Jay W

So now I broke the timing belt on the 944S after only 42,000 miles on the belt. I really thought it would go to 50,000 safely. Anyway I am removing the head and apparently I need to remove the cam gear to get at some bolts behind it. First of all has anyone removed the cam from the head without first removing the gear? And secondly I cant tell if the cheesehead bolt and the large hex part are all the same bolt or two different pieces. I looked in the factory manual and it doesnt clearly specify this. It looks all one piece on the car. Its the center bolt I am looking at. Do I hold the hex part with a large wrench and put the cheesehead socket in and turn against that?

sharky47

T-belts are only good to 30,000 or three years, whichever comes first.

I had a tbelt let loose on my "S" for an unrelated problem, and it has been a long time since I took the head off but I know you can get the gear off first. IIRC, there is a keyed slot that indexes it to the shaft.

spieln

On my S2 you hold the hex part and loosen the cheese head bolt. They are two different pieces. I am not sure about an S but on the S2 you should intall three bolt where the rotor bolted on to lock down the indexing on the cam. Do this before you loosen the center bolt or else you will need dial gauges to reindex the cams.

jgporsche

More than likely your valves are bent............ You want to sell that dead head?

AZS2

My experience is also on an S2, but I believe it should be the same.

Yes you hold the big hex with a wrench and loosen the gear with the 12pt. Get a helper to work the wrench on the big hex. You will want to use 2 hands on the 12pt. One to loosen the fastener, the other to make sure the 12pt socket stays square in the fastener. You don't want that 12pt tool walking out on you. The hex has no threads, it just creates enough friction to hold the cam while you tighten/loosen the 12pt. You have to remove the cam gear, to remove the cam. The rear piece of the cam gear housing bolts to the head and the cam bridge. Those bolts are behind the gear. The cam bridge must come off so you can remove the cams so you can un-torque the head. You will probably need to use a gear puller to get it off.

You will also want to replace that seal where the cam pokes through. Plus, all 3 black round seals at the end of the cams.

Finally regarding the putting the 3 fasteners in the gear.... I don't think this is necessary if you are dis-assembling the whole top end. I think you only do that to maintain cam timing on smaller jobs. If you are pulling the whole thing apart, you will have to set the cam timing anyway. Now when I did it, I just indexed the cam gear back to exactly where it was before. So, you may want to temporarily install 3 screws in the slotted holes that hold and set the cam timing. Then, use a sharpie to mark where it was set so you can get it back to exactly the same location upon assembly.

Hope this helps.......

Jay W

Yes this is all very helpful, AZS2 has a great explanation. I have done several 8 valve head replacements but this is my first 16 valve. New territory for me. Its a bummer they put the bolts behind the cam gear like that. I would have rather left the gear on the cam and pulled the whole thing off. I always thought 30,000 mile belt changes were a bit paranoid, and I have gone much further with the 8 valve cars. Apparently the extra cam and chain up top on the 16 valve cars causes more wear on the belt. And yes there are plenty bent valves, I already can see that ALL of the exhaust valves are bent. The cam followers on the exhaust side arent anywhere near to contacting the cam. Anyone have any used valves for a 16 valve car to sell? New ones are a bit pricey when multiplying by 16. If I decide to scrap the car (if a valve broke off and killed the block or something) I will put the head up for sale too. It has never had a chain tensioner failure, which is really what I though would kill the car eventually.

sharky47

Yeah, when I put my "S" back together (have a spare head btw) I think I will start using 20000 miles as the time to change, belts are cheap - valves are not! But yeah, these belts are subject to more stress for obvious reasons and I think the 968 belt part number superceded the original - I think they are slightly wider.....

AZS2

I just finished the same job on my S2 so its all fresh in my head. I bent all 8 exhaust valves, no intake valves. I got used valves from a local mechanic that had an extra head, he also installed them.

For the whole job, including the head work, valves, all seals and gaskets, new hall sensor(I broke), injectors sent to witchhunter, all belts, and tools from Arnworx.... I think I spent about $1200-$1300.

Jay W

I figured about $1100 on mine, that is if the valves have not broken. Amazing how most cars nowadays have 90,000 mile timing belt intervals and the 944S cant get past 42,000. Newer technology I suppose. Seems that the belts we put on our cars should be the same quality as the 90,000 belts on other cars though.

mark944turbo

There seem to be far more instances of 16 v belt failures, and far fewer 16v than 8v cars. 30k is where its at.

sharky47

My t-belt failure was my fault and mine alone.......

But I would assume you bent valves, mine stripped at idle and I killed about 10 of mine.

mark944turbo

Yes, usually 3 sets of exhaust valves get bent, and one or 2 sets of intake valves, in my experiences.

AZS2

It drives me nuts. Then, you are supposed to use a $600 tool to tension a lame duck 30000 mile belt. I don't know why these belts suck so bad.

Mine stripped at idle too, right after I started it. It started and died immediately. I understand that is more common, because the belt is motionless then you hit it with alot of force from the started. Next thing, teeth just strip off the belt.

Mine happened at about 45000 miles

Jay W

I was driving down the street at about 25 to 30 mph. I dont remember giving it alot of gas or anything and then I heard a sound like breaking sticks from the front. Not really a giant crunching noise but I knew what it was for sure. Funny thing was that the tow truck driver threw the car into gear and set it on a hill. Then it started to roll away and I had to catch it. It didnt click with him that since the valves were bent it would have zero compression. My belt didnt break, it just stripped about 10 teeth too. Thats about 9 too many. I suppose it would be worse if it were a 928 with 32 valves to bend.