I am trying to help a friend who owns an 88 F-250 diesel. Recently he experienced a serious water leak from the cooling system. He could not find the leak and after a week or so the leak stopped. He needs to go on an out-of-town trip but is concerned that the leak might start again while he is on the road. Does anyone have any ideas that might help him find and fix the problem?

 

It could be a couple things:

Too much coolant in the radiator. Ask him if he filled it up to the filler neck. If so then when he drove it and the fluid got hot it expanded and blew out the overflow hose. This is how it should work. It happened to me so I drove over to the mechanic and asked him about it. He showed me the line in the top radiator tank that is the fill level. It's just a little bit (1/4-1/2") above where the top tank and core meet.

Freeze plug leaking but all gooed up with leaking oil encursted with road grime. I finally found my leak when I put in new cooland and the new bright green Walmart coolant left it's mark.

Old radiator. I've fixed the two above but I still have some type of tiny leak in the radiator. I can see a coolant stain in the cooling fins and sometimes I can smell coolant when I walk in front of the truck after parking it. I may need a new core. (This is on my 72)

Could also be a hose or hose clamp. My hose clamp kind of wore where the screw meets it. It dripped ever so slightly.

Old water pump. I had another minor leak that became major when I flushed the system. I think I cleaned out all the rust particles that was keeping it from leaking.

Since your friend's was major and then nothing, I'm betting that he over filled it.

That's all I've got.

 

Thanks for the ideas. I have passed the information on to him.