12 cylinder motor replaced due to a bad cylinder.
Purchased used motor from repetable place in Alabama.
That motor dropped in and when I start motor a huge clunk sound that vibrated the vehicle. Turn motor off turn back on starts fine. 2 days later a tap sounding like bottom of motor.
Then that motor replaced under warranty.
3rd motor dropped in and start got a loud clunk on restart it was smooth but 2days of driving and a valve tap. The techs claim they can't figure this out and i keep puttin money in for diags and labor. Could it be something other than the motor causing this? Could it be somethng with the starter or flywheel? car sitting at the shop right now.

12 cylinder motor replaced due to a bad cylinder.
Purchased used motor from repetable place in Alabama.
That motor dropped in and when I start motor a huge clunk sound that vibrated the vehicle. Turn motor off turn back on starts fine. 2 days later a tap sounding like bottom of motor.
Then that motor replaced under warranty.
3rd motor dropped in and start got a loud clunk on restart it was smooth but 2days of driving and a valve tap. The techs claim they can't figure this out and i keep puttin money in for diags and labor. Could it be something other than the motor causing this? Could it be somethng with the starter or flywheel? car sitting at the shop right now.


Nothing magical about it - the motors you dropped in were bad and I'd get my money back on both.

Next time ask to see/hear run and have it checked out by someone knowledgeable, not some average joe mechanic BEFORE you spend time/money/effort on dropping it in.

One of the major reasons the E31 and E32 V-12s are in the wrecking yards now are because the engine or trans or both are bad and the PO couldn't deal with the cost of repairs.

Compression test will NOT reveal engine issues and that is the standard wrecking yard test. Unless I can see, hear, the engine run, I will not buy it. I will no longer replace a customer furnished engine either as ultimately I will take it in the shorts as a result of someone buying a bad engine.

It is truly buyer beware!

I will no longer replace a customer furnished engine either as ultimately I will take it in the shorts as a result of someone buying a bad engine.

had to learn this one from experience as well, look for rear-enders that you can still fire up is the best advice i can think of

ho much cheaper is an M70 engine from the junk yard compared to a complete E32-750? I'd always look for a complete car where I can test the engine instead of buying the engine alone. In Germany the difference is maybe US$1000,- max. plus of course the extra labour for pulling the engine.

the engine in the 850 i am parting out is sound. i drove the car a few times and can assure you no noise or issues with my motor.

1400$ buys it !

ok thanks but is there any possibility of maybe a loose starter bolt and whenever the car starts maybe the torque throws it into the flywheel or something then breaks a flywheel tooth and damages the motor? i'm grabbin at straws here. This is a reputable engine and reputatable techs, I think..

Do you have an oil preassure gauge?
As soon as you spin up you should have oil psi
as a matter of fact you should un plug the coils and turn the engine over till you have good psi then plug the coils in.

12 cylinder motor replaced due to a bad cylinder.
Purchased used motor from repetable place in Alabama.
That motor dropped in and when I start motor a huge clunk sound that vibrated the vehicle. Turn motor off turn back on starts fine. 2 days later a tap sounding like bottom of motor.
Then that motor replaced under warranty.
3rd motor dropped in and start got a loud clunk on restart it was smooth but 2days of driving and a valve tap. The techs claim they can't figure this out and i keep puttin money in for diags and labor. Could it be something other than the motor causing this? Could it be somethng with the starter or flywheel? car sitting at the shop right now.

I almost willing to bet the farm on this one! These motors set for awhile before being started. Cycling it with no ignition to get some oil circulating does no good, maybe temporarily. I learned something about the oil pump assy in the M70. If let sit, it builds corrosion on the plunger of the pump. Not enough to necessarily give a oil pressure warning, but not pumping enough to get the top end. Therefore, this is why you drove the car for a few miles or days before it started to tick from lack of top end lubrication. The motors were probably fine, other than what you describe as a "clunk" might be the oil pump itself. They are also known to come loose. Did anyone ever pull the pan on each motor? And do some preventative research of these anomalies of M70's? If not, better start this time! I would suggest pull the intakes/valve covers on the next one also to check the banjo bolts and oil rails for the cams. Unless, of course, you're starting to like the practice of re-installing motors!!!?

The shop figured out that one of the F/I's was bad, dumpin too much fuel and causing some type of pressure in the combustion chamber. When the piston couldn't fight the upward pressure it would force the piston back down and cause a rod or something to bend. Athough the motors were shipped with injectors the shop was using the old ones. I beleive they said if it was a newer bimmer this would have come up on diagnostics. How's this sound?

possible.