More grist to the mill - checked the belt last night and it is over tight - 3mm passed the tight side of the Kempf tool window. Too cold to mess any further.
Still could not see the make of the belt. However "MY CHOICE" car is off to see Doctor Sean for a strip down, new belt and PKensioner. Will report back on findings.
You others that are biased towards the original tensioner make your own choices - my car my choice - period.

 

For what its worth, Ive got an 81S... with an interference motor (5ltr block), Ive replaced my belt twice in the last 10 years and both times I was very lucky, as I have no warning light of course.

Each time Ive replaced the belt was because the roller bearing on the water pump failed...the belt itself was in excellent shape. And each time, the first warning was noise from a sloppy belt...

But, both times the tensioner had failed as well, the rubber boot on the tensioner became hard and brittle and cracked open. I had replaced the boot in 2007, and when I did the TB again in 2013 the soft rubber boot felt like hard plastic and was once again split open.

On an early car without a warning light, it seems the PK tensioner is a good idea.

Also, after a couple of goes now, changing the timing belt/water pump/everything else you need to do isn't really that hard to do once you have the right tools, and I bought the flywheel lock and the Kempf tool off Roger and he got them to me in no time at all... I have IT hands as well, they`re very soft!

Mind you, that first fire up once you finish the job is TERRIFYING...

 

I don't buy the idea of waiting for a detectable issue to cause sufficient belt damage that tension loss can be detected... to me that's backwards...

A seperate warning mechanism, that specifically also checks tracking can give early identification of bearing/gear wear issues before they cause collateral damage.

The warning system doesn't have to be directly part of the tensioner system.

Alan

 

The problem is that there are different failure mechanisms. One collection of failures are primarily tracking-related, but many times the flanges on the WP and crank sprocket will simply start chewing at the edges of the belt making it narrower. So an "edge detector" would need to compare both edges, or maybe look for "fur".

But this is also easy to check by peaking down the vents in the two cam covers so seems less important than tension-related problems.

Another collection of failures is primarily tension-related, e.g. worn sprockets (smaller radius), failed bearings, failing/stretching belts, etc. In this case the PKT responds by extending (until the stop is reached) while the stock tensioner quickly loses tension (which is detected).

An alarm system would ideally sense both-- tracking outside the flange limits plus tension (stock) and/or rod extension for the PKT.

The pressure on the NTN tensioner rod does change over its travel, from about 22 lb at full extension to 54 lb at full compression, and 30-35# at the normal operating range. So maybe this could be used as an indication of rod extension-- e.g. a strain gauge of some sort.

Agreed, and it can also incorporate more than one sensing component.

As to the question of "why bother, no one else monitors belts" remember that this is a big long belt, and these engines last much longer than most. Again, a personal choice.

 

Right, but by Jim's admission, the tensioning process was not calibrated. It was turned an 'X' amount based solely on the warning light illumination. The light didn't come on again, so therefore the belt was not loose. The fact that it was over tight doesn't surprise anyone who's read this and know that the adjustment was made as a stop-gap measure to insure the belt would not be too loose.

Are you sure Sean knows where to find the timing belt? I guess we could send him some books, and videos, and stuff. lol

 

I agree all the more reason to detect more things. An optical sensor - depending on the responisveness used would tend to detect furring at the belt edges - it would generally reduce the distance the belt would need to move before a lateral sensor would detect it as well as reduce the flap distance required to detect tension loss. If there is also good system to detect that the Audi adjuster is at the end of its adjustment range I think that in parallel is also a good idea. For tension I'd think the large outboard take up areas are the ideal places to sense flap particularly on the side that generates the most slack (after the crank sprocket).

I'll be interested to see what Ken comes up with here.

Alan

 

How about painting the two edges of the gears with refective paint and use optical sensors to keep an eye on the belt tracking? When the migrating belt start to cover up the reflective edges, the alarm would go off.

