Overheating

Hi, all,

Hoping someone might be able to advise me on a problem.
A few times when I was off-roading I noticed that my water temp guage had gone into the red. When this happened, I stopped the car immediately and left it for for 10/15 minutes and the temp went back to normal and then stayed normal. This only happened about 3 times over the course of several months. Generally the temp guage would sat a little under half-way. I never had steam coming out of the radiator, and coolant seemed to remain on max.

Now, this week the car started overheating on the motorway, and I stopped the car and found that the coolant bottle was empty and I could see some coolant was leaking (visible at the bottom of the radiator). 

I am obviously going to replace the radiator, but I am wondering whether I have an additional problem? Obviously, the car will overheat with the leaking radiator, but I don't know why I was getting these "sporadic" occastions when it was overheating before, and then seeming ok for weeks or months? Would this just be radiator getting blocked up as it deteriorated, or might there be a problem with some valve or sensor that controls the water flow or something? (sorry, I am not very mechanical, so don't know how the cooling system works).

Any advice very much appreciated.
Cheers,
Lee
 

Contrary to what some people may want you to believe if an m13a Jimny engine over heats as your one has it will need a new head gasket. Yes by all means replace the radiator especially if it's leaking and even the rest of the cooling system but ultimately none of that will permanently solve the issue. I speak from experience of having attempted to nurse a Jimny with your symptoms of periodically over heating and it was expensive just replacing various parts that didn't fix the problem and then having to do the gasket anyway.

Thanks for the info, Lambert. Would there not be other symptoms if it was the head gasket, like white smoke from the exhaust or something?

I would follow Lamberts advice. The coolant is probably being forced out of the hose joins of the cooling system ,as it is getting pressurized from the gasket being failed. This also air locks the system so water will not be circulating. One way to determine is wait for the engine to cool fully and then open the radiator cap. If it hisses you know that air is being forced in on the compression stroke on the engine. I had the same issue for ages and it just gets worse. 

you get a push and pull action on the oil and water. Intake stroke (sucking) will draw oil and water into the combustion stroke producing blue/white smoke. combustion stroke (push) will force exhaust gas into the oil and cooling system.

It's often the case as stated above that the failure is across the cylinder to water jacket and over pressurises the coolant more than contamination of the oil.