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-   -   Help with cavity on engine block between cylinders (blown headgasket) (http://www.m3forum.net/m3forum/showthread.php?t=431193)

e46s54guy Mon, Jan-07-2013 01:05:24 AM

Help with cavity on engine block between cylinders (blown headgasket)
 
Car is 2001 e46 M3 with 101k miles. I was having misfires and low compression in cylinder 1 and 2 and when the head was removed it turned out that my head gasket was blown between cylinder 1 and 2 (see photo). I did a complete valve job anyways since i was told the head was slightly warped but when it was time to put the head back together, the shop cleaned the block and noticed that there is a cavity between cylinder 1 and 2 (see photo). I was told this was because of the heat built up and combustion with the headgasgket broken in that area.



Do you think I should be worried about this? Would performance or reliability be affected? I heard there is a cement material that can fill in the cavity before the new headgasket is installed.

http://i9.photobucket.com/albums/a91...i/DSC03697.jpg

http://i9.photobucket.com/albums/a91...i/DSC03698.jpg

http://i9.photobucket.com/albums/a91...DSC03704-1.jpg

http://i9.photobucket.com/albums/a91...DSC03699-1.jpg

http://i9.photobucket.com/albums/a91...0395184829.jpg

Thanks for the words.

ac427 Mon, Jan-07-2013 01:12:08 AM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
I would get the block and head skimmed to match. If that cement came loose you may get worse damage. Do it right and get it machined.

nrubenstein Mon, Jan-07-2013 01:28:03 AM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Ouch. Weld or replace the block. That sucks.

nowanker Mon, Jan-07-2013 03:54:14 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Ow. A critical location to seal, options pretty much limited to resurfacing or replacing the block. I like the idea of welding it up before machining if the erosion is deep (.oo5"?). Probably not a good JB Weld candidate, as it'll be exposed to combustion flame. But might be worth a try, if you want to gamble on pulling the head again soon.

Tchleung Mon, Jan-07-2013 04:12:05 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Is there any damage to the cylinder walls in that area? I would just deck the block and give it a try

ECSTuning Mon, Jan-07-2013 04:29:43 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Quote:

Originally Posted by Tchleung (Post 1065925946)
Is there any damage to the cylinder walls in that area? I would just deck the block and give it a try

This is what I'd also do, pending no wall damage. Keep in mind that you've milled the head, if you also deck the block you're looking a bit of material there as well. You'll need to check to insure clearances are still happy.

Tchleung Mon, Jan-07-2013 04:39:25 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Also after milling the head and block, your tdc and alignment of everything will be off by a tiny bit now

e46s54guy Mon, Jan-07-2013 04:55:20 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Quote:

Originally Posted by nowanker (Post 1065925916)
Ow. A critical location to seal, options pretty much limited to resurfacing or replacing the block. I like the idea of welding it up before machining if the erosion is deep (.oo5"?). Probably not a good JB Weld candidate, as it'll be exposed to combustion flame. But might be worth a try, if you want to gamble on pulling the head again soon.

There is no damage to the cylinder walls as far as I know and the top edge of the cylinder wall does not appear to be affected by the cavity. Wouldn't the headgasket completely cover this cavity, not exposing it to combustion flame?

Tchleung Mon, Jan-07-2013 07:47:34 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Yes but there is literally no material the head gasket is sealing against in that spot because of the cavity. It would most likely result in another blown head gasket without proper repair or replacement

nrubenstein Mon, Jan-07-2013 08:11:57 PM

Re: Help with cavity on engine block between cylinders (blown headgasket)
 
Quote:

Originally Posted by e46s54guy (Post 1065926045)
There is no damage to the cylinder walls as far as I know and the top edge of the cylinder wall does not appear to be affected by the cavity. Wouldn't the headgasket completely cover this cavity, not exposing it to combustion flame?

No. Head gaskets don't have that ability. Once the surface is not flat, you can pretty much forget about it lasting. One way or another, you need the block to be flat. Either deck it or have it welded up.

Unfortunately, fixing it right just isn't really practical in the car.


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