Kawaasaki FH721V with oil coming out breather - factory defect?

[Humanfuse]

Hi,

I'm Jerry from Indiana. I have an 11 yo Farris with an old style Kawasaki FH721V-CS27-R 25 ph engine. I'm a backyard wrencher but I'm better at fixing obviously broken engines than diagnosing what is partially broken. I've googled your forums and info I've found has gotten me a few steps closer but I would appreciate hearing peoples opinions on my problem.

I'm also looking for conformation of a potential factory defect regarding the pressed-in breather valve seat and advise on the next steps.

Know current state:

• Personal, 1 yard (5+ acres) Farris ZTR bought new 11 years ago; Hour meter broken but I'd assume it's low for the age
• No engine maintenance done except change oil and blow off air filter, well and new plugs a few times...
• I neglected to change the oil in ~2 years
• Oil; level OK but dark, still oily, not broken down completely
• Road hard, put away wet several times
• Then at cold start up, smoke came from exhaust then it died
• Found breather tube was pumping out oil into intake plenum before carb (big clue!)
• From googling your forum and experience I'm reading that is related to excess crankcase pressure
• Bad rings? Valve guides or seals? Clogged breather drain or breather valve issue? Clogged air filter, ?? idk?
• Compression check=90psi in both cylinders (I know, I should have changed the oil more often but maybe not the main issue...)
• Leakdown at TDC; 30% and 32% but this was a HF automotive leak down tester with .040 in. orifice so maybe not too bad since they are similar numbers?
• Inspection of valve seals showed no issues
• Harbor Freight inspection camera down the spark plug holes showed no holes or bad scratches in cylinder walls
• Did tear down to get into breather under flywheel
• Inside I found dirt (sluge?), oil saturated breather filter and issue with breather valve (reed valve) seat

I believe the breather valve seat that is pressed into the block at the factory, was set at the incorrect height, to low, causing the breather valve to close on the "as cast" burred, aluminum surface around the hole in the block and not the inserted steel valve seat. See pictures. I'm including a drawing of the valve and valve seat insert from the service manual. I believe the drawing shows that the valve seat was pressed in from inside the block and shows that it protrudes slightly past the casting. (if accurate)



The witness marks on the valve from the burr and lack of witness marks from the valve seat are good clues that show the valve seat did not slip during use. I'm thinking that the valve worked well enough to do the job until "normal" engine wear caused crankcase pressures that the partially sealed valve could not handle. Note the non-centered burr mark circle on the back of the valve, it corresponds to the position of the installed valve.

I sent Kawasaki a message with a question about it from their site so I'm waiting for that..... In the mean time, I'm thinking about doing the following:

• Remove burr from casting for a better seating surface for the breather valve.
• New breather valve, breather filter element, canister air filters, valve cover gaskets, upgraded no leak breather cover, plugs, oil filter, oil maybe a little heavier SAE30?
• Put it back together and monitor crankcase pressure with a fuel/vacuum gauge
• If it works, use it for the rest of the season then do a freshen up rebuild with new rings and a hone job this winter. I can better inspect the valve seat for full insertion when the engine is tore down.

Thoughts?

Thanks,
Jerry from Indiana

 

[bertsmobile1]

The only "factory defect" I can see is a failure to properly secure the valve allowing it to shift off centre.
Generally you would not have a steel flap valve seating against steel.
You would seat it against something softer like alloy.
The fact that it worked quite fine when new attests to this.
So I would just fit a new one and make sure it was tight.
The tube is more likely there to prevent oil splash directly into the valve and is common on flapper valves.

 

[Humanfuse]

The only "factory defect" I can see is a failure to properly secure the valve allowing it to shift off centre.
Generally you would not have a steel flap valve seating against steel.
You would seat it against something softer like alloy.
The fact that it worked quite fine when new attests to this.
So I would just fit a new one and make sure it was tight.
The tube is more likely there to prevent oil splash directly into the valve and is common on flapper valves.

OK, interesting. Thanks for your different point of view. I assumed the tube also was the valve seat but it does have vent holes in the sides to keep oil away from the valve. If the cast surface of the block around the breather hole was intended to be the valve seating surface, then the defect in my engine could be that it was not de-burred and/or machined flat? Would they use an "as cast", block feature without secondary machining as a breather valve seat? maybe? This is part of the reason I thought the insert was also the valve seat. Plus it looks like it could be a valve seat if you have never had one apart before.

