M7040 Smoking with Fuel in Oil

[dmann33]

My 1+ year old Kubota M7040 started smoking (blue/grey) and after getting no improvement after cleaning the fuel tank and changing the fuel filter I sent it to the dealer.

Dealer discovered that fuel is getting in the crankcase (thinning the oil). Problem did not subside when hooked to remote fuel source.

Problems in #1 cylinder then discovered: cold, low compression. Backlash on valves ok and emissions equip ok and they are now waiting on Kubota Rep. It is under warranty.

I've searched the threads, but could not find any cases like this. Has anybody here seen or heard of something like this?

 

[brain55]

In the 12 years I was a Kubota dealership mechanic I only ever warranted one engine. The intake gasket hadn't sealed and you could see the path where the dirt got in and dusted the engine. Kubota's typically don't have engine problems. I hope they find the problem and get it corrected for you quickly. The last company I worked for had a 7040 it was a great machine.

Brian

 

[dmann33]

In the 12 years I was a Kubota dealership mechanic I only ever warranted one engine.
Brian

Do you mean as is in only one full engine replacement or only once did you see any engine warranty work at all?

 

[brain55]

Do you mean as is in only one full engine replacement or only once did you see any engine warranty work at all?

I only saw one engine that was repaired under warranty. Meaning that Kubota engines typically don't fail in the warranty period. Typically they don't fail period.

Please don't take this the wrong way. I'm not suggesting that you're at fault at all. Typically most engine repairs I did were from customer neglect. The rest were from living long full lives.

Brian

 

[dmann33]

No worries. I was just trying to see how amazing your claim was. I can't imagine I did anything to the engine in just 12 months considering my M5400 didn't have a single engine issue in the previous 14 years. I finally figured I would just upgrade and count myself lucky. I love the 7040. That's one reason I went back to Kubota.

 

[brain55]

One of my customers now has 3 Kubota machines with over 8000 hrs one of those is about to turn over 10,000 hrs.

 

[art]

It does happen once in a while! We have seen many over 10,000 hours and we have many more getting close to it and compared to the other makes it is rare to work on one!

 

[dmann33]

Update: I've got more bad news from the dealer.

They filed a pre-claim with Kubota on the basis of "low compression on front cylinder, front cylinder running cold and unburnt fuel going into exhaust and crankcase.

Kubota finally responded after 4 days with the following:

Compression is low, but within 10% spec of other cylinders, but the rings are so bad your dumping oil into the crankcase. At this point low compression and ring issue is not enough to validate warranty. At 729 hours this sounds more like a dusting and than a factory defect. Please tear down and inspect and validate a defect, but keep in mind if no defect is found then customer will be responsible for total repair bill."

What a crock! Its going to be about $1000 just to do this inspection.

What I really don't understand is how could the front cylinder could possibly not be firing (and therefore burning this fuel) if the compression is within spec? I'm waiting to find out what the compression actually is. As brian55 stated I might have a failed intake gasket, but it should be firing still if compression is within spec, no?

My private mech (non-warranty stuff), suggested that the injector may be bad and overloading front cylinder with fuel to the point it would not fire. That would not explain the lowered compression, but can fuel still get in the crankcase if the rings were ok?

Also, I'm not sure if my tractor has a turbo or not, but could a failing turbo result in my problems?

 

[Tx Jim]

My M7040 definitely has a turbocharger. I agree 10% low compression should still ignite fuel. I'd suggest to check valve clearance's on cyl head. Over fueling actually increases compression. An injector not atomizing fuel can cause a misfire.

 

[Gary Fowler]

I don't understand how Kubota could claim "dusting" if my definition of that is correct as it allowing dust to get into engine via bad air filter or other leak in intake air. If that is the case, all cylinders would be bad not just one. It seems Kubota has about the worst warranty(length of time) of any tractor on the market today and then they still don't want to honor it.