All mechanics HELP!!!!

[jimsavenir]

My friend has a Vetus M3.10 that is running away. The oil return galleries are clear, called all Vetus numbers and each person cannot say if there is a governor or a probable cause like linkage.

The only hint is it is just after a oil change? But he reduced the oil level just to be sure.

The engine has been stellar, no smoking etc.

Vetus said the govenor is on the side of the fuel injecton pump? Not on any diagrams. I also could not find any diagram for a mechanical governor etc?

I also looked on K3 Mitsubushi diagrams and no sign? Any ideas to help him?New feul tank, return lines etc. he has always had over suction on the fuel tank in spite of the vent to the tank and the rail return?

[Seeking Solace]

Have you checked for a vacuume leak? (not usually the problem)

Does it have very high hours on it? Have you overfilled the oil?

unless there is something causing it to siphon too much fuel or crankcase pressure pumping oil mist up there is no real reason for it to run away. Does it do it immediately at startup? Is something pressurising the fuel beyond the fuel pump?

[NCboatrx]

I would suspect that the rack in the injection pump has jammed. This is possibly as a result of a spec of rust forming when the engine was laid up for winter.
Have the injection pump removed and serviced at an injection repair specialist.

[DougR]

The governor is inside the gear case housing just ahead of the injection pump, right inside of the throttle lever....go online to Vetus web site and have a look at the parts book for this engine.

It's possible that one of the governor springs has broken or the fly weights are hanging up, or as mentioned, the fuel pump rack is stuck.

I have also seen small engine runaways result from the fuel return line being blocked.

DougR

[Diesel Bill]

I had an old Detroit 3-71 run away. Went down to the docks to test run the engine. Warmed up the engine for 10 minutes and then gave some throttle to increase RPMs.
Just then BAM! the engine took off like a raped ape. From the sound it was way past the max governed speed. Thinking a blow up imminent I jumped off the boat onto the dock. I just stood there waiting and it kept screaming away. Finally I went aboard again and crawled into the engine room and located the 2 saddle tank fuel shut off valves and closed them. No change. I found a piece of plywood and covered the air inlet. At this point the dirty bugger sucked in the oil seals on the blower and was running on lube oil.
Only after tearing down the top end did I find the original cause of the run away. Turned out the person running the boat (salmon trawler) had been in some rough seas and had plugged up the fuel filters. Running out of filters he just removed them and ran the boat back to the dock. Never told anyone about the housing with no fuel filters.
A bit of water in the fuel got up to the old style low valve unit injectors and blew the tips off the injectors. At that point fuel was poring into the cylinders. Hence the cause of the run away.
Any way the O.P. might have a stuck rack or damaged governor/ broken pin or spring. Anything is possible. Start with the throttle linkage and make sure it's connected properly. Return spring connected. Try moving the throttle linkage. Pull the cover if you can and check all linkages connected. I don't know your capabilities so you might have to call in someone to look at it.
Good luck with it. Be sure to post what's found so we all learn.

[Lepke]

When you do maintenance and then something doesn't work right, usually you moved, bumped, disconnected something to make the change happen. I'd look at the control linkage and the linkage on the injector pump. Make sure the injector pump lever goes to the stop position and it's not loose (flopping back and forth). Go thru the bleeding sequence. If the throttle is electronically controlled (no cable or manual linkage), check all connections. Work the throttle with the engine off with an observer watching the injector pump lever. Make sure all the linkage works smoothly and travels the full range. Key may need to be on. With a runaway, it's better to stop the air slowly so it doesn't suck in the seals. Use soft rags in the intake.
Detroit Diesels have a filter in the injector that looks like compressed steel wool. See pic. Running w/o filters plugged them. A Detroit pumps 6-15 gallons an hour more than it burns. The excess passes thru the injector tips for cooling. When the internal injector filter plugged, it slowed the flow thru the tips. Water didn't blow the tips, lack of cooling did.

[Diesel Bill]

Originally Posted by Lepke

When you do maintenance and then something doesn't work right, usually you moved, bumped, disconnected something to make the change happen. I'd look at the control linkage and the linkage on the injector pump. Make sure the injector pump lever goes to the stop position and it's not loose (flopping back and forth). Go thru the bleeding sequence. If the throttle is electronically controlled (no cable or manual linkage), check all connections. Work the throttle with the engine off with an observer watching the injector pump lever. Make sure all the linkage works smoothly and travels the full range. Key may need to be on. With a runaway, it's better to stop the air slowly so it doesn't suck in the seals. Use soft rags in the intake.
Detroit Diesels have a filter in the injector that looks like compressed steel wool. See pic. Running w/o filters plugged them. A Detroit pumps 6-15 gallons an hour more than it burns. The excess passes thru the injector tips for cooling. When the internal injector filter plugged, it slowed the flow thru the tips. Water didn't blow the tips, lack of cooling did.

I have a different opinion on using a soft rag to slow down a runaway engine.
To much chance of sucking the rag into the intake. use a piece of wood that won't fit through the air intake.
The final filters in unit injectors are bronze and I have replaced many of them. However when they are not in place they can't plug up. If you doubt water will blow the tip off a unit injector put one in a vice and put a little water in it and tap the plunger with a hammer and see what happens. We used to make a flame thrower with them on the bench just to see how far we could shoot the flame. (5-10 feet was average) The injectors are fitted in the head in a copper cup surrounded by engine coolant, and while I realize the fuel cools and lubricates the plungers and barrels the majority of heat is removed by coolant flow. As an ex Journeyman Diesel Mechanic (member of Machinist and Aerospace Workers union) since late 1970s worked for International Harvester, United Truck Lines, Rollins Truck Leasing and 20 plus years in the engine room as a U.S. Coast Guard licensed Marine Engineer unlimited horse power both steam and diesel. I think I have the knowledge and expertise to make a comment in this area. Any time you want to talk diesel I'm your man.
I enjoy talking engines and look forward to discussing them. I only comment to try to help anyone with less experience than myself and not to get into a pissing contest.

P.S. I agree with all the trouble shooting advise you offered the O.P.

[a64pilot]

Water will absolutely blow the tips off an injector, I have seen it happen.
However I was under the impression it was because the water turned to steam, pressures go crazy high and off goes the tip.
May not be what happens but it does happen.

[Diesel Bill]

Originally Posted by a64pilot

Water will absolutely blow the tips off an injector, I have seen it happen.
However I was under the impression it was because the water turned to steam, pressures go crazy high and off goes the tip.
May not be what happens but it does happen.

The way it was explained to me by the Detroit Diesel dealer in Fort Bragg, Ca. was that diesel fuel was so miscible that it could go through the tiny orifices of the spray tips at 2-3,000 P.S.I. and atomize into a fine spray. Water on the other hand will not pass through these tiny openings at the same pressure so as the plunger continues it's stroke the pressure builds up to a level high enough to actually blow the tip off. I know it sounds strange but that's what is supposed to happen.

[a64pilot]

I can see that, water is more dense and it's hydrogen bonding I think makes it an unusual liquid, float razor blades, expand on freezing etc. I think due to its bonding it may resist terribly being forced through a very small orifice.
I was always suspicious of the steam theory due to being under those pressures, the temp to form steam would have to be astronomical.

[topmast]

Some engines vent internals thru a tube in a plate covering the lifters. hose runs to air intake and lube oil sucks into engine after an oil change .Easy to check this off the list of possibilities.