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Thread: Resurrecting 1991 850i 6 speed - help needed

  1. #1
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    Resurrecting 1991 850i 6 speed - help needed

    Hello fellow 8ers,

    I went on a crusade in Spain 3 weeks ago and picked up this lovely 02/1991 Diamond black on black 850i with a 6 speed.

    The car reads 56k miles, I got the original service book, 3 keys and it was a single family owned since 1995. Judging by the condition of the car I'd say that's the original mileage. It was farther/son owned and simply not used and neglected, last technical inspection was in 2010 which is around the time it went off the road and into dry storage.

    Here are some pictures:









































    Before I got there, I got the usual spiel that the car is perfect, running and driving, bla bla... I arrived to find out that the guy hasn't seen the car for years and lives 2 hours away in another city while the car was in an incapable mechanic shop. The only thing they did was washed the exterior a bit.

    We tried to start the car but it was a no-go, it turns and turns but wouldn't fire up, they haven't done any preparation. I was told the car was running and driving about a month ago but that was probably a lie.
    The car has absolutely no rust at all, no signs of accidents and while the interior is super filthy it is mint, leather is perfect, headliner still holding up, doors are opening smooth, even the mid pixels were still there and the whole car feels like a low mileage time capsule. My instinct was telling me there is hope for this fine machine and that I should buy it so I did.

    The car arrived back to its birth country about a week ago and I promptly got busy.

    I was anxious to hear the engine run but first I did a series of checking and replacing stuff.

    Here's what I've done so far. First, I got 12V on both fuel pumps and they were activating and buzzing.



    Replaced fuel filters and surrounding lines. Fuel was on reserve and I didn't feel right opening the fuel tank at this point so I added 20 L of fresh fuel to mix it up.









    Replaced distributor caps & rotors. They had a date stamp from '91 so likey original.





    Replaced skanky spark plugs.





    Nasty air filters from '94.





    Fresh oil. The oil that came out was actually looking fresh and nice color. They told me it was replaced recently so that might be true.



    Hooked up new batteries and drained a bit of old coolant out.







    Took some effort but the old girl fired up. After a few seconds, a whining noise appeared so I shut it off. I overlooked to check the PS fluid canister and surely it was filled with ATF and mesh filter wasn't secured.
    Pumped the brake pedal like 30 times and sucked out as much as I could from the canister and removed the drain plug on the PS pump and filled with CHF 7.1. I plan to repeat this until it's entirely green. Also, the brake booster is leaking heavily so that's on the list as well.













    Fired it up again and PS pump complained for a few seconds but then it went quiet. Here's a short video:



    (brake booster leaked fluid all over the exhaust hence the smoke from the front right, I think)

    I was able to move it back and forth which is a great success considering it was a non-runner. It idles kinda lumpy, maybe even misfiring and won't rev past 3k rpm, it starts choking. After few minutes it started puffing blueish smoke so I had to shut it off.

    Smoke is my current concern - could be clogged VCV valves or sign of something more serious? Working theory is to let it run to see if it burns off the old stuff and hopefully clears up. Perhaps add Liqui Moly engine cleaner in oil and let it idle for 30 minutes.
    I talked to Herr Wokke and he suggested to remove the small hose from the intake and plug the hole to test the VCV and see if it still continues smoking. I was thinking to replace the VCV anyway since it can't hurt. I'm also thinking to pull a trigger on a new set of ignition wires.

    Any tips or suggestions on what else to check are more than welcome. It would be great if I had a way to plug in the scanner and read the codes since there are probably plenty of them. I have 20 pin connector and INPA version 3 something, but I'm pretty sure that it won't work. I read it's a PITA to get INPA working on early '90 cars but I'll give it a shot.

    I also picked up a set of cross spoke 16" wheels with good tires that I will be installing soon.

    Cheers!
    Last edited by sreten; 11-07-2018 at 05:16 AM.




  2. #2
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    Congrats on a great find! I am going through the fuel pump issue myself. Can't wait to see it cleaned up.
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  3. #3
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    Blue Smoke

    Blue Smoke means Oil. Valve Guides could be brittle or broken. Could also be a stuck ring, also CCV system

    Intake gaskets could be causing the rough idle

  4. #4
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    Well done for getting it running at all! By the almost identical colour of all 12 plugs I would focus on fuel/air mixture to start with - it is possible that the colour is due to soot from burning oil, it is just as likely to be an over-rich mixture on both banks. So, the best place to start is fuel pressure which should be between 3 - 3.5 Bar - the pressure can be measured anywhere between the fuel pump and the Fuel-Pressure Regulators.

