Last Lemming

Ok, I finally finished the belt change. As some of you may know I had what sounded like a bad bearing. After opening it up all the rotation bits that had bearing seemed smooth and solid feeling, however the belt was rubbing on the back cover and there was rubber shavings all over the place. I bought belts and new rollers anyway but kept the water pump since the PO put in and OEM one 1500 miles or so and the there was no indication of a bad bearing.

The whole job took me about two weeks from start to finish, but I only worked on it after work for a couple hours or so a day. and a couple days in there for waiting for parts. I took my time and read and reread alot. I used the Arnnworx tension tool, and that seemed to be pretty easy. I could not, no matter how I tried, get a .5mm distance form the bottom balance belt and the roller while being able to get the top measurement correct. I held the .5mm and the top ended up 1.5 - 2 mm play. I did make sure when tensioning the bottom balance tensioner I turned it counter clockwise.

Today I finished the putting it back together (other than the lower front lip and the belly pan). I started it up and let it run until the thermostat opened up and the fans cycled on and off a couple of times. I've attached a video after it had been running 5 minutes or so. I ran it a total of 10 min. or so. I did not drive it yet. That will be tomorrow after I fished buttoning it up on the bottom.

On initial start up I did hear a trace of the of the "sound" from under the car and it seems to be coming from between the crank and water pump - but it wasn't too bad and you cant really hear it from above the car. It sounds like belt or roller sounds I think (see video and let me know what you think). I'm not familiar with these engines to know all the idiosyncrasies about the sounds they make.

All in all it was a good learning experience. The real test will be once I take it out and flog it a bit and really get the temps up. In the initial run the oil only got about half way hot. Though Im not sure what oil temp would have to do with belt noise.

I'd like to thank all those who helped me out and answered my questions. In a few days I will have driven it and my final report will be posted here.

The video:

refresh951

Nice work!

Last Lemming

Ok I took the Car out and there is a fast buzzy vibration up to 4000 rpm but really strongest between 3.5k - 4k. After that is smooths out.

I know people will say the balance belts are off. So I checked those. With the notch dead center on the bottom of the bell housing the timing mark on the cam is out no more than 1/32" off the mark and that is the same for the lower balance shaft. I can't see the mark on top of the engine for TDC - meaning its too obscure to see anything so I half to use the bottom of the bell housing.

The top balance shaft is dead on.

What should I do?

refresh951

Did you remove the balance shaft sprockets? See here:

http://www.clarks-garage.com/pdf-manual/eng-08.pdf

Last Lemming

I did. Is it possible to have the timing marks aligned bot the shaft 180 out since there seems to be two not the woodruff key can go into?

Tom M'Guinn

Hmmm... I think your balance shafts are off. Are you using the notches on the back of the timing cover as your alignment marks for both balance shafts and at the same time? As for confirming TDC, sounds like you're there, but you can check the top of the bell housing mark by leaning way over the motor from the driver side and looking straight down with a flashlight. There is a bunch of stuff in the way, but it's just a matter of getting the right angle. If all that checks out, I second Shawn's comment about the sprocket alignment mark thingies....

Last Lemming

Here is a video of the installation marks. Please bear with it - getting the shot was a little difficult, but it does show the marks are all on.

Tom M'Guinn

Yes, I think that was a practical joke by Porsche.
Here is a good link showing the orientation, though I have to say it looks right in that video. Hard to see everything clearly in the video, so check out this link and compare your set up...

http://www.arnnworx.com/balanceshafts.htm

Last Lemming

Ok. I think want I did is since the sprockets seem to have two slots for the woodruff key to fit into I got it backwards on the lower shaft. I remember the balance shaft (on the bottom) woodruff key was pointing to 12 o'clock and that is how I put the sproket on. If I understand what I'm reading I should have aligned it towards the U or opposite the O

When I take it apart tomorrow ill know for sure.
What I do know is that it didn't make the vibration before this install.

Van

That vibration does kind of sound like the belt is fluttering or hitting one of the plastic covers. If this new belt (and rollers) is still causing contact, you might have something else causing a problem, too.

Make sure your balance shaft sprockets are keyed correctly. Maybe this diagram will help:



(note, this diagram is drawn as if the pistons were pointed straight up... since the engine is on a slant, this should be rotated about 45 degrees counter clockwise.)

Last Lemming

Well, turns out my top sprocket had the woodruff opposite the "O" not next to it like in the diagram above - I think I found the problem captain!

Van

Maybe it will line up with the mark better!

Last Lemming

Yeah that's a good point!

And if someone is thinking "you can't install the sproket like that the tang will hit the woodruff key" - they would be correct, however tangs will break on that woodruff key. Mine did and I just enough to lock it in place. Oh we'll lesson learned. Could have been worse.

Last Lemming

Gentlemen we have liftoff! Smooth as butter gentlemen smooth as butter.

The only thing I can't seem to do when setting the balance roller to .5mm to the belt and the top to 1mm (?). I held the .5mm but the top is about 2mm. Any thoughts on this? And trust me I spun that roller all kind of ways to try and close the gap.

God I hate that roller.

I haven't driven it yet, just started and revved it a bit. But there is no vibration at all!

Ill feel better once I get it out on the road for a test run but so far all is well.

TexasRider

If it is posted at " 951 " then it has got be all good.