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-   -   Nice whine from the front of the Engine and not the Turbo (http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/583456-nice-whine-front-engine-not-turbo.html)

BryO 01-03-2011 02:41 PM

Nice whine from the front of the Engine and not the Turbo
 
No water leaks, no belt dust and not running remotely hot but feeling the few month old water pump is going. New Timing belt and pulleys.

The sound is worse when you start up and quietens down but is still there. Any pointers out there before I loose the engine or head. http://forums.pelicanparts.com/uploa...1294098085.jpg

John_AZ 01-03-2011 03:11 PM

Here is a video----move to bottom of page-----"overtightened balance shaft belt" sound..

http://arnnworx.com/tensioningbelts.htm

When you check your cam belt, try the "WaterPump Pully test" to see if the cam belt is overtightened.

If the belt is too tight it will burn out the seal and the bearing

http://forums.pelicanparts.com/uploa...1294099783.jpg

GL
John

HondaDustR 01-03-2011 09:31 PM

It's probably the balance shaft belt, and it might actually be too loose given that it gets better when warmed up. That has usually been the case when my car has done that. A balance shaft belt that is too loose will whip alot more and rub on the smooth guide roller, making a whining noise that's more of a rubbing whine that sounds slightly inconsistent, whining more or less depending on the rpm, whipping kind of like harmonics in a string at certain frequencies. The too tight sound like in the video link whines very evenly and consistent across the rpm range like a supercharger sound. It could also be that the guide roller is adjusted too close to the belt. It should be just barely not touching the highest point of a tooth when the tooth is closest to it, max 0.5 mm.

It's a finnicky thing to get a feel for by hand, but luckily not very sensitive to inexact tensioning. I usually slap the AFM back on and start up after my belt job but before putting everything back together and run at various rpm up to about 3000 and watch and listen to the belt. to check my setting.

wild man 01-04-2011 06:53 AM

Quote:

Originally Posted by HondaDustR (Post 5762401)
start up after my belt job but before putting everything back together and run at various rpm up to about 3000 and watch and listen to the belt. to check my setting.

I also use that same exact technique for determining proper BB tension.

Right now it is quiet when cold, but the zinging noise does start in after it is warmed up, when rpms go above about 2K. That means just a wee bit too tight, correct?

Shifter 01-04-2011 08:10 AM

Just a silly suggestion, but is your power steering fluid full? Friend of mine chased a strange belt noise for a bit to find it was the pump whining....

BryO 01-04-2011 10:55 AM

re
 
All that is good, but I will listen and see if the pump is the cause. With it all being right there together and the way sound travels.. Interesting.

HondaDustR 01-05-2011 11:41 AM

Quote:

Originally Posted by wild man (Post 5762752)
I also use that same exact technique for determining proper BB tension.

Right now it is quiet when cold, but the zinging noise does start in after it is warmed up, when rpms go above about 2K. That means just a wee bit too tight, correct?

Most likely yes. Just tweak it a little looser.


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