Alert - 911 Carrera Chain Tensioner Installation!!!

[Wayne 962]

This just in...

One of our suppliers has sent me a letter in response to reports of increased defective Carrera chain tensioners. Please read this carefully.

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The past few months XXX has seen increased returns on hydraulic chain tensioners included in Kit XX-XX-XX. Many of the returns are for tensioenrs that have not been deployed, and others show no indication that oil has been in them. I have spoken to the supplier who has in turn checked with the one and only manufactruer in the world to determine if a defective "LOT" had gotten on the market. This is not the case, the failure rate on these has not increased, and no additional complaints have been made from Porsche or WDs.

There is no aftermarket supplier!!! All 930-105-058-03 chain tensioners come from the same factory regardless of box color, bag color, bag size, and box size. Tensioners are not always shipped in bags, they do not have to have oil on them, and they do not have to have the same casting I.D. number. Please don't let customers manupulate these facts.

Proper installation according to Porsche is as follows:

Submerge the tensioner in oil and pull the pin. Pump up the tensioner with your finger until no air comes out of the hole (this is done totally submerged in oil). Once the tensioner is full of oil, it can be checked for leaks, prior to installing on the car.

Porsche says that the procedure of installing the tensioner on the car and turning the car over to pump the tensioner up is 100% incorrect and should NOT be done. From talkng to XXXX Sales and our German contacts, most mechanics use this method, and have been for many years.

Regarldes of how long the "install and pump by cranking" method has been used it is wrong - air pockets in the tensioner can occur an cause uneven pressure, this will appear to be a "weak" tensioner when in fact it is a improper installation.

Please familiarize your customers about the correct installtion of Porsche chain tensioners, it will save them a great deal of tim and energy, and can avoid costly returns for tensioners that are prefectly fine. It can also save a mechanic a great deal of time in the event a tensioner is truly defective.

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Hmmm, I find this very interesting. The official Porsche procedure for installing these is not contained in any of the factory manuals, as far as I can remember. Does anyone have a tech bulletin with more details?

-Wayne

[Early_S_Man]

Wayne,

Very interesting letter full of revalations that seems to put to rest all of the 'rabid' detractors of the hydraulic update kits!

It also points out a not-so-minor oversight by the factory when they published the 'Parts and Technical Reference Catalog' ... there SHOULD BE a bulletin regading the update kit and proper installation of the tensioners! Somehow, I get the feeling the tensioner installation is just a bit more important than how to install a new alternator with internal regulator!

Now just how difficult would it have been for the mfr of those tensioners to put a sheet in seven languages with the proper installation procedure? I guess when you have a captive market ... such attention to detail isn't required!

Thanks for the alert! I'm sure the filling/bleeding procedure will be on the winter 'to-do' list for many Pelicanheads this winter!

[yelcab1]

Excuse me, "pump up the tensioner by hand" ??

Whose hands among us can exert the pressure of a few hundred pounds with just finger strength ??

Give me a break !! What bogus procedure is this?

[Doug Zielke]

Yeah!
When I installed them last year, you could have squeezed them down with a vise...not your fingers! (OK...maybe Superman's fingers).

[Early_S_Man]

Very funny, ol' yel! Answer is ... a guy that worked in a junk yard I waw once cut through a steel VW brake line with a tiny set of 5" diagonal pliers in a single snip!

For the rest of us who actually appreciate Wayne's alert -- instead of moaning and groaning -- a set of Vise-Grip 'C-clamps' will work just fine!

And, Wayne already told us where the procedure came from ... questions already answered are a waste of bandwidth!

[Britwrench]

Wayne,

While I can understand the reasoning behind this bulletin, it does not prove that the tensioners supplied over the last year or so were not faulty. At one time we had ten sets of leaking units ready to return. All of them were collapsing, even when we used the pump-with-oil test. In fact, if you use an ordinary oil can and pump oil into the feed line you can test a new or used tensioner.

At the moment I don't have any confidence in this type of tensioner and the bulleting actually makes me more suspicious;
those parts have been manufactured for the last 18 or so years and now there's a problem? I don't think so.

Maybe it's like a lot of the Porsche parts now, they aren't made anywhere near Germany anymore... (Bosch WR7DC plugs; made in India?)

