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Looking at a 91 E34 M5 to buy. "To me" this seems high milage and should be deemed as high risk.. Would it be about time the engine was pulled down, rings and bearing done and check that anything is within "spec". Or will it just keep going for another 150,000 miles without a problem.. In saying this, the top end was done 60K ago.
Shoot from ya hip! Thanks!
 

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It may be beneficial and informative to have a compression test carried out .

If the top end has been rebuilt then that's one major area covered .

A new set of big end shells and con rod bolts are relatively cheap and would be a sensible proactive measure after 215,000 miles , depending on the results of a compression test .

I would imagine that New Zealand's roads are similar to those of Australia and that large mileages can be clocked up in single journeys , in which case the miles covered are not necessarily that stressfull to the S38 engine when compared to short , stop and starty , journeys !

How many E34 M5's are there in NZ to choose from ?

D
 

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I'm actually in Australia now. The driving conditions are very different between NZ and Australia . Only in the South Island would you have long runs. You're right though ,there wouldn't be too many in NZ.
 

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I am not a professional mechanic but I do maintain my own cars. Everything that I have done on my car I have been taught how to do by an enthusiast in person or by an enthusiast online. Compared to many members here my experience with these cars is limited. I can only offer anecdotal information.

I bought my '91 M5 with 187k miles on it. It was bought at an auction by a young VW enthusiast who noticed the badge and took a shot at it. He drove it a few months before putting it up for sale. It had nearly $20k USD in receipts that ended with a leakdown test (From the owner who had it before it wound up at an auction). One or two of the cylinders had close to 40% leakdown (not good). I took the risk and I am very glad that I did.

The car now has 202k miles on it. I have following some DIYs that you can find here on this forum and have adjusted the valves, synced the ITBs, replaced the vacuum lines and all of the misc. fluids and filters. I have not pulled the head or done anything on the bottom end. The car pulls hard, passes emissions inspections and is as fuel efficient as can be expected from an E34 M5. Short of an oil analysis, all signs points to it still being a healthy S38 at 202k miles.

Like David said, it would be a good idea to be prepared to spend money on peace of mind repairs. But that should be the case with any used M5, or any used car at all for that matter.

Do your due diligence as a car buyer, but I would not be scared away at that mileage.
 

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I am not a professional mechanic but I do maintain my own cars. Everything that I have done on my car I have been taught how to do by an enthusiast in person or by an enthusiast online. Compared to many members here my experience with these cars is limited. I can only offer anecdotal information.

I bought my '91 M5 with 187k miles on it. It was bought at an auction by a young VW enthusiast who noticed the badge and took a shot at it. He drove it a few months before putting it up for sale. It had nearly $20k USD in receipts that ended with a leakdown test (From the owner who had it before it wound up at an auction). One or two of the cylinders had close to 40% leakdown (not good). I took the risk and I am very glad that I did.

The car now has 202k miles on it. I have following some DIYs that you can find here on this forum and have adjusted the valves, synced the ITBs, replaced the vacuum lines and all of the misc. fluids and filters. I have not pulled the head or done anything on the bottom end. The car pulls hard, passes emissions inspections and is as fuel efficient as can be expected from an E34 M5. Short of an oil analysis, all signs points to it still being a healthy S38 at 202k miles.

Like David said, it would be a good idea to be prepared to spend money on peace of mind repairs. But that should be the case with any used M5, or any used car at all for that matter.

Do your due diligence as a car buyer, but I would not be scared away at that mileage.
My original engine was making metal at 90k miles. Compression tests was more or less even at 185 highest and 169 lowest. Leakdown however showed 40% and 45% on cyl 4 and 5. It still ran smoothly but made considerably less power than a healthy car. It was deemed toast and time to be rebuilt or replaced. I replaced it.

Engine #2 was torn down and rebuilt with leakdown numbers of 11%, 8%, 8%, 8%, 18%, and 24%.

40% leak or more and/or two adjacent cylinders showing similar readings is indicative of a major issue.

Be careful. It may run smoothly and seem to pull well, but if you've never driven a fresh one, you don't know how strong 311 s38 HP really is.

Just remember, if you keep it long enough, or use it hard enough, you will end up building or buying an engine.


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I have to disagree with you there, Nik. I would wager that my 200+k mile car puts down within 5% of a sub 50k mile car, both being equal. Maybe I can find somebody to run on the same dyno on the same day with me down here.

You have two vet different opinions here, OP. Although I don't agree with Nik, I would never discount his opinion. The forum is working how it should =p
 

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I have to disagree with you there, Nik. I would wager that my 200+k mile car puts down within 5% of a sub 50k mile car, both being equal. Maybe I can find somebody to run on the same dyno on the same day with me down here.

You have two vet different opinions here, OP. Although I don't agree with Nik, I would never discount his opinion. The forum is working how it should =p
As Trevor says, though we do disagree I wouldn't discount his opinion. He does have great hands on experience with these cars and his advice should definitely be considered.

That said, this is the basis for my argument.

Here is a short clip of my car which at the time had 77k miles and was very healthy. It is running a 91 M5 with at the time 156k miles.

http://s145.photobucket.com/user/NikosxM5/media/DSCF3885-1.mp4.html

Caveat, both cars did end up getting new engines later on. The Diamondschwarz car is pretty famous here and did get a brand new rotating assembly. Mine lasted another 22k miles when the HG popped and melted pistons 4 and 5 during a hard 5th gear pull.

As you can see both cars got a solid start. The difference comes as the run continues.




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Leak down and compression tests are like dyno runs there is a lot of human factor involved.

I agree that the biggest area of concern is indication that one isolated or 2 close cylinders are doing something the rest aren't. Leak down numbers of 15-20% are not uncommon and no indication of a bad engine.

Doing a leak down test correctly is not easy even on a straight 6. Also two different people can have varying numbers and of course different gauges. Then there is reading the scale on an analog gauge which again is operator biased.

What effects those numbers and power is the cylinders ability to seal weather it be the rings or the valves. That said a engine with 200k that has tight sealing top rings or maybe has had a valve job could actually make MORE HP then say a 50k one due to less friction in the engine. Remember race cars use low tension rings and wider bearing gaps to LOOSEN up the engine. So in theory you are both right it just depends on what is worn.
 

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Several years ago a number of uk owners had a rolling road day at Surrey Rolling Road .

Calypso Candice had the best 3.6 run at 309 bhp with over 180,000 miles on the clock .

Cnut had to flick his Nos on to beat it !

D
 
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