I just got some great advice yesterday about the contol switch in my 86 e-350. The van was running great until this morning when it started to over heat.
when I added water the water wouldn't stay in.
water pump, thermostate ? any ideas

 

So the coolant is just expaning excessively to the recovery tank? Is it in liquid form or is there foam as well?

The thermostat could cause overheating, do you know if it has the OEM Ford/Navistar thermostat, or is it a knock off from an autoparts supplier?

A clogged radiator could also be the problem.

My feeling is that a water pump going bad would give off some nasty sounds, and have play in the pump shaft, you can loosen the belts to check for this.

If you have foam in the coolant, then a leaking head gasket can be suspected.

 

Yes, it's a nasty sound and there's no foam thankfully. also the thermostate is a knock off that I installed about four months ago.
As the engine gets hotter the over flow runs like crazy till the radiator is empty. or if the engine is running and the cap is off the water flows out periodically
but I think your right about the water pump. I did notice some moisture right under the pump last week. I didn't see it again so I though it was nothing.

 

Definately sounds like a water pump then, but that T-stat should be replaced as well.

I almost learned the hard way not to use generic thermostats in the IDI diesels. Had overheating problems on the highway at higher speeds (regardless of load).

Then learnd the story of the OEM style verces aftermarkets here on the forums, made me feel better spending $40 on a proper one.

 

thanks for the help David85
I'm off after wed. so I'll start working on it then.
thanks again.

 

If the water pump shaft has play in it, replace the water pump.

If the shaft breaks off the fan makes a very big hole in the radiator as it goes through.