Van overheating

You're right about the high current. If that's the problem, the fan should feel tight when you spin it by hand. Measuring the current won't really work. To vary the motor speed, the voltage is switched on and off rapidly and the percentage of on-time is increased to increase the motor speed. That's called pulse-width modulation. There is either full voltage across the relay and no current flow, or no voltage across the relay and full current. Either way, if you do the math, (volts x amps = power), one of those two will be zero, so in theory, no power is dissipated and no heat should be developed. That switching takes place hundreds of times per second. If you use a digital volt / ohm / amp meter, it takes a reading, analyzes it, displays it, then starts over again. It might take one reading when current is at 0 amps, and half a second later it could take the next reading when current is at maximum. The meter will not average the current reading like the older pointer-type meters. The display will bounce around in a confused meaningless state.

If the motor spins freely, there could be some other problem such as a wire to the motor is grounding out, or it's possible the new relay isn't even defective. Check for voltage on the 12 gauge gray wire at the relay, or you can jump that gray wire to the dark green wire and the fan should run wide open. That will prove the 12 volt feed and wiring are okay.

Many of these have two fan motors. Only one would have to be tight to draw excessive current. As a test, you could unplug one of them, then replace the 40 amp fuse with a 20 amp. The relay should hold up to the higher current of a single tight motor but the fuse will probably blow over time if that motor really is drawing heavy current. If it runs fine that way for a few days, unplug that fan and plug the other one in and try it again. If neither fan blows a 20 amp fuse, the pair shouldn't blow the 40 amp fuse. That would say they are drawing current well within the safety margin of the 40 amp fuse and the relay should be able to handle that.

To prove him wrong, fill the radiator to its level, start it up and look closely whether the coolant is squirling/ circulating around if so pinch the upper hose for a few secs then let go-the coolant should move faster. If so the water pump a okay.

Now for headgasket you should being seeing white smoke out of the exhaust pipe if not you got him or do a chemical test called block test and when blue color changes to yellow he's got you if not you save money and stay away from him, he's trying to milk you.

Also try bleeding it see below procedures:

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.

If the heat is blowing cold air you may have an air-lock in your cooling system or you may have a coolant leak.

Or another possibility would be that the heater core is plugged, but that will not result in an overheating issue unless it is leaking coolant.

I noticed that I never see the fan rotating. Do I have a fan or fan switch problem?

Try direct power from the battery to the fan motor if it comes check and test the fan relay and engine temperature gauge sending unit.

Losing the water how quickly? Do you see the water on the driveway? It may be a freeze plug leaking

Best check the thermostat again-could be stuck closed though its new and also for a clogged heater core-to include airlock and bleed it

Make sure radiator fan(s) come on and that coolant is full, if so then remove and test thermostat.

I believe that is the radiator coolant overflow hose it should connect to the overflow container

HI:

If you have that much rust in the radiator, I whould suggest having it flushed. After that is done, see if it still overheats. If it does, get back to me with specifics and I will help you figure out what is going on.

Joe