Cylinder 5 misfire

[andrewwynn]

Originally Posted by upallnight

The fact that you have compression in both cylinders, and the fact that the engine misses only at idle but runs fine at high rpm I would just drive it and till it dies. It's a 19 year old SUV and the price has come down to the point that fixing the BMW will cost just as much as buying another BMW X5.

Can't argue with that. Solid logic.

I've swapped heads on a couple M62 motors. Can't leave the header attached on the V8, that's a solid perk on the 6!

If the rest of the engine is solid and the car is worth saving I would definitely do the head gasket. Probably including the timesert as described above.

I would also do vanos refresh at the time. Anti rattle upgrade and if it's the same as M62, the o-ring upgrade.

[Effduration]

Originally Posted by ahlem

So assuming I have all the tools I need, which I do have and experience tearing down motors completely and putting them back together except not an M54, what would the reason be to expect a dead motor rather than just a head gasket?
Any used M54 would probably need at least new oil rings from what I've surmised.

Time, money, and risk of failure.

In most cases, this debate between swapping in a used engine vs doing a head gasket involves an overheated engine -apparently not the case here.

In most cases, a head gasket is more work, more time and about the same money (after machine costs and any tool rental) than buying a used M54 and slapping it in. I would also suggest a head gasket has a greater chance of failure (mine just failed 5k miles after doing a head gasket 6 months ago), though the chance of failure is low if done properly.


As mentioned above, doing a head gasket in your particular situation is what I would suggest. I would certainly get the head and valves checked and decked.

[bcredliner]

Originally Posted by andrewwynn

I use anti seize when installing plugs. Partly based on some crazy high torque values to remove.

I have a small impact wrench that I will used to release frozen parts and it’s less likely to strip than high torque however if the ceramic breaks it’s absolutely imperative that you find every crumb since BMW engines are interference engines. A buddy of mine didn’t notice that the ground electrode broke off a spark plug and fell in and now he’s got a dented rod bearing and the lovely associated knock.

I was chasing seemingly random cyl misfire on wife’s x until I swapped out two of the coils and additionally ran some Lucas injector cleaner. Problem finally disappeared.

I use anti-seize on some connectors, largely those that are subject to high heat or the elements. I don't use anti-seize on plugs because it is too easy to over torque them and because the heads are aluminum.

[bcredliner]

I would do a leak down test for more information and then pull the head to take a look.

I try hard never to give up on the engine I have. Often the devil you know is better than the devil you don't know.

[andrewwynn]

Originally Posted by bcredliner

I use anti-seize on some connectors, largely those that are subject to high heat or the elements. I don't use anti-seize on plugs because it is too easy to over torque them and because the heads are aluminum.

I use anti seize on plugs specifically because of the different metals but as it also acts as a lubricant, I used an appropriately reduced (and measured) torque. Very bad Idea to use "hand feel" for torque on a spark plug.

[ahlem]

[QUOTE=andrewwynn;Anti rattle upgrade and if it's the same as M62, the o-ring upgrade.[/QUOTE]

Can you elaborate or pontificate on the anti-rattle and o-ring upgrades?

[andrewwynn]

The vanos internal orings wear and cause them to work poorly. It's not too difficult to replace the o-rings to bring them back to like new performance.

On the M54, I've read of vanos rattle and a kit with a thicker spacer to eliminate the rattle.

If the vanos tracks requested angle properly I prob would not do the refresh but I would look into both of those If I had the valve cover off for any other repair.


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