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Go to it.
Keep organized. This is not a bad job. Label the block and each waterpump and tensioner bolt you remove - they are not all the same, and it makes a difference.

 

I'm not sure why you are replacing the belt with only 35K on it. My maintenance manual - the one that comes with the car - for my 89 says the belt should be replaced every 60K. Is that not correct or do you have another reason for the change?

 

Belts are mileage AND time dependent.. though PO doesn't say how many years since he changed...

 

I don't get real excited about the age of the belt, having seen some 10-20 years old, but if you are in there inspecting all the cam belt track components (a good idea since you didn't do the earlier job and can only hope it was done correctly), go for it. It's a rite of passage in 928 ownership, for sure. My first T belt job took me 5 days and involved some notable mishaps. You almost can't go wrong if you follow Dwayne's monumental write-up on this procedure.

http://www.dwaynesgarage.norcal928.o...0Procedure.htm

Although your car, as an 83, will be slightly different from Dwayne's write-up based on an 87.

Also, my learned-the-hard-way tips might help.
http://www.billsworkshop.com/P928S4/...rces-noWSM.pdf

 

If you are replacing the water pump, as you take them out of the water pump, place them into the new one in the same position. Then when the old one is removed, transfer it to the old pump, then take them out as you install them into the new pump.

There is no reference to time in the scheduled maintenance of the belt. Even new cars do not have time basis for replacement. They are protected from any environment that would be cause for time replacement (UV rays for example)

 

last I checked rubber ages with time clearly worse when exposed to sunlight/UV but engine heat , oil, maybe ozone from the alternator makes it an unfriendly place to live. Your tires even stored in a warehouse have a six year expiration date which is enforced in Europe. (explains some cheap closeout tires sold in the US from time to time) .
Not a big deal on a 16 valve USA engine as it is not going to bend valves seriously reduces the pucker factor when you hit the key after the change

 

I'm on my fourth belt. I've used 60K for the first one but have dropped to around 30 - 40 K since.

 

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I have the Porkensioner and Laso water pump (which appears to be the recommended WP) ready to go for my WP job. I was planning to do it before summer but have deferred it until winter as now that I have inspected it I will also need a cam gear and timing tool but want to get the car up and running ASAP. The belts still looks unworn so I figure I can risk a few 1000 more miles while I acquire the additional parts. As for your tensioning tool I'm pretty sure that becomes unnecessary once you have the Porkensioner on as it handles the tensioning.

 

Last I checked the timing belts were not just made of rubber. The reality of a tire is it is exposed to more ozone and UV rays than any timing belt. If you have oil or coolant on your timing belt you have other issues that need to be dealt with right away. I have seen 20 yo timing belts with NO sign of cracking in the rubber. The belts are the part of the construction that would be the most to worry about.

The car is a 16 valve and it makes even LESS sense to shorten the time between belt changes.

The reality is that other items in the valve train deteriorate and cause the belt to be damaged. If the belt is not damaged it will last a long time. Hell I drove 300km with a tensioner idler that had NO ball bearings left in it. Sometimes at 170km/h. I just changed the idler roller and away I went. That car is still running...

 

Timing belts on 928s do not break, the rubber lobes strip off and when enough are gone the smaller crank gear slips. The one exception is when the water pump seizes the smooth side of the belt which turns the water pump pulley still is sliding so it gets very, very hot depending on how far you drive as the engine begins to overheat. Then when you do shut it down, wait for the engine to cool, add water coolant and finally get up the nerve to restart it. As soon as it fires the belt which has vulcanized itself to the water pump pulley THEN breaks....which on the later interference engines bends the valves. There are numerous examples of this. My son in law did it to an 83 which thankfully did not bend valves.

 

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