sfierle

I can and will do some of the maintance myself (or with friends), but the timing belt is more then I want to tackle in my garage. I do plan to use the lack of timing belt replacement history, as a reason to offer less then asking price. I just wanted to know the consequences of a failure because I want to delay the replacement until next year, so I can spend a little time behind the wheel and see if anythng else is needed before I spend $1200 on the belt replacement right away. I do know the car could use tires.

neilh

My point exactly, if you decide to buy the car, have a TB party!!!!

dr bob

TB parties are a good way to share some knowledge and share some pain with other local owners. A great deal if you can get one going.

On the $1200 cost: To do the whole shootin' match, with all the rollers, all the coolant hoses, heater valve, other belts, hardware, water pump, tensioner rebuild, possibly gears, a tensioner tool if you don't have one, will cost a good portion of that figure just in parts. As you crawl around and under your prospective purchase, look for other leaks from power steering etc. A car that old that's been sitting needs some radiator attention, and now's a great time to have that done too.

With early cars that are sold for low prices due to lack of service, you can easily invest your purchase price again in the first year, as you bring all the deferred maintainance current. Tires alone can set you back many $hundreds, plus other essentials like brakes while the tires are off, and you start to get the picture. It's a -big- picture.


My advice: Go find a car with a known maintainance history, and be willing to pay more for it. That way you can get a few months of driving in this summer. A car with unknown history is like driving a time bomb. Belt breaks, and it's a $$flatbed ride to your $$mechanic, who has a very captive audience and your credit card numbers.

I HATE getting stranded for stupid stuff, and suspect that you wife feels the same way even if you don't feel that way just yet.

If you do decide that this car is one you want, get a PPI from a 928-saavy mechanic, and look carefully at the list of outstanding stuff he shares. TB and cooling system are priority one. Tires and brakes are priority one. Man, there are a lot of priority one things to do before you drive it anywhere!

Remember that you are maintaining a car that cost $45k when it was new almost 25 years ago. Expensive to buy and keep then, and cheap to buy now only because it's still expensive to keep. Plus, with a no-history car, you get to pay for the years of "keep" when you didn't even own or drive the car. It can be painful, especially if you are spending the wife's furniture fund or the kids' retirement monies.


Good luck with your investment!

SteveG

To add fuel to the fire. You may want to search here and then draw your own conclusions. Some people have reported carbon build up on pistons/valves of non-interference engine which then makes it an interference engine. It would be unanimous though that a PPI by a 928 mech is in order on a car w/o a history.

Jim bailey - 928 International

It is worth mentioning that since all 944 engines are interference and most shops saw FAR MORE 944s and the 944 engine is described as being 1/2 of a 928 engine it is easy to draw the incorrect conclusion that 16 valve 928 engines "must be" interference as well. So armed with that information I am quite sure many 16 valve 928 engines have been pulled apart to fix "bent valves" and then upon discovering that the valves looked pretty good the shop opted to go ahead and finish the valve job ANYWAY. After all the customer authorized the work was expecting to pay and the shop had pulled the engine and done so much work and it had quite a few mile on the engine anyway.....perhaps that is when they discover that carbon buildup slightly bent a couple valves... and that is the story which is told to the owner and gets repeated as "FACT" . Since many mechanics are paid on a flat rate allowance per job and NOTHING when they redo fix their own mistakes the incentive to cover up is always there. Perhaps equally as inept one large dealership L A area 32 valve car lost a timing belt so the service department convinced the customer that they should do a timing belt service with out checking the valves !!! so $1,500 later the customer is told well now you need to do a valve job and you still owe the $1,500...

AO

Since this is a US 83, I say don't worry about the TB. If it shreds, you cand easily put it back without the worry of bent valves. That's the beauty of OBs. You can take a flashlight and peek into the TB covers to see if it's shreded at all, but aside from that, I'd say drive it and enjoy it. Then this winter when you feel bored, we'll do a TB party at your house and get it squared away without paying $1200. More like $300 + beer and pizza.

blown 87

When a stealership does things like that it gives all honest mechanics a bad name and it is nothing more than theft in my book.
They did not even look at the book?

Also most mechanics use a timing belt book called "Autodata timing belts" my 2004 edition show that all 928's are interference motors, it makes no distinction between the 16 valve and 32 valve motors as far as whether it will bend valves or not.

Here is what my Autodata book says

"Model 928S/S2 16V - 928S/S2 - 928S4 - 928GT - 928GTS
year 1978-95
engine identification M28

Replacement interval guide
Porsche recommends check and adjust every 12,000 miles or 12 months, whichever comes first and replacement every 60,000 miles or 72 months, whichever comes first.
The previous use and service should be taken into account.

Check for engine damage

CAUTION: This engine has been identified as a INTERFERENCE engine in which the possibility of valve-to-piston damage in the event of a timing belt failure is MOST LIKELY to occur.
A compression check of all cylinders should be performed before removing the cylinder head.

So most shops, mine included will tell you if you call or come by that there is a possibility of bending valves on a 16 valve motor IF THEY KNOW, otherwise they will just look in the book and tell you it is a valve bender.

If i was not going to immediately replace the timing belt and everything it touches on a 16 valve motor i would at least use something like a BG product to clean the carbon off of the top of the pistons.

Personally i would replace everything, I did on mine before i ever even tried to start it.

Jim bailey - 928 International

Interesting so the Autdata service has incorrect information ...Maybe this is part of the problem.."A compression check of all cylinders should be performed before removing the cylinder head." In order to do a compression test you must have a timing belt in place. I have heard so many people state that the car was just idling when it suddenly died that they did not hear anything could not believe that valves were bent so they WANT to believe that a 32 valve will not bend valves ( I recall hearing of ONE which did not ) . The 16 valve the shop could make an honest mistake based on bad information and pull the heads the ethics part comes to play when they charge the customer for their mistake !

dr bob

So Jim, from your description, one might assume that idling the car, especially a rough idle can damage a timing belt?

[shields up!]

blown 87

What we usually do in a case (not just on 928's) like that is to go ahead and pull the cams so if the valves are not bent we wont bend them when we are doing our checks.

We get a way to hold the crank at TDC or very near TDC on each piston and do a leak down test on all the cylinders.

It really depends on if they are willing to take a gamble if they are bent or not for the labor and parts to check them out.

As far as the ethics, if you advise the customer up front of what you plan to do first, IE check then it really does not come into play, but like you say if you just go ahead and pull the heads and no valves are bent then you do have a problem.

Stan.Shaw@Excell.Net

Wow, pulling the cams has to be quite a bit of labor though.

blown 87

On some cars it is worth it, we had a Mazda 929 in the shop last month that had jumped time and we needed to know if it had bent valves.
Belive it or not but a lot of Mazda parts will make Porsche parts look cheap. Very high parts prices, about $800 in just gaskets to pull both heads, if i remember right.