I recently purchased my first Porsche, a 87 944S with about 120k, and have been searching the forum to find out a little more about the car. I've noticed the timing chain and tensioner are important maintenance items not to procrastinate on. I'm wanting to replace these items, but I'm still a little hazy on if the car uses a timing chain or belt or both, also balance shaft belts. I've seen both the timing chain and belt mentioned in the same paragraph on some of the posts. Can someone please give me some direction on what components are invloved in the timing of the engine. Also, just wanna thank everyone on this forum, it has been very informative on my quest to be a knowledgeable porsche owner. Thanks!

 

The chain connects the two camshafts on the 16V S engine. The timing belt drives one of the cams. From what I have read, at 120K your chain tensioner is a ticking time bomb (unless it's been replaced). The plastic ramp breaks and destroys the engine (valves, cam chain sprockets, maybe head, maybe pistons...). I am replacing mine now at 83K so I can sleep at night. You can replace the top pad for ~$25, but the bottom pad is not available. That's why I went with the ~$250 complete chain tensioner assembly.

Start here:

http://boerger.golden-tech.com/image...eplacement.htm

 

Has all three; tining belt, counter balance belt and under the valve cover connecting the two cams a chain.

The chain has a hard plastic pressure pad tensioned by oil pressure against the slack side of the chain. This pad embrittles and tears off the tensioner piston. Since there is not enough clearance for both the chain and the broken pad it jams the cams breaking or striping the timing belt.

Bent valves, damaged valve seats and pistons and even having the mount the tensioner is bolted to break off is typical of this type of failure.

Was a recent thread that had pictures of the plastic pad between the chain and the sprocket on the cam. Both cams had the teeth striped off. Another thread had a picture of the tensioner mount torn off.

 

Welcome to the fun world of owning a 16 valve 944

With 120k, assuming you have no records, its a very good idea to replace:
Timing belt
Balancing shaft belt
all rollers (little wheels the belts ride on)
the belt tensioner
front engine seals (motor's apart anyway, not's the time to do it)
Cam chain
Chain tensioner
I'f you really want to "freshen up" your motor pull the head and do a head gasket and valve guides. At 120k those guides are worn. At least the exhaust guides are.

Then you should be good to go for about 40k-50k.

 

Thanks for all the input. Just curious, but what's involved in replacing the timing chain. Looks like it could be quite a procedure, considering it is located right in the center of the engine. Any estimtates on how long the replacing of all these critical components might take? Thanks again!

 

fyi - it's called a timing belt, not chain. the chain is more appropriately called the camshaft chain.

see my website below for what happens if the camshaft chain tensioner breaks. not a pretty site!

 

Anybody know how much ($) extra labor is added to a timing belt job to replace the chain and tensioner. I did the upper pad 18 mos. ago.

 

free if you do it yourself

seriously - i don't know but it's not that much effort to remove the cam cover and replace those items. maybe an extra $2-300?

 

Add "water pump" to this list!

 

Toi replace the cam chain, the cams have to be removed which is a fairly complicated procedure. The tensioner can be replaced without removing the cams and is not too difficult. The chain probably does not need to be replaced but it and the teeth on the cams are subject to wear and tear and probably should be checked.

 

Actually porsche no longer makes either pad. It no longer has a part number in their computer. The whole assembly is the only thing that can be purchased.

 

hey GTROTH where in CT are you? I don't see too many 944S's around here

 

Good to meet you, Operator. I live in Fairfield. Commute to Branford. Where are you? I saw a Silver 'S" on the throughway north last week (~Bridgeport). You? Of course, I was in my suppport vehicle that day...

Hey 944S2NUT, doesn't Zims still sell the top pad? I almost went that route, but desided to get the whole assembly. The replacement did not go smoothy this weekend, however, because I couldn't compress the old tensioner fo removal (maybe you caught my other thread).

Cheers.

 

As with several other parts, IIRC these 944 top pads have been superseded by the 928 part, which is essentially the same.

 

I second what everybody said for that kind of mileage, just brace yourself for the numbers involved.

I debated having the chain replaced on mine but as it only had 48K miles I decided against it. My friendly mechanic (hi R.) told me that when you replace the chain you have time the cam's timed to each other before timing them both to the engine - lots of hours!

He checked the cam timing on my car and it was slightly out of spec, correcting it made a noticeable difference to when the engine came 'on cam'.

He took some pictures which I have attached:




You can see the timing belt going over the toothed sprocket on the exhaust valve cam and the chain connecting it to the inlet valve cam.

Chris

P.S. The dumbass PO had fitted non OEM belts and a mystery make roller, they had not worn well despited doing only 10K miles!