StratfordShark

I'm going a bit crazy here scouring through the various TB guides, PET and the WSM, trying to figure out whether I've lost any parts (or maybe they were not installed last time) or not!

First the parts associated with the sensor wire of the tensioner. I'm following Dwayne's guide and he doesn't have you disconnect the wire from the idler end of the arm before withdrawing the arm holding idler/roller. So when I took it off the whole sensor wire came with it, including the part with the spherical contact itself. PET shows (illustration103-10) a washer (32), guide sleeve (33) as well as push rod from tensioner (22).

On the close up of the spherical contact end, is it possible to tell whether I've lost any of these, or are they all present and correct i.e. push rod 22 is inserted in the guide sleeve assuming that's the white nylon part, and the washer is in there?

Another question concerns the washers for the idler. When I took the tensioner arm off it came easily off the spindle, but I heard something drop on floor. I found a thick washer on garage floor. Does this go at front or rear of idler pulley? PET is confusing as it shows a washer at the front but is different from what I found on my car - instead of a "shaft bolt" there was a countersunk screw holding a bracket that MrMerlin told me reduces stress on the pivot (it's bolted to water pump at other end). So with this bracket that isn't shown in PET, what is the correct washer arrangement? Thick washer that fell off at the back and no washer at front (the countersunk head sits neatly in bracket), or should there be a washer at front behind the bracket?

Really need the TB experts' help here! Thanks

Mrmerlin

it appears the washer that fits to the cone part is missing,
these washers are silver not yellow/gold and they are a bit thicker than the yellow washer pictured

StratfordShark

Thanks Stan, sis that washer 12 in the PET diagram here?

And so that yellow washer goes on the front, behind the bracket anchoring the arm?

Search party failed to find that washer so I've just ordered one up from local Porsche to go with the dipstick tube seal that is in poor state (at least I plugged the dipstick tube hole so washer can't be in there)

Hilton

Adrian, here's a thread about the washer. You can find the correct washer elsewhere on the car if you're in a hurry, as the same part number is used in a few places.

https://rennlist.com/forums/928-foru...rning-not.html

StratfordShark

Thanks Hilton I may as well order it now as I have some other parts on order.

I misunderstood and thought I was missing washer at rear of idler pulley (12 in diagram above). I've ordered that too just in case, but I can't believe I lost 2 big thick washers removing the tensioner arm. I wonder if they were fitted last time TB was done...

worf928

Stan (MrMerlin) is correct: you are missing the washer between the white 'cone' and the spring that slips into the tensioner. It _may_ infact be the washer shown in your post. If that washer slips (somewhat) tightly over the white 'cone' then you are good to go. The thickness of that washer is not critical. It's not a super-extra-thick washer like #12.

You didn't. Do not worry about part #12. It does not actually exist on an '87 or newer. It is a mistake in PET. It is actually for the pre-S4 tensioner roller carrier. Look in PET and check yourself: it has the same part number for '86 and '87. But, it cannot be fitted to an '87+ roller carrier assembly.

On pre-'87 the idler roller slips onto the outside of the threaded boss on the water pump. The pivot bolt threads into this boss and retains the roller carrier. That washer is used to space the pivot bolt when it bolts to the water pump.

On '87+ the pivot bolt is not removed during a belt service. The idler roller is fastened to the carrier itself via a circlip that is not shown in PET. There is no way to employ the #12 washer.

So, bottom line: #12 doesn't exist post-'86. Mistake in PET. Should be a circlip on the waterpump-side of the idler.

StratfordShark

Thanks Dave that is really enlightening!

I know exact the circlip you mean on the idler as I removed it from old idler this afternoon.

Can always eBay the now superfluous washer that is on way to me - crazy price for just a washer!

StratfordShark

Well I measured the yellow washer shown at start of this thread. It must have come from either front of idler pulley (928.105.562.00 between arm and the support brace anchored at water pump at other end, and held on arm by countersunk M6 screw), or from the guide sleeve that fits into tensioner (900.025.008.09). It may be that latter washer was never fitted in first place, and is anyhow silver colour according to MrMerlin. It does fit over the cone of the guide sleeve but is quite a loose fit, not snug. Photo attached for interest but I'm aware it may not be correct there.

