Results 1 to 25 of 25

Thread: Strange engine noise - '91 850i M70

  1. #1
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5

    Strange engine noise - '91 850i M70

    Hi folks,

    I'm in the process of reviving a Laguna green '91 850i 6-speed manual.

    The car has been off the road since around 2011. It was of course a non-runner when I got and before starting it for the first time, I did the usual:
    new fuel pumps and fuel filters, fresh fuel, new spark plugs NGK BKR6EK (the ones in there were finger tight), checked ignition cables and found 6 to be dead so replaced them as well, new distributor caps and rotors, fresh oil and filter (10W40), turned the engine by hand... removed the belts and the car started relatively easily. The idle is okayish and it revs nice and easy.

    But after a minute, there is this odd noise that I haven't experienced before, like rubbing noise, hard to describe but it should be obvious in the video.





    Sounds like it could be from the bottom part of the engine but not sure. The noise is present even with the belts removed.

    Any suggestions where to start diagnosing or the possible cause? I was thinking to drop the oil pan and see if I find something out of ordinary.


    On a different topic, the brake fluid was black gue, cleaned as much as I could. When I try to bleed the system the fluid is only coming out of the front left corner. Removed the lines before the ABS pump and it's flowing so I'm thinking the hydro unit is clogged. Any suggestions here? The pump is NLA from BMW and not sure if anyone is refurbishing these. I'm guessing used one is the only option.

  2. #2
    Join Date
    Oct 2009
    Location
    United States
    Posts
    356
    My Cars
    91 850 95dinan s/c m
    Can’t wait to see your progress with this 6speed!

  3. #3
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    Use a mechanics stethoscope, with that you can find the trouble maker easier.
    Shogun tricks and tips for the E32 series are HERE!

  4. #4
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    I ordered the stethoscope.

    Perhaps bad timing/chain related? These sound similar.




  5. #5
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    There was a problem with the old version timing chain tensioner: 90bmw17- Group 11 Engine- Bulletin Number 11 10 90 (3144) , Woodcllff Lake, NJ October 1990 Service Engineering
    SUBJECT: Modified Timing Chain Tensioning Rail MODEL:E31, E32 (with M70 engine)
    Situation: A modified timing chain tensioning rail has been phased into production as of mid-June 1990. The new style timing chain tensioning rail incorporates a roller (sprocket) in addition to the plastic-coated sliding surface. The new configuration reduces the relatively high friction loads in cold operating conditions and thus reduces wear.
    Installation Note:The timing chain adjustment distance has been reduced by 1 mm to5 +/- 0.5 mm due to the use of the new style timing chain tensioning rail. See repair manual for details on adjusting bming chain tension.
    Parts Information:The new tensioning rail (P/N 11 31 1 725 682) can be installed retroactively whenever engine repairs are performed. Upon depletion of the current parts inventory the old part number will be superseded to the new part number, 11311725682.
    https://www.bimmerforums.com/forum/s...hain+tensioner
    Shogun tricks and tips for the E32 series are HERE!

  6. #6
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    Thanks, Shogun.

    Production date of the car is 05/1991 so it should have the updated version.

  7. #7
    Join Date
    Jun 2008
    Location
    SF Bay Area
    Posts
    3,774
    My Cars
    Supercharged 850ci
    That is pretty familiar sound actually, the cams are not getting enough lubrication, banjo bolts have backed out.

  8. #8
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    You think? That was my and friends initial guess, I asked Wokke if that could be the cause and he said no. To me it sound like a power steering pump that's not getting enough lubrication. Previous owner swears the car sounded perfect some 10 years ago when he parked it...

    At this point, it can't hurt to remove the manifolds and valve covers, just not sure if I'll have time for that. I'm still waiting on the stethoscope so I'll check closer tomorrow.

    I made some progress with the brakes today.



    I disconnected 2 lines that go to the ABS pump from the MC and the fluid was flowing. Then I disconnected lines on the ABS pump one by one and the fluid was coming out, at first dark and then clean fluid. I had the power bleeder on the reservoir.

    Now I'm getting a steady flow from the front left and right wheel using the power bleeder.
    For the rear, the brake fluid is only coming out if I press the brake pedal which is rock hard and really difficult to press with the bleed screw open. Also, the pedal will only go half way and then stop, not to the floor like it should when the rear lines are open.
    I know that the rear lines go into the ASC/T hydro pump after the ABS pump. So possibly clogged there? I'm also suspecting that the master cylinder might be rusted out from the inside and I guess not a bad idea to change it.


