My new to me 944 whines like it has a supercharger, but I know it doesn’t have one. Is this sound normal? (New belts and pulleys on the front end already, sound didn’t go away)
any reassurance is appreciated
My new to me 944 whines like it has a supercharger, but I know it doesn’t have one. Is this sound normal? (New belts and pulleys on the front end already, sound didn’t go away)
any reassurance is appreciated
Did you try taking to the belts off and see if it went away?
Check your timing belt. Mine made a noise like that when a bolt backed out and started milling it down from the side. If that's not it, I'd suspect an accessory bearing which you can diagnose by taking the belts off one at a time.
Check the tension on the timing belts, they need to be tensioned after a few miles.
The whine is almost certainly either the timing belt or the balance shaft belts over-tightened. If the whine is coming from the head of the engine (the upper timing cam pulley) then it's that belt. If the whine is coming from the idler pulley, probably the balance shaft belt. The rule for 944 belts is "it should be looser than you think it should be." I've heard this from a dozen 944 guys and found it to be the case myself. If you don't have the special Porsche tension tool, IIRC the rule of thumb is that the timing belt should be loose enough that you can twist it (with some strong fingers) 45 degrees on the flat of the longest span, and that the balance shaft belts you can twist 90 degrees over. With the engine off, of course ;) Don't quote me on that (Google it!) but IIRC those were the twist angles. Of course, depends on how strong your fingers are, I guess.
Also the orientation of the idler/tension pulley can affect this. Google that as well, but when you tighten it you HAVE to go clockwise on the offset base before tightening the bolt. IIRC you should have a mm or so gap between it and the belt with the car off. All in all, it's a lot of trial and error unless you have the tensioner tool.....Porsche, arnworx, or "the cricket"
Mine whined when I did my belt changes (with new pulleys and tensioners) and one of the local 944 experts came over and said that it was too tight (it was already looser than belts in most modern cars). Loosened it up bit by bit until the whine was gone. No issues since.
Check out Clark's Garage, I think it has some of the tricks to the correct (or "good enough") tension.
Edited previous to give more information/fix something. Also check out:
http://www.clarks-garage.com/shop-manual/eng-10.htm
In reply to irish44j :
Thanks, I’m pretty sure it’s the balance shaft belt. No noise from the tower. I don’t have a tensioner, so I did use the guide from Clark’s. Seems pretty loose to me already, but I’ll do increments like you suggest. I didn’t know about the clockwise offset, so I’ll double check that too.
TR7 said:In reply to irish44j :
Thanks, I’m pretty sure it’s the balance shaft belt. No noise from the tower. I don’t have a tensioner, so I did use the guide from Clark’s. Seems pretty loose to me already, but I’ll do increments like you suggest. I didn’t know about the clockwise offset, so I’ll double check that too.
yeah, it could just be the idler pulley (the one with the offset hex-shaped base). It's kind of a pain to adjust, hold in place, and get in the right place. Took me like 10 tries. But that by itself could be causing the noise so do that first, and then eke down the belt tightness after that.
btw, i'm just telling you stuff from recent experience of doing it myself and reading the web. Stefan is certainly more of an expert than I am so if he has anything to add, listen to him!
on the upside, if the balance shaft belt slips a cog or whatever, I guess it would just make the engine run rough and not be a catastrophe like the timing belt.....so perhaps its less of a worry to loosen it more than you think it should be (I guess).
Thanks everyone, I got the balance shaft re tensioned and re indexed the idler pulley, it sounds a lot better now. I must have missed where the tensioner can only rotate in one direction and really buggered that up. Took it for a ride and everything seems good, I’ll recheck the tension again in a couple more miles.
And after posting this I realized all the info already out there about this exact noise, sometimes my google skill just don’t work out the first time.
Thanks for the help.
TR7 said:Thanks everyone, I got the balance shaft re tensioned and re indexed the idler pulley, it sounds a lot better now. I must have missed where the tensioner can only rotate in one direction and really buggered that up. Took it for a ride and everything seems good, I’ll recheck the tension again in a couple more miles.
And after posting this I realized all the info already out there about this exact noise, sometimes my google skill just don’t work out the first time.
Thanks for the help.
nice.
yeah, all the different how-tos and ways people do it can get confusing on Google anyhow lol....
You'll need to log in to post.
