geekapalooza

Garth - The whole back of the belt looks pretty clean, no out of the ordinary scuffs. The printing on the belt is still nice, white, and legible.


No, the underside looks fine. Of course it is a lot rougher from the factory, so it's harder to tell to a small degree. Best I can tell the underside looks like new.

NOW - I was just doing some closer inspection to the roller, and noticed some "blueing" of the roller that I had not seen before. So the big question for the moment - DO the new one's have this blueing? Is that just a by-product of the manufacturing process?

The blueish color is emanating from the inner diameter of the roller, adjacent to the bearing area, where the heat would be generated if indeed the bearing is bad.

Anybody have a brand new out of the box roller they can inspect, to see if the bluish color is there?

If not there, maybe we found the source of the heat? If so, that may seal the deal?

Fingers crossed on this one...

figgen

A couple of things

I had a timing belt that had a tendency to walk to the front edge of the cam gears. The culprit ended up being a worn CRANK shaft gear. It was tapered - raised at the back and worn on the front.
Worth checking if you have the covers off.

If the belt is off.....can you turn the water pump by hand???? Worth a check to ensure it is not seized.

ErnestSw

Rob,
It's possible that what you're seeing is heat transfer from the hot tensioner pully to the belt to the water pump pully. When the belt stops moving the heat in the water pump pully is then transferred to the belt in one spot making the mark you're seeing.

T_MaX

That coloration on the pulley in normal, it's part of the anodizing process.

I'm just not convinced this could be from a hot roller. I have seen pics of belts that came off of two 928 cars after a seized bearing and this isn't even close!

Think about it! A motor at idle is just under 1k RPM's, if you did any driving, I'm sure the RPM's were no less than 2,500. Therefore if this was a bearing going south, the belt would have that marking all the way around it. I will go further to say that there would also be lots of rubber dust on the inside of the T_belt cover and the pulley with the failed bearing would have skid marks on it.

If your still waiting on parts, reinstall the belt you have (for testing only) as well as everything else (but without the accessory belts) and give it a try.

SharkSkin

Something is creating the heat. Lots of good suggestions above. Check the WP pulley for resistance. put as much pressure on the tensioner pulley as you can with your hands, and see if there is any roughness at all.

If there is any problem with the washers in the tensioner... for example if the washers are not stacked in the correct, staggered sequence, then belt tension will INCREASE as the motor heats up. The job of all those washers, oil, etc. is to relieve tension on the belt as the block and heads expand. Just be really sure the tensioner is OK before you pull out too much hair.

I agree with Curtis... put it back together after checking the WP for resistance. Leave off the covers and accessory belts. You can run it a few minutes like this. When it starts moaning again, find out what's hottest in the belt train.

BTW, did you check for rubber dust inside the covers? If you wiped or blew them out then nevermind.

HTH

T_MaX

Dave, just one thing you may have over looked, he can't leave the covers off and still start the car. It's an 1987 S4, the dist. caps bolt to the upper covers

SharkSkin

DOH! Yeah, I'm livin' in the dark ages... damn single-distributor CIS car...

Also, this time through I saw that Gretch already made the point about the tensioner being designed to relax at temp....

Jeez, I oughta just go to bed. Or maybe switch to the larger font for a while.

Garth S

For what it may be worth, I've attached a pic of the timing belt that was eaten by the cratered bearing in my water pump last year.
The pulley shaft came off axis (the bearing cage collapsed) and the pulley started to nibble at the pump casting - so there was a reasonable amount of friction . BTW, the pump seal remained intact.
The edge of the belt was chewed off, filling the covers with rubber dust; however, the printing on the back side is still very legible even though the belt had to be sliding over the somewhat stalled out pulley. What I looked for this AM was the marking that shows on Rob's belt. There is a 2.75" smooth and very reflective area for 3/4 of the belt width. Clearly, this was in contact with the off axis pump pulley at the time of shutdown.
The marking is there, but different in nature - so does this mean anything? Not that I know at the moment!! As the pump and reminants of it's bearing were still bathed in coolant (OK - it boiled over as I shut it down), the temp could go only so high - bot a stalled roller could get much hotter ...?.... ? ...

geekapalooza

All of this is giving me a headache...

Anybody in Houston area care to swing by and take a look?

The water pump turns freely, but with more resistance than the one that came off the shark. Hmmmm.....

The arm was not available to order quickly, so I skipped ordering that.

First - A List of parts that are coming in:
1. Tensioner Roller
2. Pivot shaft that mounts to WP, that tensioner pivots on.
3. Tensioner bushings
4. T-Belt
5. Tensioner Roller nut and bolt

Here's a rough draft of the plan for the weekend when parts arrive.
1. Mount the tensioner assy, install belt.
2. Run engine with center TB cover off, and no accessory belts.
3. Look immediately to see if the "hunting" is still occurring where the TB goes fore and aft on the cam gears (peer through the side cam cover breather holes)
4. Listen, listen, listen...
5. Pray, pray, pray...
6. Shut down motor after a couple of minutes
7. Inspect everything til I'm blue in the face
8. Feel for an extra hot component.

Anything else?

Also, thanks for all the helpful replies. Sorry I cannot respond to every single one, life is busy right now, but I have definitely read each and every one, sometimes more than once, and used that info to help me ultimately solve the issue. Thanks!

ErnestSw

Rob,
Since you're suspicious of the new water pump why don't you replace the new one with the old one (temporarily) WYAI and remove the variable from the equation?

geekapalooza

Ernest - Great idea, but in my haste I already sent the old one back for the core credit.

Until an expert turns the WP pulley and proclaims it's health, or lack thereof, I'm still wary of the WP, due to the increased rolling resistance. Everything about the WP pulley feels fine, just harder to turn than the original.

Maybe replace it also under warranty?

Gretch

It generally should offer a bit more resistance, which will go away after some milage. Is it "stiff" to turn or only offering moderate resistance. For example, can you turn it with one finger placed on the roller, sliding back and fourth?

Garth S

That is the perfect feel for a new pump!
Rob, for the purposes of the test, I'm sure there's a lot of life left in the orriginal belt: even the newly installed one could do. You might consider reinstalling that for the first spin, if you still suspect the pump- - and especially if you leave the older 'new' tensioner roller in. Save the new belt until you are sure of the problem.

goliver

Yikes. It would seem you dodged a major bullet. Go buy a lotto ticket.

I had a tensioner bearing that I bought new to put in my old car (an '87 S4) fail about 1 week after installing it on the way to take the car to the new owner. Needless to say he did not have to buy the car and I wound up taking a bath on selling it to my uncle who is turning her into a track ride.

In any event, Everytime I do serious TB related stuff on one of these beasts I cross my fingers and hope against all hope all goes well. Mine failed at 3000K rpm in 5th on the freeway. When I took apart the engine it was not a pretty sight. Had a nice big paper weight.

Regards,

geekapalooza

Gretch wrote:
Great Avatar Gretch! I just bought the DVD, looking forward to actually watching the movie.

Did the test, and I can turn the WP with 1 finger on the front of the pulley, spinning around. If I try to spin the center axis / shaft rapidly, it does not coast at all, I'm guessing that is ok though?


Garth wrote:
Great idea Garth. I'll add that to the plan for SAturday.



Geoff wrote:
Oh great, so even when I get her running right, I'll still be paranoid! The thought of my wife killing me over a $6K engine overhaul sends shivers up the spine!