Sten Posted December 5, 2023 Share Posted December 5, 2023 Looks like the head gasket is about to give up, smoking really badly once warmed up and you can smell oil. At 220k it doesn't owe me anything, if I can find another head I could recondition it and do a straight swap. Can anyone confirm if a later head would fit, e.g. M52B25? There seems to be a lot of internet wisdom out there, not necessarily accurate. Quote Link to comment Share on other sites More sharing options...
duncan-uk Posted December 7, 2023 Share Posted December 7, 2023 On 05/12/2023 at 16:02, Sten said: Looks like the head gasket is about to give up, smoking really badly once warmed up and you can smell oil. At 220k it doesn't owe me anything, if I can find another head I could recondition it and do a straight swap. Can anyone confirm if a later head would fit, e.g. M52B25? There seems to be a lot of internet wisdom out there, not necessarily accurate. Have you had a look at RealOEM? get the PN for yours and you can see what else used it? Quote Link to comment Share on other sites More sharing options...
duncan-uk Posted December 7, 2023 Share Posted December 7, 2023 Sir anthony regents park would know, drop him a PM maybe? Quote Link to comment Share on other sites More sharing options...
Five oh Posted December 7, 2023 Share Posted December 7, 2023 If you've got the room and time to do it, I'd refurbish the original head. Before you start pulling it down, are you sure it's not a crankcase/CPV pressurisation issue? I was forced into a cyl head rebuild a little while back and I took the opportunity to completely recondition it, including new valve guides where required, recut valves & seats, replaced all stem oil seals, crack/pressure check, a light skim and all new exhaust manifold studs with new copper nuts. A bit of a phaff but worth it and surprisingly not outrageously expensive. Ok, I can do the work myself but obviously the machining and guide installation was done by specialists. I stripped it all out, gave him basically the head & valves to cut only and supplied the guides. My car is M30 powered and it became a problem sourcing the guides ultimately having to get .30 oversize from the states in the end. The trouble with this route is the rebuilt cylinder head could put more pressure on the old bottom end. Rings & shells also would always be preferable but a fair amount of work, really requiring the motor to be removed from the car. If you do go down the used 2nd head, be very wary... what you have now works. So unless you can get something ultra low mileage or your original is cracked or otherwise damaged, I'd stay with it. I did swap my head as I had one lying about, but that's a story for another day. Quote Link to comment Share on other sites More sharing options...
Sten Posted December 14, 2023 Author Share Posted December 14, 2023 Thanks for that Five oh. So before I go any further I've bought a cylinder leakdown test kit. If it ever stops raining I'll fire up my compressor and see what results it gives, hopefully I can make an informed decision after that. Quote Link to comment Share on other sites More sharing options...
Sten Posted January 17 Author Share Posted January 17 So finally got over the lurgy that everyone seems to have had. Leakdown test was OK so time to dig deeper - head is off and looks like no.6 bore is worn. Anyone got a source for 0.5 oversize pistons, everything on a quick check seems to be forged and £900 a set! Quote Link to comment Share on other sites More sharing options...
Sten Posted January 17 Author Share Posted January 17 10 minutes ago, Sten said: So finally got over the lurgy that everyone seems to have had. Leakdown test was OK so time to dig deeper - head is off and looks like no.6 bore is worn. Anyone got a source for 0.5 oversize pistons, everything on a quick check seems to be forged and £900 a set! Quote Link to comment Share on other sites More sharing options...
Sten Posted January 18 Author Share Posted January 18 Just had a price for 6 pistons 112511703461 84.480mm (+0.5) from Cotswold, £1346.46. Anyone know of any other BMW pistons that would do the job? Quote Link to comment Share on other sites More sharing options...
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