1995 Isuzu 5500 box truck 6 cyl diesel. truck overheated and water&coolant ended up in the oil pan and the motor ended up locking down. Can only spin fly wheel 1/2 to 3/4 revolution besides changing the head gasket where to i look to resolve the engine to complete a revolution???

Just a question, Did you remove the engine mount bolts?

The only place, oil and water share a gasket is the cylinder head gasket, oil and water galleries run through the engine block and head via the head gasket. The cylinder pressure will be OK, it's the oil pressure that's putting the oil in the coolant, the gasket has gone between the water and oil galleries or there is an internal crack (unlikely). A coolant pressure test should show it up.

white smoke usually means blown head gaskets,have radiator fan checked,water pump,check coolant for oil in coolant,could be blown in between cylinders,causing coolant to go out exhaust,have compression check done on cylinders.

Check this procedure for 1995 Ford Contour 2.0L MFI DOHC 4cyl...

REMOVAL & INSTALLATION
2.0L Engine (see Figures 1 through 6)

Fig. 1: Remove the coolant recovery tank hose from the water outlet

Fig. 2: Remove the upper radiator hose from the water outlet

Fig. 3: Remove the three retaining bolts for the water outlet

Fig. 4: Carefully separate the water outlet from the thermostat housing

Fig. 5: Remove the thermostat from the housing

Fig. 6: Make sure you replace the O-ring when installing a new thermostat

I hope this helps top solve it (remember comment and to rate this answer). Good luck.

Hello, chrisboetcke and thank you for asking your question on Fixya!

Here is a simple process that will walk you through a few steps that will pinpoint the overheating problem on your 1995 Isuzu Rodeo, without even using any tools. It has helped millions of people, and I am certain that it will help you, because I wrote it for people in your exact situation.
How to diagnose an overheating 1995 Isuzu Rodeo
The engine sounds like it is burnt up so bad, that it has a cracked casting.

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Is there a bleeder valve on the thermastat housing or the water pump. if not check to see if your loosing coolant and the oil level

very, very seldom does the oil get get in the coolant, it is almost always the other way around, coolant in the oil, I have 35 years of experience to back me up on this. The problem is almost certain to be leaky head gaskets, one or both, but they should be done together anyway.

Sounds like your thermostat is stuck in the closed position. I'd replace the thermostat and flush & refill the coolant.

it could be leaking somewere else , get your cooling system pressure tested at a shop

If your truck is a 4 cyl, then there is no way around pulling the motor to reseal the oil pan. if it is a 6 cyl then the frt diff will have to be removed and then the oil pan will come out of the truck. either way you are in for a full day of work.