911sc nasty noise after storage

[westyguesty]

I have been lurking around on the forum for the last few weeks and gained loads of information. What a great site !

I have now run into a problem. Here is the story so far.

Finally getting my 911sc back on the road. Covered 80,000 miles, but been stored for the last six years. Was running fine before storage.

So far I have removed all the plugs, squirt of Mobil1 in the plug holes and turned the engine over by hand a few times. New oil, filters and plugs. Drained any petrol, put in fresh and tried it ! It started straight away, bit of smoke, but soon cleared. When it had a bit of heat in the engine, gave it a few revs and heard a nasty chirping / squeeking noise The noise is higher pitched that the recording suggests.

Took the belt of next and tried again, same noise, didn't think it was going to be that easy, but worth a try. I think it's coming from the left side of the engine (but difficult to locate).

If I increase the revs slowly, not noise, but a sharp blip on the accelerator and it is there. It's probably a bit more high pitched than the recording. It does make the noise hot or cold.

Audioboo / Bubbly Car

Don't mind getting stuck in, but where do i start ?

Thanks

[Oh Haha]

It would seem that your car is underwater which could be causing the problem.....














j/k

The sound(screech) I hear seems to be metallic. Just a WAG but I would check your fan and see if it is maybe hitting the housing. I'm assuming you have just the fan belt on, correct?

[Bob Kontak]

Suspect valve guides may be making the noise. Sounds like mine when started after a top end job. My noise only lasted three seconds but I remember it well.

Give it some time and drive it like a little girl for a while.

[ant7]

hi,
check clearance between crank pully, could be end float in the crank allowing the pully to rub on the casework, just a thought!
Could also be an air/vacuum leak.
Anthony.

[westyguesty]

Thanks for the ideas so far.

I have tried removing the belts and noise still there, so that rules out a few bits.

Do the valves guides dry out ? I have had it running for about 20 mins now in total on tickover since out of storage, so would have tought if it was the valves guides they would have stopped by now, but not sure.

It had a big service, incl valve adjustments around 300 miles ago at a Porsche dealer, although several years ago, so hopefully crank pully clearance is OK, but I will try to work out how to check.

I'm thinking air leak might be most likely, as it starts well especially cold. I will try removing the oil cap on tickover later to listen for any changes.

I have been reading how you can check for airs leaks soapy water and a compressor. I can't find the original post on how to do this at the moment, so will have another look to find it.

[Bob Kontak]

I don't think an air leak causing the noise. It is some form of interference but I am not convinced it is rotating parts.

When the car is cold can you get in an blip the throttle quickly and replicate the noise? You said "after the engine warms" but then said it makes the noise hot or cold. Can't be both.

It makes the noise when torque is quickly generated so may be something to do with the movement of the whole engine rubbing on something. Check the motor mounts and see how much play they have when you lift the engine with a hydraulic jack. Also the cross bar support can break at the narrow ends near the vertical mount tubes allowing additional engine movement. The other three mounts can hold the engine close to where it should be so this can go unnoticed if the case.

There is a resonance when the noise is not occurring. Get under and wrestle the exhaust around on the left side.

What were the other services performed by the dealer? May help trigger some thoughts.

I just looked at my 81 and there is a lot of room around the crank pulley. Not much for it to rub on. You did take all the belts off, right? AC / Alt / Air pump(if equipped)

Do you have a stethoscope? That can quickly rule out oddball things like the various CIS air valves or distributor are make the noise. Also may be able to isolate the noise better.

Keep us posted.

[westyguesty]

Torque effect is a good way of descibing it, was trying to think of a way.

Just done a few more tests. If will do it hot or cold. In fact it now does it all the time when cold as it is reving a bit higher, after a few minutes if ticking over it stops unless I 'blip' the throttle. I'm guessing as it's doing it at tick over (every when warming up) it's not engine movement, but I have checked the mounts and there seems virtually no movement.

