This M54 thinks it's a diesel ?

GT456! · Post by **GT456!** » Sun Jun 14, 2026 12:10 am

Please help! at my wits end with this 06 M54 B 30.
200k or so on the clock. The X3 came in my life several years back when was running it was a strong performer! Now a different story no matter what parts I throw it's way...see for yourself!

X5Sport · Post by **X5Sport** » Sun Jun 14, 2026 9:17 am

Have you run an error code scan to see what it throws up?

GT456! · Post by **GT456!** » Mon Jun 15, 2026 7:31 am

Even the oil had a light fowl smell to it and here's what I got...!

X5Sport · Post by **X5Sport** » Mon Jun 15, 2026 3:48 pm

Um. That looks like coolant in the oil. Likely source will be a blown head gasket. Loss of compression in one or more cylinders could well be why it won’t idle properly, water in the chambers will also cause it. Steam from the exhaust is another clue.

Has the coolant changed colour? Is there any white/beige gunk on the oil cap? Both are indicators of head gasket failures with oil getting into the coolant or water into the engine oil side.

Any sign of metal shavings in the oil? If not, that’s a more positive sign, but you’re still looking at an engine rebuild of some description, even if just the top end. Metal shavings could indicate a cracked block as well as damaged main bearing shells or rings. Either way, it’s probably rebuild or replace the power unit.

Definitely be very cautious about running it any more until you’ve decided what next.

If you know someone with a boroscope then take the plugs out and inspect each bore for signs of damage (scratches, bore too clean (indicates water ‘washing’ the bore), coolant actually in the bore).

GT456! · Post by **GT456!** » Mon Jun 15, 2026 6:32 pm

I drained the oil/chocolate overnight,
Coils were clean
Vanos solenoid was a dirty
I'll do an oil change another car is due for oil change and I'll use that oil to maybe chase out any residue.
Clean idle control valve, throttle body, disa and peek at the air filter box.
Checked the antifreeze and no mixture there...
I know, I know I'm wishing on a star!
Thanks for the reply....
I'll survey the air in take maybe.

Alan Gunn · Post by **Alan Gunn** » Tue Jun 16, 2026 4:49 am

Had you lost a lot of coolant.

X5Sport · Post by **X5Sport** » Tue Jun 16, 2026 8:59 am

Another check that I’ve just remembered is to put the cooling system under pressure with a leak tester. It goes to the expansion tank and you hand pump the system up to a set pressure (no more than maybe 20psi) and see if it holds. If after 30 minutes or so there’s no drop in pressure the system is fine. If it drops then time to go hunting leaks, hence the plugs out, boroscope check.

GT456! · Post by **GT456!** » Tue Jun 16, 2026 11:36 am

Ok, great, a good one...I'll get that pump kit from AZ
Didn't check expansion tank. Was too much in a hurry to drain the chocolate milk.
This helps great.
I experienced blown head gasket many years ago with my beloved Buick... white smoke everywhere!
Thanks guys!

GT456! · Post by **GT456!** » Tue Jun 16, 2026 5:39 pm

When removing the expansion tank cap the bobber immediately bobbed to the top!
Next I'll do the pressure test...

X5Sport · Post by **X5Sport** » Tue Jun 16, 2026 6:25 pm

Might be a dumb question but……..has anyone else had access to the car? In the UK at least there have been some very shady characters who distract whilst you’re helping their ‘mate’ look at something at the other end of the car and who then proceed to put oil in the expansion tank! One way of getting the car cheap and is a deliberate con job (fraud).

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