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928 vs 951

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Old Dec 18, 2009 | 02:04 AM
  #31  
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Originally Posted by Want to be

Why would i have to rebuild the tensioner?

jpc
... because you don't want to pay for the ensuing engine rebuild if that particular elastic band breaks.
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Old Dec 18, 2009 | 02:13 AM
  #32  
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From: INDY
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It would seem the older design, what is on my car, is better to own. All i need is a special wrench to adjust the tension manually. Has anyone converted there S4 later model to an earlier manual tensionar versus a the standard unit?

What does it cost to purchase a PKsn'r ? I searched the website twice and could not locate the unit forsale price.

thanks jpc
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Old Dec 18, 2009 | 03:00 AM
  #33  
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First, check out what the "tensioner" actually does - sure it has something to do with maintaining tension, but is nothing like the Porken unit, nor is it what I am used to calling "a tensioner".

Even the "automatic tensioner" in my 944 isn't what I would call a tensioner, in that it does not change the tension on the belt duiring operation - it can't as it is bolted down after the belt tension is set with the engine stopped!

Maybe you could more accurately call it "an adjustable idler".
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Old Dec 18, 2009 | 06:30 AM
  #34  
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Originally Posted by Want to be
It would seem the older design, what is on my car, is better to own. All i need is a special wrench to adjust the tension manually. Has anyone converted there S4 later model to an earlier manual tensionar versus a the standard unit?
The stock tensioner in the 928 uses bimetallic washers that change shape as the engine warms up, to relax the belt and keep tension relatively constant as the block expands (it actually de-tensions the timing belt).

Rebuilding it is an integral part of the timing belt job, to make sure the washers are properly lubricated and free-moving, the boot and seals hold the oil in there, and the warning system is adequately connected to detect belt flutter and warn you before the engine goes south.
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Old Dec 19, 2009 | 03:40 PM
  #35  
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The 928 is a great GT.

My advice to myself, if I were shopping again for my first 928, would be to have patience, watch ebay and read through this forum and the various 928 sites for six months or so. Also, go to some gatherings and meet the locals and try to get rides or drives. After that preparation you'll be less likely to jump on the first 928 that sets your pulse racing (most of them will) and will end up getting a better car and a better deal. I.E.,

+1 to buy off this forum, search it for "for sale" posts.

I don't know what your budget is but if you have to have a budget you may not be able to afford a 928 if you're paying a shop to work on it.

All that said, flagship Porsches are great to have and drive.
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Old Dec 19, 2009 | 03:49 PM
  #36  
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1st my mechanic hates 928 and will never work on them. He believes the newer 928 are a better vehicle, but never had luck with the older ones. He was around when the new 928 first hit the dealer ships and said they had troubles day one.

Anyways, i still would want to do the work myself. The car needs work, but would be an even trade. If i replaced the steering pump and belts and rebuilt the tensioner i should be fine. Later i would work on the carpet and fixing the paint areas of concerns. I just can't see the need to put on a poken tensioner considering i doubt i would put 900 miles a year on a car. I know i can do the work and it would seem there is several guys locally than can point me to the right areas of concerns if needed. This web board is great on finding local help and getting connected to Porsche friends.

Keep up the good info guys. THANKS
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Old Dec 19, 2009 | 06:06 PM
  #37  
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Originally Posted by Want to be
The car needs work, but would be an even trade. If i replaced the steering pump and belts and rebuilt the tensioner i should be fine.
Sounds like you have your sights set pretty firmly on this car.

Unfortunately, I wouldn't call it an even trade - a well sorted 951 is worth a lot more than a dubious S4, largely due to the cost of making the S4 less dubious.

If you're dead set on this 928, then be absolutely certain before you swap titles, that the car is not suffering Thrust Bearing Failure. Failure is only apparent while driving once its very advanced - you can be in need of a whole new engine well before the car starts cranking slowly, and stalling when warm.

It afflicts later automatic 928's (84 onwards from memory, can't remember when Porsche changed the design), and causes loading on the thrust bearing that will eat into the block and destroy the block.

There's a couple of write-ups in this forum on how to release the flex plate, and measure crank end play to make sure its still in spec. Its a pretty regular occurrence for new owners to crop up here with some hard-starting issues or stalling, and it turn out to be thrust bearing failure.

To be honest, I'm pretty cynical, and the refusal of the 928 owner to cooperate or contribute time to this transaction reeks of there being issues that he would rather you didn't investigate by having the whole transaction take place on his terms and ground, thus forcing you to take the car away before closer (any?) examination.

