944 S2 Momentary Vibration/Rattle from Engine Bay on Acceleration?
#1
Rennlist Member
Thread Starter
944 S2 Momentary Vibration/Rattle from Engine Bay on Acceleration?
I recently replaced all belts and the 5 rollers on this car. Driving it today I noticed it runs great, but that there's a momentary vibration/rattle noise when accelerating that stops as acceleration increases. The sound is not loud or anything, but clearly audible.
When tensioning the belts I got both of them spot on the ideal setting per the Arnnworx P920X and I just did this a few dozen miles ago, so it can't be time for a retension.
The vibration only ocurrs when the car is in motion and not from revving the engine when sitting at idle.
Any ideas?
When tensioning the belts I got both of them spot on the ideal setting per the Arnnworx P920X and I just did this a few dozen miles ago, so it can't be time for a retension.
The vibration only ocurrs when the car is in motion and not from revving the engine when sitting at idle.
Any ideas?
#3
Rennlist Member
Thread Starter
No, the clutch was replaced with a factory spring centered unit less than 30K miles ago. The car shifts and drives normally, with minimal shift lever effort. Thanks!
#4
Three Wheelin'
Luis, you might check that the belt covers are on securely and that the rear cover is not vibrating against the engine. I have a small piece of rubber separating the rear belt, presumably installed by a PO some time ago to stop vibration here. Just a thought - noises are hard to diagnose without being there to hear them.
#6
Rennlist Member
Thread Starter
OK, I stopped by the shop that sometimes works onthe car this afternoon and they really doubt it's the differential since the noise is coming from the front.
The clutch was replaced at 138K miles and the car now has 158K so it would really suck if it were failing now. Especially when I went through the extra expense of putting in an original 944 S2 clutch from Porsche.
Any other ideas?
The clutch was replaced at 138K miles and the car now has 158K so it would really suck if it were failing now. Especially when I went through the extra expense of putting in an original 944 S2 clutch from Porsche.
Any other ideas?
#7
Does the car have the vibration at a fixed rmp. My S2 has a small resonance that is causing a faint rattle at around 3K. And this happens at any acceleration and gear. So is a engine or perhaps torque tube induced resonance. I replaced the belts and the noise did not disapear and have double checked the balance belt so is unlikely to be the belts.
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#9
I guess if I accelerate hard in 1st gear the revs will pass past 3K so quickly that I won't be able to trace the rattle. When the engine revs up and reaches 3K rpm the resonance can be heard. Once the revs go to 3.1K or 2.9K the resonance disapears.
#10
Nordschleife Master
Starter heat shield, that is where my money is...
Or possibly an exhaust heat shield...?
not loose, but vibrating... try hitting with a rubber faced hammer and see if you can hear it... the rattle that is...
Or possibly an exhaust heat shield...?
not loose, but vibrating... try hitting with a rubber faced hammer and see if you can hear it... the rattle that is...
#11
Rennlist Member
Thread Starter
Thats very interesting too, since I dropped the starter to install a flywheel lock when doing the belts, but I did not see a heat shield. Does the 944 S2 have one?
#15
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Join Date: Sep 2007
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something like this is often balance belt related....
the tension may be incorrect on the balance shaft belt, or one of the balance shafts may not be aligned correctly.
the tension may be incorrect on the balance shaft belt, or one of the balance shafts may not be aligned correctly.