Mine does the same thing - bleeds itself down to 1/2" below the fill line, then stabilizes. Brand new radiator cap, btw.

Just today I decided it must be a quirky thing some Discos do. It's funny to see it come up here.

To the OP - I'd check your head gaskets again just to be sure, then replace the thermo for sure with the 180. I'd consider replacing the radiator and clutch but probly not do it since the truck isn't running hot at all.

Then I'd stay vigilant (watch the coolant level!) and drive it like nothing is wrong.

 

Thanks all for the replies. If anyone is interested, I've noticed some interesting posts on where people locate the oil pressure send. On D2 Timing covers there is a plug above the factory send.

There is just enough room to relocate the factory send to the plug above, and then you can fit the gauge send to the original location. Autometer has all the adapters/angles you need depending on the size of your send.

 

That would be on D2's without the factory engine oil cooler, after a certain VIN.

 

Thanks for all the suggestions.

I have replaced the thermostat and the fan clutch. As it turns out, the problem manifested again last week.

The block check says head gasket. I find it hard to believe it is the radiator. When the engine was rebuilt the radiator flowed perfectly. Even though it has only been about 18,000 miles, I think it is possible that the torque spec I used on the heads is the reason. ARP says 80 ft pounds. The procedure I received with my head gaskets and studs says 65 ft pounds. Claiming that even with the studs in the block I would pull the threads out of the block after 65 foot pounds.

If I do these gaskets over I am calling ARP and using their spec, or much closer to it.

FYI, I'm in Utica, NY. The truck is in excellent shape, interior, wheels, paint, etc. The engine is what I already explained in the thread, built up from top hat liner short block. It does drip from the rear main a bit, even thought the seal was new with the short block. In any case, I don't know what it's worth to somebody, but I would sell it for $5500 before the repair is done. If I repair it, I'm keeping it of course, because I love the truck. It throws three amigos every once in a while. Not enough for me to bother checking actual cause. In three years it never permanently stayed on.