pjg

While waiting for the exhaust bolts to soak in penetrating oil, ( flex plate check ),
figured I would take a look at the timing belt and cam gears. looks pretty good for the age, also got a reading of 6 on the Porsche tension tool ( little high ).

Plan is to do the TB / WP idler etc over the winter.

Manfred

Are you parking the car until you do the TB job? I'd be worried about a belt that's thirteen years old (despite the fact that it looks fine and is tensioned fairly well).

leperboy

Man, those cam gears look fantastic.

I'd do the belt now. If you don't, how much fun would the miles be when you spent them thinking about that 13 year old timing belt?

Matt

pcar928fan

Belt is FAR TO OLD!

pjg

I agree, just making an observation, expected it to look much worse, car is parked and will be replacing TB/WP over the winter.

Bill Ball

Technically, there is no particular age limit for the belt. If the car was stored in mild climate conditions it could be perfectly OK. After I bought my car I did the belt because it was 9 years old even though it had only been 30K miles since it was installed. When I examined the belt I could not tell it from the new one except that the writing on the back was smudged. So, anyway, I'm not all that sold on setting an age limit. I've worked on some 928s that have the original belt, one of them 20 years old. That one scared me a bit, but the belt was fine.

However, since it's not clear what a belt going bad looks like other than one that has obviously been damaged by other bad parts, sure, change it out. The gears look very good - just a few tiny wear-through spots. The gears should make it at least to the next belt change if you get the tension correct. The idlers do almost nothing, so I would just make sure they spin freely and not replace them unless they were terribly trashed. The main tensioner roller, oil pump gear, the tensioner arm plastic bushings and servicing of the tensioner are the critical parts of the job. You can also argue that a water pump that is working well and has a firm bearing with no play or freewheeling of the pulley should be left alone. It's a good time to examine the front main seal and oil pump seals. If they are leaking, replace them. I leave them alone if they are not leaking. Others change them out as a matter of routine, but those people are generally getting paid to do it.

blown 87

Except for the shiny spots, they are on their way out if that is in fact areas that are worn through, and it sure looks like that to me.

I would not trust a timing belt that was that old, not with what is at risk if it does break.

danglerb

I figure belts are "likely" similar to tires, the guts may still be fine, but 13 years old the elastomers could be all gone with cracks just waiting to happen, teeth break off etc.

OTOH how often to we hear about a belt precipitating a problem vs something else fails and the belt is the fuse that breaks and prevents further damage?

Podguy

I stored my 78 with a new belt for 15 years. It took about 100 miles before the teeth stripped off. So age is a factor and 13 years is not much different from 15 years it took my Porsche installed belt to rot.

The pulleys look great.

paalw

Just curious, why change the belt and then let it sit for 15 years? and even more strange, why not change it before you take it out 15 years later?

FredR

If the engine was fired up religiously every week, even though not driven, the belt may be [relatively] fine given that the rubber would at least have been worked to keep the molecules flexxed However if you do not know the use profile -as one might suspect will be the case- then to some extent you are rolling the dice with your valves if you fire up the motor- it really is as simple as that

Low mileage examples- can be just as problemmatical as high mileage examples that have been abused. My mindset with 928's is that "low mileage used" is potentially the same as "high mileage abused" if the owner has not taken appropriate precautions to protect the car when not in use.

Check the crank end float-hopefully it is in the 0.2mm range and make sure you consolildate the flex plate grip with one of the TBF solutions available. Do not fall into a false sense of security if you find there is no pre-load. Mileage wise you are entering the TBF "Bermuda triangle".

Sincerely hope you are trouble free and that you have a nice ownership experience.

Best wishes

Fred

pjg

Released the flexplate and checked the endplay the reading I got was .2mm, so need to worry about TBF. The whole job took about 3 hrs, those 2 back bolts on inspection cover were difficult to remove with the exhaust in place, but after removing the heat shields I managed to get the bolts cut off with a sawsall.

FredR

Paul,

Not quite right- if you get TBF from hereon you only have yourself to blame!

As I said, ensure you have the clamp secured with either of the recognised methods from either PorKen or Constantine or go cheap like me and use the Loctite method. Do not fall into the trap of thinking that because you are OK to date you are somehow home and dry.

Make sure you keep this one sweet!

Regards

Fred

pjg

Pklamp will be installed at the next annual check, now that the rear bolts are off the cover it will be very easy.

hernanca

I was told that when our 928's sit, without being cranked regularly, the timing belt "rests" on two (or three - can't remember) places (maybe the cam gears?), and this creates a weak spot on the timing belt, over time. I was told this is where the belt will break, when it breaks. Anyone else ever hear something like this?

If this is true, and the car was not religiously cranked, I would definitely change that belt before running the motor any more.