Hellish misfire

[X5chemist]

Did you check valve lash? Next, put a little oil down the plug hole. Do a compression check. Does it go up? Oh, air intake should maxed out. Remove the throttle body or another intake hose. On older engines, flooring the pedal would open the throttle body. Can't do it on an electric TB. Or does BMW have a flooding clear option by flooring the pedal?

[Aidzer0]

Originally Posted by ahlem

Do you have the adapter for your compression tester that allows you to put some compressed air to it? At TDC with compressed air, you should hear something somewhere.

I do not, I will check whether I can cobble something together because this is a brilliant idea! Thanks!

Originally Posted by X5chemist

Did you check valve lash? Next, put a little oil down the plug hole. Do a compression check. Does it go up? Oh, air intake should maxed out. Remove the throttle body or another intake hose. On older engines, flooring the pedal would open the throttle body. Can't do it on an electric TB. Or does BMW have a flooding clear option by flooring the pedal?

I did not check for valve lash as I do not have feeler gauges (yet), I ordered some, they will take a while to get here... I live in the sticks so any part/tools take forever to get to me... I will see if the father in law has some to bring with tomorrow.



When you say a little bit of oil, how much are we talking? I would prefer to avoid bending the rod :P I am guessing like ~2 tablespoons would be good? For the intake, I do not have a spare TB gasket, would me removing the CCV hose be enough?


Thank you! And happy holidays all!

[X5chemist]

Actually less oil! It would only take a few drops to see if compression changes. At top dead center, another emission style test can be done. Using a vacuum cleaner. Connect the hose on the vacuum outlet. Connect the vacuum hose to the exhaust. Turn on the vacuum cleaner. Where is the air coming out?

Disconnecting a top intake CCV hose would work. Not the valve cover one.

[Aidzer0]

Gotcha, thanks X5chemist, I will try the few drops of oil + compression test on Tuesday.

If it so happens to change the outcome of this method compression test what would it prove? I’m guessing piston rings being shot or maybe head gasket?

[aureliusmax]

guys. if you have zero compression in cylinder 7, you are having burnt valve that is warped and not seating on the valve seat. there's no point in doing anymore checks, OP already took over valve cover and the keepers/springs seem to be undamaged and that was the only check needed. while other member's posts are coming from a good place, it's really all a waste of time after the compression was determined as zero and then checking physically valve gear from the top after removing the cylinder cover.
Replace the engine head with a good used unit, or remove and send damaged head for repairs.

[X5chemist]

Very true!

Adding more checks. If you suspect a head gasket, pressure test the cooling system.

[Aidzer0]

Originally Posted by aureliusmax

guys. if you have zero compression in cylinder 7, you are having burnt valve that is warped and not seating on the valve seat. there's no point in doing anymore checks, OP already took over valve cover and the keepers/springs seem to be undamaged and that was the only check needed. while other member's posts are coming from a good place, it's really all a waste of time after the compression was determined as zero and then checking physically valve gear from the top after removing the cylinder cover.
Replace the engine head with a good used unit, or remove and send damaged head for repairs.

As unfortunate as this news might be, I would prefer to stop working in a frozen garage haha.

I will still wait for the borescope to arrive and do a few mundane tests before calling it. Besides the head gasket and intake/exhaust gaskets, are there any other gaskets I should order/prepare for? Maybe valley pan gasket while I’m there?

Thank you!!! And happy holidays.

[Aidzer0]

Hey guys, so the borescope finally arrived...

Well needless to say I found the issue....

So it also seems that I need a new block, since there is no-one around me that could possibly work on alusil cylinders and for that matter I would not trust the work. I have seen too many "rebuilds" fail.

That said, anyone know of a N62B44 engine for sale in Canada that won't cost an arm, a leg and a kidney? LOL.

Thank you to all that have submitted all of the great advice and suggestions, I really appreciate it. Happy new year to all!

[80stech]

I would look for a replacement engine. ;(

It might not be a contributing factor but were you using regular gas by chance?
Or maybe pissed someone off who put something in your tank ??

[Aidzer0]

Originally Posted by 80stech

I would look for a replacement engine. ;(

It might not be a contributing factor but were you using regular gas by chance?
Or maybe pissed someone off who put something in your tank ??

No, I was using shell premium since getting the car and no signs of tampering of the gas filler neck/tube so I would say no to vandalism. I use shell premium in all my beemers.

I think the issue was that the spark plug tube was leaking for a long time before we got the car. I believe the oil crud buildup on the valve is what caused this. I could be wrong though. It’s a shame she was running so good up until the misfire started.