箱720

Ive heard the block on the z24 engines are pretty bulletproof. As long as that is fine, I can work with it. Would a head gasket make that knocking noise though? The sound doesn't seem like it is coming from underneath so much as from everywhere. I assumed it was maybe just misfiring that was making the noise? The rpms do occasionally jump on idle.

The concern I have is if the block is damaged in a way that I cannot see, such as a hairline fissure. I just don't have the tools to be able to detect that, and I just dont have the time and know-how to do a full engine rebuild. I know it's hard to tell without knowing everything I've put into it and whatnot, but if it's more than the head gasket, do you think it's worth just doing a whole new motor swap?

I had a coolant hose blow unbeknownst to me on my 1986 720 and the engine overheated. Since then and replacing the coolant hoses, the engine has been making an odd noise, almost like a rod knock. Checked the oil and it is a grey watery mix with swirls in it where something is separating from the oil. Couldn't tell if there were any small metal shavings in there. Checked exhaust too and it has oil coming out of it as well. I'm fairly certain the head gasket blew, I just dont know how bad the damage is. I pulled the valve cover but everything up top looked fine. Is there any way to tell what it may be without pulling the whole engine apart? I dont want to have a couple hundred dollar fix turn into a couple thousand-dollar fix.