Loose oil pump bolts on M50 six?

[Russell]

Someone tried to tell me there is an issue on the M50 with loose oil pump bolts. This is news to me. I have heard of the issue on M60 V8s.

Checked the archives and did not see anything on M50 oil pump bolts, plenty on the M60. Any truth here? TIA

[Jon K]

This is true.

[Russell]

Jon, can you tell me more?

[Jon K]

Sure, all of the M50/S50/M52/S52 motors have had this issue. In fact, my friends supercharger M54B30 had this happen and the motor blew due to loss of oil pressure. Another friend with a NA S52B32 had the oil pump fall off, but luckily the S52 threw a oil pressure light immediately and he shut it down, no damage.

Basically, all of the oil pump nut designs have the potential to back off. When I build my motor in the summer, I am going to weld the nut on. That, or just break some of the threading so that the nut cannot be easily worked off. But I am pretty sure I will just weld it on.

[Russell]

do you need to pull the pan to check? Pulling the pan does not look like something I can do myself to check. Bentley makesit seem to be above myskills and facilites-no lift handy.

Sure, all of the M50/S50/M52/S52 motors have had this issue. In fact, my friends supercharger M54B30 had this happen and the motor blew due to loss of oil pressure. Another friend with a NA S52B32 had the oil pump fall off, but luckily the S52 threw a oil pressure light immediately and he shut it down, no damage.

Basically, all of the oil pump nut designs have the potential to back off. When I build my motor in the summer, I am going to weld the nut on. That, or just break some of the threading so that the nut cannot be easily worked off. But I am pretty sure I will just weld it on.

[Jon K]

Russell do you have an issue or are you doing this as preventative maintenance? The pan does need to be dropped. If you do not have an issue you are probably fine with 118k miles - though anything can happen. What brings this up?

[Russell]

I have sort of noticed what seems to a repetitive hard knock when the engine is first started on a cold day. Hard to really describe or even hear as it seems distant or muffled. Seems to go away after engine is warmed up.

Russell do you have an issue or are you doing this as preventative maintenance? The pan does need to be dropped. If you do not have an issue you are probably fine with 118k miles - though anything can happen. What brings this up?

[RobPatt]

....?

[Russell]

Could be. I may be looking for imaginary problems. Been reading/participating in BMW boards/forums too long/often

[632 Regal]

probably crank bearing play...might be wirth looking into the bolts. Loctite them after cleaning the threads and holes with brake cleaner.