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Thread: 1991 BMW 750il wont start! Mechanic stuck! Been in shop >8 months!

  1. #101
    Join Date
    Dec 2017
    Location
    Dallas texas
    Posts
    55
    My Cars
    1991 bmw 750il
    Thats great got those ordered now! Also found some 20w50 full synthetic motor oil on amazon - link here https://www.amazon.com/Valvoline-Adv.../dp/B000GAN3GC - yet to order but planning on stocking up with a few cases. For some reason was not able to open the link on your site for the top end rebuild. I was however able to look at the fuel injector rebuild - and that looked amazingly easy and photos very detailed. Not sure if I need to do this but I assume mine are nasty like the ones in the photos. Add it to the list lol. The only problem is every time I go on your site I find like 5 more things I want to do to the car HAHA! But I guess thats part of the fun in it too! Don't know what we would do without all the work/effort you put in to keep these cars on the road for years to come! Thank you Sir feel like I owe you a donation or something for all the work you put in and for others benefit

  2. #102
    Join Date
    Dec 2017
    Location
    Dallas texas
    Posts
    55
    My Cars
    1991 bmw 750il
    When I turn the windshield wipers on - they make a terrible noise whacking back and forth. I was thinking there must be an old grommet or something that needs replacing but really don't know . I thought I had read something about it somewhere . Also, my windshield wiper reservoir is cracked and needs replacing - currently searching the web without much luck whatsoever.

  3. #103
    Join Date
    Dec 2017
    Location
    Dallas texas
    Posts
    55
    My Cars
    1991 bmw 750il
    https://www.hemmings.com/classifieds...l/2216803.html

    nice looking e32 but have a hard time believing it will auction close to the estimate

  4. #104
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    top end overhaul M70 https://www.bimmerforums.com/forum/s...haul-DIY-guide
    wiper angle adjustment : chattering windshield wipers? How to fix http://www.bimmerboard.com/forums/posts/292534/
    Shogun tricks and tips for the E32 series are HERE!

  5. #105
    Join Date
    Mar 2013
    Location
    Green Bay, WI
    Posts
    1,332
    My Cars
    1992 750il / 1991 560 SE
    You can get less expensive fuel pumps from eBay. They are direct fit and work well. But I did have an issue as outlines in the thread. VERY quickly resolved by the seller.
    https://www.bimmerforums.com/forum/s...mps-in-a-750iL

    I removed the heads on my 1992 750iL without pulling the engine. It was not difficult really. The hardest part was actually the coolant crossover pipe in back, the install. As for head bolts being broke, I had none which surprised me as its a known issue. So I expected to have to deal with that and was happy not to. With that said, replace with proper deadbolts following the manual. You do NOT lubricate the new ones, you can crack the block if you do. Also the bolt hole must be clean and 100% dry. New bolts will come with a very light coating, like a graphite material. I recommend Rhein bolts.

    The exhaust manifold nuts can be a little tricky. They usually come out with the stud. Once removed, you should break them apart, clean them up and then put the studs back on the heads before putting the heads in. That way when the nut goes back on you can get proper torque. If you simply put the rusted together stud and nut in then the stud may bottom out and the nut will not compressor the manifold.

    Pulling the heads opens a can of worms though. You will want to remove/replace the valley cover gasket. Known to leak. The bolt on this almost always break but they are small and easy to extract. With any luck just the head brakes off so once the cover is removed you can just used a vise-grip to clamp down and work it back and forth slowly until it comes out. I had a few I needed to remove this way.

    You used to be able to get a top end gasket kit. Included TONS of stuff. Victor Reinz. Saves heaps of money. The kit does not include the valley cover gasket or head gaskets. If you can find this kits, its great.
    https://www.amazon.com/dp/B001G64RCY..._26725410_item

    So as you stand now, you are probably safe. Like I said, the M70 is known for head bolts snapping but its not known for blowing head gaskets. So a few can pop without issue. But when installing new gaskets, you NEED to have all the bolts in place for proper compression and torquing. What is probably preventing head gasket failures on engine with snapped bolts is age and bonding of the old gaskets. With new gaskets, there is no baked in bonding so I would expect them to blow.

