Whining noise, engine

[Sirendancer]

I just went through all of the postings and didn't really see an answer to a problem I'm having. I've got a 1987 944 non-turbo, about 70K on the clock. About 1 year ago I changed the water pump with a rebuilt unit from a reputable source. Prior to the R/R, the car ran and sounded like a normal 944. After I changed the pump and belts, I noticed a considerable "whine" coming from the engine bay. Long story short. The rebuilt pump blew a seal and rust froze it. I went back to square one only this time I went the full distance; new seals, pump, all belts, all rollers, all tensioners, everything. While I had the front torn down I noticed that 2 of the rollers were shot. Not a problem since they were on the replace list and I assumed that the "whine" I was hearing was one of these bad rollers. Everything's now back together and adjusted properly. Problem: the whine is still there. I've been working on cars for over 20 years and although I'm not an expert by any means, I can't determine where this whine is coming from and it's starting to worry me that there's a possible "explosion" in the near future. I know the reputation that Porsche motors have for near indestructability but I really would rather not take a chance on blowing this one sky high. Any help would be greatly appreciated. Thanks in advance!!

[pearldrum]

i also had a whining problom, and realized it was one of the belt idlers, i think you said that you replaced them all. but we took a steel pipe and held it up to anything that moved with the belts, and it amplified the sound on one of the idlers, so we replaced it, and that solved it completely, did you replace all the idlers too?

[Mrmerlin]

Hi bro, it sounds like you have a timing belt/balance belt too tight, to check run the car till it gets hot, IE normal operating temp. then remove the front top timing cover, at the longest runs of each belt, you should be able to turn the belt 90 deg from the plane of rotation.


This is what happens, the belt gets installed when the engine is cold and the engine is in the shrunk mode, as the engine warms up the pulley centerlines grow or rather the whole engine expands due to heat, if the belt was tight when the engine was cold it will get even tighter when things are hot.
So this test will require you to check the belt tension when things are hot,if you feel that one or both belts are so tight they are about to snap, you will need to loosen things just a lil bit, cause if you do too much the belt will be too loose when the engine is cold and possibly jump timing.
Only do an adjustment on one belt at a time if both are too tight. Restart the engine and see if the whine is gone.....this is also based on the fact that you have replaced all of the Idlers, and tensioners,and none of them have been contaminated with coolant or water, if there are any doubts put the engine at TDC and remove the belts and spin the rollers/tensioners and see that they all spin smoothly, any roughness indicates a bad roller, replace it........
Now if this still doesnt clear things up remove the power steering belt and start the car, if still no joy then remove the alternator belt and run the engine ,you should find out when the noise goes away... my bet is a too tight timing belt/balance belt.....Stan

[Sirendancer]

Thanks everyone for the responses. Stan: As you already suggested, I systematically removed and readjusted each belt with no joy. I was hoping I'd find a bad alternater bearing or a bad power steering pump, I didn't. As you already know, the 1987's had the spring loaded self adjuster for the cam belt and I know this is adjusted properly. I read your suggestion about the belts being turnable to 90 degrees, and I'm not arguing with you because it's obvious you know more about this than I, but just out shear desperation I loosened the cam and balance shaft belts to way beyond specs and ran the car for about 30 seconds to see if maybe the belts were too tight. I could hear the belts slapping against that chrome belt runner that's under the cam belt and once again, the whine is still there. I have the Haynes manual that I've been using for referrence, but I'm not impressed. The book has lousy pictures and poorly reproduced diagrams. Also the book doesn't deal with the cars produced after 1984-1985.5 so there aren't any suggestions about troubleshooting the belts themselves with the new rollers and tensioners. The book does make the suggestion that 'the belts need to be adjusted per factory specs and should be left to a qualified techician'. I don't buy that, I fully believe that any of us can repair these cars properly if we just had the proper specs. I did follow one other Renlister's suggestion and purchased a CD off of eBay with all the factory manuals but that won't be in for several weeks. Is there any possiblility that there is a cam bearing or a balance shaft bearing that's bad? I really appreciate your help so far and maybe together we can sort this out.

[ChrisBennet]

Sirendancer,
Just a thought. There is a certain idler that is supposed to be adjusted to something like .8mm from touching the belt. If that idler is just a little out of place it hits the teeth of a belt above or below it which may make the sound you describe.
-Chris

[Sirendancer]

Thanks Chris, I'm going to tackle the thing tomorrow and definitely use the suggestions that you and Stan have provided so far. Acutually everyone has been real helpful and at the risk sounding silly, I'm really proud to be a member of group of people like all of you. I remember many years ago when I was a kid I used to restore old Mustangs. One of the things I remember the most was how no matter how well you put a car together someone always had some snide comment to make about correctness or taste. Not so with the Porshephiles. Thanks a million for the help.

[eligunn]

It's just the noise new balance belts make. Sometimes it can be adjusted out, sometimes it can't. Just get it to where it's as quiet as you can get it, then forget about it.

[Mrmerlin]

Hi , if the belts are not too tight then I would adjust them and leave it alone . To note there will be some noise from the belts, a lil whine is good but a loud wine is not ,
So if your this far is there a possibility that you might have one of the Idler/Tensioner rollers reversed on its shaft...this might let the side of the timing belt/balance belt hit the timing cover, this could also be causing your problem..........
The only other thing I could think of is to try to see where the noise is coming from IE the bottom pass. side or the top drivers side if this is so there is a possibility that the balance belt housing might need repositioning.........
WARNING/........WARNING.....the balance cover is held on with approx 8 bolts and is further glued to the block with the Orange locktite... to reposition this cover you would loosen the bolts about 2 turns from snug..try to move the balance shaft cover till it feels like it is not binding then tighten the bolts per your Haynes manual.........THE only WARNING is that you might create an oil leak as you will be breaking the glue seal from the Locktite when you move the cover..so this is for you to decide to do this, I would not try this unless your prepared to fully remove this cover and reseal it ..So proceed at your own risk..........
As a final thought might your clutch throw out bearing be going bad? You know to not allow water to sprayed towards the rear of the engine with out covering the speed sensors, water will go directly into your clutch/ and TOB. making its life very short...Stan

[Yan]

Originally posted by Stan Kolen
A lil whine is good but a loud wine is not.

My 951 also has that particular whine but it only occurs over 3000 RPM when pushed hard up to the redline, the sound being louder exactly at 3000 RPM. The car runs ok below that. Is it what we can call a "good whine"?

Thanks
Yan

[muso58]

to cancel out possible balance shaft /belt probs why not take off belt and test for noise minus driven bal shafts some folks run cars without bal shafts for increased hp