing chains get loose enough to slap the timing cover.

To check for timing chain slack, you remove all the spark plugs, then use a socket
on the large bolt in the center of the crank damper, along with a breaker bar. Turn
the crankshaft in both directions, noting where it changes from moving freely, to
where you feel some resistance. That resistance is the valve train starting to move,
and the number of degrees that you can turn the crank without feeling resistance
indicates timing chain slack. A couple degrees is pretty normal, but if you have any
more than 4 degrees, it's time for a new chain and sprockets.

You can also watch the distributor rotor while you're turning the crank, to get some
visual indication to go along with feel.

[Hans]

Thanks for your input.

I will check that for sure.
Suspect the chain saw never any maintenance at all. Cover doesn't seem to be removed ever.

So the original sprockets don't last long?
Where can I find info on better replacing parts? (I will search this forum first).

Regards,
Hans.

[gregpro50]

The original timing chain set had a nylon coating on the sprockets to keep them quiet. The problem was that the nylon coating would wear off and leave the chain very slack which would hit the timing cover. I had a '79 302 with that exact problem.

[NAVYCAT]

might be the alt bearings ot the belt tensioner, I had the same thing going on