Some overheating problems...

[Orangys280Z]

My '77 coupe has been having some seroius overheating issues lately. I'm afraid it may be the head, but I'm hoping is something simpler and less expensive than that. I bypassed the heater core since I don't have the money for it at the moment, and it ran well for a while with water in the system. Then I put coolant in the system(pre-mixed).

I did make the idiot mistake of not watching the temp gauge due to the new coolant, and the lower hose blew. The needle was past 250. I pulled over immidiately to let it cool down, and got a ride to a near by Autozone to get new coolant and a new lower radiator hose. I also got a new radiator cap and thermostat. Once everything was patched up, I started driving and the lower hose blew off(wasn't tight enough). I tightened it back and was only able to put water in the system. A while later it overheated(didn't overheat when the hose blew off). Once it cooled down for about 40 minutes I started it back up and I noticed some white smoke was coming out the tail pipe. I got it home after it cooled a bit longer. I put some head sealant for a temp fix and worked fine for a bit. Then overheated again(the next day). I let it cool down for a while, then drove it again, only to find white smoke coming out again. I found that there was a crack in the thermostat housing. Anyone know how that may have happened?

I haven't driven the old girl for about two weeks now(I've had no money lately). I checked the plugs earlier. #6 plug was wet, had oil and smelled like gas(I didn't started before I checked the plugs). The other plugs were black, a couple had the smell of raw gas, while a couple didn't. I know I did some stupid things(especially for a UTI student going into their third class tomorrow), but does anyone have any idea about what may be the problem with my Z?

[kenz240z]

White, billowy smoke out the tail pipe is a sign of coolant getting into a combustion chamber. Did you happen to notice if it smelled kind of sweet? The smell is another sign of this. You may have a blown head gasket, a problem with the head or a problem with the block.

I had the same white, billowy smoke coming out the tail pipe when I still had the L24 in my 240Z (got an '82 L28 in the car now). I pulled the head and found that the aluminum had deteriorated on the head between a water passage and a combustion chamber. I ended up having the engine rebuilt with a different head.

[70 Cam Guy]

Like Kenny said, sweet smelling, white smoke is a tell tale sign of a blown head gasket.

If you are student at UTI, see if you can borrow their cooling system pressure tester. It may not work too well if you have a crack in the thermostat housing. When I blew the head gaskets in my old Camaro, I pulled all the plugs and cranked the engine. Water shot out a couple of the spark plug holes... that's another way if it's really a bad leak. Just don't stand in the line of fire when you crank it.

You can also go to a NAPA or other auto parts store and get a block check kit. These check for hydrocarbons in the coolant and can help diagnose a head gasket

Engines with aluminum heads are vulnerable to blown head gaskets if the engine overheats. Very common to see that after an overheat.

Edited September 14, 2009 by 70 Cam Guy
added stuff

[Orangys280Z]

Thanks guys. I just realized that I did an oil change last week on it, and the oil looked like coffee with cream in it. I'm assuming that will also be caused by a cracked head?

[Weasel73240Z]

Thanks guys. I just realized that I did an oil change last week on it, and the oil looked like coffee with cream in it. I'm assuming that will also be caused by a cracked head?

Sounds like it. Probably a crack in the head near a combustion chamber and oil galley.

[z74z90]

Yep, been there, a blown head gasket or cracked head. Hope it is just a gasket! Mine was a cracked head.

[Orangys280Z]

Does anyone know where I might be able to get a new head for cheap?

[rtaylor]

Maybe not new, but used. Give Elvin a call at 909) 908-0804 He's local, just over Kellogg Hill.

[z74z90]

Incidently, in my case the fan belt broke, the engine overheated and the head cracked in no time at all.

[Frankensteinz2]

Could try ebay, buy beware though

[Weasel73240Z]

Incidently, in my case the fan belt broke, the engine overheated and the head cracked in no time at all.

Aluminum heads are great until they get hot.

If you're running the stock 74 head, you might want to look into one of the better flowing ones (larger valves) from the later Z years.

[FastWoman]

Unless I'm misunderstanding something here, it's possible your head is cracked, but it's also quite possible you've just blown the head gasket. I wouldn't write off the head before knowing for sure there's a crack. And even then, some cracks can apparently be welded closed.

Edited September 16, 2009 by FastWoman