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Old 11-01-2015, 16:39   #1
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Unburnt Fuel after rebuild

Hi All:

This is the first engine I have ever rebuilt. It is a Kubota EA300 7hp single cylinder and it runs my generator. It is horizontal engine and water got in the fuel and ruined one of the valves. I had the valve reground and put it back together. I am trying to bench test it and it won't run.


I cannot find the correct adapter to do either a leak down or compression test so I am trying to make one but am having problems with that.

I did take the injector off the block and run it against a piece of cardboard and it looks like it has a good spray pattern.

At first I was getting nothing out of the exhaust but now I am getting what I believe is unburnt diesel in a white cloud. NOrmally I would think water but there is no heat in the exhaust or the engine.

Could I have the timing set backwards so that fuel is going in at the wrong stroke?

The injection pump is timed with shims so I don't think that that is wrong.

Also the engine is not giving any hint of wanting to start.

I am using a gravity to feed the injection pump but don't see that as a problem.

Any thoughts or ideas would be helpful.

I hope I don't have to take it apart again.
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Old 11-01-2015, 17:07   #2
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Re: Unburnt Fuel after rebuild

It does sound as if you have the timing way off, as the injection pump is like a cam in that it turns at half speed, I think it is entirely possible that you have it 180 out, also ensure your cam timing is correct.
But I know nothing in particular about this engine, my statement is generic. There are two TDC's of course TDC compression and TDC exhaust


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Old 11-01-2015, 17:14   #3
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Re: Unburnt Fuel after rebuild

How far was the engine stripped down?
Was the valve the only fault found?
Do you have any reason to suspect lack of compression?
The compression can artificially raised by adding a small amount of oil into the clyinder to temporary seal poor rings etc.
Is it possible for the timing to be 180 degrees out??? This would mean injection occurs on the exhaust stroke rather than the compression stroke.
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Old 11-01-2015, 17:15   #4
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Re: Unburnt Fuel after rebuild

And A64 has faster fingers than me
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Old 11-01-2015, 17:25   #5
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Re: Unburnt Fuel after rebuild

I will have to study it and see if I could have put the timing 180* off. I'm not sure if it is possible on this engine. There are timing gears and they all needed to be aligned in order to get everything together. But I do agree that what is happening seems like it is 180* off.

I don't suspect low compression but thought it would be good to check before putting it in the difficult cubby it goes into.

I tore the engine all the way down.
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Old 11-01-2015, 17:28   #6
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Re: Unburnt Fuel after rebuild

With timing gears on the crank and cam, if the timing marks aline exactly across from each other then its timed correctly. If the marks do not meet then you may be off a tooth. With helical cut gears that is easy to do.

With a timing belt or chain its easier setting the timing off, but with gears, if the timing marks aline then its correct.

I would check the valves are seating properly and valve lash.
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Old 11-01-2015, 17:53   #7
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Re: Unburnt Fuel after rebuild

Quote:
Originally Posted by sailorchic34 View Post
With timing gears on the crank and cam, if the timing marks aline exactly across from each other then its timed correctly. If the marks do not meet then you may be off a tooth. With helical cut gears that is easy to do.
I was just studying the book and it does not seem like I could have the timing 180* off on this engine. Thanks for confirming that.

Quote:
Originally Posted by sailorchic34 View Post
With a timing belt or chain its easier setting the timing off, but with gears, if the timing marks aline then its correct.

I would check the valves are seating properly and valve lash.
I am going to check the valve clearance next. I have to order a part in order to do a compression check and hopefully I can work that part to do a leak down check.

Thanks Sailor Chic.
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Old 12-01-2015, 11:38   #8
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Re: Unburnt Fuel after rebuild

I rebuilt a Kubota 2 cyl engine
i flattened 4 batteries before it eventually started
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Old 12-01-2015, 12:06   #9
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Re: Unburnt Fuel after rebuild

I just rebuilt a kubota z600. 2 cylinder horizontal. It is a bear to start. The glow plugs need to be used for it to have a chance to start. Lots of white smoke as it tries to start . It always eventually gets going, smoke clears and it runs and produces enough power to load generator head to max rating. I detailed most of what I did on the " kubota generator rebuild. ". Thread.
It starts normally after it is warmed up. Someone else on the forum mentioned this type engine was hard starting.
I was considering using this on my Schucker 436 rebuild but the hard starting would be a pain, along with the white smoke. I replaced rings and rebuilt the head so compression "should" be good. But I guess that may be the place to start. Also was going to check the injectors spray pattern like the OP did. I left the crank in and did not mess with the fuel injection timing but I purchased the generator in non running condition so it is possible the fuel timing is off. But it does run well after warmed up.
I pulled a rusted out Onan generator off the schucker, on that one it looked like it had a heat devise screwed into the intake manifold I assume to help with starting. I could possibly adapt that warmer to my kubota. Also I was wondering if the fact that the throttle is solenoid controlled and moves the throttle nearly wide open when starting is hurting things on start. I could figure a way to bypass this if it would help the engine start easier if the throttle setting was lower on start. Any ideas on how to make this diesel start on demand?


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Old 29-01-2015, 12:27   #10
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Re: Unburnt Fuel after rebuild

Hi Just a little update:

Sailor Chic was right!!! I adjusted the valves and ran a compression and leak down test. I had a helluva time getting an adapter that would fit to run a compression test so I ended up making one. Compression was at 200 spec is a minimum of 377. I then made another adapter for my leak down tester and found that the exhaust valve was not holding. I removed the head and found that the machine shop had done a lousy job of cutting a new seat. I ordered new valves and head gasket, found a better machine shop, and am going to have an valve seat insert cut to the new valves.

Wish me luck.
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Between us there was, as I have already said somewhere, the bond of the sea. Besides holding our hearts together through long periods of separation, it had the effect of making us tolerant of each other's yarns -- and even convictions. Heart of Darkness
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