    2 11121729247 Cylinder Head Bolt Set; 14 Bolts for 1 Cylinder Head
    1 11121729893 Cylinder Head Gasket; Right (Cylinders 1-6); 1.64mm
    1 11121729897 Cylinder Head Gasket; Left (Cylinders 7-12); 1.64mm


    IMG_0501.jpg
    IMG_0694.jpg
    IMG_0697.jpg
    IMG_0776.jpg
    ______________________________
    1992 750iL

  6. #106
    Join Date
    Dec 2017
    Location
    Dallas texas
    Posts
    55
    My Cars
    1991 bmw 750il
    Unity - thanks very much for this detailed info and photos! Extremely helpful! Its something I definitely want to fix for piece of mind especially with all the time, effort, and money I've put into the car. I plan on keeping it forever - so it will need addressing at some point. The zionsville aluminum radiator arrives this evening! Yahoo! Super excited to get that installed along with new expansion tank and radiator hoses. Then I just have to do the new stainless steel brake lines that came yesterday (75$ usd on FCP EURO). I also have all new dog bones and subframe bushings to install - new wiring harness off pin 7 (thinking this may be easier than trying to locate the short but I will spend a few hours attempting this first) and lastly two new fuel pumps, fuel regulators and vacuum hoses! Getting very close especially since I have most the parts needed to finish the job now. Hoping to get all this finished in the next week, then put some miles on the car and see how it feels - will make a decision from there on whether to do the head bolts, head gaskets, and whatever else while in there now or wait. Valley cover gaskets were replaced by Frank - the ex mechanic when he was in there last. Thanks again for all the help!

  7. #107
    Join Date
    Mar 2013
    Location
    Green Bay, WI
    Posts
    1,332
    My Cars
    1992 750il / 1991 560 SE
    Welcome. I can be of more help if needed as I have been into the M70 engine a few times. Now she sits ready for sale though.

    Also, I dont want to read the whole post again so I will ask. Did you ever take care of the oil bar banjo bolts? If you dont know what I am talking about, its something you should look into.
    ______________________________
    1992 750iL

  8. #108
    Join Date
    Mar 2014
    Location
    san antonio texas
    Posts
    319
    My Cars
    1989 bmw 750il
    Hey Unity, when you replaced your head gaskets did you mill your heads?

  9. #109
    Join Date
    Mar 2013
    Location
    Green Bay, WI
    Posts
    1,332
    My Cars
    1992 750il / 1991 560 SE
    No, they were not out of spec enough to require it. Plus with these heads its not something I would really want to do.
    ______________________________
    1992 750iL

  10. #110
    Join Date
    Dec 2017
    Location
    Dallas texas
    Posts
    55
    My Cars
    1991 bmw 750il
    Update On car:
    Have replaced entire cooling system
    -aluminum radiator and hoses
    -water pump
    -thermostat
    -Expansion tank etc
    -new bmw coolant
    Replaced both fuel pumps
    -fuel filters and hoses already done
    Still need to put in the new fuel pressure regulators but have done vacuum lines.
    I have not done the fuel injector rebuild yet (sort of hoping to drive the car awhile first)
    Entire ignition system has been replaced
    - ignition coils
    -plugs
    -plug wires
    -caps and rotors
    New brake hoses with stainless steel, bleed and flush system
    New brake bomb
    Replaced rear subframe bushings with AKG Poly (I know not oem and may need to grease in a few years) I have not noticed much difference with NVH but much better feel especially into corners . Anything would have been better compared to worn out oem bushings
    Fixed the torn rear sway bar and now the rear self leveling shocks work
    Replace dogbones with lemforder
    Motor Mounts and Trans mounts done
    Adjusted shifter cable to properly engage the parking pawl
    Replaced both bushings for the throttle pedal
    Installed Shoguns 3 chips - These are a great upgrade and I highly recommend with a noticeable difference driving especially from a stop.
    Fixed the electrical fault causing limp mode . This took forever. Detailed write up below. Any advice on the unknown plug is appreciated.

    Root cause was a blown #20 fuse that prevented the EML light from coming on, triggering limp mode.Direct short on the F20 circuit was then narrowed down to the X15 plug, on pin 7 feeding the park vent relay, chime module, and on board computer (OBC).Removed all lower dash panels and inspected wiring for damage. No short could be found in the A15 park ventilation relay box, or the sub harness connecting the X607 plug from the A15 relay to the X512 plug that powered it. The wiring from pin 7 of the X15 plug to the X577 splice that powers the 3 modules on this circuit was then inspected by removing the factory friction tape bundling the harness and separating out the 4 wires. Tracing them, no damage to the harness could be observed. Further testing revealed that when the chime module was unplugged, the direct short to ground disappeared, however testing of the chime module showed no signs of internal failure causing this, nor could any failure be found in the X518 plug harness that also connects to the chime module. With any 1 of the 3 components (H10 chime module, X522 3-pin white plug, X518 4-pin black plug) the fault vanished, however all 3 combined resulted in the direct short to ground. The X518 4-pin black plug, which is keyed to only plug into the chime module one way, had it's power/ground wires on pins 1/4 arranged so that they were the reverse of the +/- markings on the chime module itself. Looking at the pictures provided by BMW in the electrical troubleshooting manual, section 7100-24-3, showed that everything appeared as it should - a white 3-wire plug with 3 wires and a black 4-wire plug with 4 wires connected to the chime module. Looking further into the ETM, the section for On Board Computer->Chime Module, 6581-07 (pg 478/592), showed that the connections to the chime module should be X522 pins 1+2+3, and X518 pins 2+3, with nothing noted for X518 pins 1+2. Closer examination of the immediate area revealed a black 4-pin plug with only pins 2&3 populated tucked into one of the wiring harnesses. With this plug connected to the chime module, the short to ground was eliminated, and upon the re-pinning of X15 pin 7 fuse 20 no longer blew, the EML light functioned, the car no longer forced limp mode, and the chime module functioned. The 4-pin, 4-wire black plug that was previously believed to be the X518 plug is still unidentified. Any help identifying this plug is
    greatly appreciated. This is all in addition to the things that were done in the original post I made. I know I am forgetting some things like intake gaskets etc.