[john walker's workshop]

ah, controversy! i can tell you that i have pumped oil thru several of these til the cows came home, and they never solidified. to me, that's a defective one, and it ain't going in the engine. had a couple that the aluminum plug in the side was installed improperly and leaked. of course they aren't going to admit any fault. and why were they pulled off the market so long if there was no problem? hmmm.

[Oldporsche]

I am very suspicious of this bulletin.

I attended almost every tech clinic that Warbonnet PCA Region put on. This was the "other" yearly event for Porsche/PCA engineers and dignitaries to attend other than the Parade.

In each tech Q & A session someone on the Expert Panel would ask how many had tensioner failures that year. A number of hands woud go up. In one session someone on the panel noted to the audience that the number of hands raised were fewer than the previous time the poll was taken. Everyone would smile and nod heads.

What wasn't done was to ask the how many people were in the room. One of my buddies was keeping track of the percentage of people affected. For several years the number changed however the percentage didn't.

Good luck,
David Duffield

[Jim T]

I'll go with JWW's real world wisdom (there is simply no substitute for EXPERIENCE), rather than blindly accepting that stuff as gospel. Or just guessing that it is correct.

People have been installing these things for 15 years. As that "bulletin" says, the past few months have seen an increase in failure. Hmm, has the whole world started installing them in new manner in the past few months?

If I were doing this procedure (I did it, 10 years ago, using the standard procedure), I'd call Andial, Walker or some other reputable shop and ask how they do it. I'd be comfortable with their advice, rather than blind reliance and acceptance of that "bulletin," which contains stuff that makes one question its credibility, IMO.

[Kevin Stewart]

Ok you guys got me worried, i was planning new chains and ramps next month and maybe valve seals, i was seriously thinking that my oil fed tensioners may need to be replaced, they have around 100,000 miles on them, do they need replaced? or are they a part that last longer? I really dont need a new junk tensioner damaging the motor, any help would be appreciated, how many miles have you guys got on them, Thanks, Kevin

[Jim T]

BTW, I don't know if that info is right or wrong ("I don't know," not hard to say), I'm just saying that it is on its face of questionable credibility, and I certainly would not accept it as the gospel and not "waste" any more bandwidth thinking about it.

I'd keep an open mind and seek answers from people with real credentials and experience, if I were installing these in the near future.

[pjv911]

I have allready installed them without pumping them up. Does this mean i should remove them and bleed with oil? They appear to be working excellent. Please advise

[83SC in PA]

I just installed a pair of PF tensioners in Nov. One of them failed immediately and when removed could bed depressed with finger pressure and it was was replaced with a 'good' one. Is this memo suggesting that since it wasn't immersed in oil and pumped up by hand before installation that it is 'my' fault it failed? Seems unlikely to me since the one that didn't fail and the replacement tensioner needed to be put in a vice to depress....this alert from the manufacturer seems fishy to me.

[speeder]

And, Wayne already told us where the procedure came from.... questions already answered are a waste of bandwidth

Yes, Warren, the procedure came from "one of our suppliers", and from reading entire post it is clear that the supplier is not Porsche. Wait, I get it- Porsche has an official procedure for installing this extremely popular upgrade for 911's, but they will not print it and only make it available to aftermarket suppliers of their parts. Yes, this makes sense.

Of course this makes no sense whatsoever. Porsche is one of the most prolific suppliers of service bulletins in all of auto industry and one of the only that disseminate them to general public. It also makes no sense to anyone who understands working of this part that they would not prime by installing and applying oil pressure(cranking). They have no pressure relief?

Also this bulletin makes no sense with claim that people are returning them as defective w/ no oil in them and have not been deployed(?) "This procedure" came from an aftermarket supplier with a vested interest in squashing defective tensioner talk and a vested interest in Wayne not choosing a different supplier for this part. I certainly don't blame Pelican or any other reputable seller for these defects because they stand behind the parts they sell.

Lastly, a short lesson on auto parts. Porsche does not manufacture these tensioners or most of the other components on their cars, nor does any other auto maker. They outsource them. The whole "box size, bag color" quote is telling. Supplier of factory tensioners, or any other part, has different lots from every batch of parts they make. There is sometimes slight variations in quality of acceptable parts that can be sold, with auto maker always getting "first lot" parts and everyone else getting the rest. This is NOT to say that aftermarket suppliers get junk or that anyone is intentionally being sold defective parts. From story of panel w/ Porsche engineers, it sounds like dealers are selling them too.

