Possible engine trouble? L3400

[LD1]

Not sure what just happened to me today. Started the tractor up to move a few rounds of firewood out of the way. After bout 2 minutes of running (long enough to pull out of garage and get to rounds and hop off the seat to load), the engine started puffing some blue smoke (probably oil), and running rough sounding like it was going to die. Also seemed a good bit louder than normal. Diesels are pretty noisy to begin with, and this didnt sound any different, just louder.

I started to nurse it back to the shop, and it cleared up and ran fine. But got it in the shop anyway and looked things over. Oil level is good, oil pressure light never came on, everything seems fine. So after about 10 minutes of looking it over, and finding nothing, thinking maybe it was just a fluke and I am imagining things. So I head back out to move the wood I started to in the first place. After I get them moved, it does it again on my way back to the shop. Gets really loud like a valve with 10x's too much lash, but then clears up.

Not sure what is going on and if it will do it again. Looking to TBN for some help. Any Ideas?

Tractor has 585hrs, oil always changed on schedule and always good oil. Either rotella, delo, or delvac. (actually do for a change @ 600hrs). I have never had any issues out of this tractor but this has me worried.

Also important to note, I use old 5 gal hydraulic oil buckets for fuel. I have maybe 8 of them. Always just empty the pail into whatever I am changing hydraulic oil in, then use for diesel, thinking that the tad bit of residual oil wont hurt anything. (Especially on my 1967 7000hr backhoe). Been doing that for years, and never an issue. I just filled up the tractor out of one of these pails yesterday and I think this is the first time this one has been used. So it would have a tad higher concentration of hydro oil, but I certainly wouldnt think it would cause this...

Any ideas?

 

[rbargeron]

The symptoms are like when a valve seat has come loose. With luck it hasn't seriously damaged the piston or the head - but it should not be started up again until a compression check has been done to rule it out.

When a seat comes loose, it can rattle up and down with the valve, sometimes going back into its recess, but other times getting hung up and holding the valve open. Then the piston may smack the open valve and cause all kinds of carnage. A compression test will tell if the head needs to come off for inspection. I believe this kind of failure is rare on Kubota engines.

If the total amount of "foreign" oil in the fuel pail was just a few teaspoons it would be pretty dispersed and would not be expected to cause a sudden change in engine smoke or clatter. Once running a diesel will tolerate almost anything that can get through the filter (except volatiles like gasoline or cleaning solvents).

When it made the noise the second time, did it go back to normal before you shut it off? How long did each time last? Can you describe it in more detail? Smoke first?, noise first?, skipping? any skipping after the noise stopped? etc.

 

[LD1]

When it made the noise the second time, did it go back to normal before you shut it off? How long did each time last? Can you describe it in more detail? Smoke first?, noise first?, skipping? any skipping after the noise stopped? etc.

Yes it went back to normal. Each time, the incident lasted maybe 5 seconds or so.

I think it started as a little smoke puffing first, then as the smoke got thicker, the noise got louder at the same time. And then the noise and smoke finally slowed down and stopped. So it wasnt really and issue instantly and disappeared instantly, more gradual, lasting a total of 5 seconds each time.

Didnt really do any skipping or missing. Just slowed down, kinda like going from idle (~700rpm) and forcing it to slow down to ~350 rpm, and then allowing it to get back to idle.

 

[rbargeron]

Yes it went back to normal. Each time, the incident lasted maybe 5 seconds or so.

I think it started as a little smoke puffing first, then as the smoke got thicker, the noise got louder at the same time. And then the noise and smoke finally slowed down and stopped. So it wasnt really and issue instantly and disappeared instantly, more gradual, lasting a total of 5 seconds each time.

Didnt really do any skipping or missing. Just slowed down, kinda like going from idle (~700rpm) and forcing it to slow down to ~350 rpm, and then allowing it to get back to idle.

A tiny leak of anti-freeze in the chamber(s) could smoke blue-ish-white and would run rough and slow it down - but it's odd that it would show up in random small doses. Usually a head gasket leaks invisibly while its running and then a few drops go in after shutoff - making serious smoke later when started again. But it would smoke right away not run ok first. If a compression test doesn't show anything, then I'd try starting it again and let it just idle for a while & see how it acts. If it does it again there's something getting into a cylinder or two that shouldn't be. A new head gasket is not a huge job on these engines. Good luck. Dick B

 

[Chilly807]

Were the fuel buckets stored outside where water could accumulate on the top during a rain? If it's possible that happened, what can take place is the bucket expands during the heat of the day, then contracts as it cools at night. When it contracts, it pulls any water laying on top of the bucket inside. More common with metal drums, but it can occur with pails too.

In any case, I'd drain the fuel tank and replace with fresh fuel before you go to any heroic lengths engine-wise.

Sean

Sean

 

[kuboman]

Quite possibly fuel related. If its not contaminated diesel fuel I would bet a stuck injector. Get yourself a high quality fuel conditioner and run some high doses of that for a while.

 

[skyhook]

Quite possibly fuel related. If its not contaminated diesel fuel I would bet a stuck injector. Get yourself a high quality fuel conditioner and run some high doses of that for a while.

I was thinking the same,
with only that many hours on the machine, I would concentrate on fuel condition,
could be some debris thats stuck in the IP or as stated, an injector is clogging.
Give her a new tank of fuel, maybe throw a treat in there, thats what i'd do.

 

[LD1]

Forgot to update this thread.

I took the fuel filter out and it was pretty mucky and did look like it could have had a little water in it. I cleaned it and drained and flushed the tank. I forgot that about 10 hours ago I had to replace the fuel cap as it had a crack. The top had kinda "popped" out of the threaded portion as it would if you over-tighten it. It wasnt bad, and ran it a few hours with it cracked (not in the rain), until I got the replacement. Never gave it a second thought, but since the fuel filter was pretty dirty and knowing the cap was cracked, I drained and flushed anyway.

After all of that, ran the tractor for about an hour doing odd jobs and moving stuff and no re-occurrence yet.

 

[rbargeron]

Good to hear about the fuel cap. Never mind the engine tests. :drink:

 

[LD1]

Yea, I kinda forgot about it and didnt really give it any thought. Cause I had ran for the last 10 or so hours without a hitch. And while the cap was cracked, maybe only ran 1 can of fuel through it?? IT wasnt like I left the cap off or anything. Just a small crack, that would open up (spread) the more the cap was tightned. So it was a balancing act between tight enough not to come off, but not too tight the crack opened up wide.