Hi,

I have a 93 300zx NA that up until a week ago was running like a champ. Then, while sitting at a red light on a cold night the car started running rough, struggling for power, and the temperature skyrocketed. I was two blocks from my house and managed to get in the garage before the needle hit red. I let it cool for a few minutes and fired it up. I was greeted by huge plumes of white smoke coming from my exhaust. The needle again quickly started to heading towards the redline. I know in my heart what that means, but I need someone else to say it. The head gasket right? Any other possibilities?

Thanks for the advice or the bullet to put it out of it's misery.

-M

 

Probably the head gasket... on an NA, that's the only way coolant could get into the engine to burn (white smoke is coolant, as I'm sure you already knew based on your own diagnostics).

Acquire a compression gauge, test compression and do a leakdown test. Check the coolant level and the quality of the coolant (if the HG is blown, it could allow coolant and oil to mix, resulting in a coffee+creamer colored fluid). Drain the oil and check for the same. Oil in the coolant or coolant in the oil will tell the tale absolutely (but if you don't see the mix, that doesn't rule out the head gasket... it only means that it didn't leak in such a way that allowed them to mix). Low compression or poor results on the leakdown test will suggest that it's a problem in how the cylinders are sealing (which limits it to piston rings, valves, and the head gasket... and no matter which it is, you'll be pulling the heads off, and you'll probably know if it's the head gasket when you do that).