    Sent from my SM-G965F using Tapatalk

  9. #9
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    With the car running and stationary, the brake pedal is soft and goes only half way and then stops, can't be pushed passed that.
    When I drive it and step on the brake pedal, it's rock hard. Brake bomb/accumulator is kaput?

    Sent from my SM-G965F using Tapatalk

  10. #10
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    my collection, H31 system explained https://www.bimmerforums.com/forum/s...teering-system
    Shogun tricks and tips for the E32 series are HERE!

  11. #11
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    Soo, the stethoscope got delayed again but I used a long screwdriver and the noise is definitely most audible from the timing chain tensioner.



    I adjusted it to be tighter by 3 mm more but it made no difference. I know guides are not a common failure on the M70 but we are talking about nearly 30 years old car that's been off the road for the last 10. Nothing lasts forever.

    I'm thinking to replace the spring, the piston and leaking O-ring of the tensioner and see if it makes any difference. This is relatively easy and inexpensive.

    If no difference, then drop the pan and look for plastic bits. If no remains of the guide, pop off the valve covers for a better look and check cam timing.

    On top of that, it's smoking decently white/blueish smoke, not sure if it's just burning off from sitting or this engine will need a complete overhaul.

    Any tips/suggestions?





    Sent from my SM-G965F using Tapatalk

  12. #12
    Join Date
    Oct 2016
    Location
    Shoreview MN
    Posts
    977
    My Cars
    Had a 1991 BMW 850

    Smoke

    White Smoke is likely coolant, What does it smell Like?

    Check your oil for the Chocolate Milkshake

    Definative test is a compression check

  13. #13
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    There is a bit of condensation on the cap but not sure yet if it's just that or deeper, the car has been idling only for a few minutes and moved back and forth to feel the clutch and brakes. I didn't drive it properly yet so some condensation is to be expected.

    I ordered parts for the tensioner and the compression tester.

  14. #14
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    Fixed!

    Decided to change the timing chain tensioner today before dropping the pan. This is what I found.

    The old spring was noticeable more compressed and shorter than the new one.






    Scoring on the piston - from all the pictures that I saw of the piston inserted in the engine, I'm not really sure what would cause this or how it would happen? It looked like it was properly installed but hard to tell for sure.






    Anyways, new stuff installed, it fired up drama-free and the engine is working beautifully! No more noise!



    I'm very happy. Now just to see if the smoke will clear up. I'm hoping it will as I had the same thing with the previous E31, just a lot of condensation from sitting.
    So far it's been only idling for a few minutes which is the worst thing, I'm planning to drive it around the yard once I come back from vacation in 7 days. But at least I can relax now knowing the engine sounds healthy.

  15. #15
    Join Date
    Jul 2007
    Location
    Iceland
    Posts
    4,675
    My Cars
    BMW 850
    Good job. I love your thread

  16. #16
    Join Date
    Nov 2015
    Location
    Ger
    Posts
    29
    My Cars
    E31 850iA 1992
    Hi,

    I also replaced these parts. (see image)
    Unfortunately, the sounds are still there.
    :-(
    https://youtu.be/FmP8BewRnTc

    1.jpg

  17. #17
    Join Date
    Mar 2016
    Location
    Frankfurt, Deutschland
    Posts
    376
    My Cars
    Le Mans Blue e39 M5
    Mine has been fine so far, I got it fully warmed up and drove it around the yard, even the smoke cleared up. It was just condensation.



    In your case, I would start by removing the oil pan and see if you find anything there. If clean, then pop the valve covers off and look from above. I think lubrication might the issue as well.

  18. #18
    Join Date
    Aug 2018
    Location
    Hamburg
    Posts
    15
    My Cars
    1997 520i, 1992 850i
    Sreten! Love your videos, I learnt a lot from them.

    I just pulled the trigger on a 6-speed 1992 850i which is not in such a bad shape. However, I'm noticing a very slight clicking/ticking noise when I'm close to it, seems to be coming from directly behind the timing chain on the Ansaugbrücke but I don't notice it getting any louder when I open the Oil fill cap. It does it at any temperature. What are the chances that I'm gonna have to pull off the valve-cover before I even registered it?
    Last edited by Kylemontanaro; 03-02-2024 at 09:47 AM. Reason: typo of - off

  19. #19
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    besides the timing chain tensioner + spring there can be also other items making noise like hydraulic lifters etc, here is a Spanish language website with lots of pics showing what can break / making noise in the top of the M70 engine
    SOLUCIONAR SONIDO A TAQUES EN BMW 750I E32 - Taqué nuevo frente a uno usado = new tappet vs used pics http://www.gti16.com/usr/coco/bmw_m7...70_taques.html
    Last edited by shogun; 03-03-2024 at 03:09 AM.
    Shogun tricks and tips for the E32 series are HERE!