Lastly - the most significant advice. Pay an independent shop who knows the 928 well for a thorough Pre-Purchase Inspection. That means a shop who is recommended by someone here, not a shop that says "yeah we work on them from time to time". Sure it'll maybe cost you a few hundred dollars, but at the end of it you'll be sure you're not buying a lemon, and you'll have a nice thorough job list to start prioritising your way through
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Old Dec 19, 2009 | 06:53 PM
  #38  
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Originally Posted by namasgt
Go on the sponsors section and you will find 928 part suppliers, don't buy parts from ebay. I use 928srus or 928 international, there is also 928 specialist.
as far as water pump goes, the genuine Porsche water pump goes for 800 to $1000 with plastic impeller (so if the impeller fails it would not damage the block). the new improved Laso ones are around $220 with a steel impeller (so if it fails it will damage the block and cause future cooling problems).
I would not buy a rebuilt, but you can get them for $120 with core.
just do a search and you will find out how some of the water pumps fail to damage the block.
Also there is a tone of information on how to maintain these cars on this forum, you just have to search for it.

here is an example for pump failure:
https://rennlist.com/forums/928-foru...ned-block.html
Don't forget Carl at 928 Motorsports.
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Old Dec 20, 2009 | 02:30 PM
  #39  
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Phil (JPC/want to be),
I like the advice of "learning, looking, then buying" that was essentially given above. There are a lot of nice 928's for sale in this economic down turn, and the prices are qute attractive. Get together with the guys in Indy, look at their cars and chat over a drink or so to "learn". Then, look at a few that are for sale in the area - and on Rennlist or even eBay. Finally, within about 3-6 months you'll find the model etc. that you want to live with - at least for a while. In regard to the quality, reliability, etc. of the 928, I'll relate a brief part of my reason for buying a 928 (my first and only Porsche model), and my experience with the 6 I've owned.

In the late '80's, I had a business relationship with Hans Metzger, who was head of Porsche Advanced Engine design at Weissach. He had been the designer of the original 911 engine, the 917 racing engine, and the 928 engine. When I asked him and his associate "What is the best used Porsche to buy, as I've never owned a Porsche, and I don't buy new cars", a summary of their response after a few minutes of discussion is: "Buy a 911 SC (early '80's car), or a 928. The 911 SC if I wanted fun on short trips, the 928 if I wanted the ultimate GT car". I bought an '87 928 a few years later, have owned 3 '88 928's, and now own an '89 and a '94.

I do a thorough "go over" with the mechanicals and electronics when I buy it, and have never had a problem with any of them. Several road trips have involved 2-3K miles round trip - only need was gasoline!

Good luck, if you get the right 928, I'm confident you will be happy with it (and please join the 928 Owners Club as well).

Gary Knox
928 Owners Club Treasurer

Last edited by Gary Knox; Dec 21, 2009 at 12:31 PM.
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Old Dec 20, 2009 | 02:47 PM
  #40  
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WOW!

A 928 vs. 951 thread that is civil, and has not degenerated in mud slinging.

Good to read

Merry Christmas all,
Michael
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Old Dec 20, 2009 | 04:57 PM
  #41  
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Originally Posted by Want to be
Later i would work on the carpet and fixing the paint areas of concerns. I just can't see the need to put on a poken tensioner considering i doubt i would put 900 miles a year on a car. I know i can do the work and it would seem there is several guys locally than can point me to the right areas of concerns if needed.
Keep up the good info guys. THANKS
If your driving is limited, then I would say the porken tensioner is the way to go. If you look at the cost of going with it, versus rebuilding the stock unit, the price isn't much higher. People mention that Porken's unit uses Audi parts. Those Audi parts are also VW parts. As an added bonus, going with Porken's design also makes the smog pump much easier to access.

When I got my '85 and I changed the timing belt the first time around, I rebuilt the factory tensioner. The boot on the end of the tensioner had dry rotted, broken apart, and there was no oil left in it. Back in August, when I changed it again, I switched to the Porkensioner. This time around, I was changing the belt because I had put on about 45K miles. The tensioner had leaked out most of the oil. There's really nothing that can leak on the porken unit.

As for the water pumps. There will be endless debate on the best choice. When I replaced my belt the first time around, I took off a Porsche water pump with a metal impeller. The pump was still in excellent condition, the impeller hadn't moved, and it still spun nice and smooth. I put on a new Laso. It was the older style. When I changed it. The impeller had moved, and it too, spun nice and smooth. I replaced it with a new design Laso and probably have about 3000 miles on it with no trouble. I personally don't have an issue with Laso pumps.
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Old Dec 20, 2009 | 05:20 PM
  #42  
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Guys, thanks for the help. I appreciate all the info regarding the 928 purchase. I had not heard about the thrust bearing issue. While every car has some type of issue, this one is a little scary.

I am still waiting on the owner to send me the VIN number before i would consider swapping title. My title is clean and i don't want to swap with one that isnot.

The more i think about it, i might just stay with my 951. I'll just wait until he sends more photos and the VIN #.

I will then decide if i need a PPO done.

thanks jpc
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Old Dec 20, 2009 | 05:38 PM
  #43  
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Originally Posted by Want to be
Guys, thanks for the help. I appreciate all the info regarding the 928 purchase. I had not heard about the thrust bearing issue. While every car has some type of issue, this one is a little scary.



thanks jpc
Don't be too put off by the thrust bearing issue, since it is a low percentage of 928s that have been damaged by this, plus checking it annually is relatively easy to do.
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