RichS 1986928

So, I've looked through a lot of posts with T-belt as a topic.. Honestly,
it's making me sick to my stomach... Just the thought of it breaking!

Anyways,

86.0, 5spd, 125K,
Last year, T-Belt, Waterpump replaced, tensioner rebuilt...
Pulleys were inspected and the bill was double the estimate.

Belt tension was checked with Kemph tool at 1,000 miles and was ok.
Checked again around 2,000 miles and needed slight adjustment to
get it to the advised edge of the window.

The problem started a month or two ago with the T-Belt light coming
on occasionally after the car sat overnight. It came on ~3 minutes after
starting. This required restarting, then it's good to go for the rest of
the day, no more warnings.

Now it's gotten a little colder here in Massachusetts and it's happening every
morning.

Needless to say, seeing that warning light is an awful way to start the day.

Any advice on why this is happening or how to stop it? Again, it only happens
when the motor is cold and the belt tension is Correct (tight edge of window).

Thanks,
Rich

heinrich

You need to check the belt drive system. I think your tensioner has lost its fluid.

John Veninger

Rich,
Were the tension arm bushing and rollers replaced when the T-belt service was done?

SharkSkin

The t-belt warning has a 3 minute delay. This means it has to be too loose for 3 consecutive minutes to trigger the light. It could be triggering the warning circuit occasionally when warm, just not long enough to get a warning light. As Heinrich says, you need to go through the whole TB system. The belt is loose for a reason, and tightening it up then forgetting about it is a potential disaster waiting to happen.

whitefox

I was under the impression that when using the Kepmf tool, the correct tension was in the middle of the window.

RichS 1986928

Re Whitefox: I was told by David Lloyd, mr. 928 himself that the tighter edge of the window was
correct. I've also seen it posted here.

Yes, the tension arm bushings and rollers were replaced as part of the tensioner rebuild.

Here's the thing, it was having almost the exact symptoms before I checked it the first time.
The result was "perfect tension" when I checked it.

1500 miles later with the same symptoms, I rechecked it and it only needed a very slight adjustment.
So it's not like I'm constantly adjusting the tension.

The tension is correct, I followed the instructions carefully.

This ONLY happens when the motor is cold. If I re-start immediately after the light comes on the
first time (so the motor is still basically pretty cold). The warning Never comes back until it sits
for another night. I can't see how the sensor is gettting the first 3 consecutive minutes but then
not again when warm.

It does seem to be related to the motor running rough until it warms up.. Any thoughts with that
included? Anyway to avoid the rough start up??? Gas additive? I was told the Ethanol is really
bad for starting.. but why would rough starting effect the T-Belt Tension?? I'm Stumped.

Rich

Bill Ball

Running rough produces more belt vibration. And, per Heirnich's comment, a dry tensioner does not dampen these belt vibrations. The tensioner warning ground breaks due to belt vibration.

A dry tensioner also has other effects in that the washer pack inside does not heat as quickly as the engine warms up. As the engine warms up, the block expands, increasing belt tension. The washer pack is designed to flatten when heated and compensate for block expansion by keeping the belt tension in the proper range. If this does not happen, when the engine warms up the tension rises out of range and the belt stretches. The cold belt tension drops due to belt stretch, warning lights come on. This happened on my car. The oil fill in the tensioner should be checked whenever the belt tension is checked, especially if you observe a belt stretching outside of the first 1500 miles.

RichS 1986928

So far so good,

I filled the tensioner with oil last night.. This morning: no T-Belt warning.

It was a relatively warm night though.

littleball_s4

I tested myself before I knew rennlist: there is no way to get no tbelt light without oil in the tensioner, excepting overtightening. tensioner is inexpensive to refill-rebuild. Do it.

RichS 1986928

Ok, I "tried" to fill the Tensioner with oil, I thought it worked but I've gotten the T-belt warning
two cold mornings in a row.

I used a bottle of 80W gear oil and a small hose.. I just put the hose on the plastic bottle, opened
both bleeders and tried to squeeze it in. I thought it was successful.. but maybe not? What's
the best way to squirt in some gear oil?? Some sort of brake bleeding/vacum pump? Is that necessary?

Rich

heinrich

first step is to use the right oil.

RichS 1986928

What's the right one 90? I've read you can get away with motor oil to grease...
Isn't 80 close enough?? It sounds like it's a pretty simple case of heat transfer in there.

What does Porsche recommend?

littleball_s4

Do a search. The one I used was the one recommended in several places (look at the links of 928intl, for example) and I had no warnings since then. I had to "rebuild" the tensioner, though. Installed a new boot, that is. The old one was driping the oil out as I filled it in.

RichS 1986928

Ok, I just need to find a trigger type oil can I guess.
The tensioner was just rebuilt (not by me) so hopefully it will hold oil and this is the problem.

Gretch

The old style oil can works if the spout is a flexible. I have one of those and it is perfect for this task.