All the exhaust nuts and bolts seem fine and nothign obviously loose, although it is original, so fairly rusty around the joints, no obvious leaks though.

All the belts off, just had the smog pump, not permantly off, and the fan/alt belt off.

Only one owner before me, so history really detailed, the only work ever done on it appart from routine is a warm up regualtor and one of the lone oil lines to the front, so everything very original.

When warm it only make the noise when you first rev it, so if I rev quick/hard to say 3000rpm, short noise then gone if I hold the revs there. Back down ok, noise back again when reved. I hoping nothing too major wrong with the engine otherwise it would be there all the time.

I have recorded a better sound clip, will upload later.

Thanks again.

[RSTarga]

I think it's mechanical interference too, does it do it with the clutch pressed in?

[Bob Kontak]

Originally Posted by RSTarga

I think it's mechanical interference too, does it do it with the clutch pressed in?

Good thought. If it goes away, that sure narrows it down.

[matt curtain]

I stored my Carrera for a couple years without using it, and once I pulled it out for use, the throw out bearing made a "tick" noice every time I pushed the clutch. After about 50 miles of driving the bearing siezed and I heard a loud "Bang" - the shifting fork in the tranny broke off. I discovered all this after the transmission & engine wa spulled for inspection.

[westyguesty]

Just tried with the clutch down and same noise.

I presume 'mechanical interference' is a bad thing

I rally can't tell which area it is coming from, seems louder from under the car, but think that's just all the sound goes straight down.

Will upload the other sound clip soon.

[Bob Kontak]

Mechanical vs air leak. Mechanical is something rubbing on something else vs a whistle from a leak.

You may end up under the car with a helper running the throttle. Long screwdriver works as a good stethoscope. Skip the necktie when checking out the top half of the engine. :-)

[jbryan]

KInda sounds like the chain tensioner issue I had on an older 911 many years ago

[westyguesty]

I was thinking maybe tensioner issue, after I have thought about, broken studs, belts, air leaks, clutch . . . . . . . . Everytime I read more on the forum I find something else to look out, without the forum I would be completely stuck !

It has the original tensioners, are this still oil fed at oil, could they dry out and stop working ? If it is one of the chain tensioners, I presume using a long screwdriver I would get a much louder/clearer noise from the problem side.

[westyguesty]

Here is the new recording, starting at the engine bay, then moving down to under the car.

Audioboo / Engine Noise

[Bob Kontak]

The hydraulic piston that provides the tension for the tension sprocket collapses. The timing chain is then allowed to flop around and jump teeth on the cam sprocket and allow the valves to interfere with the piston. The noise though, is not the chirping you here. It will sound like a chain dragging over a metal garbage can. I don't think this is your problem - failing tensioner pressure, that is.

Get the screwdriver out. A short one will work if you can get your ear close.

[westyguesty]

Had a poke around with a screw driver on all the bits I could and couldn't identify where the noise is coming from. Only good point I suppose, is when on the cam covers etc, I could hear the internals pretty smooth, rather than the squeaking noise. Only really a few minutes for me to check though as once warmed up, it was hard to pinpoint anything with the engine reving to replicate the noise.

What next ? Start taking things appart ?

[westyguesty]

Just got the engine warmer than before a few thousand revs for 5 minutes, and I think the sound becomes higher pitched and needs more torque / quicker reving to make it happening.

So maybe a leak somewhere that is getting smaller as something expands ?

[ant7]

hi,
Another thought, have a check with a torch around the crank pulley, under it you will see quite a bit of space, maybe something has fallen down in there and is rubbing on the crank pulley.
Worth a look, i found my engine lid inspection light housing down in mine!
Anthony.

[jeffs9146]

Originally Posted by ant7

hi,
Another thought, have a check with a torch around the crank pulley, under it you will see quite a bit of space, maybe something has fallen down in there and is rubbing on the crank pulley.
Worth a look, i found my engine lid inspection light housing down in mine!
Anthony.

FYI: A torch in the UK is a Flash Light here in the US not a welding torch!!