L2350 Fuel injector gasket problem?

[717SacredLand]

Evening Folks,
I've got a L2350 front end loader, Great machine, had it for a few years now. Recently while operating it, I heard a loud POP! followed by a hissing sound, I couldn't locate the source, but at that time a very small leak developed somewhere around the injector pump, though I was never able to identify the exact source, and all the bolts were properly tightened. Well today, I started to use it, and it sputtered and died right away, subsequent attempts to start had the same result. I bled the injector lines, but still no starts. When bleeding however, it seemed that the pressure of the fuel was far lower than it should have been, more of a drip than a spray.
Research around forums indicates that that popping sound was likely a copper gasket failing. Is there anyway that a failed gasket could have shifted and is now in a position either to obstruct the fuel or introduce air pockets?

Thanks so much, I've really come to appreciate this forum, which I've been reading for a few years, even though I've only now made and account.

 

[North Idaho Wolfman]

If an injector gasket failed it would hiss air while cranking.
it would be fairly loud.
It wouldn't effect much of anything else, besides that cylinder not firing.

Your going to have to do some serious trouble shooting.
But here are some guesses:
Failed lift pump
Failed Injection pump (check oil for fuel), pull all the injection lines and set throttle to high, while cranking the engine, each port should fountain fuel up about the same amount on each, if one doesn't it's a bad pump, if all of them only spit a small amount of fuel, you need to look at the fuel system before the Injection pump.

I'll send you a link to download the WSM for that tractor and it should help with specifics.

 

[717SacredLand]

Update!
Cleaned off the engine area to get a better idea of exactly how much fuel was coming out of the lines. Before taking off the lines, I decided to turn it over to check if I still have good battery charge, and low and behold, it actually started! It sounded pretty weak and sputtering, but it started and I ran it up and down the driveway. It's leak is more pronounced, and it now has a bad belt slipping noise (Engine fan, I think), and the OIL CHANGE light on now. So hopefully that rules out a bad injector pump, and points instead to problem with the fuel system, air getting in, etc...
I guess from here I'll replace all the gaskets and check all the lines for seal. Should I still be looking at the lift pump? Thanks for your response and the WSM, by the way, it's been really helpful to read.

 

[North Idaho Wolfman]

I think you have some serious issue!

That light is not an "oil change light" it a "NO OIL PRESSURE" light, STOP Running it, or your going to do some serious damage!

Where is the leak exactly and is it diesel fuel or water / antifreeze?

If the belt is slipping it could be you have a seized water pump.

But more troubling is the lack of oil pressure, check the oil, I would even drain it to check it, your looking for water / antifreeze in the oil.

 

[717SacredLand]

Okay, update!
Found and fixed the leak. Turned out, there was an entire gasket missing on the intake into the fuel injector, no idea where it might have went since that leak only developed recently after a loud popping sound. Guess it broke and fell off. Anyway, got a new gasket on and no more leak.
As for the oil, I drained it and it seemed fine in terms of being just oil, with no water or coolant in it. It was very very used however. I put new oil in and changed the filter, and after that there was no more oil pressure light.
I put some belt dressing on the belt and that took care of the slipping/squeak.
However, something is still wrong... the engine starts up, runs, and idles, but it sounds a bit wrong. More of a popping then the deep tumble I'm used to. It also seems to stall out very easily under a load. Nearest thing I can compare the way it sounds/feels to is an old car with the timing off. Any ideas on that? Thanks for all your help so far.

Unrelated, a hydraulic line sprung a leak, so back to the supplier for a replacement hose.

 

[D2Cat]

Sounds like it had been a long time between oil changes. Might have a similar problem with the fuel filter. It may be restricted form being too long in the fuel line!!! Replace it.

 

[North Idaho Wolfman]

Sounds like you have an issue with the fuel injection pump or the fuel injectors.

 

[717SacredLand]

Okey dokey, checked the fuel lines today. loosened then at the upper end, and had a solid diesel spray from two, but no diesel at all from the third one.

