Fuel contamination on Oil Analysis

[ejuan]

Hi guys, hope everyone is doing fine. I sent a sample of engine oil of one of our hauler trucks the other day. It came back reporting High fuel contamination, check fuel inyection system. I have to send another sample in the next 100 hours. I'm just starting an oil analysis program so I´m not so experienced in this area. Do you know what are the causes for finding fuel contamination in engine oil?, what points should I check?. By the way fuel economy on this hauler is not as good as the other one, exactly the same brand, model and engine, same amount of hours.

Thanks in advance for your help.

Juan

 

[gpap123]

In my opinion the first think you have to check is injection system and valves clearance.

 

[mitch504]

What engine is it?

 

[ILLICEMAN]

Look into the injection pump drive shaft seal and or fuel pump seals.

 

[ejuan]

It is a Komatsu SAA6D140 on a Komatsu HD-405-6 Haul Dumper

 

[ejuan]

I´ll go chech the fuel pump shaft seal as my first option.... any other sugestions will be aprecciated

 

[ohiofleet]

9 times out of 10 it will be an injector how did you ck them

 

[ejuan]

Well I have not checked them yet, I guess I´ll have to get them checked at a Fuel Injection Laboratory right?

 

[Cat_man320]

On Most engines the only place that fuel oil can get into the lube oil is through the injection pump . I am assumming that the injection pump is mounted to the front housing which includes the timeing gears etc. when the front seal in the injection pump fails , fuel run into the timing gear housing and down into the base .
Its possible it could be an injector but i suspect if it was the engine would be putting out a lot of black smoke and maybe a slight miss under load . I'd say , get your self a injection pump front seal .

 

[John C.]

The injectors are the first thing to check. You can remove them and have these pop tested by someone that has a test hand pump and the proper hookup fittings. Old injectors can leak fuel which drains onto the piston and down past the rings when the engine is shut down. How is your smoke when you start the engine in the mourning?

The fuel pump is the next likely place. If you have a bad injector you can try changing that first or maybe just install a set. In many cases if you have multiple bad injectors, you will also have a bad fuel injection pump. As I recall those pumps use engine oil to lubricate the pump cam and bearings. A leaking plunger and barrel assembly will contaminate the oil as easily as a bad injector.

How is this machine running?

 

[ejuan]

The machine is running normally, the only thing is that it´s fuel efficiency is the worst of the two haul trucks. Today I'm going to check the fuel pump shaft seal. I´ll ask the operator how is the smoke when started in the morning.

 

[Dozerboy]

How high are we talking here they normally give you a %? Lots of idling can cause fuel contamination.

 

[ejuan]

They did not give me a % but reported over normal parameters. I sent another sample yesterday with the oil having 150 hours in engine just to make sure before I start checking the fuel system. It is a common rail fuel injection system, I dont want to mess with it until Im totally sure there is fuel contamination.