  20. #20
    Join Date
    Aug 2018
    Location
    Hamburg
    Posts
    15
    My Cars
    1997 520i, 1992 850i
    Thanks mate, that was interesting to read! Could very well be the hydraulic lifters as well because I've noticed heavy carbonisation in some areas. I wouldn't be surprised if some of the lifters got a bit gunked up. I got an oil cleaner that I'm planning to throw in the oil system before I do an oil change but I'm not allowed to idle the 850 for 15 mins in the garage cause the neighbours would (rightly) complain. So I need to get it registered and drive it outside for a bit.

  21. #21
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    My wrenching buddy here in Japan made a good write up and pics of the lifters in his M70 Alpina B12 which we replaced in my garage https://e32b12.blogspot.com/search/l...valve%20lifter
    Then you could have lose banjo bolts in the oil line in the head causing damage to the camshafts , Engl in Germany has Sicherungsbleche für die obenliegenden Ölleitungen der Nockenwellen (Motor M70) http://www.engl-production.de/sicherungsblech.html
    Last edited by shogun; 03-03-2024 at 06:34 AM.
    Shogun tricks and tips for the E32 series are HERE!

  22. #22
    Join Date
    Aug 2018
    Location
    Hamburg
    Posts
    15
    My Cars
    1997 520i, 1992 850i
    Oh man... that would be something! I will eventually open that up and have a look, but first I want to get driving around a bit to know the car a bit. I love working on it but I don't want to go through all the hassle to later realise there was something else I needed to fix when it was open.
    Great write-up by your friend! These forums have really collected a treasure trove of info.

    Sorry to go off-topic a bit, but do you know anything about computer diagnostics? I've dug through everything I could find the past few weeks, I have a laptop with a serial port, ADS adapter, Windows XP and DIS V44 & DIS V57 and I still can't get it to read. Considering the rest of the car has been so far playing nice to me, this has been a real headache.

  23. #23
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    for computer diagnostics there are other experts here which hopefully will chime in.
    Shogun tricks and tips for the E32 series are HERE!

  24. #24
    Join Date
    Aug 2018
    Location
    Hamburg
    Posts
    15
    My Cars
    1997 520i, 1992 850i
    Thanks mate. I'll keep digging.

  25. #25
    Join Date
    Jan 2019
    Location
    Finland
    Posts
    5
    My Cars
    1991 BMW 850i manual
    Quote Originally Posted by shogun View Post
    jakoketjun kiristimen + jousen lisäksi voi olla myös muita ääniä aiheuttavia esineitä, kuten hydraulinostimet jne., tässä on espanjankielinen verkkosivusto, jossa on paljon kuvia, jotka osoittavat, mikä voi rikkoutua / aiheuttaa ääntä M70:n yläosassa moottori
    SOLUCIONAR SONIDO A TAQUES FI BMW 750I E32 - Taqué nuevo frente a uno usado = uusi nostolaite vs käytetyt kuvat http://www.gti16.com/usr/coco/bmw_m7...70_taques.html
    The sound that was at the beginning of the message thread that Sreten was struggling with comes from the timing chain tensioner wheel bearing, replace the timing chain tensioner rail m73 with the engine rail and the problem is gone. The sound may also disappear over time, this happened with my own m70 engine.

Similar Threads

  1. Strange engine noise
    By Afanasi in forum 1991 - 1999 (E36)
    Replies: 22
    Last Post: 09-03-2007, 07:28 AM
  2. strange ticking noise... 91 318is
    By kowalski in forum 1983 - 1991 (E30)
    Replies: 6
    Last Post: 01-19-2006, 11:13 PM
  3. Strange engine noise 540i
    By betep in forum 1996 - 2003 (E39)
    Replies: 9
    Last Post: 07-24-2005, 07:16 PM
  4. Strange engine noises.
    By KGB in forum 1988 - 1996 (E34)
    Replies: 7
    Last Post: 02-15-2005, 04:55 PM
  5. Help: Strange engine noise, suggestions please.
    By ChadsM3 in forum 1992 - 1999 M3 (E36)
    Replies: 8
    Last Post: 03-29-2004, 05:15 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •