I was recently faxed an article about 968 cam chains stretching at around the 75K mark...can't recall the magazine, but it was a British publication. Since I just bought this car in December, it was in for belts and hoses, anyway, and my mechanic took a look...sure enough he found the chains to be stretched also.

I don't think this fellow is the type to try and create business for himself. He and I are of the preventative maintenance philosophy, and it has worked so far.

My car has 88K on it, so that needs to be taken into account, also, but the article did mention quite a few 968's that did have the same issue. Sounds to me like this area is a possible source of a major repair if it's not looked into every 50K or so; so I felt I'd share the info with the group.

Anyway, as the saying goes...YMMV!

Regards,

Jason

 

Thanks for the info, my car now has 60K on it and I will keep this in mind.

 

The magazine is 911 and Porsche World, The article actually features an 944S2 but the idea is the same. It also talks about the little teflon "piston" that alters the valve timing cracking. This of course would mean a major engine failure similar to broken cam belt. The part (piston) is quite expensive. As my car is going in for new belts next week (140K km approx 88K miles). I will enquire. Interestingly there is no mention of this as a maintenance item. It's certainly kept me awake at night recently.

Darrin '92 968.

 

Hi - I have a 92 coupe tip, with about 88K miles on it. It recently started making a light whirring/grinding/meshing noise from the top end at startup. Once warm it goes away. It doesn't use any oil or have any other bad signs. Sounds like this could be it. If anyone has any articles/references which talk about cam chain symtoms, I'd appreciate a pointer...
Thanks, Murph

 

Hi Murph

The chain on my car was badly in need of replacement but the car ran perfectly, so I would definitely get it checked over if it's noisy.

If it stretches too much, it can break the teeth off the sprockets on each camshaft. If this happens (as on mine) you need new camshafts which are big bucks. if it just needs the chain though I don't think these are expensive.

Regards, Alex

 

Murph,
The noise you are hearing is most likely your hydraulic lifters. They click until the oil pressure has come up. The cam chain tensioner or vario-cam tensioner (968's) has not maintenance replacement interval. However, from the 944S2 mail list it is widely considered smart to replace the entire tensioner between 75k and 100k. Yes, you can just replace the top ramp but you are already in there and spending $300 now vice $25 for just the ramp is much better than spending $2500-$5000 later. While you have the valve cover off take a look at your chain and the teeth on the cam sprockets. If they show excessive wear then you should consider replacement. Also, keep in mind...if you have to replace the chain the cams have to come off so it would be smart to spend the extra money at that time and replace the cams. If you put a new chain on worn out sprockets it won't last very long. The majority of the cost for cam chain replacement (like most things with Porsche stamped on it) is the labor rather than the parts. Cam chain/cam replacement is NOT for the average backyard mechainic. This a fairly advanced item and should be done by someone who really knows what they are doing. Guess work will most likely meet with disaster.

***When replacing the cam chain tensioner PLUG ALL OF THE HOLES IN THE HEAD BEFORE YOU REMOVE ANY SCREWS/WASHERS ETC... that are under the valve cover!!! Don't ask me how I know to do this. The J-tube crush washers are aluminum so if you drop one in the oil return galley it will be very tough to get out. Also, the little 6mm allen head bolts that hold on the cam chain tensioner will easily fit into the oil return galleys and will also be extremely difficult to retrieve (i.e. it will likely require oil pan removal to retrieve it which equals mucho time or much $$$)

Regards,
Max

p.s.- Sunset Porsche in Beaverton, OR has great prices on the parts to replace. Cost me ~$290 for all gaskets, j-tube, tensioner, & crush washers. No affiliation, just satisfied customer.

 

Max,

While I agree that the cam chain replacement is a little tricky, I have done it myself on a 944S and it was fairly straightforward. The only special tools I needed were the flywheel lock and a home-made pin spanner for the balance shaft pulleys, if I recall. I wrote up a detailed procedure that was hosted by Clark (forget his last name) on his website, "Clark's Garage". Unfortunately that seems to be no longer operating but I can mail the procedure to anyone who is interested. The only really tricky part is getting the cam timing right without using the dial gauge method called for in the factory manuals. However, my method ensures that the cam timing is reset to exactly where it was before strip down.

The 968 is a little different, with the variocam mechanism but from a quick look-see at my own 968, I don't think that will present any additional difficulties.

cheers

Derek
Linköping, Sweden

 

Derek H,

Could you email me your procedure? I might do this soon. Everything looked ok when I did the timing chain tensioner, but my car does have 132K miles on the original chain and sprockets

MadMax I second that, I did drop a crush washer but was lucky enough to not have it fall down into the oil pan. I guess I would rather be lucky than good.

Thank you,

 

Just a word of advice. Drop the $300 or so that the whole assembly costs rather than just buying the $25 pad replacement. They may work fine, but since you have the top of the engie open and new cams cost about $1000 a piece, not to mention other damage that could occur if the pad slips off the tensioner, I would spend the extra bucks. I did the whole nine yards. It's like the Mr. Goodwrench ad....You can pay me now or pay me later.

 

[quote]Originally posted by craig001:
<strong>Just a word of advice. Drop the $300 or so that the whole assembly costs rather than just buying the $25 pad replacement.</strong><hr></blockquote>
The 968 doesn't use the $250 944 S2 tensioner, it has a Variocam tensioner that costs somewhere in the neighborhood of...$1800.

 

So what is the consensus 12 years later?

 

Pads and cam chain should be a 60k service item.

 

I did mine with around 54k on the clock. My pads didn't have too much wear on them but were getting a little pitting, the chain still felt tight but I replaced it as well.

 

Is there a time limit on cam chains like with timing belt? Looking at a car, it has 30k on the chain, but done 8 years ago.

Thanks for advice.

 

No, because the timing belt is made of rubber, it has a limited life span. Rubber will not only detriorate with mileage, but also with age. Cam chain is made out of metal and tensioner pads are hard plastic. I would do it every 60k to be safe.