Based on your feedback, I'll try to get my FH inspection camera inside the engine and up to the tube that is pressed into the block. If you are right and the drawing correct, I will see that the inserted tube is pressed into the block until it hit the shoulder of the tube. See drawing from manual above (or below?) If I see a gap, I'll report back.

If I fail on the camera verification and don't get any other opinions before the parts get here, I'll stick with the plan to clean up and de-burr the alloy seating surface and put it back together with new parts and 30 weight. I'll then test and report back.

Thanks for the help,

Jerry

 

[bertsmobile1]

Just keep in mind that it is a mower, not a lunar rover or a top fuel dragster.
It is built down to a price and that price drops every year so if the finish on the pressure die casting is good enough to do the job most f the time , no need to add another machining operation.
Mower engines are designed for a 10 year service life @ around 50 hrs/yr
This is why they cost around 1/2 to 1/3 of an identical engine with a horozontal shaft which is designed to run 8 to 12 hours a day, 5 days a week, 52 weeks a year because they go on pumps & compressors & generators.

 

[Humanfuse]

New info, I'm still waiting for the parts but worked tonight to get ready. I removed the burr on the casting and smoothed it with fine paper. Then I started to change the oil and filter. I said the oil was OK but I was wrong. I missed that it had gasoline in it. The dip stick was at the low tick mark and I pumped about one tick marks worth of oil on my shop floor so I did not see the issue until I drained the oil tonight and it came out too fast.... FYI: The oil in the pan caught fire when I hit it with the mapp torch. confirmed gas, I'm thinking.

So, I'll check the fuel pump, that I bought cheap off ebay this spring, for a ripped diaphragm and then I'm thinking it has to be in the carburetor float or? I had a neighbor kid cut and put the mower away, the last time it was used, and he said there wasn't any issues so I have that data point. It has a fuel cutoff solenoid on it so I'm thinking the float and the solenoid would have to both fail for gas to seep in while it was just sitting there? Wait, did the kid leave the key on so fuel flow on and the float has a slow leak? I did not check the oil when I started the engine the last time. Maybe it was overfull? The breather may be working just fine and I just had oil being pumped out the breather because the crankcase oil was thin/overfull from the gas? hummmm

Any other ideas? I'll report back after I check the carb and fuel pump.

Sorry for the goose chase on the valve seat, bertsmobile1.

 

[bertsmobile1]

The fuel solenoid rams a bung up the main jet preventing any fuel from entering via the emulsion tube.
It does not prevent the float bowl overfilling and fuel running out the bowl vent passageways down the venturii and filling up the engine.
This naturally causes the crankcase to overfill and so spew a fuel oil mix into the breather as there is no seperation chamber there other then the tube.

 

[Humanfuse]

The fuel solenoid rams a bung up the main jet preventing any fuel from entering via the emulsion tube.
It does not prevent the float bowl overfilling and fuel running out the bowl vent passageways down the venturii and filling up the engine.
This naturally causes the crankcase to overfill and so spew a fuel oil mix into the breather as there is no seperation chamber there other then the tube.

OK, Thanks! I now see they call it a backfire preventer and not a fuel cutoff solenoid. Makes sense now. I have a bad habit of extrapolating my engineering knowledge into places where I have little experience. My bad mower engine diagnosis in this thread is a good example of my problem. : - ( Thank you for your help.

I checked the fuel pump by blowing into the inlet while holding my finger on the output. I did not get air out the crankcase connection of the pump so assume it is not the source of the fuel in the oil. With my new understanding that the solenoid is not likely part of the problem, I'm assuming the problem is the float valve or the o-ring or dirt. I'll tear it down soon and report back.

 

[bertsmobile1]

EPA emission regulations were expanded to include starting and stopping.
That is the only reason why car engines went over to very light oils, so they started faster and emitted less unburned fuel..
For the same reason engines now run a lot leaner so a lot hotter.
Thus the unburned fuel in the red hot exhaust explodes once enough air gets in there to reach a combustible ratio at atmospheric pressure.

Mower engines are made as cheaply as possible and way too many people apply a substantially higher level of engineering to.
I always encourage my customers to fit a fuel tap and starve engines off when they have finished for the day.

While in theory the float should stop fuel flow just remember a motorcycle carb is around $ 500
And a 10Hp mower engine, complete with carb & starter motor is the same price so don't expect the same level of engineering & manufacturing quality.

Your thread has been a good one.
Science is a process of observation, postulating a theory, then trying to dispprove it so you have followed sound scientific principles.

Thread is clear and easy to follow so should provide a very good refference for others .