intermitant overheating

[discocrazy]

engine will not blow out hot air for heater unless load is on engine. If I am sitting at idle engine will start to overheat. Will smell hot antifreeze.
Did pressure test no leaks.

Is this a thermostat issue? If anyone could help would appreciate

[kevin-ct]

I had worked on a Disco that did the same thing, I replaced the t-stat and retested and it did the same thing. replaced the radiator and it was fixed.

Also check fan clutch.

[Rineheitzgabot]

It sounds like you have the classic DII issue.

Do not run this vehicle anymore until you do something with the coolant level. The pump is not circulating the coolant, for some reason (either it is low, or there is air, or the pump is shot). These aluminum engines are delicate, and cannot be overheated. See below.

I am surprised that the pressure test did not find any leaks, because it sure sounds like your coolant level is low, and generally speaking, they get that way from leaks.

Try adding coolant to the overflow tank. Then bleed the system. Since I don't have anything in front of me about doing this, I am reciting this off the top of my head:

1. Remove over flow tank from mounting, there are no fasteners; only snap clasps.
2. Remove coolant hoses from from plastic "pinch-mount" on top of fan shroud (sounds difficult, but it is not-just squeeze the hose and pop it out).
3. Loosen bleeder screw at plastic "T" fitting located in the hoses in the previous step; do not overtighten as I did once, and strip it out.
4. Elevate overflow tank and fill with coolant until coolant starts to leak from bleeder screw (air will leak out first; and by the sound of it, you have air)
5. Run engine, and drive it a few minutes/miles.
6. Repeat steps 1-5 as needed.

You may want to google this, and get the procedure from a manual or something official.

I'll bet that this will give you heat.

In saying that you smell hot antifreeze, I would bet that you have a leak, in the typical place that DII's get leaks, and it gets burnt off by the exhaust before it leave a puddle on the ground.

I may be wrong about all of this, but my DII is doing the exact same thing right now. I am pretty sure I have a blown head gasket. I am keeping the coolant topped off, but it is a precarious situation to be in, as I don't want to forget, and have the motor overheat.

Hope this helps.

[discocrazy]

Thank for the info. So if you think you have a blown head gasket, that possibly means I have one aswell. How can you tell? Is it an expensive fix? If the fan clutch was bad would it even work.

[Rineheitzgabot]

Update:

Had our regional Rover expert check it out, and it turned out to be a leak in the plenum de-icer. I bought a repair kit for $45, and can fix it in an hour.

This doesn't mean that I don't have a bad head gasket, but at least the major leak will be fixed soon. Not only is it a bad place to leak, but it is high in the coolant circuit, and causes more air to be introduced into the circuit. Air in the circuit can cause the exact symptoms that you describe in yours...

Whatever you do, keep it filled with coolant. Be obsessive about it.

Also, don't forget to bleed it.

-Gary