Kelvin J3 running away

[M.Myatt]

Hi,

 

 My Kelvin J3 is being naughty. I went to start it and it started fine, but then ran away with itself. it went to 0 to out of control. Fortunately, we have a way of stopping them before any real damage occurs. I've checked the engine and no obvious signs of diesel in there, but I'm going to give it an oil change anyway. Does anyone have any insight as to what it could be?

 

 Thanks

 

 Mike

[Tony Brooks]

1 hour ago, M.Myatt said:

Hi,

 

 My Kelvin J3 is being naughty. I went to start it and it started fine, but then ran away with itself. it went to 0 to out of control. Fortunately, we have a way of stopping them before any real damage occurs. I've checked the engine and no obvious signs of diesel in there, but I'm going to give it an oil change anyway. Does anyone have any insight as to what it could be?

 

 Thanks

 

 Mike

 

If the oil level is OK, then it sounds as if the rack/control rod or governor stuck in the maximum fuel position, Especially if it stopped when the stop control was operated or the rack pulled back. I can't think what else it could be.

 

If the J3 has separate injector pumps like the small air cooled ones, then maybe one of the pumps has/is twisted slightly because that can make the racks stiff.

[M.Myatt]

That

31 minutes ago, Tony Brooks said:

 

If the oil level is OK, then it sounds as if the rack/control rod or governor stuck in the maximum fuel position, Especially if it stopped when the stop control was operated or the rack pulled back. I can't think what else it could be.

 

If the J3 has separate injector pumps like the small air cooled ones, then maybe one of the pumps has/is twisted slightly because that can make the racks stiff.

That makes sense. I shall have a look when I get back later. Someone suggested that the day tank could have leaked and diesel sealed into the oil, but as I said the oil looked ok when I tested it on kitchen roll

[Tony Brooks]

1 minute ago, M.Myatt said:

That

That makes sense. I shall have a look when I get back later. Someone suggested that the day tank could have leaked and diesel sealed into the oil, but as I said the oil looked ok when I tested it on kitchen roll

 

You "test" the oil more by small and feel, but for oil dilution to cause a runaway it would either have to be very full of diesel so mist got drawn through the breather system or when it got hot enough to produce fuel vapour. Yours sounds as it did it from cold.

 

I don't think kitchen towel would be very good for doing the test (forgotten the name right now) where you out a drop of oil on blotting paper and see what the leaching through the paper shows. I there is fuel in the oil you should get an outer ring than is cleaner than the rest.

[MtB]

5 hours ago, M.Myatt said:

Fortunately, we have a way of stopping them before any real damage occurs.

 

So how DID you stop it? 

 

This info might help narrow down the possible cause.

 

 

[matty40s]

4 minutes ago, MtB said:

 

So how DID you stop it? 

 

This info might help narrow down the possible cause.

 

 

I have a suitable block of wood, (never had to use it in anger), which blocks the elephants trunk inlet, therefore denying the engine air.

[MtB]

2 minutes ago, matty40s said:

 

I have a suitable block of wood, (never had to use it in anger), which blocks the elephants trunk inlet, therefore denying the engine air.

 

I guess I was hoping the OP would mention loosening the injector bypass valves. If that stopped it, then we can 100% rule out the engine drinking its own oil.

[agg221]

The only time our J2 has done this it has been down to the fuel rack position. On the J, the injectors have a bypass for starting on petrol which are unlikely to have been removed. If you leave these unscrewed, any diesel leakage from the day tank runs back through the governor and into whatever overflow arrangement you have. If you have the petrol start fitted, even just the valves, then the compression ratio can be immediately dropped which stops the engine.

 

Alec

[BEngo]

Check the oil level in the governor.  If it is low, or empty, there is no speed signal and the spring will hold the rack in the fully open position.

 

If nothing comes out of the petcock on the governor aft face, add diesel through the hole/flap ( as fitted to your governor) on top until diesel comes from the petcock.

 Check that the rack is free to move in the fuel pump- unhook the spring  and it should move freely.

 

N