968 Timing Belt Condition

[wassergekühlt]

Howdy folks, ive been a lurker but first post... need some wisdom shared.

I took the timing covers off today to see how everything was doing a year after my timing belt job. Found some interesting things.

1. Plastic idler t belt almost seized. causing a striped pattern perpendicular to the length of travel

2. Rubber shavings, almost like black cotton, collecting around different parts

3. an angled wear pattern on the front of the timing belt only, starting from the teeth sloping in to the top of the belt.

Needless to say its alllll coming apart next weekend, until I find whats contacting the belt. All parts were Dealer sourced. I did NOT replace the waterpump as it looked brand new and previous owner had records of it being replaced 3K before I bought it (5 K total since pump) I replaced belts just for piece of mind. No good deed goes unpunished..

Thoughts so far is that the waterpump pulley looks awfully close to the front of the belt. I cant see anything else touching it.



Pics are the most important so here it is. Any experiences?

[rufrob]

Looks like one of the rollers are on backwards pushing the Tbelt forward or the seized idler bearing collapsed pushing the tbelt forward. If memory serves the rollers/idlers guide the belt. I had the same issue a while back. Look for lips on the rollers.


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[88Silver924S]

Does this help? This fellow discusses alignment: 968 Timing belt tensioner problems - Rennlist Discussion Forums

From his second post: "So after all the testing and the one possibility that the o-rings help to keep it lined up and they could be worn, all I had to do was put it together and make sure the tensioner arm is sitting in the right position. The pressure of the hydraulic tensioner is holding it in place after I pulled it to the correct alignment. "

Was the tensioner pulley installed with the flange on the correct side? Good luck.

[wassergekühlt]

Thanks for the feedback
Re:

"rufrob Looks like one of the rollers are on backwards pushing the Tbelt forward or the seized idler bearing collapsed pushing the tbelt forward."

The tensioner roller has a lip facing the engine block, from pictures i see on the interwebs this is the correct orientation. If anything a lip facing the other direction would pull the belt away from the pump pulley lip id think, Also not sure if the idler roller would have any impact. The belt has to go around the cam pulley and its fairly centered on this pulley. likewise the crank pulley

This seems to be to be something to do with the tensioner arm or pulley. The fact that the wear is at an angle seems like the belt is being twisted as it comes off the waterpump. Im thinking taking a straight edge from the tensioner pivot to the tensionr roller? id think any play on either the arm pivot guide, the roller, or maybe even a bent tensioner arm could be rulled out this way

[Fast Freddy 944]

If all else fails, take it to a qualified Porsche repair garage and have it done correctly, you do know that after a belt replacement, you have to have them re-tensioned after 1000 mi?

[flash968]

actually, it is only the balance belt that needs re-tensioning on the 968, as the timing belt has a hydraulic tensioner. also, the re-tensioning on the balance belt is specced at 2400 miles after new belts, and then every 15k (or 1 year, whichever comes first) after that.

[wassergekühlt]

New parts ordered, should have some more clarity this weekend as it comes apart.

Re: A qualified Porsche repair facility doing it correctly, if only things were that simple life would be peachy. Qualified repair facility in north NJ did the belts for the prior owner "correctly" ( white-out applied to mark timing on cogs, completely half assed) second qualified repair facility in MD ( IMSA guy who I highly respect) said no, your hearing things its drives like a normal 968. Of course I go to do the belts, and sure as can be the lower balance belt is out of phase by 10 degrees, aligned with the "correct" white out marks. I think most any mechanically competent person can read a manual and understand how to do belts on these cars. We all take for granted certain replacement parts are within spec / tolerance as we replace them.

[dgcantrell]

I have never ever used the "marking the pulleys" method for changing a timing belt on ANYTHING. Hell, I would think it would be harder to keep things in time that way anyway. The factory TDC and other marks DO NOT LIE. Use'em and be sure.

[Fast Freddy 944]

Originally Posted by wassergekühlt

New parts ordered, should have some more clarity this weekend as it comes apart.

Re: A qualified Porsche repair facility doing it correctly, if only things were that simple life would be peachy. Qualified repair facility in north NJ did the belts for the prior owner "correctly" ( white-out applied to mark timing on cogs, completely half assed) second qualified repair facility in MD ( IMSA guy who I highly respect) said no, your hearing things its drives like a normal 968. Of course I go to do the belts, and sure as can be the lower balance belt is out of phase by 10 degrees, aligned with the "correct" white out marks. I think most any mechanically competent person can read a manual and understand how to do belts on these cars. We all take for granted certain replacement parts are within spec / tolerance as we replace them.

Well there's your problem, you took it to New Jersey to be fixed! lol, Buy a manual if you don't already have one, then have at it hoss!

[wassergekühlt]

"Qualified repair facility in north NJ did the belts for the prior owner"

Is this a good place to insert a literacy joke about Texans?

Seriously miss DFW every day. Such a great car scene. As a 300ZX TT friend down there told me once ( referring to HP) In TX, if it doesn't have a comma, it ain't sh#t.

[kevingross]

Hard to tell from the photos with certainty, but it looks like the rubbing may be from the front edge of the belt, which looks worn. Again hard to be sure, but it also looks likely to be rubbing the front lip of the water pump pulley. Good luck!

[Grandad#3]

When replacing the timing belt buy a "Gates" Belt.

Cheers,
Larry

[djnolan]

Can you provide a pic of the timing belt tensioner roller to check the orientation? The minor fraying looks is probably normal but just in case, check to make sure the roller is not on backwards. If all is installed properly check the belt in a few more thousand for further fraying.

[Fast Freddy 944]

Originally Posted by wassergekühlt

"Qualified repair facility in north NJ did the belts for the prior owner"

Is this a good place to insert a literacy joke about Texans?

Seriously miss DFW every day. Such a great car scene. As a 300ZX TT friend down there told me once ( referring to HP) In TX, if it doesn't have a comma, it ain't sh#t.

LOL! Your name sounds German wassergekuhlt, maybe even Viking? 70% of Texans have German heritage, so any literacy jokes yall' make might be about das germans down here. LOL! The NJ timing belt replacement "joke" was not aimed at the shop, but its a redneck way of poking fun at said shops. A dude walks into a shop to fix his ride, he returns to find many more problems than he thought about. The redneck mechanic points to a part that he just removed from the engine, and says "there's your problem" and then he charges him double. Its a old tongue and cheek joke! Die erindung betrifft produkte der dekoratriven kosmetik mit wassergehalt? lolTexan literacy, yeuppers we gots some.We have a great car scene, I personally like the hot rod shows at the Texas Motor Speed way, on huge event! Fast Freddy

[peteb]

Is the lower bushing on tensioner arm worn out? This is where the arm pivots and is bolted to the block. The tension pulley will be out of alignment if the bushing is worn out.

Just something to check.....

Peter