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Thread: M52 hard to start when cold, worse when warm

  1. #1
    Join Date
    Sep 2022
    Location
    South Africa
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    My Cars
    E39 528i

    M52 hard to start when cold, worse when warm

    Hi everyone


    My grandfather is possibly looking to sell his 1998 E39 528i (M52 2.8L) which has around 100k miles on the clock.
    As a result, I am thinking about selling my (very reliable- not sarcasm) daily driver to be able to buy this BMW.
    Cosmetically and (mostly) mechanically, it's in superb condition, having lived its entire life in a garage.

    The water pump was replaced about 30k miles ago.

    Around three years (250 miles) ago, a hose split and the engine overheated- warping the head.
    The head has since been machined and the car seems to be running nicely- has lots of power but seems very slightly sluggish below 3k RPM.
    I'm not sure if it's the same as it was before the head was cracked, as I never drove it before.

    It's pretty much sat ever since, maybe starting up and going for a drive once or twice a year.


    Now the issue

    Since even before the head was warped, it's had an issue with cold starts.
    You have to crank it for around two seconds for it to catch on, then it hesitantly builds revs to a fine idle. About one to two seconds.

    It's worse when it's warm, cranking for around three seconds, but it will not build revs to idle unless you depress the throttle pedal.

    I know he once had somebody from BMW come and have a look at why it does this but it was fruitless.
    I'm not entirely sure what this guy did, but I've heard that he messed around with the crank/cam/any sensors.

    I've read around online, and a fuel-related issue seems to be quite possible. Perhaps a leaking injector?
    Maybe this is why the guy from BMW did not solve the issue. Perhaps he couldn't work on the fuel system without the car being at BMW?

    This starting issue still occurred on its first start in about a year. The ignition was on for more than ten seconds before starting.
    Haven't had the chance yet to read any codes. No warning lamps are illuminated.

    I'm not sure what the first step to take is to diagnose this issue, or if it's even worth it.

    I am somewhat mechanically inclined, but only really on dead simple 1960s British classics.


    I'd love to daily this BMW, as it's a much better car than my current daily driver (except in reliability, fuel, and maintenance costs- unarguable).
    Please help me to try justify this terrifying decision, which I am yet to make.

    I keep trying to tell myself that life is too short to drive boring cars...
    and a car that breaks constantly will always have you on your toes!


    Thank you.

  2. #2
    Join Date
    Jul 2007
    Location
    Costa Rica
    Posts
    6,709
    My Cars
    Blown 528i, KE30, Pathy
    Mine (also an M52 single vanos 528i) does the same thing from time to time, albeit not as severe as what you describe, the blower and bigger injectors may have something to do in my case too, but some of it can be attributed to just engines being 25 years old at this point.

    Quote Originally Posted by mrdawgza View Post
    Around three years (250 miles) ago, a hose split and the engine overheated- warping the head.
    The head has since been machined and the car seems to be running nicely- has lots of power but seems very slightly sluggish below 3k RPM.
    Because of this part, I'd start by doing a compression test and comparing all cylinders. Also, are there any codes?

    It could be something as simple as a vacuum leak, or like you said, leaking injectors are an option as they could flood the engine when doing warm/hot starts (even when cold, since the pump starts working as soon as you move the key to ignition).
    Resident Third World Country Advisor

  3. #3
    Join Date
    Aug 2010
    Location
    Oregon
    Posts
    1,269
    My Cars
    '99 528i/5, '01 Boobaru
    Quote Originally Posted by mrdawgza View Post
    Hi everyone


    My grandfather is possibly looking to sell his 1998 E39 528i (M52 2.8L) which has around 100k miles on the clock.
    As a result, I am thinking about selling my (very reliable- not sarcasm) daily driver to be able to buy this BMW.
    Cosmetically and (mostly) mechanically, it's in superb condition, having lived its entire life in a garage.

    The water pump was replaced about 30k miles ago.

    Around three years (250 miles) ago, a hose split and the engine overheated- warping the head.
    The head has since been machined and the car seems to be running nicely- has lots of power but seems very slightly sluggish below 3k RPM.
    I'm not sure if it's the same as it was before the head was cracked, as I never drove it before.

    It's pretty much sat ever since, maybe starting up and going for a drive once or twice a year.


    Now the issue

    Since even before the head was warped, it's had an issue with cold starts.
    You have to crank it for around two seconds for it to catch on, then it hesitantly builds revs to a fine idle. About one to two seconds.

    It's worse when it's warm, cranking for around three seconds, but it will not build revs to idle unless you depress the throttle pedal.

    I know he once had somebody from BMW come and have a look at why it does this but it was fruitless.
    I'm not entirely sure what this guy did, but I've heard that he messed around with the crank/cam/any sensors.

    I've read around online, and a fuel-related issue seems to be quite possible. Perhaps a leaking injector?
    Maybe this is why the guy from BMW did not solve the issue. Perhaps he couldn't work on the fuel system without the car being at BMW?

    This starting issue still occurred on its first start in about a year. The ignition was on for more than ten seconds before starting.
    Haven't had the chance yet to read any codes. No warning lamps are illuminated.

    I'm not sure what the first step to take is to diagnose this issue, or if it's even worth it.

    I am somewhat mechanically inclined, but only really on dead simple 1960s British classics.


    I'd love to daily this BMW, as it's a much better car than my current daily driver (except in reliability, fuel, and maintenance costs- unarguable).
    Please help me to try justify this terrifying decision, which I am yet to make.

    I keep trying to tell myself that life is too short to drive boring cars...
    and a car that breaks constantly will always have you on your toes!


    Thank you.
    Until you get more people here to chime in, I'd say this: Find a BMW compatible code scanner and get the fault codes, then report back. You may need one that connects to the round diagnostic port under the hood, but that usually requires only an adapter to plug in a scanner meant for the squarish diagnostic port under the dash (that car probably has both).

    Also, mechanics can't really "mess with" the crank/cam sensors, they can only replace them. Best that the replacements be genuine, not off-brand aftermarket, in this case.

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