cam belt question

[dogleg]

hi im new on here i,ve just put an 81 928 manual euro on the road and working my way through the usual issues i have purchased the new cambelt kit and plan to fit it soon.i have heard this early model 16v engine does no valve damage if the cam belt breaks unlike the 32v model is this true?

[gbgastowers]

Mixed opinions- but I think the 80-82 Euro S models are non-interference.But what do I know....Gunar

[Pete R]

There is no guarantee. I've had early motors that weren't supposed to be interference but were. Machining the the head, different pistons, and even carbon build up could effect this. Your best option is to do the proper belt maintenance and just assume it is interference.

[dogleg]

cheers for replies probably play safe and get it done asaphow long would it take for a good mechanic to fit the belt and tensioners

[harborman]

Originally Posted by dogleg

cheers for replies probably play safe and get it done asaphow long would it take for a good mechanic to fit the belt and tensioners

The shop time indicated in mechanics book is about 10 hours I think. Doing it yourself the first time should not be a rush job. I have been given prices ranging from $1,000 to $2,200 depending on what they run into and who does it.

[dogleg]

[QUOTE=harborman;5899355]The shop time indicated in mechanics book is about 10 hours I think. Doing it yourself the first time should not be a rush job. I have been given prices ranging from $1,000 to $2,200 depending on what they run into and who does it.[/Q wow thats alot of labour charge your model is probably a lot more involved to do than my 16 valve i hope

[riber.bentsen]

The cam belt change is about the same 16/32V vise. Remember, the two cams are chained together, so on the front of the engine there is near to no difference.

[Landseer]

16 V is pretty straightforward, consider doing it yourself.

[dogleg]

just thought the 32v would have twin cam pullies on each bank?

[tmpusfugit]

Changing out the water pump and timing belt waas my first exposure to 928 engines. The most difficult part of the job was cleaning off all the oil and grime on the front of the engine, while not flushing it into "wrong places". The second most difficult part of the job was keeping all the proper bolts and other fittings together (plastic sandwich bags with labels on each is a requirement IMO). While there are several good writes up on how to do the timing belts, (find one you like and use it carefully) keep in mind you will want to do replace the front crankshaft seal, the 2 seals in the thermostat housing, rebuild the belt tensioner completely, replace the idler pulleys, and replace the nylon bearings on the idler shaft, along with a NEW water pump. Parts here to do all this runs about $800. And most repair people here, who will do the job, do want $1200-2000 labor...and Landseer is very correct you can do it yourself...oh, you will need a flywheel lock as well as a robust 27mm socket to loosen and tighten the crank bolt. Check out SharkSkin - Shark Attack Round Twenty-Seven - Timing Belt/Water Pump for one very detailed write up on this process. By the way, many shops who might take on this job have never done one, so if you decide you don't want to do it you will need seek out a shop that really does work on 928's with some regularity.....understands them, and is willing to do the job RIGHT!

[dogleg]

cheers for all the info ill be doing it myself i worked as a mechanic for 10 years and recently did my skyline,will take my time and cover all the points you have made.cheers

[Mrmerlin]

to add to this dont forget to rebuild the oil pump and replace the O ring and radial seal and 3 bolt O rings, use STP in the pump gears and on the shaft of the pump before you put it togther make sure the ring gear has the square edge facing to the block the little dots on the gears will confirm this.

Consider to update all of the gears and belt to Hi Torque Drive or curved tooth design.
If you do this then you will put on the updated oil pump pulley that is steel and remove the 1mm spacer behind the aluminum gear

[dogleg]

holy lambim hoping shes bone dry in there with no play in bearings ect and just fit new belt and tensioners.do i need to strip out oil pump?

[dcrasta]

Porkentensioner is your friend.

[Landseer]

Originally Posted by dogleg

holy lambim hoping shes bone dry in there with no play in bearings ect and just fit new belt and tensioners.do i need to strip out oil pump?

No, but its a simple preemptive step.

Water pump almost assuredly, too. And here is where the enthusiasts have found a terrible weakness --- and we are fitting only brand-new water pumps with new castings and plastic impeller. Never a rebuilt one. Rebuilds are prone to failure with metal impeller striking and machining the block such that a pump can no longer cool the engine. Porsche spec unit is prohibitively expensive for most of us. Laso makes now a new one to enthusiast specifications. Beware new no-name unit or counterfeit (ebay deals).

Simple rebuild of tensioner is effective and required. Pivot bolt and associated expensive plastic bushings are a must!

Audi-based spring tensioner, mentioned above by dcrasta, is an alternative. I have one on a car, but have also rebuilt 6 cars using the original tensioner parts.

[Pete R]

+1 on what landseer said.
Your car has been going 30 years with the stock components. I wouldn't bother going nuts, changing tensioners and gears just for the sake of it. If an inspection determines that they are bad only then would I consider anything other than what's in there already.

[dogleg]

thanks again for all the advice will definitely go with a new waterpump, as was said above seems to be a weak spot lots of guys on here with bad water leaks from the pump.tks tmpusfugit for the link on doing the job. brilliant!!! exactly what i was looking for, very clear pics too.if anyones interested i,ll let you know how i get on doing the job..mark