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Thread: 1990 BMW 535i Running Rough and Fighting Starter - Oil on Plugs/Jumped Timing??

  1. #1
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    1990 BMW 535i Running Rough and Fighting Starter - Oil on Plugs/Jumped Timing??

    Hello,

    I have 1990 BMW 535i that I was driving at about 55mph and then I noticed a shudder (felt like a miss/spark jumping) but within a mile or so began to feel much worse and I lost some power, once I pulled into my driveway I parked it and it would barely idle. I then turned the car off and went to restart it just to see how it acted and it felt like the motor was bound up - first I thought hydrolocked but then it started but it really wants to die and runs extremely rough. I also noticed a small oil drip out of the exhaust manifold that was never there before, pulled the rear spark plug (closest to firewall) and it was covered in oil.

    Does this sound like a timing chain jumped or something else? Also, are these interference motors or not? The car has 260,000 miles and I wanted to get a few peoples opinions before I pull of the valve cover and check into the timing chain and guides and go from there. I do have a spare motor with about 160,000 if I need to go that route

    Thanks for the help!

  2. #2
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    If you can get your hands on a bore scope I'd take a look inside #6. The oil concerns me, you might have dropped a valve that holed a piston. Does it have excessive blowby? Noises?

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  3. #3
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    I will see what I can do about a bore scope sometime this weekend. The engine itself makes quite a bit of racket when I can get it running - when its fighting itself to stay running it sucks a ton of air to compensate so that is the majority of what I can hear, otherwise there is a lot of excess engine noise and what sounds as though things are dry and fighting to move, thats what led me to timing jump because too advanced and the motor will fight itself etc. How else do you think I can check for excessive blowby? If I'm not mistaken this should show up pretty easily in the intake since it cycles the blowby back through to burn it up but all of my intake boots/MAF are nice and dry.

  4. #4
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    Remove the oil filler cap while running(if you can because this creates a big vacuum leak)and watch for smoke. If you have a hole in a piston compression/combustion will be let into the crankcase, you'll know.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  5. #5
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    Got a chance to remove the oil fill cap while it was running and there was no smoke or anything abnormal that I could see. Now starting the car from a cold start I can see quite a bit of oil coming out the exhaust and holding my hand in front of it I get a decent amount build up on my hand within a few seconds, so I guess there is a pretty significant amount of blowby that I never had before.

  6. #6
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    To clarify, blowby is combustion gasses into the crankcase via worn/broken rings or a ventilated piston.
    Crap out the exhaust may just be soot and moisture, especially on a cold start. If indeed oil coming out of there you have a serious problem.
    Good luck

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  7. #7
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    Ah sorry for misunderstanding - I was thinking of oil being "blowby" like in a worn turbo or diesel engines etc. I definitely do not think I have combustion blowby then that I can find. I also spent a little more time today letting the car run from cold start to almost operating temperature - I then checked the oil and now see the classic milky/water in oil signs of a blown head gasket as well as the white smoke out the exhaust. I did not catch this before because at the time when I lost power and the engine started to run odd I was close to home and only had let the engine run another few minutes so water had not yet really made its way into the oil. I believe the head gasket has suffered a pretty significant blow because I now have oil seeping out of the flange off of the manifold (drop down pipe) and also have water in the oil. If anyone has any recommendations or further insight I would love to hear - otherwise I think it would make the most sense to replace the engine with a lower mileage one than try to replace the head gasket etc on this 260k mile one.

  8. #8
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    Going through this same dilemma, but with my replacement engine (245k on the clock compared to probably ~400k, considering the ODO broke for the previous owner 6 years ago at 299k). And I considered that releatively low miles lol.
    The bottom end of these things likes to keep chugging along (sans oil starvation), it’s usually the top end that needs work anyways. It’s all about how much you wanna spend, and what you want the end result to be.

    If you can find a replacement engine cheap, that might not be a bad option. A head gasket job done right is probably gonna cost around the same price, considering the machine work, refresh etc. And the steps of removing the head, and removing the whole engine, are basically both the same. Just missing the big ones like unbolting trans, motor mounts, and accessories.

    I would wonder why the gasket blew in the first place too...

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    Head gasket sucks but not the end of the world.
    Yours sounds like it just rotted away, which happens on poorly maintained cooling systems. If you haven't overheated a simply gasket swap is probably all it needs. Have a machinist check the head for straightness but I suspect you might be fine with a fresh gasket.
    One thing to watch for in these situations is a corroded head or block surface. If the head a quick skim should fix it and make it perfectly straight again as well. If the block is pitted you might not be able to make the gasket seal without decking the block which means engine out. I've heard stories of epoxy(JB Weld) repairs but can't speak to that personally.
    Last edited by ross1; 09-26-2018 at 03:02 PM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  10. #10
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    I do already have a spare engine that I pulled and I didn't think that was so bad pulling that and the trans together so I don't have to put any money out at all to get a spare motor other than freshening it up a bit (plugs/wires/fluids/etc.) And by the sounds of it (compared to the service you got out of yours) my spare motor with about 160k is still pretty young haha.

    I would be the one doing the head gasket work or the motor swap so I was just considering which one people thought was easier to do and what the best options would be.

  11. #11
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    Also, @ross1, I imagine mine did finally rot away because of poorly maintained cooling system from the previous owners - I did a ton of work to the cooling system about 1 year ago because I don't think anyone ever messed with it so now I have a new water pump/thermostat/heater control valve/heater core/heater crossover pipe/fan clutch etc but I bet the deterioration had already begun on the head gasket and it finally let loose.

    I haven't had any major overheating and definitely not since my latest issue we are discussing now - if it were your motor would you pull the head and see how bad it is (see if it needs decking or is pitted) and if it looks okay put a new gasket in? Or worst case scenario if its bad enough put my replacement engine in and decide what to do with the high mileage motor after? Or just forget checking into the motor thats in the car now and just put my spare one in?


    Side topic - if I were to "consider" putting a moderate turbo on this engine should I even consider using the high mileage motor with a thicker head gasket and all that or just stick with modifying the low mileage motor and fix the high mileage motor in it now?

  12. #12
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    My motor I would pull the head and inspect. Whole job sans machine work can be done in a solid day.
    I would actually take the opposite route for your side project. Fix the high mileage motor in it, and blow that up instead of the nice new low mileage example. Just my two cents.

  13. #13
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    Ah okay okay that also sounds reasonable - I don't want to go crazy and blow the motor up, I was just concerned about the high miles with "any" amount of boost being too much versus the lower mileage one being able to take it better with less wear altogether, but what youre saying makes sense.

  14. #14
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    Quote Originally Posted by theBMWbeast View Post
    My motor I would pull the head and inspect. Whole job sans machine work can be done in a solid day.
    I would actually take the opposite route for your side project. Fix the high mileage motor in it, and blow that up instead of the nice new low mileage example. Just my two cents.
    Agreed

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

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