Car over heating

[Tim 76' 280Z]

Well I had bad connections to my Water temp sensor and my thermo time switch and my water temp switch needed replacing. I replaced the connectors, water temp sensor and water temp switch. I did not replace the thermo time switch just the connector to it. Then put the radiator fluid back in that had come out.

Ok here is the problem im having... I took the Z for a drive for about 10 minutes. Got back and the radiator was over flowing! So whats going on???

Does it matter what wires you connect to what wires when you put a new connector on?

It seems like something is not doing its job...:stupid:

[Tim 76' 280Z]

The coolant reservoir is where it was over flowing at... well shooting out of the little hole in the cap that is...

[sblake01]

Doesn't matter which wires since all the connection does is complete a ground allowing the signal from the starter to get to the cold start valve when the temperature in 35 degrees celsius or less. I think it's just coincidence that the problem started after you replaced the water temp switch because it has no effect on cooling. Check for the usual things, collapsed cooling hoses, thermostat sticking, fan clutch not operating properly, water pump, etc.

[Tim 76' 280Z]

Ok.... The problem is still there... In an earlier post I said that I was having problems with the 280 starting so.... I changed all the parts that are listed above then took her for a ten minute drive then she over heated. Well now im having problems with her starting again. The motor is getting fuel but shes just not firing! Once she does start I can rev her up then she will die on me. Vapor lock maybe?

[JimmyZ]

I agree with Sblake. Check the thermostat first. Take the radiatior cap off (With engine cold) and run the engine. After a couple minutes the water in the radiator should start to circulate at a good speed. This indicates that the thermostat has opened. The water will be warming up but should not be boiling or extremely turbulent. If the water is boiling, bubbling or shooting out of the open radiator then you have a blown head gasket. A blown head gasket will cause the water to heat very rapidly and can cause some extreme pressures in the system. On modern cars the plastic tanks on the radiators have been known to crack or explode under these pressures. It would be funny if it werent so expensive. Our Z's have brass tanks and might develop cracks at the leaded joints.

Don't know much about 280Z FI and Blake is the expert. IIRC the water temp has some bearing on fuel mixture.

It's also possible that you have a lean fuel mixture. (for whatever reason) For those ten minutes that it's running is the engine making decent/normal power? If the engine seems a little weak then you're probably lean. Check the condition of the plugs if you suspect it's lean. There are lots of pics/descriptions on the 'net as to what lean plugs look like.

Don't run it long if it's overheating. Just take it for a quick spin and see what kind of power it's making.

2c

Jim

Edited November 10, 2008 by JimmyZ

[zbane]

Sounds all to familiar... Do a compression check, I'm leaning towards head gasket failure...

[Tim 76' 280Z]

The car was running with normal power. Got home and the water was shooting out of the coolant reservoir. Now she is having a problem starting again. Back to square one... I ran the car in the drive way for about ten minutes today and she didnt over heat. But have not takin it for a drive do to the car not starting now.

Edited November 10, 2008 by Tim 76' 280Z

[Tim 76' 280Z]

I just went out and warmed the car up. It only dies and wont start when its warm.

[JimmyZ]

Pull the plugs and check them. You are looking for signs of a blown head gasket or fouling on them. Did you do the tests I mentioned above??

If they are covered in fluffy black deposits it's rich fuel.

Black slick deposits oil fouling. (Rings, valve seals/guides)

White crusty deposits = water

I had a friend who had a bad ECU. (The prob went away after the ECU was replaced.. Odd) I asked him to check the plugs and he said he "just" replaced them and that they were fine. When I went to check them they were completely fouled from a rich fuel condition.

Check your oil too. If you have a blown head gasket you might find water or milky deposits on the dipstick. The coolant will have oil floating in the surface. (Look in radiator when it's cool) It's also possible for a head gasket failure to not mix the fluids. In such cases it just fills a cylinder with whatever it allows to pass by.

When the engine dies or will not start connect a timing light to a plug wire and see if it's actually firing. Checking ignition on 280Z's requires a little care. I've been told that doing the usual "lay the bare plug on a valve cover" approach may damage the ECU. This is just hearsay but perhaps Sblake can chime in. Using a timing light is foolproof though.

Edited November 11, 2008 by JimmyZ

[Tim 76' 280Z]

I did pull the plugs. They are alittle black with a little bit of black stuff. not much tho. There doesnt apper to be any oil in the coolant.

[sblake01]

Checking ignition on 280Z's requires a little care. I've been told that doing the usual "lay the bare plug on a valve cover" approach may damage the ECU. This is just hearsay but perhaps Sblake can chime in.

I've never heard of that causing ECU damage but I've heard of cases and actually seen one case where it sends a spike back to the distributor and fries the module. So it's not just 280Z's. I wouldn't do that on any car that has electronic ignition.

[zbane]

When my head gasket blew, there was no oil in the coolant (at least not enough to be noticeable), nor was there an obvious amount of water in the exhaust (though it was winter which made it hard to tell if the exhaust was white or not).

However, after driving for about ten minutes, I would notice the temp spike above midway (I have a zx, the gauge is different) and I would hear a "pop." The pop sound was the reservoir lid popping open and vomiting coolant into the bay.

What was causing this, in my case anyway, was exhaust gas getting into the coolant and forcing its way out by the only means possible-the reservoir.

Check your compression.