Is it a head Gasket

[Edward.21]

Hi all
Recently the engine in my moggy blew up so I swapped it out with a spare one that I had lying around after the initial run everything was good ( apart from a ticking/nocking sound when going over 45 mph) so I took her for a 20mile or so run, on the way back she over heated so I filled her up and she made it home it was late by then so I didn't look at it that night when I stared her in the morning she started (only just) but there was A lot of steam coming out of the exaughst, so I took out the plugs and did a compression test. The results were (front to back ) 1. 125psi clean 2.125psi clean 3.125psi clean 4.180 psi soaked in water . So I turned it over with no plug in no.4 and water spurted out about 15 feet (fortunately it missed me,mostly ) so the main thing was do you reckon it is a head gasket or do you think it's a burst water channel of something more serious
TIA Edward

[mike.perry]

Whatever the problem you are going to have to take the head off so no point in guessing.
Don't understand you compression readings, they should be around 150 psi.

[Edward.21]

Thanks I was just wondering if anyone else had this problem because one is higher than it should be and the others are lower which is vaery odd as if it was just a head gasket I'd expect the two in the middle to be lower and the outer one to be good
Hrmm perplexing it is (in yodas voice)

[liammonty]

The head gasket doesn't have to have blown between 2 cylinders- it could be letting water from one of the water ways into the cylinder that you said shot water out.

Surely if the cylinder had a lot of water in it, that would explain the higher compression reading too- it's full of water so there's far less air to compress. Still, as has been said, you'll need to whip the head off to see anyway, so no point guessing! Good luck.

[chrisryder]

you said it overheated and you filled it up. did you allow it to cool, or fill with warm water, so as not to cause thermal shock and rapid contraction of the hot engine?

possible you could have cracked the head or block, and that's where your water is creeping in.

as already said, yes, higher compression would be down to the incompressible water. i'd be worried you could have bent something, like a con-rod, compressing too much water. a good idea, if you get the head off, would be to make sure all pistons come to the top of the block. if number 4 doesn't come all the way up, possibly bent the conrod.

[bmcecosse]

The compressions are all hopelessly low..... and as others have pointed out - you only got the one 'good ' one because it was filled with water. Actually - you had better hope the water hasn't done any major damage - bent conrod - that sort of thing... I assume the head is now off??

[Edward.21]

Head not off yet I'll post if I find out the problem

[MarkyB]

Your compression tester may be full of water now, if it has a button to release the pressure I'd tape it down and let the hose dangle for a day or two.