Cross-threaded spark plug and coolant leak

[Rus]

Hello all!

After bringing my newly acquired 535i home, I finally decided to figure out why the engine was running like crap. Turns out that all of the spark plugs were gapped too narrow and plug #5 was cross-threaded in only about 5mm (if I ever find the person who did this, they'll regret it dearly). I've purchased a spark plug thread chaser in hopes of restoring the threads, but I cannot get it to line up correctly in the hole. Only the first few threads are damaged, but that is enough to make it close to impossible to align the tap. Does anyone have any insight about fixing the threads? I am also loosing coolant and the leak appears to be on the passenger front of the engine. It doesn't seem like there are any hoses or fittings that could leak on that side, but the junction between the head and the block appears wet in the corner. Is this corner a common area of concern when it comes to blown head gaskets? The car isn't using coolant (no smoke and plugs are dry) and there is no coolant in the oil either. If I do end up pulling the head, where should I obtain the proper gaskets for it and what do the gasket kits include? (Looked on BMA but no info is provided regarding the contents of gasket kits) What are common symptoms for a warped head? Thank you in advance for any input.

[bill g]

M30 head gasket failure seems to be more common on exhaust side near rear next to number 6 cyl. Mine leaked into the cylinder but I have heard of them leaking to outside.
VRS gasket set (valve regrind set or whatever it is called in US) usually includes all gaskets and seals necessary to remove head and replace it, including manifold gaskets, cam cover gasket, valve guide seals, etc.
With the spark plug you could try using an old spark plug as a kind of tap - grind or file the threads to take the sharp edges off to about half depth of thread, clean off any burrs or rough bits and try carefully screwing it in straight (oil the plug threads) until it hooks up with the undamaged part of the thread in the head. If you can get it to screw in straight then you should be able to get a good plug in there. No guarantees - you have to go by sight and what feels right - there is some risk of completely buggering the thread in the head.

Bill G

[chinist]

Hello all!

After bringing my newly acquired 535i home, I finally decided to figure out why the engine was running like crap. Turns out that all of the spark plugs were gapped too narrow and plug #5 was cross-threaded in only about 5mm (if I ever find the person who did this, they'll regret it dearly). I've purchased a spark plug thread chaser in hopes of restoring the threads, but I cannot get it to line up correctly in the hole. Only the first few threads are damaged, but that is enough to make it close to impossible to align the tap. Does anyone have any insight about fixing the threads? I am also loosing coolant and the leak appears to be on the passenger front of the engine. It doesn't seem like there are any hoses or fittings that could leak on that side, but the junction between the head and the block appears wet in the corner. Is this corner a common area of concern when it comes to blown head gaskets? The car isn't using coolant (no smoke and plugs are dry) and there is no coolant in the oil either. If I do end up pulling the head, where should I obtain the proper gaskets for it and what do the gasket kits include? (Looked on BMA but no info is provided regarding the contents of gasket kits) What are common symptoms for a warped head? Thank you in advance for any input.


for this problem. If I remember right, you insert it into hole, then expand it and tap on the way out. This has a couple of advantages. You use the good threads at the bottom of the hole to get it started, and all of the threading chips come out of the hole with the tap. I will check to see if I can find out who sell's it.

[callen]

You may want to take the plunge and pull the head...then you'll have better shot of fixing threads...maybe going from inside out....even with a spark plug rather than a chaser.....
I bought my head gasket sets from BMW..didn't want to chance it....neither of my cars heads were warped and after a good cleanup they're both purring nicely with simple gasket swap.

Good luck.

[Rus]

Thank you all for the responses! I've managed to finally run a tap through the threads. I believe that since the plug wasn't screwed in all the way, the threads became caked with carbon. After about an hour of slowly making my way down the threads, I achieved success (and no metal shavings in the tap indicate that I didn't do anything but clean the threads). I was also relieved to find that the coolant leak is coming from somewhere up front in the crankshaft pulley area and not the head. The engine is much smoother at idle now, but now has started throwing code 1222 at idle. I suspect the fuel system and possibly vacuum leak somewhere. Previously the engine would encounter code 1221 above 2500rpm. Once again, thank you for your input! I'm sure I'll be dipping into this virtual vessel of knowledge again pretty soon. Best wishes!