D1503 engine no compression...huh?

[kilohertz]

Hi gang,

Just bought my first orange machine, an RX303 mini excavator, and it has an engine issue.

Was told it was run out of oil and seized. The PO took it to a machine shop and was told it needs new sleeves and pistons and would be $5K to rebuild. He sold it to us as is. The engine is out, and actually not seized, however it turns over by hand with no compression bumps at all, there should be 3?? The machine shop never did take off the head, only the oil pan. We have it on a stand right now and head and pan off, and the engine is extremely clean inside, no sludge, cylinders looks good, no ring ridge, and pistons all intact. Only issue is one rod bearing spun, otherwise, no visible damage or heat problems. We just can't figure out why there is no compression. Going to mic it all today, but the rings seem tight in the bore, and pistons move up/down with normal resistance, valves look good and timing gears are fine and were set properly. Don't see a decompression lever on this one...All injectors were new last year and glow plugs still installed. Where is the compression leak, on all 3 cylinders?

Any thought? It's a D1503-KA, (not sure what the suffix means and how it could be different than say an LA or AE etc.?)

Any help, greatly appreciated.

Cheers

 

[lugbolt]

Are there ANY scratches in the bores? What is the ring gap with the ring in the bore? Have you checked the valves and seats yet? Dump a little kerosene or diesel down into a cylinder head port and see if it leaks out of the valve.

Spun bearing=lack of lube. Usually also means the crank and/or rod is FUBAR. Crankshaft can be ground. Rod can be replaced.

 

[kilohertz]

Thanks lugbolt,

Well, I don't see any scratches in the bore, just a few black water marks (it's been sitting for about 2 months in the back of a pickup). Ring gap with it sitting about an inch down in the bore is .011-.014" in all 3 cylinders. Will try diesel dribble into the ports and see if the valves leak. Crank rod journal is .018" under and well scored on just #1 and bearing shell is completely gone and rod pounded beyond reuse. (and heated) Are there rod bearings available .020" over? All other rods and bearings look good, crank mains are still installed but feel fine. It looks like the head has been off before, as the head gasket is a bit buggered up so that could be the issue of low compression. Someone removed it with a screwdriver and messed up the surface near #1 cyl, then put it back together. May have been the machine shop that did the diagnosis.

Depending on what feedback we get here, and how much/available parts are, we may just look for another engine and swap out the accessories. Need to figure out what US/Canada engines are the same as this Japan version.

thanks again for any and all help.

Cheers