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Old 03-08-2012, 17:14   #1
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Fordson Dexta Ran Away, Now What?

Gdayteam, thanks for your time in reading this.


My engine was blowing a lot of white smoke a few weeks back and I pulled the injectors and sent them away to get refurbished.

Yesterday I recieved my cleaned up injectors back with new nozzles on them.

I installed them this morning and started the engine up. It went fine, started easily and idled smoothly for about 10 min there was some white smoke but nowhere near as much as previously.

After 10min I noticed the revs were not steady anymore (by ear, no tacho) they had a surging rhythm.

I was checking the injector seat bolts when suddenly the revs starting increasing quickly I pulled the stop lever to shut off the fuel at the injector pump and it didn't stop the engine was now revving very high.

I knocked off the air cleaner and blocked the intake with a piece of wood and the revs came back down to a normal range but the engine still wouldn't stop.

I undid all 3 injector lines while holding the wood over the intake and it still wouldn't stop.

There is a breather from the crankcase to the air intake and I was in the process of undoing this to block it when the engine finally stopped. It ran for 3-4minutes after I disconnected injector lines.

It stopped like it normally would not seized or anything making major noise from inside.

There was oil coming out of the air cleaner though.

...........

Whats next?

How do I figure out the cause?

What should I check for damage?

My rings haven't been showing sign of wear, ie no black/blue smoke.

I can only think it has something to do with the recent injector replacement. But then it ran for 3-4 min after I disconnected the injector pipes. So must have been getting 'fuel' from the crankcase breather.

Any ideas?

Any and all help very much appreciated.
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Old 03-08-2012, 17:25   #2
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Re: Fordson Dexta ran away, now what?

Check you engine oil level and smell it to see if it smells like fuel. This is a classic case of a bad diaphram in the lift pump causing the oil level to be too high. It could be other problems but it sounds like a bad lift pump.____Grant.
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Old 03-08-2012, 17:53   #3
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Re: Fordson Dexta ran away, now what?

Cheers for your reply. Oil level is 50% which is the same as before the run away. Can't smell any diesel in there.
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Old 03-08-2012, 20:48   #4
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Re: Fordson Dexta ran away, now what?

Does the engine have a turbo?
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Old 03-08-2012, 21:35   #5
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Re: Fordson Dexta ran away, now what?

Sounds like you engine was using oil as a fuel, maybe pulling across a gasket maybe.
It can only get oil in the combustion chamber in a few way's, Valve's, Gaskets, Rings, Cracked block, Turbo or lift pump.
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Old 03-08-2012, 21:39   #6
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Re: Fordson Dexta ran away, now what?

Quote:
Originally Posted by perchance View Post
Does the engine have a turbo?
Never mind. I Googled it. Turns out it's a tractor engine.
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Old 03-08-2012, 21:41   #7
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Re: Fordson Dexta ran away, now what?

Would a blown head gasket or a cracked head create those symptoms? White smoke = Steam from coolant getting into the cylinder? Oil getting into the cylinder and acting as fuel?
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Old 03-08-2012, 21:47   #8
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Re: Fordson Dexta ran away, now what?

It can only be diesel fuel or engine oil. The trick is figuring out which it is and how it's getting into the combustion chambers.
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Old 03-08-2012, 22:04   #9
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Re: Fordson Dexta ran away, now what?

It is possible to have Oil and water mix and combust like diesel would, have seen it many times.
Water mixed with machine oil can detonate with dire consequences, think hydrogen mixed with diesel.
The resulting combustion can super heat the valves causing non compression detonation which would give you a runaway state,,very scary..
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Old 04-08-2012, 00:05   #10
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Re: Fordson Dexta ran away, now what?

Depending on how old and neglected the engine is, you might have motor oil building up in the top end of the engine and being sucked down the valve guides. Try pulling the valve cover off and seeing if there is so much sludge that the oil takes a long time to drain back to the sump. If it looks real ugly, try cleaning the oil drain holes that allow oil from the cylinder head to drain back to the sump. I have only seen this in very neglected engines, but it is a possibility. _____Grant.
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Old 04-08-2012, 12:18   #11
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Re: Fordson Dexta ran away, now what?

If you disconnected the injector lines while the engine was running and it continued to run it was running on motor oil. The only source for motor oil to get into the combustion chamber is either passed the rings ( Detroit diesels were notorious for this when they got old ) or it is sucking it in through the breather tube. To a lesser degree it could possibly suck some oil through the valve stems. White smoke is usually an indication of unburned fuel, most probably in your case oil getting into the combustion chamber. ( making major noise from inside. ) Did you hear major noise or are you saying you did not? These are just random thoughts as most of my experience is with much larger diesel engines.

1. Drain some oil and check it for viscosity.
2. Disconnect the breather tube and check for oil. If you find signs of heavy oil as someone said above pull the valve cover and check to see that the return oil passages are clean. ( You might go so far as to pour some oil on the valve and make sure you disappears into the crankcase. )

3. With the injector lines disconnected and the fuel shut off in the off position check and make sure no fuel is getting to the injectors.
4. Remove the lift pump and check for leakage.
5. Run a compression check.
Just my two cents, Mike.
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Old 04-08-2012, 15:58   #12
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Re: Fordson Dexta ran away, now what?

Wow thanks for all the knowledge guys.

I think that Florida Mike and gjordan are on the right track, this would explain the oil coming from the air cleaner. Either through the breather or the valve stems. I'm embarrased to say that it hasn't had an oil change in quite some time.

It didn't make any major noise when it happened.

I have replaced the head gasket 15 hours ago, so I'm pretty sure its not that or cracked head.

I can't get down to the boat for a few days but I will let you all know how I get on.

Once again thanks for all the help.
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Old 04-08-2012, 18:34   #13
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Re: Fordson Dexta ran away, now what?

If you haven’t run the engine since you changed the head gasket some gaskets are sensitive to which way is up. In particularly Volkswagen , engines. Just a thought, Mike.
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Old 04-08-2012, 18:43   #14
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Re: Fordson Dexta ran away, now what?

A long shot, but it did happen and with catastrophic results. Is it possible that there's some nearby source of fuel being drawn in with the air, like gasoline or propane fumes? Those items and things like starting fluid spray can cause the type of runaway described.
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Old 04-08-2012, 20:40   #15
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Re: Fordson Dexta ran away, now what?

Quote:
Originally Posted by Florida Mike View Post
If you havenít run the engine since you changed the head gasket some gaskets are sensitive to which way is up. In particularly Volkswagen , engines. Just a thought, Mike.

Sorry I should have said 15 engine hours ago.
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