    Other issues I am currently dealing with are as follows:
    Have a flashing SRS light which I understand is something to do with the airbags and I need a SRI3 reset tool which is unavailable anywhere. If there is another way to reset this please help.
    I have a oil level sensor in the dash cluster - I am surprised the sensor is bad?
    I have brake light circuit and check control indicator in dash intermittently . Brake lights function as they should
    I am having pixel problems now also in cluster intermittently just when the car starts and then goes away after driving awhile.
    I am having vibration and shaking steering wheel when braking - going to order new rotors and pads ? Are the cheapest rotors I can find ok centric etc? OEM pads?
    I have noticed some vibration at highway speeds that make me think the front suspension is bad and needs replaced even though all this was done less than 10k miles ago. I will probably try an aftermarket thrust arm bushing in hopes of getting more use out of it
    I have a weird humming/electrical noise coming from the rear of the car just on the inside - its driving me nuts. I think it is coming from the back speaker so probably something easy and not mechanical although it does change in interval when I hit the gas. Going to disconnect the amp in the trunk as the sub that was there was stolen awhile back and stereo is not currently functioning anyways
    The ac works but does not blow out of the rear vents anymore , one of the front vents will also only blow out hot air while the other three blow cold air. The air feels cooler on the driver side then the passenger side that does actually blow coolish air - its more like Luke warm. The heat is functioning properly but won't blow out of the front vents only will blow onto the windshield and do feel some heat on the floor.
    I also still feel like the car is missing a little bit at idle - I just feel a slight vibration that is annoying me to death (maybe I'm a perfectionist idk) . Maybe a vacuum leak but it shouldn't be after everything I've done and replaced on this car! What really made me confirm my suspicion that it is missing is that when I put my hand up to the muffler - the gases coming out are not perfectly smooth if you know what I am trying to say. I was hoping the engine would be smooth as butter after everything I've done.
    Decided to ignore the head bolt problem for now unless I notice any loss of coolant or something like that.
    At least I don't have any leaks anymore and can drive the car some hahah!
    Last edited by Bimmerboatmd25; 04-24-2019 at 10:35 PM.

  11. #111
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    SIR3 airbag reset tools I no longer have, sold out, the cheapo B800 from China and the Peake tool do not work on E32. Find someone with a laptop and INPA.

    Oil level sensor: check the 2 wires next to the heater valve, there are 2 wires coming from the sensor + 1 wire from the alternator = the exciter wire, they go with the fat wire from the alternator thru the metal pipe left side on engine and come out of that pipe near cylinder 12, and from there to this connection, which sometimes breaks http://bmwe32.masscom.net/sean750/sp...gConnector.jpg
    Also the float inside the sensor can get dirty and does not go up.

    "I have brake light circuit and check control indicator in dash intermittently . Brake lights function as they should">>>> http://www.nmia.com/~dgnrg/page_25.htm
    I am having pixel problems now also in cluster intermittently just when the car starts and then goes away after driving awhile. >>>>>>check the bulbs first, otherwise change the capacitors

    "I am having vibration and shaking steering wheel when braking - going to order new rotors and pads ? Are the cheapest rotors I can find ok centric etc? OEM pads?">>>could be also steering links

    I have noticed some vibration at highway speeds that make me think the front suspension is bad and needs replaced even though all this was done less than 10k miles ago. I will probably try an aftermarket thrust arm bushing in hopes of getting more use out of it >>>>check http://www.bmwe34.net/E34main/Mainte...ering_link.htm

    AC: check heater valves, stepper motors
    Shogun tricks and tips for the E32 series are HERE!

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