timing belt

[tmpusfugit]

I have a pair of the cam gears off an '81. they are steel, but they are far better condition than what you have. I may have the crank drive gear as well as the oil pump drive gear too...not certain about the crank gear. You can have them all for the cost of shipping if you end up not buying new parts. If you decide you are interested in mine I will dig them out, take photos, and post here for the collective wisdom of the group....about a recommendation, or not, to use them.....

[tychain99]

Originally Posted by Spin-Master

On the liftbar site, there is a PDF file and the bottom of the PKtensioner part.......Here is a link for the whole Timingbelt/Waterpump replacement procedure...http://members.rennlist.com/pirtle/tbelt.html.......as for the rebuilt waterpump, it can be a crapshoot as to the quality of the rebuild.

web page not found....

[Spin-Master]

Try this 928 S4 Service - Timing Belt

I didn't notice that it carried the extra .......as, sorry

[camo]

Thanks Spin-Master, what parts do i eliminate by putting in a PKtensioner?

[camo]

Thanks tmpusfugit, Ill let you know if I need them

[Spin-Master]

Originally Posted by camo

Thanks Spin-Master, what parts do i eliminate by putting in a PKtensioner?

If you look at the pictures in the PKtensioner on the liftbar site, you will see the differences. The part that is "eliminated" is the upper roller that you can see between the toothed portions of the belt For those that are familiar with the 911, the "tensioner" used in the PK kit is very similar looking which makes one wonder why Porsche didn't stick with that design and maybe just improve it a bit.

[dcrasta]

Camo > If I were you I would take Camo up on his offer.

You are going to have to replace the belt, and rebuild or replace the tensioner.

Looks like you car has run with the tension too tight for some time. The damage may be isolated to the cam gear (The crank gear is steel).

If you get the parts from Tmp, and his gears are in good condition, you may end up only having a bad oil pump gear.

In any case take the member up on his offer, and (if you have a space the car can sit for a few days) remove the front timing covers and accessories (so we have access to the tensioner and the belt run).

In for a penny in for a pound. You can do this with hand tools and the willingness to get dirty. Lil 16valve is a piece of cake bro. Getting those square profile gear-parts can be tough however.


Oh, order a flywheel locking tool now. This is definitely one tool you will need forever.

[tmpusfugit]

These are steel gears, removed from a car that showed 72k miles on the ODO, which had not worked in a very long time. The car was abused in so many ways,I would guess these gears had at least 150k miles on them...along with the rest of the car...it does not appear to me that Porsche went the right direction when they went from steel to anodized aluminum gears....looks like the steel gears are able to run a lot longer...

[dcrasta]

Those look magnitudes better than what he has and have minor wear. At least until he can get his $$ together (if he wants to convert to the round profile gear) ..

[camo]

Wow, yeah that would be great tmpusfugit. Ill PM you my info Thanks

[camo]

Hey, so im needing to order a tensioner now. I can get the regular tensioner for like $150, but im looking at the PKtensioner and wondering if it will be any harder to install, and im not sure which one i need, JUST the tensioner, or the tensioner with the air pump. I'm pretty sure i dont need the kit, cuz i got the timing belt and gears. Is it really worth it to get the PKtensioner?

[camo]

P.S. Im paying to have it done cuz its a MUCH bigger project than i expected.

[Dean_Fuller]

The "kit" includes the custom MOUNTING PLATE that allows the Audi tensioner to be used. You can order a plate with the air pump bracket made on it to run a stock air pump ( if you state requires air pump ) or without. If you are removing the air pump then you will need this one. If at any time you need the air pump ( or sell the car to a owner in a state that needs it) it will need to be replaced.
The "KIT" does not include the belt. he sells the kit for the buyer that needs to install for the first time. After that all you will need to replace is the tensioner and pulley. I have installed 2 and I highly recommend them.

