Alan

Car is all back together - took it for a 35 mile drive in varying conditions (apart from the consistently scorching heat) - no tensioner warnings - seems to be working OK to start with.

So far so good - now only time, and maybe the seasons, will tell more.

Alan

Imo000

At what point is the warning supposed to come on? This could be safely tested on a 16V US engine.

Alan

If the piston of the tensioner ever electrically disconnects from the rotating lever that pushes the tensioner roller into the belt loop then the warning will trigger.

There are 2 obvious primary causes of that:

1) The tensioner piston binds up for some reason and does not consistently exert pressure on the lever

2) The tensioner runs out of extension and does not consistently exert pressure on the lever

The first of these would relate to some failure of the audi tensioner, the second is more likely to be due to the belt stretching just too much. Its not easy to test either of these because both are essentially failure modes that are difficult to model. Before you pull the pin on the tensioner you have a case a bit like 1). Perhaps using part of an old belt you could more or less realistically simulate 2). However the belt warning is not detected when the car is still cold - so there is a timeout window (about 3 mins) that has to pass first. This should not be needed on the PKT system - but is built in to the warning system.

The static tension on the belt with the PKT was lower than the stock static tension spec. But of course the PKT will try maintain a similar tension over time, (so no re-tensioning is required after a new belt install) while the stock system will vary depending on the engine temperature and with belt stretching over time. Unless the belt stretches excessively the PKT should be able to manage the belt tension for the life of the belt.

The Audi tensioner is designed to extend quickly but retract slowly (that's the hydraulic damping) so it should maintain the min sprung static tension - but may allow higher short term dynamic tension. You would tend to expect that would serve to maintain a good connection between the piston & the lever - but its hard to know what else might be going on dynamically. It's also not clear exactly how quickly the stock warning system responds to the tension "switch"*.

Static tension on the PKT after rotation was 4.25 units on the Porsche tension tool Vs. the 32V spec of 5.0 - 5.3 (there is of course no adjustment to make with the PKT).

*e.g. Would it ignore very short duration open circuits? Adding a large value capacitor across the sensor switch could potentially extend this time if it were problematic.

Alan

Alan

A few more pictures:

More of it going together - unfortunately I have a lot of extra plumbing that needs to be connected up.

Alan

Alan

Well its been 2 weeks and no warnings or false alarms in quite a bit of driving. I'm quite pleased so far - my biggest concern was false warnings - so I'd say it's a success. I will take another look next year and make sure the isolation is still good. To do that I'll need to wind the tensioner back in so I can re-pin it and then break contact with the cam/lever to detect if the sensor triggers.

I think at this point this is rather easy to implement, and a worthwhile addition to the PKT, maybe still not perfect - but a lot better than a grounded sensor wire.

Alan

davek9

Great news Alan, good job

I'm waiting on one of those Racing grade Gates belt and some good used Cam gears to arrive

Thanks again for doing and sharing this.

Dave

Alan

Ken its been a month now driving every day and no false warnings - seems totally stable. I need to take it through the winter for different conditions, but it seems to be working fine. Of course always assuming it hasn't shorted to ground - which is hard to tell - Will take a look at that next year.

At this point it seems this is a worthwhile thing to do along with a PKT install - no real downsides, cheap, relatively easy to implement. Relatively easy to revert if needed, I'd just add 2 terminals: 1 directly grounded under 1 bolt head and one connected to the tensioner body - so under a second bolt head and also under the mylar/mica insulating washer.

Alan

Schocki

Hello Alan,

great job and a very good update. Keep us posted!

@Ken
Future upgrade kit on the horizon?

Un saludo
Schocki

Alan

Well - it has been almost 5 years now and I can confirm no warnings in that time and I can also confirm that the tensioner body is still properly isolated from the engine. Static tension also seems basically unchanged. I'm going to continue to use this method with refresh of parts as needed.

Alan

Schocki

Any chance of an update kit on the horizon?
Roger, Ken?