 

Not to add fuel to the fire.... but what happened to preventive maintenance & inspect the belt periodically?

This thread has it all.... from hurty feelers to fur dectectors....

 

Jeez, chumming the waters/working the crowd....

 

Blasphemy!

You
shall
be
flogged.

 

Hah - True!

I do think correct preventative maintenance is still critcal - and as with fire - it will protect you from the many risks that really are predictable - but it doesn't eliminate all risks - so you do need a good backup system watching over you..

For some maybe thats just having a real spring tensioner - for others maybe it requires a Belt & Braces solution (Suspenders for you Americans... that means something quite different to some of us...).

Alan

 

I cannot speak for anyone else, but my primary motivation for using a PorKensioner has little to do with wanting to avoid regular inspection and proper maintenance. I don't try to fix oil leaks just so I can avoid checking my oil, either. Instead, my primary motivation is my belief that dampening the belt reduces the stresses on other components of the engine. Other things being equal, I prefer smoother to rougher (we're still talking about engines, right?).

 

This is put very well and applies to me also.

I've had the PKT on my car with worn gears and the Gates Racing Belt for close to two years. I used the worn gears because I wanted to know how much wear the GRB was putting on gears. It was said that the GRB was wearing the stock gears at a much accelerated rate and I figured what the hell, let's put it all on there and test. So far after 19 months and 13,xxx miles, the gears are no more worn than they were when I put the belt on there. I don't baby my car at all and consider it some hard miles that I've put on. As this is only a user observation on my car and not tossed through a some approved engineering firm it doesn't mean jack squat right?

Let me reiterate what I just said. The gear wear on worn Porsche gears, has not increased in the slightest after installing the PKT. Is this going to happen to your cars? Fvck if I know. I have also got 2 other cars with different gears, different belts and much more miles on them for a reference that I am keeping close tabs on. And don't think that the other couple dozen are not being looked at each time they come in, as they are. Stupid **** like in this thread makes me wish I had been keeping detailed data on every PKT I've installed so the "data" could be shoved up some peoples back sides. Hind site is 20/20 though.

Is the PKT perfect? Nope and some of the short comings are being addressed with the new iteration that Porken should be announcing soon. Do I consider it a better option than the factory one? For me yes. For 80% of my customers the answer would be yes and that is not due to me or Roger trying to sell something as I let them make up their own mind on it. Discussion like this is great for everyone but when you have one or two people who have always said the same things over and over, it gets old. Especially when one of them seems to have a nice grudge when Roger or Greg post about a product they have.

ImoOOo, check your comprehension again, I never brought up your wife but I wish her all the best being married to you.

 

I feel like I need to weigh in here with my experience as well. I had stock gears stock belts and stock tensioners. I had repeated instances where the light would come on, and I would pull it all apart and never find the problem except I could never keep the tensioner full of oil. When I was building my stroker engine I ran my engine on the dyno without the lower cover and was amazed at the flap on the belt during dyno testing.... fast forward about 8 years and I did the same thing with the porken tensioner.... not nearly as much flap on the belt. (actually almost none) I have put close to 20K Hard miles.... hard miles.... like the kind of miles that burned up 2 sets of tires..... high speed runs... days and days of dyno time.... and I've taken it all apart since.... its going back together with the porkensioner and the gates racing belt.... and serious piece of mind.... I trust this set up better than the factory one with a warning light every day of the week and then some.... I garantee that my stroker engine accellerates much faster than a stock engine by far...

 

Sean it's not my fault that you don't understand what you wrote. Think a little longer and how it brings my SO into the discussion.

And please understand that to claim something is better, there needs to be solid proof, otherwise it's just an opinion. Yes it would have been a good idea to keep some record of your observation if you want to claim this product is better. Would have ended any discussion long time ago. It is not shove it up anyones back side but to prove what you claim. Also, I have no idea why out of all people, take a technical discussion personal. Keep it professional.