harrisonrick

I looked up that thread...the new chain did not come with a masterlink...so removal of the camshafts was done. There's a comment by a mechanic member that they do have a masterlink in his experience, so breaking the chain may be possible to save yourself some work.

I believe the timing chain on a 911 has a masterlink to avoid splitting the cases, however it is a duplex type chain vs. the 944 which is a simplex type chain....food for thought I guess.

As far as the wear on the camshaft sprockets vs. a new, unseated chain goes...Tom has a good point. I'd say its a case by case thing, and perhaps if there was an oiling issue there'd be enough wear to make a significant difference. After you put on a new chain, and have the timing belts on, turning the engine over by hand would show you if the chain is jumping on the cams due to tooth wear.

Anyone else?

Tom R.

Thats the word, sprocket. Thanks spacely!
Now what exactly is the difference between a sprocket and a cog?

With 200K miles chances are the sprockets are worn. I think "Jonnybgoode" had a freshly rebuilt 16v head grenade on him as well. not sure of the details. again, search is your friend.

AndyK

I learned how to do it from this site:

S2 Cam Chain Tensioner Replacment

Jay W

Also be careful when tightening down the bolts that hold the tensioner to the head and the J-Bolt bolts. I used a torque wrench and applied the recommended torque and promptly stripped one of the mounting bolts. My car had 2 previous valve replacements, me doing it the third time, so maybe someone in the past over-torqued it and weakened the threads but who knows. I replaced the chain on cams with alot of miles on them with no ill effects. That was 4000 miles ago.

Techno Duck

Is it even possible to change the sprockets on the cam's?

This may be something i actually need to worry about in a year or so, including the vario-cam.

aribop

How much money do you want to spend??

The sprokets are cast with the cams...all one piece. I have heard of people cutting them off and welding in new ones but I do not know how well that works.

gtroth

Let's see...
-- Careful when removing the cover bolts or they will break (wake them up first). ~$26 for a short bolt, ~$12 for a long one. I would use antisieze when you put it all back together. Torque everything right.
-- Replace the gasket, spark plug opening sealing rings, and the 13 bolt seals (grommets). You'll need some sealant on the corners where the gasket breaks up off of the plane of the head. I used RTV for this. I hear you have to let silcone cure for 24hrs before you start the car or the vapors can foul the O2 sensor.
-- Replace all of the crush washers. --edit-- p/n N.013.807.4,~$0.50 ea, you need 4.Try 944online.com.
-- Stuff rags or paper towels in the head (anywhere a slippery washer or bolt might fall).
-- J-tube is pricey (~$130). Mine was pristine @ ~85Kmi when I did mine tensioner, so I left in the original tube.
-- Save the old tensioner, clean it up and put it on your desk at work (nice little trophy).
-- If all goes well, this job can be done in 1~2 hours. It's not hard at all. Unless you break bolts.

GodSpeed

(wake them up first)

how do you do that?

aribop

You set the alarm clock for them.




Actually...tap them very lightly with a hammer...really!

Legoland951

I actually have a pair of cams from a 16v S sitting around....

Jay W

Oh and another scary moment I had. While adjusting the cam timing on the 16 valve, mind you this was after everything was back together and the car had been running a few days, I took the valve cover back off and was working on the cam bridges. While using the cheesehead tool, the socket slipped off the end of the ratchet, bounced and fell down the oil return passage, and slipped around a corner inside the head and out of sight! It was just barely big enough to fit around the corner. Too heavy to pull out for a regular magnet on a string. Had to rip apart a computer hard drive to get one of those really strong magnets, put it on a string and spend 2 hours fishing it around the corner and out of the hole. Otherwise I would have to have taken the head back off the car and that was not an option I wanted. So to reiterate what others have said, DEFINITELY cover all oil return passages when doing any work under the valve cover, and dont forget to uncover them before you start the motor.

bleucamaro

I replaced the Chain tensioner, Chain, valve-cover gasket, and all the rubber doughnut gaskets for the sparkplugs & hardware at 95,000 miles. I now have 115,000+ and it still runs great. Clark's garage is a good resource, as is the factory manual.

FRporscheman

The j-tube is only on the 968's hydraulic tensioner (variocam). The S and S2 use something with a spring, right? Replace the tensioner, make sure you have TWO new pads, and check your sprockets.

The S/S2 tensioner is priced reasonably enough that you can afford to replace it. The variocam tensioner costs $1600 from the dealer, IIRC. NO THANKS! I did this job on my car the instant I bought it, replaced both tensioner pads. The top one (the visible one) looked 90% OK, but the bottom one, once I got it out, was down to about 30%. I bought a new chain, but decided not to put it in, due to the whole hype of new chains wearing out old sprockets. I still am not convinced about this issue either way.

Good luck!

gtroth

No, the S tensioner is oil pressure driven. It has a J-shaped, hard metal oil pipeline.

jonnybgood

Nope I had the "T belt failure on the drive home from the eBay sale". Tom, you might be referring to Jo Mitro. He had the tensioner failure and I linked to it in previous posts. Here it is for anyone who hasn't seen it and wants to look. tensioner failure pics

Seems like most everything is covered in previous posts. I would re state the importance of locating all the oil returns to the pan and block them off in some way.

When I replaced my tensioner the two M5 mounting bolts would not torque and I could tell they were about to strip. I drilled out the holes and installed helicoils. This may happen to you. Use a torque wrench when you install. The torque spec is not very much so I think this where the more is better crowd screw up the threads for the next guy. Since you have 200k on this car tensioner replacement must have been done in the past.

I don't buy Tifo's idea of wear on the sprockets. Mild steel bike sprockets wear due to exposure to dirt. There isn't dirt in engine oil and these are nitride hardend camshafts and sprockets. I have seen pictures of badly worn 968 sprockets but I think this is due to the larger mis adjustment that can occur with worn pads and variocam.

George B. from 944 Ecology did a write up on service intervals for the S/S2 tensioner and chain that was published in Panorama. I don't recall the specifics. do a search. Chain replacement is a much more involved task as mentioned before.