[924CarreraGTP]

Let me ask a loaded question here. Do you guys recommend a PKtensioner for a race car? I know my stock tensioner will take hours of abuse without any breaking or slipping. Do you guys know that to be true with the PK tensioner? Has this product been tested and developed in real world racing situations? Just wondering.
The original tensioner doesn't keep the same constant tension upon start up and through the whole rpm range. I'm skeptical if the PK unit wouldn't cause more premature wear. Just a thought.

[stepson]

Justin,
I believe the idea with the Porkensioner is that although the tension IS slightly less than factory specs, it is constant. In other words, when the engine is cold, it is the same tension as when the engine is at operating temperature even though the engine has expanded due to the heat. Because it is spring loaded, it should reduce timing belt flutter such as happens when running at high speed and load and then braking heavily. (This flutter just happened to me in my GTS and has happened before in my '89. There is nothing that will make your butt pucker like a digital dash timing belt warning!!!) And yes, the timing belts in both had been checked just before the flutter happened.

[924CarreraGTP]

Not sure who Brad is. My name is Justin. I understand this about the PK unit, but the original tensioner made the belt more rested and loose until the engine heats up. At that point the tension increases. If the tension is always the same, it would have to be higher than the factory unit upon start up. I would think that would probably cause more wear at start up. Probably less when the engine is hot as it would be close to factory tension. I'm still not sold on using this as I don't know how well the PK tensioner has been tested. I do know that my original tensioners are still working fine from 1983 and 1984. Cheaper may not be the best route on a 32 valve motor. I guess on this particular engine it really doesn't matter, but I would hate for the aspect of cutting corners for untested products to ruin someone's GT or GTS on a track.

[Dean_Fuller]

I know a stroker motor running one...plus several racers. I have MUCH more faith in this tensioner than the stock one. It is more money ( especially at first ) but no chance of oil leaking out and never needing to check tension is very nice.

[stepson]

Originally Posted by 924CarreraGTP

Not sure who Brad is. My name is Justin. I understand this about the PK unit, but the original tensioner made the belt more rested and loose until the engine heats up. At that point the tension increases. If the tension is always the same, it would have to be higher than the factory unit upon start up. I would think that would probably cause more wear at start up. Probably less when the engine is hot as it would be close to factory tension. I'm still not sold on using this as I don't know how well the PK tensioner has been tested. I do know that my original tensioners are still working fine from 1983 and 1984. Cheaper may not be the best route on a 32 valve motor. I guess on this particular engine it really doesn't matter, but I would hate for the aspect of cutting corners for untested products to ruin someone's GT or GTS on a track.

Sorry about the name mix-up. Corrected. You do know that the original tensioner is not actually a tensioner, right? It is actually a de-tensioner that works as the engine expands as it gets hot and keeps the belt from becoming too tight.

Porkensioner is an individual choice. I do not have one currently on my cars, however if a method to detect a timing belt problem and subsequent warning is devised, I will have one. The lack of warning is the only deterrent for me.

[tmpusfugit]

There are a lot of cars running the PK tensioner. A couple are approaching 50,000 miles IIRC. Also, keep in mind the technology is pulled from a similar Audi engine in a family of cars that has run millions of miles and has been used on 10's of thousands of cars, if not substantially more. Also, it is really a spring tensioner, and they are used on many modern cars for tensioning a timing belt...I favor a constant tension such as this PK tensioner will provide over one that is too loose cold and too tight hot, and dependent to some degree on oil that may or may not be there....etc...etc.. I suspect in hindsight the original Porsche solution was over engineered and not really necessary....

[Spin-Master]

To make it very simple, the PKtensioner works very similar to the tensioner on the accessory serpentine belt the runs the alternator, airconditioning compressor, power steering pump, and water pump on your normal chevy, ford or mopar vehicle. When the Engineers at Porsche designed their tensioner, they forgot 1 golden rule of engineering: the KISS principle---Keep It Simple Stupid.