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I purchased a Lestec 3682 Articulating mower with a Kubota V1505 4 cylinder diesel engine (serial #1J1878), with 2770 hours on it. Every hose had a leak on it so I took all of it apart and pressure washed it. Covered all the holes to keep water out. I also replaced the oil sending unit (oil switch) because it was leaking oil out of the bolt that holds the wire. It is the Lestec part # 028547, which was matched up close as possible by a Kubota dealer with Kubota part #15841-39010.

I had every intention in replacing all the upper gaskets and seals on it since I had it apart but after taking the valve cover off everything really looked good on the whole engine, so I figure not to mess with it. However I did find a nail, yes a nail stuck against the valve push rod. After removing the nail, I use a wrench to rotate the crank just to make sure everything moved ok, and it did. I don稚 think I made any changes to the settings since none of the components such as rocker arms or anything was touched, it just went through its cycle. I replaced the valve cover and reinstalled all new filters for everything to include diesel / water separating fuel filter. After bleeding the air out of the fuel system I started up but it smoked like crazy. I let it run for a while figuring it will burn off, but it never did.

Below are some videos of before and after the engine running. Anyone have any ideas? Nothing was touched or rebuilt just replaced filters and pressure washed it.

Running before it was taken apart MVI 1702 - YouTube

Running after v1505 kubota smoking - YouTube

Check the inside of the air intake hose for evidence of dust. Kubota's will not take much dust.

Sounds like it is running on two cylinders.
Suggest doing a compression test, and then evaluate for a possible injection pump and injector overhaul.

Mad Mackie said:

Sounds like it is running on two cylinders.
Suggest doing a compression test, and then evaluate for a possible injection pump and injector overhaul.

Click to expand...

Since I didn't touch anything mechanically to it at all could there injection pump or injector be damaged by the following method of priming the fuel:
1. Using a big syringe full of diesel and pumping it into the hose coming out of the fuel filter going into the mechanical pump
2. On the opposite side of the mechanical fuel pump where the fuel goes into is a breather bolt I opened to drain air until fuel started coming out, which I closed then
3. I cranked engine until it started and it instantly smoked



see pic

There may still be some air at one injector, or one injector may be leaking or opening at too low of pressure, particularly if the engine blows white smoke at initial start which usually indicates unburned fuel.
You may be able to find a manual on line for this engine.

Mad Mackie said:

There may still be some air at one injector, or one injector may be leaking or opening at too low of pressure, particularly if the engine blows white smoke at initial start which usually indicates unburned fuel.
You may be able to find a manual on line for this engine.

Click to expand...

Those are great suggestions, I might be going around about it the wrong way in testing it just because I don't have the tools to measure some of those things. This is what I did and you can look at the video MVI 2506 - YouTube . I love videos, they show so much more. First I loosened each of the fuel lines and cranked it over and they all were pumping fuel. Second, I took off the exhausted manifold to see which cylinders are smoking. When I saw it was the two left ones and since it didn't smoke originally before I striped the mower to clean it and worked great before, I assumed maybe its the glow plugs. So I took the two left glow plugs and swapped them with the two right ones where cylinders didn't smoke. The results are the same, no change. However the exhausted from two right ones was coming out hot/warm but the exhaust from the rear two was not. So its not the glow plugs because the results were the same when I swapped them.

So what is my next step, is it to check the cylinder pressure, or something else and how do I do that?

MVI 2506 - YouTube

newbe101 said:

Those are great suggestions, I might be going around about it the wrong way in testing it just because I don't have the tools to measure some of those things. This is what I did and you can look at the video MVI 2506 - YouTube . I love videos, they show so much more. First I loosened each of the fuel lines and cranked it over and they all were pumping fuel. Second, I took off the exhausted manifold to see which cylinders are smoking. When I saw it was the two left ones and since it didn't smoke originally before I striped the mower to clean it and worked great before, I assumed maybe its the glow plugs. So I took the two left glow plugs and swapped them with the two right ones where cylinders didn't smoke. The results are the same, no change. However the exhausted from two right ones was coming out hot/warm but the exhaust from the rear two was not. So its not the glow plugs because the results were the same when I swapped them.

So what is my next step, is it to check the cylinder pressure, or something else and how do I do that?

MVI 2506 - YouTube

Click to expand...

A few thoughts, but I have not watched the video yet, maybe later.
First of all glow plugs only affect starting, they have nothing to do with how it runs once it starts.
You can take the injectors out and have them checked by a diesel injection repair facility.
Without running a compression check it is hard to tell what shape the engine is in. With two adjacent cylinders affected a head gasket is a possibility. We can guess all day but until some basic checks are done it is hard to say.

OK so I can close this thread with some good news. First thank you all for your info, it's always appreciated. Since I didn't have the tools to do or the checking I figured it would be worth it to take it to a Kubota dealer just for diagnostic and pressure check of the fuel pump and cylinders. Well, all cylinders were with in spec to include one which was a bit low but still passed the pressure test. Then they tested the fuel pump and found one of the injectors wasn't pumping. Apparently one of the springs at the pump was stuck so they took the pump off sprayed cleaner where the spring is and loosened it. Everything was reinstalled and $202 later it works just like it did before I took it apart. It was worth the money instead of taking things apart and guessing at things. I had it looked at here in Dickerson Kubota in Fredericksburg VA. It always help when you can talk to the service people verses just some clerk.