Head Scratcher.

wlhequipment · Feb 2, 2023

I'm looking for help thinking my way through a problem. Mitsubishi grey market tractor from the '70s. It has a 2 cylinder diesel, KE95, makes about 22 hp (supposedly). It's all mechanical. The only wire on the engine is on the glow plugs. I haven't checked compression yet, but it fires up quickly and idles nice. Injectors both crack at around 1700 psi, which is spec, and give nice chatter, and mist, and don't leak. Cylinder head just got a new valve job, and decked. New head gasket (of course) and just re-torqued today. It runs great up to about 1500 - 1600 rpm, when it starts to bog and spit white smoke. If I push it, rpm doesn't go beyond about 1800 (redline is around 2500), and it's missing and spitting until I throttle it back to about 1500, where it likes to be. Both cylinders doing the spitting and missing. I ran it with the exhaust manifold off, and watched it. No leaks. No coolant loss. No blowby (I was watching that too). Also ran it with an aux tank, no change. I'm open to suggestion.

John C. · Feb 2, 2023

Sound kind of timing related to me. Does the engine have some kind of timing advance?

wlhequipment · Feb 2, 2023

John C. said:
Sound kind of timing related to me. Does the engine have some kind of timing advance?

No, it’s geared internally and otherwise fixed. No adjustment at all, as far as I can see.

John C. · Feb 2, 2023

Do you know if the cam was checked?

Coaldust · Feb 2, 2023

My first thought was timing related. Are you certain the copper nozzle gaskets are the correct thickness? How’s the valve adjustment? What a cool little engine.

wlhequipment · Feb 2, 2023

John C. said:
Do you know if the cam was checked?

No engine internals have been out, as far as I know.

wlhequipment · Feb 2, 2023

Coaldust said:
My first thought was timing related. Are you certain the copper nozzle gaskets are the correct thickness? How’s the valve adjustment? What a cool little engine.

Good question about the injector gaskets! Not sure. I’ll pull them tomorrow and have a look. Overheads just done. That damn engine is a unicorn. There’s a couple variants that are more popular like the KE70, KE75, KE130… but this 95 is a real oddball. My first time messing with one.

Delmer · Feb 2, 2023

I thought timing too, but air in the fuel is easier to check. Put the fuel return into a clear hose or into a jar to see if there's any bubbles. Or check the fuel supply.

Zewnten · Feb 2, 2023

Is the fuel good? No water, not old.

heymccall · Feb 2, 2023

My TL150 machines will do that with a fuel supply deficiency.

wlhequipment · Feb 2, 2023

Delmer said:
I thought timing too, but air in the fuel is easier to check. Put the fuel return into a clear hose or into a jar to see if there's any bubbles. Or check the fuel supply.

There is almost no return from these injectors. Maybe a tiny drop at full throttle. Fuel system is gravity feed, and I’ve tried an aux tank and lines as well, in case the existing tank and lines were bad.

wlhequipment · Feb 2, 2023

Zewnten said:
Is the fuel good? No water, not old.

Fuel is brand new. No water.

wlhequipment · Feb 2, 2023

heymccall said:
My TL150 machines will do that with a fuel supply deficiency.

With the white smoke too? That’s the part that’s actually throwing me off. I’ve never seen a starvation situation with smoke. Smoke always means something else. Others have suggested a timing related issue, and that makes more sense to me.

Zewnten · Feb 2, 2023

wlhequipment said:
Fuel is brand new. No water.

Purge the fuel system? Just trying to get a grasp on what you're working with.

wlhequipment · Feb 2, 2023

Zewnten said:
Purge the fuel system? Just trying to get a grasp on what you're working with.

I definitely appreciate it! Yes I bled as much as I could. I guess it’s possible I still have air in the system, and I just need to run it until it all gets out.

funwithfuel · Feb 2, 2023

Gravity feed to the injection pump or to the lift pump? How old are the lines from tank to filter and so on? Is the tank rusty inside? Do the hoses crack when you bend them? Does fuel dribble from the tank bung or does it pour?

wlhequipment · Feb 2, 2023

funwithfuel said:
Gravity feed to the injection pump or to the lift pump? How old are the lines from tank to filter and so on? Is the tank rusty inside? Do the hoses crack when you bend them? Does fuel dribble from the tank bung or does it pour?

Gravity feed to the injection pump. No lift pump. All lines and filter are new. Tank is clean, and flow is good. I also ran it with an aux tank held up higher than the regular tank, to assure good fuel delivery, and got the same result.

cfherrman · Feb 2, 2023

Put a electric fuel pump on it, probably even carb style might work.

funwithfuel · Feb 2, 2023

I would introduce an inline pump to the filter( a cheap diaphragm pump for testing.) I'm guessing that the filter, while clean and new may be more restrictive than when it was manufactured. Additionally, i would make sure the tank is properly vented. Maybe leave the cap off or loose. Verify that your fuel hoses didn't get pinched or kinked anywhere.
Is this engine naturally aspirated? Is there a fuel return?

wlhequipment · Feb 2, 2023

cfherrman said:
Put an electric fuel pump on it, probably even carb style might work.

What I’ll try tomorrow is, bring the engine right up to the point it starts to stumble, and use shop air to pressurize the tank a little, and see what that does.

Head Scratcher.

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