Lessons from 200K miles on a 1994 850 NA

icelandic · Post by **icelandic** » 11 Apr 2009, 08:48

For sometime my 1994 850 NA had been burning oil. Even though power was good, I thought that it might be valve seals or valve guides and kept putting off a head repair job. Until one day, driving at 60mph, engine started misfiring. To make along story short, a small piece of an exhaust valve on Cyl3 broke of. We took the head appart and found that actually the seals were bad. Probably the valve broke due to a piece of carbon build up that got on the way when the valve closed. For an engine this old, running with a 25% ethanol content gasoline, the amount of carbon was comparable to much lower mileage engines. No oil sludge of any kind, cams are perfect, valve lifters are perfect. Very small amount of carbon like material on oil passage ways. Head gasket looked like new. Coolant passageways clear and clean thrughout.
We decided to take pistons out. Oil pan also clean, no sludge, just the brownish varnish like inside. O-rings looked perfect. Pistons look perfect after clean up. Rings appear to be perfect also, although I decided to replace them, since I found some carbon build up on them. Cylinder walls are in exceptional good shape, no visible wear, and still have the polishing markings. No ovalization either. Piston rods and pins look new, as the crank does. Only significant finding was that one of the piston rod bearings had some scratch markings on it that could be felt if one passed the fingernail on it. Water pump, still the original one, has no leaks and no play. Looks new, but I will replace it anyway.
Having taken good care of this car since new, however exposing it to long traffic jams in Sao Paulo with long, extended idling times, I concluded that after we put everything back with new rings, rebuilt head, and new piston rod bearings, and new OEM water pump, it will be good to go for many years more. I was impressed on how wear was minimal.

Icelandic

Post by **MadeInJapan** » 11 Apr 2009, 09:02

Excellent news! I too have a '94 850 I just bought a month ago- it runs very strong. After probing the ECU for mileage and fixing the odometer gear, I'm at 192K miles- so I'm approaching your mileage of 200K. It's good to know that these cars keep on going. I of course replaced all essential timing components and water pump. I still have some positive pressure after getting rid of the flame trap and cleaning out the EGR.. I'm hoping that PCV clean-up or replacement (previous owner replaced it approx. 55K miles ago), it will run without the pressure. Also have sway bar end links to replace (if my son would get home with it! ha). Anyway, thanks for posting- the way the car runs I would expect all internal engine parts to be in good shape on my 850 as well!
MIJ

dan2286 · Post by **dan2286** » 11 Apr 2009, 15:08

That makes me feel better about buying one with 300,000 miles on it

_HighVoltage_ · Post by **_HighVoltage_** » 14 Apr 2009, 15:11

Makes me feel good about my 152,000 mile 94NA. I've driven it 1000 miles so far and it doesn't seem to burn any oil. At least for the moment...

volvomileage · Post by **volvomileage** » 14 Apr 2009, 18:20

feels great to see that they are really built to last lolll

by the way mij how do you probe the ecu for mileage

thanks

Post by **matthew1** » 14 Apr 2009, 18:33

How to Read Your Actual Mileage from the ECU

Post by **MadeInJapan** » 14 Apr 2009, 18:48

Thanks Matt!

Post by **matthew1** » 14 Apr 2009, 18:55

^^^

(My first instinct is to nag users about not doing a search for things like this, but the site isn't organized perfectly yet, and things can still be hard to find. You and I know if something's there to be found at all. In business it's called "knowing where the bodies are buried.")

volvomileage · Post by **volvomileage** » 14 Apr 2009, 19:03

thanks Matt...for the link and for not nagging

lollll

thumbs up for ur site

cheers !

Post by **Matty Moo** » 14 Apr 2009, 19:50

200k is amazing for a car that runs on 25% ethanol and idles in traffic everyday.