 

[717SacredLand]

Okay, I took the lines off and cleaned them, and now I do once again have a very strong steady spray of fuel from all three when I crank then engine with the lines loosened. However, I still have a lack of power, an unusual amount of smoke and a tendency to stall out.
What should I be looking at next? Thanks!

 

[North Idaho Wolfman]

Sounds like you have a dead and dirty injector.

 

[CountryBumkin]

You may be able to do a cylinder drop test. I'm not sure how well this test works on small cylinder engines (i.e. 3 cyl.) as I only worked on large equipment in my day.

But what you do is, you set the rpm to a speed (like 1500 rpm) where the engine won't stall out during the test. We did this test with the engine at slightly above idle speed. Then with the engine running, you loosen one injector line and record how far the rpm drops, then tighten that line, let the engine speed recover/stabilize, then do the same to the next line, and so on.

The problem cylinder will not drop as much (or any) rpm as the good cylinders. Once you determine where the bad cylinder is you can start troubleshooting the reason (bad injector, low compression, valve, ect.).

 

[North Idaho Wolfman]

Simple way to find out if you have an injector problem or an injection pump problem, pull the injectors and swap them, if it's an injector the dead cylinder will follow the injector, dead injection pump the dead cylinder will stay on the same cylinder.

You do need to verify that you have good compression and eliminate that as the cause of the non fire.

If you do need to rebuild or replace an injector, replace or rebuild all of them!

 

[CountryBumkin]

You may be able to do a cylinder drop test. I'm not sure how well this test works on small cylinder engines (i.e. 3 cyl.) as I only worked on large equipment in my day.

But what you do is, you set the rpm to a speed (like 1500 rpm) where the engine won't stall out during the test. We did this test with the engine at slightly above idle speed. Then with the engine running, you loosen one injector line and record how far the rpm drops, then tighten that line, let the engine speed recover/stabilize, then do the same to the next line, and so on.

The problem cylinder will not drop as much (or any) rpm as the good cylinders. Once you determine where the bad cylinder is you can start troubleshooting the reason (bad injector, low compression, valve, ect.).

EDIT: Once you determine if you have a bad cylinder then you would swap injectors to see if the problem moves with the injector. But if you just swap injectors to start with, the engine is going to run the same (its just a different cylinder now that is weak), unless you have a known good injector to swap with.

 

[717SacredLand]

Wow! Lot's of replies! Thanks guys!
I'll do that cylinder drop test tomorrow.
Pending that, how hard is it to pull the injectors? I've never done that myself before?
Thanks!

 

[CountryBumkin]

Wow! Lot's of replies! Thanks guys!
I'll do that cylinder drop test tomorrow.
Pending that, how hard is it to pull the injectors? I've never done that myself before?
Thanks!

Like I said, I've never done a cylinder drop test on an engine that small, so I don't know if it will work. The smallest stuff I worked on was 6-cylinder.

A more common test, and less messy, was to use an infrared thermometer gun to measure temp at the cylinder's exhaust port on the manifold and see if all the cylinders where the same temp (but I assume you don't have one of these).

I'm not sure how rough the engine run (or if it will run) when you drop to 2 cylinders. The key to the test is having all cylinders drop the same rpm until you get to the one cylinder where the rpm drop is less.

I think Wolfman is a Kubota mechanic - perhaps he can comment on whether they do this test in his shop (but most shops would probably have a thermal gun). Or report back if it works if you try. If you do perform this test, have a rag ready to lay over the line when you crack it loose to help capture the spray.

 

[North Idaho Wolfman]

The "drop test is very accurate and easy on Kubota's, they will drop a lot of RPM, but usually not die, when it goes from a live cylinder to dead.
No real need for a rag to catch the spray, on these it's more of a heavy drizzle when you crack the line.

You can usually tell by ear if one is off, as it will not drop as much in RPM's as the others.

Also on these little guys from a cold start, you can start them and touch the exhaust manifold output and move from one to the other and feel if one is colder than the others, they don't get real hot real fast.
I agree a temp gun is really good to have around to do these kind of tasks!

Pulling the injectors on this model is easy, it's just a matter of removing feed lines, and return lines, then pulling them out like a spark plug.
Use brake parts cleaner around the injectors to remove crud before taking them out.