white scum under oil cap

[stevokr32]

Its a rb20det , ive with scum under the oil cap and low comp on cyl 4 and it runs rough what do you think it could be?
There is no smoke but it blew a water pipe fixed it and ran ok for a bit .ive bought a full head gasket set already but could it be a cracked head? Bottom end problems?
Thanks

[rps13Carlow]

Sounds like head gasket alright, you will just have to take her apart, as regards cracked head, ask to get it pressure tested when you drop it in for skimming, bout extra €40.

[stevokr32]

Oh not so bad hope i doesnt come down to a new head.

[Mick K]

An Rb that boiled? Hardly

[stevokr32]

Didnt boil over just running bad.:)