I bought a mitsubishi shogun 3.2 diesel at auction, and it is losing coolant.
my exhaust is not white, so i don't think its going into the combustion chamber.
my oil is not creamy, so its not getting in there.
there are no visible leaks.
on the motorway, after 20 min, it runs hot - 3/4 indication on coolant temp gauge. Then it suddenly drops, as if the thermostat has opened. When I get home the reservoir is empty, and after the rad cools, i open it and need to add a litre and a half of water.
Sounds identical to a problem I had on my motor this year. The EGR or exaust gas recirculation cooler to give it, its full name had failed. Basically a little radiator sits on top of the exaust manifold and admits some exaust gas back into the engine. Its water cooled and they do split loosing coolant internally into the exaust. Good news is its an easy job to replace not so good news is they cost £220. To check yours you need to remove it and look into the pipe that feeds the inlet manifold, any sign of water there and its goosed. Hope this helps, Neil
Have a pressure test done on your hoses, you may have a small hole that allows the coolant to escape while the system is under higher pressure
but is not present at idle
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Thank you RazFL. I will pressure test asap.
I should have also mentioned that when it is on the motorway for more than 15 minutes that the overheating causes the coolant (now water) to boil through the overflow.
The fact that it cools down quite quickly when I take my foot off the gas made me suspect that the water pump is not circulating under load. My belts are looking old. I suspected a slipping water pump belt. Unfortunately, I see no belt running my pump. It must run off the timing chain.
Could my coolant be gelling? It is mostly water by now. I plan to flush the system using a commercial product, and refill with coolant/water in the hope of improving the system's efficiency and reduce the boiling point.
If i had a cracked head, block, or leaking head gasket, wouldn't i lose coolant at all operating ranges? I can drive all day in the city without losing a drop!
This is so weird.
Latest development is the discovery that the rad cap is not sealing due to significant deterioration of the rad filler neck. Shame to replace the whole rad over this. Will try resin and a dremmel.
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