M30 head bolt removal mystery--advice sought

[Ferret]

I'm stopping ~1" out because at that point the bolts really get stiff, and I don't want to force them for fear of buggering the threads machined into the block.

So, rather than taking the chance of messing up the threads, I thought I'd ask advice from others more knowledgeable.

I've removed the head on an M30 a couple of times, but never had this sort of difficulty--normally the bolts just loosen to easily remove by finger after a turn or so with the wrench. Not these, though. What could be fouling them? I squirted some penetrating oil down each bolt shaft, so we'll see if that helped overnight.

This is a replacement engine from a wreck, so I don't know its history. Any chance such engine could be so warped as to foul the middle headbolts?

The first M30 I played with did this - I have no idea what caused it, though I suspect it was oil on the threads creating an airlock/etc. Wind them back in and out several times - see if you can get them to loosen up? The one I had I just got a bigger bar to wind them out, no damage just very clean threads.

There's always the possiblity that they've been stretched and the threads are a bit shot on them

[Jeff in MN]

Seems a stiff 20 to 30 ftlbs would be ok. Any higher and I might be scratching my head too. Keep us posted after you let'm soak for a while.

[632 Regal]

as mentioned tighten and loosen. For whatever reason the last few threads are binding up. did you start loosening these on a warm engine?

I'm stopping ~1" out because at that point the bolts really get stiff, and I don't want to force them for fear of buggering the threads machined into the block.

So, rather than taking the chance of messing up the threads, I thought I'd ask advice from others more knowledgeable.

I've removed the head on an M30 a couple of times, but never had this sort of difficulty--normally the bolts just loosen to easily remove by finger after a turn or so with the wrench. Not these, though. What could be fouling them? I squirted some penetrating oil down each bolt shaft, so we'll see if that helped overnight.

This is a replacement engine from a wreck, so I don't know its history. Any chance such engine could be so warped as to foul the middle headbolts?

[genphreak]

*** WHATEVER YOU DO... don't force them out.***

The holes are tapered towards the top of the head. The gunk builds up like tar around the bolts in the cavity, and when you want to pull/push them out (only way out is up) it just has nowhere to go, forcing them may CRACK the head. Another example of Frederick's bastardry.

M30 parts are strong, but don't risk it. Happened on mine, only a few bolts were really hard to get out though. I did force mine with a rubber hammer (screw Frederick!), as it turned out I was lucky. Only worked out Frederick's tapered hole trick was fooling us, after we got them out, so was worried until the outcome of the tank test put me at ease.

Just use some carb cleaner/degreaser to soak the gunk away and/or break it up. It should just ooze out when you push them, instead of jamming up solid- if you leave it long enough.

Nick

[632 Regal]

Claimed into a blind hole so nothing should corrode or otherwise cause malfunction... mechanical error perhaps?

*** WHATEVER YOU DO... don't force them out.***

The holes are tapered towards the top of the head. The gunk builds up around the bolts in teh cavity, and when you want to pull/push them out (only way out is up) it up has nowhere to go, forcing it may CRACK the head. Another example of Frederick's bastardry. M30 parts are strong, but don't risk it. Happened on mine, only a few were really hard- I was lucky, but was worried until the tank test put me at ease. Only wokred it out after we got them out.

Just use some carb cleaner/degreaser to soak the gunk away and/or break it up. Shoudl just ooze out when you puch them, instead of jamming up if you leave it long enough.

Nick

[Dash01]

So far, I've let the sticky bolts soak in penetrating oil and carburetor cleaner, and this seems to help.

The gunk on them is like tar, and the prior suggestion about working them a bit in and out helps with loosening, as it seems to allow the penetrating oil/carburetor cleaner to seep further down. Actually, given that the thread grip on the bolt ends is only ~1", it seems the tar is the only thing holding them in.

Perhaps I'm being too gentle with these bolts, but better safe than sorry.

What would cause the oil to become so tar-like? Would such cause also damage the engine? (Again, this engine is from a junker, so I don't know its history.)

[genphreak]

Old oil and short trips causes it I think, good to hear you are taking it easy. That is the only way with these things, the hammer never wins much progress on a BMW- in fact it usually screws things up Royally.