When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
OK guys - I need your help. I just got done with my timing / balance belt and water pump change. Got the car started and I was so proud that the engine was idling relatively smooth. I come inside and my wife says, "what is that whine?".
I swear I didnt hear it, but after my wifes comment I think I have the dreaded whine. I took a short video. Can you guys watch it and give me some ideas to proceed? I think the whine is accentuated on the video and it doesnt sound that bad IMO.
I read that whine is due to incorrect belt tension. I adjusted the timing belt to 90 degree bend and balance belt to 180 degree bend. Everything is brand new and the car is on the jack stands.
I was thinking that I should drive it for 20-30 miles just to let the belt "seat" and clean off any assembly oils etc. I used a stethoscope and noise seems very loud around the cam. I checked the CAM toward the back of the engine and it was loud back there too...
I also noticed that the V-belt pulley at the crank was tight but wobbly as it rotated. I guess that wasnt put on properly. Is that keyed? I dont remember a stud or keyway.
That sounds like an odd issue I have had. You need to remove each belt one at a time, if you make it to the timing belt you need to closely inspect the water pump belt/ roller guard for signs of the belt rubbing on the metal belt guard, I had rubber shaving all around it. To fix mine I had to take off the guard and bend in until it was no longer rubbing, this made it tough to reinstall, but fixed the problem.
I did two timing belt since I've owned my car. First time by feel and the second time with the Arnnworx 920x tool. And yes my car whine like that also at first after the second belt replacement but quite down after a drive. I call it the "Porsche" whine.
My other hobby car is a 86 Dodge Daytona Turbo Z. I also have the specialized tool for setting the timing belt tension for that car also. I've noticed that the 944 Porsche timing belt is a bit tighter than the Dodge's belt. It's also a known that Dodge's do jump belt timing but the belt almost never breaks either and goes 100,000 no problem. Also no whine from the Dodge either.
I bought this up because I feel the belt tension on the Porsche is a bit tight is why water pumps, rollers, and belts are prone to failure. I'm thinking Porsche Sets the belt tension tight because it's high RPM engine? Just some food for thought.
And wife's are good for busting b@lls if they don't like your car.
Last edited by marc abrams; 09-02-2016 at 10:55 AM.
Yes they sound a little tight.
If the job is freshly done they will settle in and quiet down after a few heat cycles.
It sounds like it is struggling a bit to idle...what speed do you have it at?
When you opened the throttle around 9 seconds in the video you hear that booming noise? That shouldn't happen on a happy engine. You may want to snug down the nuts holding the exhaust manifolds to the head.
I can't tell what that is but I get belt noise after changes by having the balance shaft belt too tight. The timing belt is tight but the balance shaft needs to be comparatively loose.
Thanks for the input guys. I will take it for a drive and monitor the noise. I also need to figure out why the PS pulley is wobbly. Of course I need to address that first (fix the obvious first, right?).
@spencer Im not sure about the sound. The car was fitted a long time ago with aftermarket exhaust and it has a modified DME (there is a ?.com sticker on it). So maybe it has some kind of chip mapping? the car was idling 800-900.
@marc your right, my wife is busting my ***** since Ive been spending every night with 944 trying to get this done. I figure if she can hear it, it must be bad even if she is being passive aggressive.
Have you checked your belt tension? Usually this is the balance shaft, which whines like a supercharger if it's too tight. The spec for this belt is such that when it's tight, it feels really loose.
Yes I have.
But I'll try to check them again today. Just I'm not sure how much whine is normal. I've read in several posts that 'some' whine is normal.
And I've also read so many different info about the idler roller settings...
If you look closely at the balance belt diagram, you'll see some measurement specs:
Many people suggest that the top spec indicates a space of 0.1mm; I believe this is wrong. I believe the diagram indicates a sitting deflection or some other observation, but not a space. When I set it to have a space both top and bottom, I get the whine. When I only set the 0.5mm gap on the bottom and leave the top touching, no whine (unless it sits for a long period then it whines on start up but not after that; daily driving no whine whatsoever).
Than for the re-tensioning I've tried to set the idler to have a tiny lift on the belt at top, (0,5mm lower gap).
It whined. Could be that this time the tension was a bit much. More than a 90degree but definitely far from 180.
Next step will be to loosen the belt a bit and I'll shoot another video just to document my progress.
(Just I'm not sure which setup to follow with the idler. I'll try them till I find a silent engine.)
Keep the same idler .1mm lift and loosen the belt; just when you think it's loose enogh, a tad bit more. Then warm up the engine by driving around. Go to the store for groceries and take the long way back. I suspect your whine will be gone when you get home.
09-02-2016, 02:57 AM
Do I have timing belt whine?
