Engine whine after timing/balance belt replacement...help please
 

I have just had some work done on my 1984 944 by a car repair shop [not Porsche specialists].
Namely.....timing and balance belts replaced....new belt rollers...new oil pump drive sleeve... front engine seals.
Engine now has a whine that was not apparent prior to the work.
I have since removed the two outside drive belts so as to eliminate the compressor, alternator and power steering pump as the source. Therefore the whine is confined to the front engine work.
I need to know what the possible source of this whine could be before I complain to the mechanic that did the work.
Comments please.

Most likely the balance shaft belt is too tight. I'd guess that the timing belt tension is also suspect.

Balance belt is commonly installed too tight. Installers aren't used to the fact that if the belt can be twisted by hand around 90 degrees it's not too loose. When it's installed too tight, it'll whine.

Has anyone ever tried taking the covers off the belts and running the engine while adjusting their rollers before?

Just out of curiosity.

I haven't. I'd be too afraid of having a finger ripped off...

I think longer wrenches would be in order if you wanted to do it though. Especially if you REALLY wanted to have PS and your ALT hooked up too to check it out.

I think that'd be a interesting thing to try out. Of course, It's not very safe... but it works.

One slip and they'll be calling you Lefty....

My BB made some noise for a couple thousand miles, then quieted down. It was plenty loose to begin with.

yes you can . some 944 cup guys run no t-belt covers

How many of them run balance belts? I'd be amazed if any of them adjust their belts with the engine running.

You are quite insane, between the cooling fans and the belts there is no way in hell i'm sticking my hands in to adjust a belt on a running motor.

Be smart, keep your fingers, and have a helper stop/start the car for you for rapid tension adjustments.

adjusting the BS belt tension WHILE The engine is running? that's ****ing GUTSY and darwin potential.

i once accidentally left the socket+breaker on the crank bolt. holy hell i'm lucky i didn't do any damage when i cranked her up.

yea there are some people that run w/o covers, myself included. but i still wouldn't do a live running tension adjustment.

to OP: if it looks like it's "tensioned" it's too tight. if it looks like "wow that's loose" it's probably about right. as long as the belt is tight enough to not skip a tooth when it runs, it's tight enough.

I run without the covers.



Most do. The vibration damage potential (like a cracked oil pickup tube) doesn't justify trying to run without it, in my book.


I tighten the balance shaft adjustment pulley with just my fingers - no wrench.

You should be able to twist the belt 180 degrees. My engine whined like crazy (I told people I had a supercharger :thumbup:) and when I popped off the timing belt cover I couldn't twist the balance shaft belt more than 45 degrees. I loosened it up a bit and the noise was pretty much gone. All 944 engines will whine to some degree, so some noise is normal.

Balance belt whine
 

Hi all,

Balance belts whine a little when new but if it is loud, it is the lower idler roller rubbing on the lower balance shaft pulley.

Just loosen it off and lift the idler up until it is just barely touching the belt section above. This is the correct position.

I don't have balance shafts and even my timing belt whines a little. I have the Arnnworx tools and it's tensioned correctly, and even on the low end of the spectrum. I think it's just normal to have a little whine. It's only noticeable when I'm driving through an alley with the windows down but it's there.