L4600 Engine question

[majog]

After changing fuel filter and bleeding injectors my Kubota L4600 ran but seemed to not have as much power. The service guy came out and diagnosed that I had a fuel injector that was not providing fuel to the number 3 cylinder. After pulling and retightening all the fuel lines it started working but with the number 3 fuel line attached smoked black smoke and had a metallic pinning noise coming from the exhaust. Loosen the fuel line so that it does not get fuel and it goes away so know whatever the issue is it is with the number 3 cylinder.

My question is this. He stated that Kubota's get their cylinder lubrication from the diesel fuel (not sure that is correct as diesel is a cleaner not a lubricant) and that since I ran it for about 16 hours without diesel going to the cylinder that it was probably shot and they would need to do a pressure test and likely replace just that cylinder.

Does this sound remotely possible to any of you? Sort of sounds fishy to me and I think it is just an injector problem.

RM

 

[D2Cat]

Welcome to the forum. It does sound like you have an injector that needs attention. You could remove the injector, take it to a diesel injection pump repair shop and have them test it to confirm. Or, you could buy a new injector. I would not recommend an after market injector, because you may find out the new one you buy is not much better than the one you took out.

Might give these folks a call. https://oregonfuelinjection.com/ They have good products, prices and service. After you check with them you may decide to replace all the injectors while you're at it.

 

[majog]

Thx d2cat. I could. Not figure out how not getting fuel would trash the cylinder


Rm

 

[D2Cat]

No, your cylinder is fine. That noise you hear that sounds like your engine is coming unglued is most likely the injector.

Seems kind of odd that you had injector trouble after changing the fuel filter. During those hours you ran the tractor, what did you notice....like missing out, lack of power all the time or just some time, lots of black smoke?

If you're handy with wrenches, you could remove that injector and loosen the steel line going to it. Get the line off to the side of the engine, and install the injector. DO NOT BEND THE STEEL LINE. Loosen it to rotate it. Then turn the engine over and see how the spray pattern is. You have to be careful the pressure is a couple of thousand PSI and the fuel can penetrate your skin. Put a piece of cardboard a few inches under the injector and see what it does. The injector should put out a mist patern, not a stream.

 

[majog]

Thanks cat

After the fuel filter change it had 2 times in 16 hours where it would just loose power like it was not getting fuel at all. If I reved it high and let it run it worked itself back out. That is why I thought I might have crud in the tank or fuel line. The kubota mechanic was a young kid and bled the system again by loosing all the injector lines one by one and did not use the fuel return bleeder knob. When he followed the number 3 fuel line back to the district line he found it a bit loose on the distribution bar ad tighten. When he did number3 started back online but with black smoke and a pinging noise.

Rm

 

[D2Cat]

Might just try some injector cleaner like Howes (you can get that at WalMart) and run it for a while. It may still have some air in the fuel lines, or sucking air someplace. If it runs good and then doesn't makes me think it's getting air somewhere.

 

[North Idaho Wolfman]

Black smoke and pinging point to a bad injector!

Move the injector to another cylinder and see if the problem moves with the injector.

If he messed with the delivery valve on the injection pump (he said a line was loose) he could have very well messed up the pump.

 

[thepumpguysc]

THATS just what I was thinkin NIW.. Loose delivery valve holder.. An easy fix w/ the right tools..{torque wrench & either a 17 or 19mm socket}}
Its still possible theres crud in the tank, slowing down the fuel to the inj. pump.. BUT the pinging is, Dollars to doughnuts, a weak injector or loose delivery valve holder..
The holder on the pump, the piece the line screws on to, has to be tightened/torqued to 30-35 ftlbs..
IF ITS LOOSE> it will leak internally or externally & not deliver a "full shot" of fuel to the injector, causing a low power problem or a ping or hammering noise..
The "service guy" sounds like a rookie.?? That's probably the easiest diagnosis there is.!! "Those guys" aren't allowed to touch the inj. pumps.. their job is to REPLACE THEM.. at a BIG $$ amount..
You'll be $$ ahead if you can turn wrenches yourself or get a local guy to come help..
The "service guy" wasn't doing you any favors & is spending you money..
SURE, if you get the pump, injectors & the engine rebuilt, the noise WILL go away.. {if ya know what I mean}..

 

[majog]

Thx guys appreciate all the advice! Moving the injectors was brilliant advice. Will let you all know what it turned out to be.

J

 

[majog]

OK Guys,

It has been 2 weeks and I finally got my tractor back from repair. Basically it was a problem with the number 3 cylinder plunger in the fuel prawn (the distribution bar between the pump and injectors.

Problem was self imposed when I changed the fuel filter. I had to bleed the system to get the tractor to start and run. In doing so I could not get to the top of the fuel line housing on the number 3 injector so bled that one on the fuel pawls for that cylinder. Apparently un-beknownst to me, there is a spring and plunger on each of the fuel distribution points feeding the injectors. You can't see them without removing the whole pawl. When loosen the fuel line, the plunger can and usually does get tilted. This does 2 things, first it can cause the fuel to that cylinder to cut out which did happen. Secondly it can cause the timing to get off for some reason. Still don't understand that one but ok.

So $1800 dollars later (all for labor @ 18 hours plus tax only $75 in parts), they removed all the injectors testing them, then checked the fuel injection pump. They also had to take off and put back on the glow plugs, intake manifold, do a pressure test, and rest the throttle springs.

I tried to save a couple of hundred dollars doing my own fluid and filter services and not bleeding the fuel system correctly cost me the equivalent of 4 services, LOL. Nothing like shooting yourself in the foot.