    It is also possible (and quite likely) that the catalytic converters are blocked - running the engine with either an over-rich mixture or high levels of oil-smoke will kill them it quick order - and blocked cats can certainly limit the engine speed as they will cause excessive back-pressure.
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  5. #5
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    great find ! congrats. The same car as mine , manual, black on black . Mine is from 01/1991 ( registrated ) , so our chassis# won't be that far from each other. Mine is CB12221 . On Realoem i see it was manufactured 10/90.

    Succes with solving the problems !

    PS some people here will tell you to have the wrong plugs…. they must be NGK BKR6EK ….. so i installed them.

  6. #6
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    Quote Originally Posted by rogbmw View Post
    Congrats on a great find! I am going through the fuel pump issue myself. Can't wait to see it cleaned up.
    Thanks! It will be a slow process.

    Quote Originally Posted by rjjablo View Post
    Blue Smoke means Oil. Valve Guides could be brittle or broken. Could also be a stuck ring, also CCV system

    Intake gaskets could be causing the rough idle
    I'm aware of all of that, just don't want to jump to conclusions yet and go step by step.

    Quote Originally Posted by Timm View Post
    Well done for getting it running at all! By the almost identical colour of all 12 plugs I would focus on fuel/air mixture to start with - it is possible that the colour is due to soot from burning oil, it is just as likely to be an over-rich mixture on both banks. So, the best place to start is fuel pressure which should be between 3 - 3.5 Bar - the pressure can be measured anywhere between the fuel pump and the Fuel-Pressure Regulators.

    It is also possible (and quite likely) that the catalytic converters are blocked - running the engine with either an over-rich mixture or high levels of oil-smoke will kill them it quick order - and blocked cats can certainly limit the engine speed as they will cause excessive back-pressure.
    Thanks, Timm! I'm very happy I got it running again. It's highly likely that plugs were original judging by the dates of the other parts I removed. That's a good tip and something I'll try to test.

    Quote Originally Posted by Belgiumbarry View Post
    great find ! congrats. The same car as mine , manual, black on black . Mine is from 01/1991 ( registrated ) , so our chassis# won't be that far from each other. Mine is CB12221 . On Realoem i see it was manufactured 10/90.

    Succes with solving the problems !

    PS some people here will tell you to have the wrong plugs…. they must be NGK BKR6EK ….. so i installed them.
    Thank you! This is my 3rd E31, the last one was also black on black and it went to Belgium.

    From what I understand, both BKR6EK and ZFR5F should be correct fit.




  7. #7
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    The interesting thing is that this looks like a "Radio-Delete" car, yet has the cassette E-Box in the center console.
    As for the ATF in the PENTOSIN canister, make sure that system is thoroughly flushed, or you will have problems down the road.
    '93 850Ci - Mineralweiss Metallic
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  8. #8
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    Congratulations on the new to you 8. Clearly you know what you are doing, it should be close to perfect in no time.
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  9. #9
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    Nice pick up of a fairly rare early 6 speed.
    My Cars - 1991 BMW 850i - mine for fun, 1993 Saab 900c - mine for fun, 2008 Lexus is250 - my daily driver, 2003 Dodge Durango - my wife's, 1994 Acura Legend - gave it to kid

  10. #10
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    Quote Originally Posted by TxGR8White View Post
    The interesting thing is that this looks like a "Radio-Delete" car, yet has the cassette E-Box in the center console.
    As for the ATF in the PENTOSIN canister, make sure that system is thoroughly flushed, or you will have problems down the road.
    And no opening for the hands free microphone either. I like it.
    Desecrator of all things Sacred

  11. #11
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    Quote Originally Posted by sreten View Post
    From what I understand, both BKR6EK and ZFR5F should be correct fit.
    |

    They might "fit", but the ZFR5F plugs are higher resistance plugs - that is what causes trouble in our aging ignition systems. This is why the BKR6EK are the right choice, 1ohm plugs
    '91 Dinan 860 Stage III (soon to be Dinan TT 6L)
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    '91 850i 6sp (getting there)
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  12. #12
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    Cartoonz ment 1 K Ohm plugs....

  13. #13
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    Quote Originally Posted by cartoonz View Post
    |

    They might "fit", but the ZFR5F plugs are higher resistance plugs - that is what causes trouble in our aging ignition systems. This is why the BKR6EK are the right choice, 1ohm plugs
    I ended up reading more on this topic and saw few people mentioning this. The ignition wires are likely original so I ordered a new set that I'm planning to install over the weekend.
    BKR6EK are not expensive and I can get a new set quickly just not sure if it's worth the trouble at this point. Many other stuff still needs doing.

    Will it really make a big difference to justify replacing them again?

    Sent from my SM-G965F using Tapatalk
    Last edited by sreten; 11-06-2018 at 06:48 PM.




  14. #14
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    Regarding your power steering flush, there is a hex bolt drain plug on the bottom of the power steering pump which is at the bottom of the system. I always drained my fluid from there.