My washer is OD 20mm, ID 10.14mm, T 2.3mm

The thread referred to here says the 900.025.008.09 tensioner washer is 20.7mm OD, 2mm thick, 10.6mm ID. That would make it an even looser fit on the cone, so would fall off very easily as guide sleeve removed from tensioner and lifted out unless you were as well-prepared as more experienced people here!

So it looks like my yellow washer is from front of idler. Actually it is slightly distorted, which is perhaps from lifetime pivoting on tensioner arm?

Anyway I have coming to me from Porsche both the washers, so I can compare with my yellow washer, and if the yellow washer is from idler I will have new perfectly flat one, and the washer missing from tensioner! If that washer is missing then the tension can go lower before warning triggered, which is worrying. I couldn't check my current tension before removing the belt as sod's law says I have loaned the tool out to another owner till next week!

Will post results of comparing with new washers from Porsche. The lost washer will probably immediately turn up hidden on oil pan somewhere!

John Speake

This may help you to determine if the light system is going to work with whatever combination of washers you are considering...

http://members.rennlist.com/v1uhoh/timing.htm

StratfordShark

Thanks John. That is an excellent write-up. For laughs I may check the trigger tension on the Kempf tool with and without the washer, if it's easy to remove the guide sleeve from the spring once everything is in place. Will be interesting to see what difference the washer makes. The warning system itself should be ok as all the wires/connectors have continuity, and the connectors I removed (at top of tensioner arm and at front of centre cam cover) were clean.

But since the washer is 2.0mm thick, that would suggest more than one turn of the tensioner bolt to compensate if it's missing. I think I saw a thread once suggesting that a 1/4 turn took indicated tension from bottom of tool to around 3/4 in the window which suggests it is important!

worf928

There is no washer in the 'idler stack' after mid-'87 when the pivot bolt cross brace was introduced. #45 is the end of the brace not a washer (and another PET error.)

StratfordShark

In which case I think the yellow washer must have been on the tensioner. Maybe the lost the exact one at the last install and used this instead, or happened at earlier belt change. It's not exactly original dimensions but near enough.

Thanks for saving me from putting unnecessary washer in idler stack -could have caused some alignment problems.

Adrian

Mrmerlin

FWIW the silver washer is a calibrated part,
this will let the trigger system unload the piston in the tensioner cylinder so to remove the ground path.

I do admit that the whole system is hard to measure exactly as to when it becomes unseated.

But I have to figure this system has had much money spent testing its operation

NOTE adding a thinner washer that that called for will mean the trigger will need the belt to be more loose as compared to the thicker washer before it unseats and triggers the waring

StratfordShark

Thanks MrMerlin. The "substitute" washer that was almost certainly on my tensioner was 2.4mm v the stock 2.0mm, so I suppose it had potential to trigger false warning when the tension was in fact adequate. I haven't had any warnings since I bought the car 6 years ago. I set it to high end of window then with Kempf tool but don't recall what the recorded tension was. Correct washer should arrive tomorrow which is good timing as rebuilt tensioner today with new o-ring, boot and cleaned washers. Only did it for the experience as the tensioner was in excellent condition - boot ten years old but as supple as the new one, full of oil and washers very clean as immersed in oil.

Mrmerlin

I would suggest to use STP oil treatment to refill the tensioner,
use Honda bond 4 on the tensioner gasket.;
NOTE With the bimetallic washers out ,
put the whole stack onto the piston then into a vice and gently clamp the assembly a few times so the washers will work back into each other.
This will prevent the tensioner from losing pressure once it gets hot.
Then carefully feed the stack into the tensioner and then clkamp on the boot
NOTE the inner boot clamp ring should have its open area facing to the sky.
Use a visene bottle filled with STP to refill the tensioner after you have tensioned the belt,

NOTE fill from the hole furthest from the crank,
have both of the bleeders removed for fill .
Put a rag under the bleeders to catch any drips