Engine clunking when shut down
 

Hiya. Every time the engine is turned off of my '89 944 I hear a metal on metal clunking type noise that sounds as if it is coming from the engine. It is the last sound heard before there is silence. I plan to do the belts soon and thought maybe the timing or balance could be off a little and causing some parts to touch on shut down? I have some noise while running but it sounds more like noisy injectors or lifters, no clunking. I believe my timing belt to be too tight from the PO as I cannot for the life of me turn the water pump by hand (as I heard you should be able to) and I have the "supercharger whine" as revs increase. The car has been rarely started for the several months I've owned it and I dont plan to start it again until I do the belts. Any ideas?

If its like a hollow metal "tonk, tonk, tonk" it could be the door in the air flow sensor clunking. I have heard several 944s make that sound when shutting down. It's an odd noise, some cars make it, some cars dont.

-Nick

Random ideas...
How many miles do you have on the "89?--time for a rod bearing replacement?

What weight and brand oil do you use? Use what the owners manual says printed in 1989!

Have you checked the heat sheilds by the exhaust?
Metal on metal could also be the rubber clutch disc "make it home tabs" clicking. Do you have the rubber center disc?


The WP test will not work on a WP if the WP pully has a knurled or similiar pattern on the pully. If your pully has a smooth face, wash your hands and then use Windex on the finger tips to get body oils off---then check on a cold engine.

When you do the belts, check the WP bearing for noise and wobble.
http://www.arnnworx.com/h2o-pump.htm

Click the "home" button for more good technical information and tools.

GL
John_AZ
1988 924S + 1987 924S

Thanks for the replies. I would bet money that the clunking is either crank related or possibly the clutch. I'm not great at describing sounds or diagnosing them but it just seems like it has to be more than the barn door as I can feel the clunking in the cabin. It sure would be great if it was just the barn door though.

The car has 108000 and I received no records from the retarded PO so I'm assuming I will have to replace everything. I'm sure the clutch is original but I havent checked the inspection hole yet.

The oil in the car is the same that was in there when I bought it. Looks clean but I'm not sure what it is. No evidence of milkshake and the compression seemed good when I checked it last (can't remember #'s but I think each was about 160 cold, not sure). I bought some mobil 1 10w40 for another car and thought I would put it in when I did the filter change but I'll look at what the manual says.

I'll look more into the waterpump test. When I do the belts it will all come together.

I've read some info about the rod bearings and plan to do the pan gasket and bearings in the future. Could the clunking be the rod bearing? What other symptoms might I have from the rod bearing? If not easily known off the top of one's head then I'll do a search.

Thanks again :)

10w40 is not the right oil

use 20w50

I advise to use what the 1989 manual says for oil even with all the advances in science and chemistry. Try some Valvoline RO (racing oil-lots of ZDDP) 20-50 and see if the clicking sound is less.

You can read about oil here:
http://forums.pelicanparts.com/showthread.php?t=367300&highlight=engine+oil+threa d

Rod bearings

If the PO had coolant in the engine due to the oil cooler gasket, and did not notice it for a long time in the coolant reservoir or dipstick, Porsche wants the rod bearings replaced. Antifreeze will distroy rod bearings.

http://forums.pelicanparts.com/uploa...1249259139.jpg

Rod bearings should be replaced at about 125K +-

Related:
http://forums.rennlist.com/rennforums/924-931-944-951-968-forum/350563-knocking-from-cam-tower.html

GL
John_AZ

The owners manual and repair manual both refer the owner to a chart that shows various grades of acceptable oil. There cannot be a "right" oil because it depends on the climate in which you drive. I'm no expert by any means but 10w40 tends to have the best range of temp operation for my situation. That is not to say that I have never tried other weights of oil and may experiment with the 944 with 20w50 but it cannot be said that there is only one oil for the 944. With 3 motorcycles I rarely drive a car during the warmer months (mar-sep) so I can afford to experiment with 20w50 and will give is a shot. I have no intention of starting an oil war; I will try various oils and see which works best for my specific situation; I appreciate the advice to try 20w50. I have no idea what is in the 944 now but the oil looks nice and clean on the stick. I'll drain it soon and see if the stick check is misleading as far as a coolant leak goes.

I suppose at this point I'm stuck until I dive in and see what happens. If changing the belts and oil solves the problem, then great but if not...well, I will cross that bridge when I get there. I'll provide updates when I get my hands dirty. Thanks again for the help.

What condition are your engine mounts in? I have seen a 944S2 that had engine mounts so worn the exhaust manifold would just knock the steering column (Right hand drive car) under hard acceleration and on shutting down the engine

Hmmm, that may be possible. I havent checked the condition of mine yet but have seen instructions on how to do so. I have vibration at idle but it isnt bad. It seems exasperated by the worn shifter (which rattles like crazy and will be fixed soon) and I'm assuming heat shield of some kind that causes a slight rattle. The noise sounds terminal and I'm nervous when I start the car (which has been a total of maybe 5 times). I plan to do the pan gasket, bearings, mounts and all the other "while I'm there" stuff at some point but I'll go ahead and check the mounts out. Thanks for the lead.

Definately check the engine mounts. If they are bad you'll have vibration under 1000 rpm, get a "clunk" on shutdown, and smooth out at 1000/1200.
FWIT I use 20W50 oil.:cool:

I agree. I would bet..........motor mounts! I had the same symptoms and that's what it was!

I had a weird clunk that was caused by a broken A/C compressor mounting bolt.