  15. #15
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    Quote Originally Posted by Belgiumbarry View Post
    Cartoonz ment 1 K Ohm plugs....
    Yes, he did. Thanks

    Quote Originally Posted by sreten View Post
    BKR6EK are not expensive and I can get a new set quickly just not sure if it's worth the trouble at this point. Many other stuff still needs doing.

    Will it really make a big difference to justify replacing them again?
    Here's the thing... *sometimes* there is no issue with the higher resistance plugs. As our cars age, this becomes more unlikely. The 10Kv coils and other components degrade over time and, since the whole system was designed to drive only 1Kohm (thank you Barry) plugs, throwing in the higher resistance ones is just inviting problems. Misfires, loss of signal to the donut sensors, general hair pulling issues... all are typical.

    Like you said, plugs are cheap. Why risk it? Shoulds like you have plenty of work ahead of you, might as well do it right. It looks like you scored a really nice car. There will be stuff other than cleaning that you'll likely run into, good idea to keep that to a minimum.

    That's how I'd look at it

  16. #16
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    Quote Originally Posted by TxGR8White View Post
    The interesting thing is that this looks like a "Radio-Delete" car, yet has the cassette E-Box in the center console.
    As for the ATF in the PENTOSIN canister, make sure that system is thoroughly flushed, or you will have problems down the road.
    Yeah, no radio. It has cool options though - heated front seats, power steering column, electric rear sunshade, auto dip interior mirror, sunroof (which I daren't to touch yet), alarm system...

    I plan to drain and refill PS fluid every time before I start the car until it’s entirely green.

    Quote Originally Posted by 72tpik5 View Post
    Congratulations on the new to you 8. Clearly you know what you are doing, it should be close to perfect in no time.
    Thank you! e39/e38/e46 is more up my alley but I'm no stranger to e31, I'm trying to do lots of research and talk to the right people when it comes to e31. Wokke is 2 and a half hours away from me and has been a great source of information.

    Quote Originally Posted by PabloRock View Post
    Nice pick up of a fairly rare early 6 speed.
    Thank you! I concur.

    Quote Originally Posted by Sniff38 View Post
    Regarding your power steering flush, there is a hex bolt drain plug on the bottom of the power steering pump which is at the bottom of the system. I always drained my fluid from there.
    Thanks, that's exactly how I drained it as well.

    Quote Originally Posted by cartoonz View Post
    Here's the thing... *sometimes* there is no issue with the higher resistance plugs. As our cars age, this becomes more unlikely. The 10Kv coils and other components degrade over time and, since the whole system was designed to drive only 1Kohm (thank you Barry) plugs, throwing in the higher resistance ones is just inviting problems. Misfires, loss of signal to the donut sensors, general hair pulling issues... all are typical.

    Like you said, plugs are cheap. Why risk it? Shoulds like you have plenty of work ahead of you, might as well do it right. It looks like you scored a really nice car. There will be stuff other than cleaning that you'll likely run into, good idea to keep that to a minimum.

    That's how I'd look at it
    It does make sense. Well, I just ordered few more parts and I went for a new set of BKR6EK as well. I'll throw them in before I change the ignition wires and start the car to see if I can feel any change. I have VCV parts coming and a new thermostat, I have a funny feeling the one on the car is probably stuck open and I want to fully warm up the car and since it's chilly outside tstat needs to be good.

    The right headlight doesn't pop up and after a quick search I found headlight relay to be the common issue, so I took it apart and resoldered all of the contacts (which looked fairly good) but no dice, lights are working but the headlight is staying put. That would've been too easy.
    Last edited by sreten; 11-07-2018 at 10:20 AM.




  17. #17
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    There isn't much that is easy on an 8, but they are definitely worth it.
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  18. #18
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    Strange to find a BMW's GT cruiser to have no radio... perhaps there was a new radio/GPS installed and they removed it ?

    I plan to visit Wokke once the car is running fine.... think for me it's a 3 h drive.... or 2 with the charger and loosing my driving license … and...if i drive at night to avoid the traffic jam in Antwerp…

    Perhaps we can meet over there ? would be fun . In the near future….

  19. #19
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    They probably took out the radio since it has the cassette holder option. But it does look like some sort of factory plate in it's place.

    That's like when I was visiting my brother in Montana and we had to drive from Big Sky to Billings. I asked how long of a drive and he said "3 1/2 hours, or 2 1/2 in the M3". So I took the M3.
    My Cars - 1991 BMW 850i - mine for fun, 1993 Saab 900c - mine for fun, 2008 Lexus is250 - my daily driver, 2003 Dodge Durango - my wife's, 1994 Acura Legend - gave it to kid

  20. #20
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    Pretty neat, thanks for sharing! You gave me ideas for 'resurrecting' one that's been sitting just about that same amount of time.

    Sent from my XT1710-02 using Tapatalk

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