l3400 Motor noise

[grizzjeeper]

Brought my l3400 hst in for service because of an engine noise. After machine is warmed up anything over 1800 RPM had a knocking noise. Sounded like it was coming from the valvetrain. Dealer hears noice but doesnt know what the problem is but says something deffinately isnt right. They looked at the valvetrain and couldnt see anything there so they say its probably deeper in the motor. Their answer was just keep running it...

So now I am pretty po's about this. 26k tractor 5 years old with 180 hours..
What do I do? I imagine once it breaks it will be a huge repair bill....

 

[rbargeron]

Brought my l3400 hst in for service because of an engine noise. After machine is warmed up anything over 1800 RPM had a knocking noise. Sounded like it was coming from the valvetrain. Dealer hears noice but doesnt know what the problem is but says something deffinately isnt right. They looked at the valvetrain and couldnt see anything there so they say its probably deeper in the motor. Their answer was just keep running it...

So now I am pretty po's about this. 26k tractor 5 years old with 180 hours..
What do I do? I imagine once it breaks it will be a huge repair bill....

I agree "just run it" is a poor response unless they can show it is minor and why it's not likely to escalate into a big repair. Did they get the Kubota rep to look into it? Usually if the dealer's people can't help they call the factory guy. (There used to be only be one guy for all of New England and western NY). If it is a loose valve seat or something repairing the head would be a lot cheaper than if the engine block eats it. Does the noise change with engine load? or just with rpm? Does the governor work normally? A broken governor spring may be a possibility - it would allow some clatter at higher rpm - but you'd notice a poor response to load - like when driving up a hill. You might want to get a sharper (bigger) dealer involved. Good luck - and let us know how it develops. Take care, Dick B

 

[firefighter jim]

I know this is elementary but change the oil and filter and see if the problem persists.

 

[grizzjeeper]

Yes did change oil still persists. ts actuall been there for about a year and two oil changes. Its just getting worse.

 

[Dead Horse]

"Keep running it" is advice someone gives when they are NOT talking about their money.......

take a stethascope like device and seeif you can locate more precisely the "knock".

Start at the head and work down, cylinder by cylinder.

If it is real low, you may get lucky and just have to replace a set of rod bearings. 180 hours is nothing, 36 hours a year......... it sure does not get used much.

 

[B2400]

Check your fan belt and see if it might be missing a "chunk".

 

[Adiredneck]

Mine has a similar sound when revved high. I rarely get to 2500 RPM's, but when I cross the road from my neighbor's house in High range, It rattles a bit.

 

[grizzjeeper]

Update

Pressed dealer to look deeper, they pulled oil pan nothing in bottom end, took head off and brought it to the machine shop where they discovered carbon build up on the valves. Cleaned carbon off and no more noise. They said I am not letting it get hot enough.. I disagree as anytime this tractor has been uses its been used for long durations. So the question is how to prevent this from happening again.

Oh and the cost was just about 1k to do this. NOT impressed... but no leg to stand on....

 

[teg]

Thanks for the update :thumbsup: I don't have an answer about how to prevent carbon build up... but hoping someone else will chime in so I can find out

 

[LD1]

Oh and the cost was just about 1k to do this. NOT impressed... but no leg to stand on....

You mean they charged YOU $1k?????

Is it still under warrenty??

Did they charge you the first time when they looked it over and told you to just drive it anyway??

It sounds like you dont have a very good dealer.

 

[grizzjeeper]

Not under warranty due to age, stinks as its just 190 hours..

I never picked it up from the dealer on first analysis, they had it until I pressured them to work harder.

Hammond Tractor is my dealer.

To all the folks in central maine, there is a comercial about "the Friendly folks" which is Union tractor. I now know why they use that slogan and will be doing my business there instead of hammond.

 

[brain55]

$1000 for that repair does not seem unreasonable to me. I would be more upset that I had to push the dealer to look deeper, than I would be about that bill. Did you really expect them to tear into and repair your 5 year old tractor for free? If your car has a 3 year 36K mile warranty and 5 years later you only have 10K miles on it do you expect that dealer to repair your car for free? There was no defect in workmanship or quality here. I would say it is the crappy fuel we have to run now, or lack of desire to run the machine up in the RPM where it was designed to run, or a combination of the two.

If I was doing the diagnosis and repair on that tractor, I would have charged pretty close to the same amount maybe a little more. The cost is not out of line. To try and prevent this in the future I would either run Redline diesel fuel catalyst, or Lucas Oil fuel treatment on a regular basis.

Brian

 

[ccsial]

Update

Pressed dealer to look deeper, they pulled oil pan nothing in bottom end, took head off and brought it to the machine shop where they discovered carbon build up on the valves. Cleaned carbon off and no more noise. They said I am not letting it get hot enough.. I disagree as anytime this tractor has been uses its been used for long durations. So the question is how to prevent this from happening again.

Oh and the cost was just about 1k to do this. NOT impressed... but no leg to stand on....

Long duration alone does not mean it will get hot. Hard work over time does that. It is not good to run at lower RPM all the time. Not saying you were doing this, just saying it can be a problem.

As mentioned there are some additives that should help. Had you put in an additive and worked it hard for a while it may have shed some of the carbon by itself. Of course you would have had to know what the problem was and I can understand not knowing that. I also wonder about the fuel your using.

I have 240 hours on my L3400 mowing and snow blowing with no problems yet.

 

[dodge man]

I agree, that bill is not out of line at all. They tore into the motor pretty deep to find the problem. They may even have given you a break on the cost. All I can say is to write a nice letter to Kubota and see if they will do anything for you. Tell them your situation and the low hours and see what happens. I wouldn't expect anything, but you never know?

Back to the original problem and maybe someone else will have some input, but why would carbon build up cause a knock? The only reason I can come up with is that a valve wasn't sealing good and you could hear the cylinder firing through a partly open valve. Does this make sense to anyone else?

I'm not sure what could cause this problem on an engine with such low hours? Could it be lack of use?

 

[Larry Caldwell]

Update

Pressed dealer to look deeper, they pulled oil pan nothing in bottom end, took head off and brought it to the machine shop where they discovered carbon build up on the valves. Cleaned carbon off and no more noise. They said I am not letting it get hot enough.. I disagree as anytime this tractor has been uses its been used for long durations. So the question is how to prevent this from happening again.

Oh and the cost was just about 1k to do this. NOT impressed... but no leg to stand on....

There are diesel fuel conditioners that are supposed to reduce carbon buildup. Shop the shelves at a major truck stop. I run Gunk Diesel Tone and a 100:1 mix of 2-cycle motor oil in the fuel since they went to low sulfur. There are a lot of other options.

 

[kuboman]

There are diesel fuel conditioners that are supposed to reduce carbon buildup. Shop the shelves at a major truck stop. I run Gunk Diesel Tone and a 100:1 mix of 2-cycle motor oil in the fuel since they went to low sulfur. There are a lot of other options.

I think it is a fueling problem. Maybe dirty injectors. Give it a good dose of fuel conditioner plus an injector cleaner. I carboned up engine will get to be real noisy. A real good work out helps with the carbon build up:thumbsup:

 

[brain55]

I think it is a fueling problem. Maybe dirty injectors. Give it a good dose of fuel conditioner plus an injector cleaner. I carboned up engine will get to be real noisy. A real good work out helps with the carbon build up:thumbsup:

I'm hoping they tested the injectors while they had it apart, I know I would have.

Brian