Where's my water going?

[DougV]

Hi, guys. It's been a long time, but I need some more advice. I think I already know the problem, but I need to confirm it before I go tearing into my Z.

First of all, the Z has been running better and better. I now get full RPM range when I want it, and the majority of the power I've been missing seems to be coming back. I think that whatever funk was left in the fuel lines or the gas tank has finally flushed out of the system. That, and I started getting gas at the slightly more expensive gas stations. I had my radiator cleaned and I replaced the water pump a few months ago because I was having cooling issues, but I realized it was because of a different problem.

The problem is.. I noticed that after a few weeks of daily driving, the temperature gauge begins to go a little higher and higher... so I check the coolant level to find that there's not a lot of coolant in there. Weird, since there are no leaks of any kind, and the temperature isn't going over mid anymore. (until the coolant is low again) The overflow tank is always at the same level, so what's the deal?

So, my guess is that there's a small leak in the head gasket, and water/coolant is burning off in the cylinder.

I do notice in the morning now that it's cold, that when it cranks, it wants to hesitate in one spot, probably the wet cylinder, and when it starts, there is vapor, mostly white coming from the tailpipe, and a little drips out of the small leak in the exhaust 'header'. That, and it smells sickly sweet like antifreeze. So the question is.. can I use a product to seal it or is that for idiots who like to clog up their engine with gunk and really foul things up?

I'm sure you're going to say 'Take off the head, rebuild it, get new seals and gaskets, check the rings and bearings and put it all back together again.' right?

[SteveJ]

Right.

[DougV]

*Sigh* Figures...

[Z Babe]

Since your overflow tank stays at the same level, it appears that the coolant is not flowing back into the radiator. Therefore, I would replace the thermostat (only a Nismo – no aftermarket brand). Also make sure your radiator is free of any debris, as this can cause the car to overheat.

One more thing, does the overheating occur at all times or just when idling? Does the temperature gauge go down at all when traveling or when the heater is turned on?