WICruiser

Thanks guys. I suspect that when I pull the passenger side cover it will become more obvious.

The longer term plan is always to drive it more but it resides in Wisconsin and I spend all week in Chicago so weekends are my only opportunity and somehow other stuff seems to always get higher priority.

I am seriously considering the Porken tensioner change when I do the next belt change, just not sure when that will be yet. I would like to think the 5 year rule is less critical than the mileage rule but that may be wishful thinking.

I replaced the water pump when I did the belt, I don't recall the brand but it is a rebuild from one of the big three suppliers. If the bearing is moving in the pump housing is there any outward appearance change? Mine looked really good with the belt tracking where it should, etc.

I hope to get time this weekend to pull the cover and check it out.

Mrmerlin

if the bearing is moving in the WP housing then you may not be able to notice this unless you measured it prior to installation,
the bearing only has to move a small amount to loosen the belt

dr bob

I'm not sure that the too-common bearing movement in the WP would change the belt tension much. My impression has been that the bearing or more specifically the shaft inside the bearing moves longitudinally. That would move the belt sideways in its normal path, and not affect tension. Is my understanding of the WP bearing problem wrong?

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To the OP--

There was a Continental belt that was shipped regularly at about the time you last changed your belt. Known stretching issues, based on other users' experiences and reports. I used a genuine Porsche belt made by somebody in my last change, and used the standard Gates with a Porkensioner on James M's Euro '85 project car. Both seem to be doing well. I really like the Porkensioner, and will probably add one to my car at the next belt change (in the next year or so) along with some kind of stretch detector to replace the original tension warning switch.

Mrmerlin

Dr Bob the belt pushes the bottom side of the pulley upwards and thus it tilts the top side of the impeller into the block so the bearing must be moving inwards and at an angle as well

Landseer

I've had the light trigger on 2 continental belts on 2 different cars last fall --- some time after retensioning.
So I retensioned them again.

cold_beer839

I rebuilt the tensioner twice on my '87 S4 before it stopped leaking and I trusted it. The original tensioner design is just awkward and full of bugs that get worse with age. To me that qualifies it as junk compared to the Porkensioner. Put on the Porkensioner and a quality TB and replace it every 5 years regardless of miles, no more guess work and trouble shooting electrical gremlins in the warning circuit. Replace the WP as needed.

Don't get me wrong, the stock tensioner was a great design for the early/mid 70's, but a little over-engineered (typical German). Ask the surviving German tank maintenance man from WW2 what was going through his head as he wrenched like hell on a mega over-engineered Panther while the T-34's and Shermans were firing rounds over his head and driving through the gates of the Fatherland. He'd say the stock tenioner on this Panther tank is trödel!!!!

Landseer

So let's add the factory description of system and light operation

Mike Frye

Well played. I think there is actually some confusion even among the very experienced wrenches here.
When I saw this part in the documentation that comes with the Morehouse CDs it cleared up a few misconceptions for me at least.

Landseer

I wish they showed a top-down view, too.

It would show why --- why any slop in pivot point A kills you.

The expensive little plastic bushings are critical.
The straightness of the pivot bolt is critical and its got a fragility issue.
The condition of the bearings in the tensioner pulley is important.

As Mike and I both know ('cause others like Porken and GarthS and Roger have shown us), the 85 car is particularly susceptible to escalation of wear, once wear begins. This is due to the "twist" or moment that is magnified on pure 85 cars because of the design of the arm. Begining early 86 that was lessened somewhat with revised arm design, but its still a big issue. Gotta scrutinize, some say always refresh, the pivot bolt and bushings at least.

Mrmerlin

if you have any play on the pivot bolt to bushing,
they both should be replaced,
a loose pivot mount will let the tensioning roller tilt ever so much towards the rear of the crank damper.
This will let the belt run towards the damper and in extreme wear cases the belt actually grinds away on the rear of the damper till it fails

WICruiser

I pulled the passenger side upper cover and confirmed belt tension is at the high end of the notch on the Kempf tool, where it was set last week - so no early movement/loss of tension.

Checked the continuity between the pin for the wire connection and ground, and at first it seemed suspect. Removed the inner wire from the terminal (it seemed loose) and tried to deform the female terminal slightly to get a tight fit on the spade connection. Confirmed the wire connection had continuity to ground, and put it back together.

Test drive resulted in the tension warning coming on again, basically as soon as the time delay expired.

It appears I will need to pull the lower cover again to get a good look at the tension contact strap and teminal. You really can not see or do much with only the one top cover removed.

Pivot bolt bushings and tension roller were replaced with the TB job done ~5 years ago. I am pretty sure the tension roller is tracking well on the belt and not pushing it into the damper but I will confirm when I pull the lower cover again.

borland

Since you've already cofirmed the belt tension is correct and that the switch/sensor is functional, the next step should be a check of the warning circuit.

Try grounding the circuit from the CE panel using a jumper wire. Take a look at the WSM wiring diagrams to identify the CE panel electrical plugs through which the switch signal passes through. There are two plugs that you can connect and test for tensioner switch signal or to apply a ground for testing the warning circuit.

WallyP

You can start by hooking the wire that plugs into the belt cover to an engine ground - this is the wire, not the connector on the cover. If the tension warning light is still set, the problem is a faulty connection somewhere between that point and the warning computer (located under the dead pedal for your left foot).

Mrmerlin

then use a ohm meter set to beep to test for ground continuity from the pin connector on the front of the timing cover to ground

WICruiser

OK - I think I have it sorted out and fixed.

The test with the wire disconnected from the front cover, but attached to ground resulted in no warning.

Checked the pin in the cover for ground again, OK both statically and with the engine running. Checked with various engine speeds and waited several minutes to confirm it was stable.

Concluded that the wire to cover pin connection must be loose but couldn't see how to tweak the wire (socket end) connection to ensure a tight fit. Installed about three strands from a 16 guage standed wire in a U shape fitting internal and external to the socket connector and plugged it back into the cover connection.

No more warning light! Ran for several minutes and then took a spirited test drive that saw several different 5000 rpm shift points and still no warning light.

Thanks everyone for your help on this.