mspiegle

I think sometimes with engines, its hard to tell where some sounds are coming from. It could almost sound like its coming from everywhere.

Have you tried a mechanic's stethoscope?

worf928

Uh huh... is it a stock manual (5-speed) transaxle or a stock automatic transaxle? If the former then you have a clutch. If the latter then you can have thurst bearing failure. But not the reverse. And in both cases noises would not be coming from the rear of the car.

I agree with Heinrich - if it's a lifter it's making a noise I've never heard a lifter make.

Bill Ball

Agreed, that is one odd noisy lifter, if that is what it is. The noise does sound way too raspy. It doesn't have the sharp rap of a stuck lifter. If you told me nothing about the noise I would say it sounds like someone cranking a starter motor.

The location is right for a lifter, unless the noise is being radiated diffusely from below. Anything more serious in that area (broken valve spring, etc.) and the car would run worse.

Regarding location, when George Suennen's flexplate broke a couple of arms, the noise initially sounded like it was near the top of the motor, but with careful listening with a long hose, we tracked it to the lower bellhousing area.

Get something like 3 or 4 feet of 1/2"or 3/4" heater hose and put one end to your ear and move the other end around to see where the noise is the loudest.

worf928

The noise is somewhat similar to the noise my AC compressor clutch bearing made when it fragged on the way to SITM in the GTS.

You need to consider all the items that are moving at engine speed.

Have you looked into the inspection holes in the timing belt covers to ensure that the belt is tracking true on the sprockets?

If you have a clutch, does the noise change at all with the clutch disengaged or engaged?

Have you considered removing each accessory belt sequentially to eliminate each accessory?

The above are easy to do and will eliminate accessories and the timing belt from the equation.

kaptnknemo

This is all great stuff, thanks, but a lot of it is over my simple head! I am going by my local wrench's tonite on the way home to drop it off. He is a factory trained 928 mechanic who likes working on them. Right off the bat, he thinks it maybe an increase in lifter noise due to the recent oil change (he has not heard it yet). Since he knows the car, I'll let him check it before I try any of the other stuff.

I will still try to filter out the engine noise to give youguys a better sound and more carefully note the location of the noise.

BTW it has an automatic tranny.

Later KK

Big Dave

Good luck, and I hope your mechanic finds it quickly. Dropping off a 928 for a mechanic to hunt down a noise can be an expensive adventure.

AO

I'd like to change my answer after hearing it's an automatic:

TBF!

(For the record I hope I'm wrong.)

worf928

Sigh. Yup. The only variable would be a torque tube replacement. If it isn't the original torque tube then I'd have to go with checking crank end-play as the first test for the mechanic.

AO

Personally, I'd tow it to the mech's rather than run the engine any more. Thrust bearing failure can result in the engine going bye bye for good! Happened to a guy here in Michigan, so it's not a myth.

Mongo

If this is a thrust bearing failure, would this be caught in time to prevent any other catastrophic things on his car? or is he too late?

Jim bailey - 928 International

Thrust bearing failure is typically a very quiet grinding away of the shoulder of the bearing then the webbing of the block it does NOT warn you by loudly screaming for HELP or knocking! It is usually diagnosed only after the engine refuses to crank on the starter motor when the engine is hot. Same with a water pump machining the block it is well lubricated and makes no noise. As was mentioned it maybe an A/C compressor /clutch noise, alternator, possibly timing belt roller issue. Very real possibility it might be a lifter noise.

Gretch

OK, the thread got my interest and I listened to the wave file. That is (IMO) definately NOT a lifter.....and the wave cycle is too rapid for it to be a wrist pin knock, or piston stroke related, it is happening at about twice idle speed......I have a deep fear that this is a crankshaft issue........and I am betting (to be safe) TBF, (about to chernoble)......I strongly recommend against running the car anymore. Ramp truck it to the wrench. Do a flex plate inspection and tension release then check crank end play. Your engine is very sick...........Do these procedures, and you may find out it is not the worst thing it can be.

Good luck

heinrich

Dude you need to stop agreeing with me

Garth S

To my calloused ears, the frequency is above idle - which makes it tough to be a lifter.
Have you checked that the starter gear is disengaged fully from the flywheel ring gear?

killingmoon65

That sound is very close to when my smog pump began to fail. Do you have one on that car?