Mongo

Okay, who can answer this for me?

After correcting the balance shaft timing, I retensioned the balance shaft belt. Since the idler is not supposed to be touching the belt, I ended up removing the idler in order to get the tension. When I installed the idler, I used a .508mm feeler gauge between the idler and the belt to maintain the spacing.

After tightening, and driving it, I now have a rattling / knocking sound coming from the timing belt case. This can either be the idler rattling because of the balance shaft belt rolling on it due to improper tension, or the damn idler is loose and I missed torquing it

Was I supposed to remove the idler to tension the balance shaft belt, or should I have kept it on there in order to make sure that there isn't too much tension on the belt. The balance shafts are kind of singing even at the 90 degree feel tension.

Stan944

Yes, you remove the idle (smooth ) roller to measure the tension. One important issue not everyone knows: you need to back the engine a fraction of the cam tooth in order to make the tension on the belt uniform. If you don't do it, you end up with slightly too low tension on the belt.
In any case, remove the top belt cover, and you might be able to see where the belt causes the knocking you noticed. Also look at all sprockets and check that thay spin evenly.

Zero10

Yup, 2 revolutions, then back 10* to check tension.
For twist method, balance shaft belt should be 110* twist, not 90* like the cam belt
At least that's how I do it.

Mike C.

You don't have to actually remove the idler. Just rotate it such that it is no longer in contact with the B/S belt. Also, IIRC, it isn't necessary to rotate the engine back 10 degrees for the B/S belt (only the timing belt).

F18Rep

I think Mike is right, theoretically, the balance shafts are loose to rotate (ableit slightly) when the balance belt is deflected for tension tests. This is differnt than the cam belt. Check Porsche's procedure, I don't think you will find the rotate-back-10-degrees note on the balance belt procedure. Just my opinion though...Bruce

Jfrahm

I thought the rule of thumb was: Cam belt 45 degree twist, BS Belt 90 degree twist. The BS belt feels really loose when properly set up. I have a 9201 but used the twist method for a year or so before getting it, the first time I set the BS belt it was too tight and howled.

-Joel.

Zero10

Nope, cam 90*, balance shaft is 110-120*
I checked my by-hand values with the 9201, and they were bang-on.

Yeah, both belts feel very loose when properly set. It's kind of disturbing until you get used to it.

Mongo

when I did the tension by feel, and my buddy came over with the P9201, the tension was like a 4.5 because I got paranoid that the tension was too lose

Mongo

Uh oh. All idlers are in tension and the nuts are still torqued. The noise is coming from the top part of the motor around the water pump housing. This is a rebuilt pump with only like 2,000 miles on it. Just outta curiousity, could the fact that air in the coolant system cause the water pump to knock? I have not bled my cooling system yet.

Mighty Shilling

Just thought of something Andy... A while back I heard a knocking sound, and it confused me. it was from the front of the engine...

so, I pulled off the belt covers, and checked tension of the belts. I pushed it over, saw that it could tap the belt cover bottom... then started the car, and confirmed, that was the problem. see if it's able to hit the belt cover. if it is, check tension. tighten accordingly. good luck man. I know you used a 9201, but it might've not been calibrated... check things out. 9201 IIRC needs a calibration after EVERY 4 belt tensions

Mongo

what the!? It does?! Who the hell makes this tool the Chinese!? (no offense, I just had many tools from that country broken)

I'm going to try and add more coolant, and bleed the air out of the system since I never bled the car when I ran it for the first time. Perhaps there's so much air in there it's tweaking the water pump still.

Anyways, as far as the knocking goes, it's not rhythmic so that may rule out the rod bearings. It also goes away when the car warms up a little bit...more like comes and goes.

Mongo

bleeding the cooling system seems to have dampened the noise on the front of the motor. I'm betting there was air in the impeller or something causing the knocking.

Very mysterious...

I have a feeling this may not be the end of this

TO BE CONTINUED...