Slight Problem - The Unofficial BMW M5 Messageboard (m5board.com)

clean540i · 5th July 2005, 08:13

So i got an SES light today and the car started running very bad (misfiring). I get it home to find the spark plug cover all busted up on the left side. I pull it and see that a spark plug had been shot out of the cylinder and the coil is shot. I'm going to replace the coil hopefully tomorrow. Will there be more to it than that? Do i need a rebuild? Car is a 99 540i, intake, exh, stage 2 soft. Thanks in advance

shadowman · 5th July 2005, 08:45

Quote:

Originally Posted by clean540i

So i got an SES light today and the car started running very bad (misfiring). I get it home to find the spark plug cover all busted up on the left side. I pull it and see that a spark plug had been shot out of the cylinder and the coil is shot. I'm going to replace the coil hopefully tomorrow. Will there be more to it than that? Do i need a rebuild? Car is a 99 540i, intake, exh, stage 2 soft. Thanks in advance

This one sounds a bit extreme...... I have seen spark plugs take flight...however only after they were improperly installed. You gave no short term service history so I have to speculate.

As for other concerns, huuummmm.... if you were fortunate to have the plug leave and not take the threads within the head with it during the process you should be fine...... look closely at the threads....... awkward...... and if all looks good...... properly install the spark plug, torque it to spec......and consider yourself "Lucky"

Take care

Shadowman

TCM · 5th July 2005, 09:02

I have seen this happen on a couple 540s. All needed to have the heads be rethreaded. If this is the case, you can buy a new head ($$$$) or try to have a machinist rethread the spark plug hole for you. Also, be sure to inspect the piston head for any scaring from shards of the coil plastic and or spark plug pieces. Please let us know how you make you.

clean540i · 6th July 2005, 04:33

well i bought a new boot, coil, and plug today and will put them in shortly. I appreciate the help and i'll be sure to let you guys know what happens.

clean540i · 6th July 2005, 05:51

well it turns out that the threads are shot and i suppose i will need to pull the head off and take it to a machine shop. Would it be easier to have the car towed or take the head off myself? Is there a price range for this job? Thanks again.

TCM · 6th July 2005, 06:13

The head needs to come off either way. So probably best to try and remove it yourself and save the hassle of the towing. Not sure about the pricing of the machinist but as long as it is under the cost of a new head, you should be ok. Please keep us updated with how you make out.

DavidS · 6th July 2005, 12:04

Maybe you should talk sweetly with BMW NA? Threads failing like that on a not-very-old car is indeed extreme. Good thing the injector was shut down so you didnt get petrol sprayed all over and had a fire.

I would definitely think of getting a new head. The other threads could be weakened too.

David

ray540inyc · 6th July 2005, 18:01

there has been a set of 540i heads on ebay off and on for the last 3 months or so , try to search past auctions if it isnt listed.
i think they wanted 300 for the set.

good luck

DavidS · 6th July 2005, 18:04

Quote:

Originally Posted by ray540inyc

there has been a set of 540i heads on ebay off and on for the last 3 months or so , try to search past auctions if it isnt listed.
i think they wanted 300 for the set.

good luck

If it look like it would seal well, I would definitely go with that rather than renovating the damaged head.

David

clean540i · 9th July 2005, 20:40

I got the car towed on a flatbed down to the local Bmw shop (not dealer). He said he'd be there at ten and wasn't so i guess i'll find out what the damage is once he gives me a call.