First in order to diagnose the problem correctly it should have a wet and dry compression test and a cylinder leakdown test performed. This will give you an idea of the mechanical condition of the engine. If you want to rebuild the heads you will be looking at a total cost in the $2k neighborhood. If you just want to clean up the heads and replace a couple of valves, then you could probably get by on $500-$600.
Does it have a new timing belt on it? You will need one if not and if so I would check the timing marks to make sure it was installed correctly. I have redone several for people after pro shops have done a T-belt replacement incorrectly.
I bought mine with a bad engine several years ago and with $9k into just the longblock it is bullet-proof. The aftermarket support for the VG30 components is very good so which ever way you go you should be fine.
1992 S13 240SX SE Fastback KA24DE 5 spd
1993 U13 Altima SE KA24DET 5 spd
1990 Z32 300ZX VG30DETT 5 spd
Still trying to import a 1988 R31 Skyline GTS-R w/ RB20DET-R
Last edited by KA24Tech; Feb 5th, 2004 at 02:44 AM.