My 5U7474 has a stuck engine (4000 hrs). The machine sat for over twenty years.   I'm going south for the rest of winter and thinking of dumping 1/2 MMO  1/2 trans fluid down both stacks till I'm back late spring next year..  No antifreeze in the engine oil - engine can be turned slightly by hand with the belt.  Pony is free, no obvious issues.  Any reason NOT to do this?  Your advice is much appreciated.

Thank you Neil. I am taking your advice. The engine can be turned by hand, with the belt maybe 10 degrees. It could be acorns or who knows stuck somewhere? Pulling the valve cover off ... everything under there is spotless. Can't wait till next spring. THX again.
BD Alexander MT USA

I have encountered machines that had a stuck lifter is all. You could pour some of your magic mix into the valve train and hope that it soaks up the lifter bodies as well. I have had to replace the entire body before, as someone had become anxious and damaged them, not to mention bending the push rods. Good luck on your repairs. Hope to see a video of it running laps soon. JM

Also check the meshing of the ring gear to starter pinion tooth engagement (If the starter pinion is engaged or stuck from rust). We've run into some of these that were sitting and the clutch compartment got water in there and a tiny bit of rust gets into one or more teeth causing the flywheel to turn until it hits the junk in the teeth.

Yeah, when your into the valve cover; put some of your oil mixture on the valve stems and see if you can move any of them in. I've had luck on some engines to hit some with a soft hammer or even use some vice grips on ones that were stuck open and jiggle them some to free up. Just be careful not to chew up the stems.
Looking at your picture, I can see that the steering clutches are most likely stuck judging by the position of the levers.
You may want to consider putting some diesel fuel or kerosene in the steering clutch/brake compartments to soak . Make sure you have the drain plugs installed. That may help you since your going away and that may give you a jump next spring.

I use a brass hammer or drift ,even a piece of oak and tap the main engine rocker arms on the valve side to see if any valves are stuck.

Juiceman, Side-Seat, and Steeltracs... Thank you men for the advice. I would not have thought about the valve train but sure could be. I will also soak the clutches now. I'm a little nervous about "tapping" on anything but will for sure if it's not loosened up by spring time. Regards, BD Alexander

we freed up a siezed engine simply by soaking with diesel mind you it was a single cyl and we had the head off but the principal is the same.

i would fill the manifold with diesel or you transfluid and kero mix(thats all that mystery oil is is kero in a light oil with afew additives), remove rocker cover and spray valve gear liberally with inox, penetrene, wd40 etc then gently tap each valve tappet with a hammer use a bit of pine etc as a drift so you dont hurt things as the fluid level drop in the manifold top it up
repeat till it doesnt take anymore fluid.

or simply back off the valve adjustment and pull the head and fill each cyl with oil mix and bolt head back on nipping the bolts by hand the idea is just to keep dirt out.

another way is pull the injectors and pour oil mix straight down the pre comps into the bore.

what ever you do you'll have to pull the head anyway so its no big deal.

Had a D4 stuck /sat for 20 years - poured mix down ex and intake and onto valve train - waited and bounce taped on valves with brass hammer and eventually turned over -ran for years never pulled head. That machine looks good so you will probably be lucky.

Hey THX trainzkid, I have both stacks full of MMO and ATF mixed. I'll pull the valve cover and take your advice on spraying and tapping. The engine is turning maybe a degree at a time with the belt, by hand. I assume that will stop as there must be a hydro lock in one cylinder anyway.