Stylemobile

Symptom:
Running car for last 300 miles with passenger side (US) timing belt cover off to check for issues.
Upon initial cover removal, timing belt tracking was about 2/3 to rear, 1/3 to front (meaning there was a little more sprocket showing at the front than the rear.
Belt now tracks with belt's rear edge lining up with edge of sprocket.
For about 1 minute after shutting down engine, there is a small wiff of smoke rising from under and behind the cam gear. This smoke smells like burning rubber. It stops being produced rather quickly. The amount is 1/4 or less than that of a cigarette resting in an ash tray.
The belt is running cool as is the cam gear.
There seems to be a black, somewhat oily but sticky residue forming uniformly on the inside back cover of the entire exposed timing belt cover. There does not seem to be an odor to this residue.
The backside edge of the belt also seems to have a slight smear of this residue although it is not on either the smooth or toothed mating surfaces. Belt looks clean otherwise and shows no sign of wear.
Nothing is rubbing on the timing belt section that is now exposed.
The engine seems to run very smoothly.

History:
Used replacement engine installed in car for about 4000 miles and 7 months.

Replaced or added before engine went into car:
Timing Belt
Water Pump
PorKension'r
(air pump eliminated)
Cam Gears
Head Gaskets
Oil Pan Gasket
Water Bridge Gaskets
Misc. things either related or not. I cannot recall at the moment. I must check my 928sRUs parts receipts.

What could this be? Where should I begin looking for a cause and/or solution? Does this even seem a problem? How serious does this seem to be? (Last 2 questions are kinda subjective.)

Attached are pics of new engine during replacement time.

Your experiences and knowledge are always valued.

Thank You,

Allen in Allentown, PA

Stylemobile

P.S. Belt can be read from the front of the car.
The car is a 1984 automatic. No mods.

Drewster67

Any rubber shavings to be found? Is the width of the Tbelt less than when purchased? The black residue may be beltshavings mixed with grease/grime dirt. I had the similiar problem on my previous 84 Euro. Tbelt was riding the back of the sprockets and rubbing at a lower piont on the motor.. Turned out I had a broken tensioner bolt.

GregBBRD

Inner belt trust washer missing behind the crank drive gear? Can't see it in your picture, but it would be hard to see from your camera angle.

SeanR

That was my first guess also.

Stylemobile

Would I be able to see the inner belt thrust washer behind the crank drive gear without any disassembly? The belly pan is already off and I can lift it in my driveway.

Of note: There are no belt shavings and the belt has no visible wear on any face or edge.

Also, the belt tracked fine for most of it's 4000 mile life and has gradually moved aft within the last few hundred miles. Would not the absence of the inner belt thrust washer make the belt track rearward almost immediately after the car started running without it?

I will check this though. Does anyone have a photo already of what this looks like?

Stylemobile

Also, the water pump is brand new. I would hope that this would not be the source.

Mrmerlin

Here are few more threads on T belt install

http://forums.pelicanparts.com/porsc...years-but.html

https://rennlist.com/forums/928-foru...questions.html

https://rennlist.com/forums/928-foru...-belt-job.html

Stylemobile

Here are 3 more pics taken with my blackberry tonight. Not the best but not bad for a cell phone camera.
I have only removed the passenger (right) side timing belt cover over the cam gear so far. I know that it will take more removal but not in cards at moment.
I discovered something perhaps pertinent tonight.
With a flashlight, I looked down the inside of the remaining TB cover along the exposed belt leading down from the cam gear. It seems as though the tensioner pulley is canted rearward at the top of this pulley. (Unable to capture with this camera.) This may be an optical illusion but if true, may account for forcing the belt rearward a bit. I judged this be eye aligning the cam gear and this pulley and they seem out of parallel. If it is canted, could I have perhaps installed it incorrectly or could a mounting bolt that holds it in place be working it's way loose allowing for gradual canting of this pulley?
Hmmmnnn.........
I also see that there is now a thin strip (about 1-1.5 mm) of the oily/sticky substance along the smooth side rear of the belt. I will be far more cautious with the running of the engine as the problem seems to be advancing.

All food for speculation, reasoning and banter.

Let me have it, Folks.


.

PorKen

That's too far back. Something's up. The goo could be oil or coolant.


Can you see the water pump pulley? See if there's space between the pulley and the housing, top and bottom. (byrdman454 had a pump fail within a few thousand miles.)


Are you sure that the tensioner pulley was installed with two washers, one on each side, and the bolt torqued to spec?

Stylemobile

Too cold for outdoor car work lately and computer getting upgraded in shop. Wish. CAr in shoP and computer getting fixEd in driveway. .
Sent this from my phone.
Stay tuned...

Mrmerlin

Ken in the top photo the belt looks to be back from the front edge of the tensioner roller does this seem correct to you?
Is it possible that the operator may have installed the tensioner incorrectly??.
If the rear thrust washer was missing from the cran that would then let the timing gear and the front thrust washer move rearwards and thus move the belt back.
It would also be a good idea to remove the belt and inspect the waterpump and to measure the pulley to housing clearance.
let us know what you find

PorKen

Hard to say. In the photos of the original post, the engine hasn't been turned by the starter. The belt will be where you string it initially until it turns a few revs.

The only way the tensioner pulley could be crooked (besides the bolt being terribly loose) is if the rear washer were missing, but then pulley would not extend, either.

Mrmerlin

Ken the reason i asked is that i was looking at your avatar and noticed how the belts riding on your roller.
I guess more investigation is due

Landseer

How about taking a couple measurements from the outside edge of the cam gears to the back cam covers with a mm ruler and posting the data? I have an 84 without cam covers we can compare with.

Also, would you please post the part numbers of your cam gears.