blown head gasket problems, help!

[Yolandi2]

hi all, so the other week I blew my head gasket, ive had the gasket changed, head skimmed and new head bolts however it sounds weird when its running , its burbeling like a Subaru lol

also its blowing a lot of oil out the crank breather, compression test came back as 160psi cyl 1-3 and 115psi on cyl 4
if I put my thumb over the crank breather the revs pick up

whats most likely happened? rings gone in cyl 4?

(engine is 1.8 8v with weber carb)

[unknownmale]

Have you done a wet compression test on 4?

Put a bit of oil in the cylinder and do another compression test, if it goes up then the low compression is due to rings. To find out if there is an issue with the head gasket/ sealing or valves you'd ideally do a leak down test, or hook up a smoke machine on cylinder 4 (Obviously you'd need to rotate the crank to have cylinder 4 at the top of the compression stroke (So both exhaust and intake valves are closed) look for the smoke.

The sound suggests back pressure to me, like the exhaust being slightly blocked? Did you do all the gaskets and seals for exhaust and intake when you put it back together?

[Yolandi2]

done a wet compression test and it went up to 150psi, we don't thing the rings are gone now as its not smoking and we have just noticed the intake rubber has split annoyingly

[Yolandi2]

ok so the car is back up and running ok but its blowing a lot of oil out the crank breather there seems to be a lot of crank pressure also because it blows the dipstick out, ive changed my mind and think the rings have died in cyl 4, but could this be anything else? the bores are mint and the valves didn't leak petrol when the head was off

[unknownmale]

I would suggest cleaning out the grate for the crank case breather pipe on the rocker cover, but due to the low compression it does seem like worn rings (Blow by). There is the chance that something dropped into cylinder 4 when you were putting the head back on which may have damaged the cylinder wall or the rings. Could take the plug out and see if you can see anything obvious. But ether way it sounds like it has to come apart.

[Yolandi2]

the burbeling idle im guessing is because of the low compression in 4, it starting sounding like that when the head blew so im guessing when it over heated it killed the rings at the same time :( nothing definitely fell into the cyl when it was being reassembled