Lizard928

I've run 7 years on a belt and porkensioner with no issues (open covers too).
The 50k miles is commonly referred to as the best practice on the forums for the cars that I've read before converting the first time.
As to the time/age, the 5 year service is more required for a car that has done less than 20kmiles in that time. The grease in the bearings (WP, tensioner roller), and the seals in the tensioner tend to harden much faster with very infrequent servicing.

If the car is driven daily, I wouldn't hesitate to go longer myself. But I'm not going to recommend that on a customers car!

PorKen

IIRC, the Audi 2.8 (30V, where the PKT parts come from) often had water pump problems before the original 170K km/105K mile service interval.

One reason why it was reduced to ~60K miles.

DKWalser

I think, as with most things, the answer is "it depends". I doubt belts last as long in Phoenix as they do in Ontario. Our summers eat up belts, hoses, tires, and batteries. You might be comfortable with a belt that's been on a car for 8+ years. Given your climate, you might have every reason to be. Those of us in the desert Southwest might feel a need to replace belts after 5 years without regard to mileage. Given our climate, that inclination might be justified.

Which is the problem with rules of thumb like "replace the belt every 5 years or 50,000 miles", rules of thumb don't apply equally well in all situations.

whatudrivin

Bump... Recent discussion in another thread talking about this. Might as well bring this back to the top for more ideas.

polecat702

I've run 7 years on a belt and porkensioner with no issues (open covers too).

Colin, makes an interesting point, running open covers. I've run Gates HTD belts longer than anyone here on this forum.

Dick Allen invented the "belt drive" for Harleys after watching Blown Fuel dragsters at the Pomona Drags, back in the late 60's. At the time only one company developed a reliable belt drive, Phase III.
Pacific Broach, in L.A. made the pulleys, and Gates developed the belts. In the early 80's Harley gave Gates a Lowrider, and told them to develop a primary belt drive for the factory. When Gates returned the bike, it had both a primary, and final drive belt. Harley named the bike, " The Sturgis." The primary drive didn't work out for 2 reasons. The engine pulley had a rubber center like a vulcanized motor mount. The big electric start aluminum primary cover and housing held in the heat, and any detergent oil that got on the belt would degrade the belts construction. Heat and detergent oil ate up the rubber of the belt, and motor pulley. Harley abandoned the primary belt after 1 year in production, and went back to chain driven primary. Harley still uses the belt on their final drive for every bike in production. The final drive belt will last the life of the drive train. It also runs without covers.

I've run belt drives on my motorcycles for 40 years, and they are reliable. I haven't been able to shred the teeth on a HTD belt since 1984. And that was on my twin engine'd Bonneville racer.

The only difference between the belt on our 928, and a Harley belt drive, is the width, and length.

IMO, only engine oil, and heat will degrade the belt. There's a lot of heat, under the hood of a 928. Plus Doc Brown is of the opinion that heat is what causes the motor mounts to deteriorate, and collapse, when the under tray with the cooling ducts are missing.

I'm using Ken's tensioner too, and I live in Vegas. It's furnace hot in the summer. Greg Nettles recommendation was all I needed, and I bought the PKT kit from Roger. Money well spent, I don't think the warning light is needed, the Porkensioner doesn't work the same way as the stock set up.

gruffalo

I don't wanna beat this subject to death, but: other things than the tensioner can fail too. In that case a warning light might come in handy.

Imo000

Do you disable your smoke detector and hope by keeping a close eye on the house, you'll never need it? The odds are you will never need a smoke detector.

davek9

Ok thanks for revisiting this thread, can we PLEASE get it back on topic

Ken, how about using what you proposed:
the nylon washers, shrink tube on bolts, some Blue loctite

And some of those mechanical bolt fasters to keep the bolts from getting loose due to the reduced friction provided by the nylon washers.
This way the installed ones won't need a stud retro fit?

Thanks,

Dave

PorKen

6mm studs and nylock nuts would be the best?

There is a whole lot of threads for those 6mm bolts. Way more than is needed for steel. One would think that Loctite would work OK?




Coolant pressure switch

Since most of the belt management issues, outside of the tensioning system, center on the water pump, why not install a low-pressue 10mm (12?) oil-pressure-switch in one of the block drains. (This could be done with the stock tensioner, too.)
With a S4 water pump, it could be used as a plug.

This would indicate loss of coolant or impeller/pulley failure?



Since most pressure switches are open under pressure it would have to be wired to the coolant temp light, not the tension light.

davek9

Coolant pressure switch, would it trigger the belt light or add a new guage? We all like more guages

Agreed the studs would be the most solid, however would require welding them to existing bracket already sold?

I was looking for a solution in hand, and Red loctite would be best if it sticks.
isn't there a mechanical fastener for bolts or even mechanics wire like old XKE cam gear bolts?

Thanks,
Dave

dr bob

Coolant system pressure is much more a function of temperature than water pump function. Maybe a differential pressure detector, to detect flow through the radiator or some other known flow resistance in the loop.

The Audi tensioner differs a lot from the stock tensioner, providing a mach larger range of travel with a much smaller change in pressure in that travel. I expect the piston to extend in normal operation, so deciding at what point it's overextended is tough. More to the point, I want to know when it needs to extend to maintain pressure on the belt, but hasn't. So we need both an over-travel detection to see when something else has failed, with an under-travel plus low-pressure detection to see if the tensioner piston isn't keeping up, and an over-travvel plus under-pressure detection to see if the tensioner has fallen off. Too many failure-detection conditions relate to what can also be described as normal desired operation.

davek9

What does the Audi use?

j.kenzie@sbcglobal.net

Do any other cars use timing belt warning lights in their interference engines?

Lizard928

Only one in the world that I am aware of. The diesel toyota hilux, and only for certain markets.

69gaugeman

Wouldn't the Toyota make two?