Briggs and Stratton experts in here

[[CJ]]

Need a little help with a Craftsman power washer with a 7.75hp B&S engine. The part number is 13 0507 62 40803. The problem I'm having is after limited use the oil gets really dirty. It's brand new with a total run time of about 2 hours on it.

I first ran it for about an hour and a half with castrol 10w-30, checked the oil after and it was black. I drained it ran it for another 30 min. with the same results. After this I checked the plug, it had some carbon deposits on it and the air filter which along with the housing was soaked in oil. The machine does not run rough, does'nt seem down on power and does not smoke.

Any ideas what the isue could be?

 

[jkwilson]

What kind of filter does it have? Any chance it's got an oil-soaked prefilter and somebody got carried away?

 

[Wakefield]

If I remember most of those (paper) air filters are not supposed to be oiled.
On some of them if the engine is tipped over a wrong way oil will come through the breather and go onto the air filter. Looks like it has a real choke,if the engine is run a lot without the choke all of the way open it might get rich enough to blacken the oil. Usually if grossly rich it will make black smoke and smell gassy.
I think a healthy mower engine will darken oil faster than a good car engine.

Oil not overfilled?

 

[[CJ]]

What kind of filter does it have? Any chance it's got an oil-soaked prefilter and somebody got carried away?

It's a foam filter, dont believe it has a prefilter but, I'll have to check.

 

[[CJ]]

If I remember most of those (paper) air filters are not supposed to be oiled.
On some of them if the engine is tipped over a wrong way oil will come through the breather and go onto the air filter. Looks like it has a real choke,if the engine is run a lot without the choke all of the way open it might get rich enough to blacken the oil. Usually if grossly rich it will make black smoke and smell gassy.
I think a healthy mower engine will darken oil faster than a good car engine.

Oil not overfilled?

Oil level is where it needs to be. I have a push mower with a B&S, have used it at least 5 times this season and the oil is still honey colored, same oil by the way. There isnt any choke lever on the engine though.

 

[G_P]

Is the muffler all blackened? That could be a sign that its running too rich.

 

[bochnak]

The plug does not look rich too me.

 

[[CJ]]

Is the muffler all blackened? That could be a sign that its running too rich.

The muffler still looks new.

The plug does not look rich too me.

Me neither, It almost looks like its running kind of lean.

 

[bochnak]

Me neither, It almost looks like its running kind of lean.

Does the top ring have a full turn of color?

 

[Chris Stapley]

First shot shows the choke completely shut, hope it wasn't running like that? If so and it didn't appear to be running rich, I'd remove the carb and give it a thorough cleaning so the poor thing will run on its own without choke.

 

[Wakefield]

Does it have some kind of "automatic choke" or "one start"? Is it opening the choke completely when running?
Should have some kind of warranty on new engine. I would be reluctant to do much to it if it still has warranty.

 

[[CJ]]

Does it have some kind of "automatic choke" or "one start"? Is it opening the choke completely when running?
Should have some kind of warranty on new engine. I would be reluctant to do much to it if it still has warranty.

Don't know about the choke. I'm going to play around with it after work.

 

[theoldwizard1]

It could be normal !

Most pressure washer have a high load on the engine. The carburetor is probably calibrated a bit rich when the governor has the throttle is wide open which is why it appears to be running rich.

2 things to check

1. Smell the old oil. Does it smell like gas ? (Washing the cylinder walls.)
2. Carefully measure the oil going into the engine and what comes out. If more comes out than you put in, you have wall washing.

If you have wall washing, you need to figure out how to recalibrate the carb at high load/WOT.

Other than that, don't worry about it. I don't know what the recommend oil change interval is on that engine, but cut it by at least 50%.

 

[Hako86]

These are engines with a lot of load on them and they run constantly at high rpm. It could be there is oil entering the combustion chamber and then gets forged back between the cilynder and the piston into the crankcase. The oil will get black really quickly because of the exhaust fumes and carbon mixing with the oil. I have the same thing with my old riding mower (small 5hp Briggs). The engine runs just fine and I haven't had any problems with it.
I just don't know if this is what happens with your engine. Could be, could be not... As long as it runs fine and you keep watching the oil, you should be ok