Diesel racing out of control (not linkages)

[skalie]

Help, I decided give the 306D a good tune up before taking it for it's way overdue technical check.

Unfortunately, either something has broken coincidentally or I have managed to break something somehow as when I start the engine it keeps speeding up blowing lots of gray or white smoke and sounds like it is going to keep speeding up till it blows up.

The engine a 220 diesel type model from the 70's, the motor is in the cabin so I can play around with the linkages while testing.

Here's what I did....

#1 repaired the vacuum line from the front of the block to the inlet manifold, it was bent.

#2 adjusted the tappets, I rotated the engine clockwise looking at it from the radiator end, I hope that wasn't the wrong direction !!??

#3 tightened down the four number 19 connections on top of the injection pump, VERY hard, as one was letting in air.

#4 put in new washer type thingines that go under the injectors, they had a larger hole than the original ones as it goes.

....possible scenarios....

#1 the vacuum is faulty somehow, fixing the pipe actually just made it worse.

#2 rotated the engine the wrong way

#3 broke something in the injection pump by being too heavy handed

#4 wrong washers under the injectors

I was expecting the engine to run better after all that, but not to rev away like a Japanese motorcycle.

Any thoughts on this one most gratefully appreciated.

[Mark DiSilvestro]

My first guess is you're sucking oil through the vacuum tube. Try disconnecting the tube and plugging the manifold port and see what happens. (maybe it was bent for a reason)

My second guess is you should install washer thingies with the correct size holes.

Happy Motoring, Mark

[300SDog]

Its gotta be the injector pump.

Here's thread about runaway diesel engine winding into oblivion and burning out in matter of minutes...... owner was unable to shut it down.

Destroyed the Engine in my Daughter's 300D

[skalie]

.........er,

Called a friend who came round while I was charging the battery for a second attempt.

He took a look around, emphasis on vacuum, seems that I'd forgotten to tighten the tube on the inlet manifold that goes to the back of the injection pump.

"Could it be that?"

It was.

Seems that the vacuum from the manifold regulates the injection pump, if it isn't working the motor will take off on it's own accord.

Lesson for the day.

Heard some interesting stories about old Dutch diesels going postal in boats today as it goes, they used to have a flyweigt type system or something in the injection pump, that would break and make them unstoppable, even when the diesel ran out they would kick on using the oil in the motor as fuel.

[dabenz]

skalie, the thing in front of the engine block is the vacuum pump. Normally it sucks from the brake vacuum reservior that the brake master cylinder mounts to. The vacuum pump outlet goes to the engine inlet manifold or piping. If there is oil in the line between the pump and engine inlet then the pump is going bad and you need to fix it before it breaks apart inside the engine.

The "back of the injector pump" is the the governor, which governs engine speed under load. The other end goes to the throttle body, which is simply a venturi that creates vacuum for the governor. You adjust maximum engine speed by adjusting the screws on the other side of the throttle body, where the metal rods end. Those screws adjust the travel of the butterfly valve inside the venturi, which in turn limits the amount of air admitted to the engine. I suspect that the butterfly valve is not set properly, and you need to clean and adjust. You've already learned that the governor is working when vacuum is applied.

It's frightening to hear an engine wind up on its own, but it shouldn't blow up with a properly adjusted throttle body.