Head gasket and knocking noise??!!

[zacseaman]

Last night I pulled away from a junction, changed to second and then all of a sudden a knocking noise came on and I lost nearly all power. I got recovered home as it had no power and wouldn't even idle, chucking out smoke (couldn't tell the colour as it was pitch black out). This morning I have had the handle out and there is little compression on 2 of the strokes, indicating HG failure. Plugs out and had a look down the bores and in 4 there was obvious water in there, and in 3 there was an oily watery gloop. So my head tells me this is head gasket. (I wont take the head off yet as I don't have a torque wrench and I want to fix it all in one go). My question to everybody is where the knocking noise would be from? Could a HG failure cause a knocking in time with the engine??

[minor65]

Yes the knocking noise is due to the head gasket. One of my minors blew a head gasket last month and it sounded much worse than just a head gasket. It will have blown between, for example 1+2 or 3+4 cylinders.

Here's my link

http://www.mmoc.org.uk/viewtopic.php?f=4&t=51715

I think the noise is cause by the compression bouncing between the 2 cylinders, maybe I'm wrong

[bmcecosse]

Take the head off immediately - so you can mop out the water and also check the head (and block) for flatness...

[zacseaman]

Thank you for all the replies, luckily it is just a head gasket! Is it worth grinding in the valves while I have the head off? Many thanks

[bmcecosse]

Of COURSE it is !

[JOWETTJAVELIN]

Decoke essential and very worthwhile whilst head is off in my book.