Blown head gasket, warped head, or damage to engine internals?

[trickedoutdsm05]

well when i first bought my 91 gs-t it ran pretty well. when i put a boost guage on it it was only reading 7psi at WOT. i kept tinkering with it and my dad said that my cat might be plugged up.. well i gutted it and put it back on and i noticed that nothing changed.. but when it was off it ran around 14-15 psi at WOT with no problems. being that it was almost running straight header. for a few days it ran perfect with no missing or bucking whatsoever.. and beating a few 5.0s and camaros was also fun. so i havent put the cat back on.. well after around a week it started missing sometimes in the upper rpms and backfireing.. but sometimes it wouldnt.. like a day to day thing.. so i thought it was plugs and wires but i didnt have the money at the time to fix it.. well it got worse and worse and the other day i went to the track and was coaxed into racing my car. it ran great with no missing until the 6th or so pass. now after around a week of getting really bad missfire also i have either a rod knocking or valvetrain noise.. also coolant is not leaking but after a day of driving most of it is gone.. there is no coolant in the oil being that it is not milky.. and my boost has dropped to around 10 psi. mods are as follows... everything stock but free mods.. k&n filter.. boost guage.. and no exhaust after flex pipe.. so is this warped head/blown head gasket,, melted out piston...or some other problem.. and please no posts saying im retarted for removing my exhaust to run more boost.. i realize this now.. thx

 

[GSX_RCR]

Tough to say, given those circumstances. I would first suggest running a compression test to check out the internals.

As far as the blown HG theory, it's tricky to diagnose. If there's no evidence of coolant in the oil (check under your valvecover for milky residue), and no leak on the block, then maybe it's only blowing through at higher rpms/psi levels. Has it started overheating?

Also, I would check your turbo for any leaks and shaft play? It's possible for the coolant to leak from there. That might explain your lower than usual boost levels.

Have you replaced the lifters with a set of revised ones? I would check that out first for the valvetrain noise. Also, it could be as simple as sticky valves? Clean it out with some ATX fluid, or Seafoam.

Hard to say really. If you're really convinced it's the HG, just open it up and check around. Heck, you could use a new metal HG with some ARP studs with the amount of boost you're running. BTW, if you haven't done so already, do a fuel pump rewire before you start boosting anymore.

 

[Anomoly#5]

I agree, at this point if you plan on keeping the car then I would recommend pulling the head off, looking at the cylinders & pistons, it doesnt hurt, and its good practice, im sure upon disassembly and thorough inspections you will find the culprit, how many miles are on the engine?