I will believe this "service bulletin" when it exists. Hope this wasn't too much of a "waste of bandwidth".

[911pcars]

Not sure if this applies to the type of common tensioner failures, but during the rebuild of my 2.7, one pressure-fed tensioner never came up to proper tension. In fact, I didn't notice this until I fired it up and got a faint rattling sound from the chain. The internal spring was holding up the tensioner (sort of), but with no/little oil pressure.

Upon inspection, oil was not getting into the chamber. I blasted some compressed air into the inlet port and heard a click. It was the sound of the check ball dislodging from whatever was keeping it from moving (bad casting/machining flashing?). Apparently this fixed it as the passage opened up. The tensioner has worked fine since (4+ yrs.).

The PF tensioner is basically a hunk of metal with a piston supported by oil pressure. The piston-to-wall clearance allows oil to slowly bleed out but not so fast as to collapse the piston (sort of like a hydraulic lifter). Are these failures caused by too large piston clearance or restricted inlet oil flow? Also, not sure how priming a new tensioner validates it'll work under pressure unless excessive piston clearance doesn't allow the piston to extend and provide adequate tension during the install.

Just my $.02
Sherwood Lee
http://members.rennlist.org/911pcars

[T Bird]

I don't buy the explanation either. How do you check a PF tensioner for leaks after it is primed with oil? The PF tensioner is itself a controlled oil leak. Activating it should produce an oil leak. The part about pumping the tensioner with "your finger" demonstrates to me that whoever wrote this doesn't quite get it.

[rstoll]

Put 'em in. Fired 'er up. They work!! I must have bought the "pre-fingered" ones.

[Doug Zielke]

...in tensioner land!

There was not a scrap of instruction packed with my tensioner kit. Therefore, I used the tech article from Pelican to guide me.

After all was done, I started the motor. It did rattle somewhat at first, and that frightened me. Did I f*** it up? Just as I was going to turn off the motor and prepare to slash my wrists, the noise disappeared, never to return. The chains have been quiet ever since.

Re-read "speeder's" post in the queue. It makes sense. Stop worrying and drive!

[RoninLB]

Not an expert, but when I did install I saw a relatively dry "Chevy Hyd. Lifter" with no instructions. I did the oil can and soft mechanical finger act. Watched bubbles float out. Thought this was better than installing dry. Didn't like idea of possible dry tens. slamming around with close tolerences.

[Wayne 962]

Hi everyone again. I just sent this to one of our customers:

If your tensioners are running fine, and not making any additional noise, then you should be ok. Seems to affect cars right away, with obvious noisy results. This is new info to me, and didn't make it into the 101 Book. I'm investigating, and will update the www.101projects.com website when more specific information becomes available.

All of this information is new to us here at Pelican. We want to make sure that the parts that we are selling are quality, and won't damage or destroy your motor. Here are some facts from our neck of the woods:

- From the tensioners that we've sold (and we've sold a lot of them in the past year), we've had two returns for apparent failures. This accounts for about a 1% rate. In the past it was rarer to hear of a chain tensioner not functioning properly out of the box.

- If the chain tensioner is not working properly, you will hear it when you start your engine. Chain failure should not happen (haven't heard of this happening yet...) because these tensioners are both spring and pressure-fed. If the pressure part of the tensioner doesn't work, the spring part will. Granted, it won't hold as strong as the pressure-fed part, but it is designed to keep the chain tight when there is no oil pressure (starting the car, etc.)

- When installing new tensioners, if you hear a loud rattling noise from the chain housing, then your chain tensioner probably is only running using the spring, and not the oil. On a new install, it will take a few moments for pressure to build up in the chain tensioner.

- I believe that all of these units are manufactured by the same manufacturer. I don't believe that the aftermarker 'crowd' gets the second, or inferior lot. Spending many years in manufacturing, I doubt that they divide up the piles into good, better, and bad. It doesn't make any sense, as I am sure that there are tolerance specs on these units that have to be met no matter where they are sold.

- No one that we know of (in the world) has had their motor damaged from a recent chain tensioner installation and failure.

It would appear that this may be a new problem or new procedure for these new style tensioners. Again, I do not have enough information on this yet to form an opinion either way. Regardless, it seems that only a small number of tensioners are affected either way.

I'll keep everyone posted...

-Wayne