Kawasaki 23HP Twin Overheating

[djg james]

Not really large equipment but I didn't know where else to put it. I spoke about it in another thread and it was suggested I start a new one.

Lately, my zero turn with the above mentioned engine dies after 30-60 min of mowing. Seems to be overheating causing the gas to vaporize. Or so I've been told. I've change the oil/filter and it is at the proper level. I've removed the cover and cleaned the cooling fins on top as well as removed 90% of the crude off the cylinder fins. I replaced the fuel filter. The fuel filter is slightly smaller body, but that shouldn't matter. If it's working at the beginning of the mowing period, then size shouldn't matter.

The engine runs smoothly, no popping etc. until it dies. I'm open to suggestions.

 

[Big_Eddy]

You’ve probably done most of these, but I’ll include them anyway. Even if you have, they might benefit the next guy to come along.
First - clean all screens on the mower of blockages and grass that might be preventing airflow. Many mowers have a perforated belly pan that gets blocked up.
Second - always run the engine at rated RPM. The cooling is proportional to fan speed which is directly tied to engine speed. It is false economy to run the engine at less than rated speed to reduce gas consumption or noise.
Third - make sure all engine shrouds and plastics are in place and properly fastened to direct the air where it needs to go.

When it stops, does it restart or not? If not, how long to restart?
If the fuel has vaporized, it likely won’t restart for a while.
What happens if you run it hard for 45 mins on those hot days, then shut it off and let it sit for 5 mins, then restart? If the issue is fuel boiling, that a 2-5 min sit on a hot engine with no airflow will induce the problem.
Have you checked for spark after it quits? It could be a failing ignition coil instead, which is a simple replacement

 

[djg james]

You’ve probably done most of these, but I’ll include them anyway. Even if you have, they might benefit the next guy to come along.
First - clean all screens on the mower of blockages and grass that might be preventing airflow. Many mowers have a perforated belly pan that gets blocked up.
Second - always run the engine at rated RPM. The cooling is proportional to fan speed which is directly tied to engine speed. It is false economy to run the engine at less than rated speed to reduce gas consumption or noise.
Third - make sure all engine shrouds and plastics are in place and properly fastened to direct the air where it needs to go.

When it stops, does it restart or not? If not, how long to restart?
If the fuel has vaporized, it likely won’t restart for a while.
What happens if you run it hard for 45 mins on those hot days, then shut it off and let it sit for 5 mins, then restart? If the issue is fuel boiling, that a 2-5 min sit on a hot engine with no airflow will induce the problem.
Have you checked for spark after it quits? It could be a failing ignition coil instead, which is a simple replacement

Every nook and cranny that I can see has been cleaned. I had a hydraulic leak that was hard to find and the engine got coated in oil/dirt. I've cleaned that all up.

I always run at the max rpm when mowing because I have an electric PTO that requires it for cooling. I only run on half throttle to move to a location.

I have all the covers in place when running.

When it dies, I wait a minimum of 2 minutes before I can restart it. IF I try to run at full throttle and continue to mow, it dies either immediately or within 50 feet of travel. I CAN restart and drive it half throttle a hundred yards to the shade tree to cool down or the garage. I have let it cool down under the tree for 2 hours, and then start mowing again. That only gains me about 15 minutes of mowing before it happens again. So I limp it back to the garage and hopefully finish mowing the next day. It only takes me a little over an hour and a half to do my whole yard. Now I have to break it up into two or three days.

I have not run it for a while and then shut it off and then tried to restart it.

My mower has two spark plugs and TWO coils (called them condensers before). If one plug or condenser failed during running, wouldn't at least the other cylinder still run? I find it hard to believe that both spark plugs/condensers are coincidentally failing at the same time.

(These two photos show the condensers and the cylinders. The cylinder fins HAVE been cleaned since these photos. This just shows the oil/dirt buildup prior to cleaning.)


The cleaned top fins

 

[blades]

Considering the crazy temps -fuel vaporization is most likley the bulk of the problem. Try a larger fuel filter and if you are running ethanol gas replace the fuel lines, they could be swelling restricting the fuel flow as ethanol attacks most fuel lines even those rated for it.

 

[Big_Eddy]

The strange thing here is you can restart it. Usually once you have vapour in either the fuel line or carb, you’re dead in the water until it cools and the vapour condenses. Somehow you’re getting some fuel, but not enough fuel, which is inconsistent with the usual vapour lock.
Where is the fuel tank located? Gravity feed, electric fuel pump, or engine mounted fuel pump?
I agree it does not sound like the coils, but it could be the low oil sensor or other safety switch/wiring cutting off spark when it gets hot.

 

[djg james]

The strange thing here is you can restart it. Usually once you have vapour in either the fuel line or carb, you’re dead in the water until it cools and the vapour condenses. Somehow you’re getting some fuel, but not enough fuel, which is inconsistent with the usual vapour lock.
Where is the fuel tank located? Gravity feed, electric fuel pump, or engine mounted fuel pump?
I agree it does not sound like the coils, but it could be the low oil sensor or other safety switch/wiring cutting off spark when it gets hot.

I'll check on gas line routing and see if there is a fuel pump. Too hot outside to do it today. I'll have to jump on my Craftsman riding mower to finish the mowing today. It also has issues but it runs.

Wouldn't a bad oil sensor stay bad all the time? The oil IS full and I check every time I mow. New oil/filter also.

 

[Big_Eddy]

My log splitter oil sensor occasionally acts up even when the oil level is fine, especially if I toss a large log on and it bounces the splitter. Maybe with the thinner hot oil, it’s not getting good read.
Easy to rule out the oil sensor. Just disconnect the wire (after confirming oil level one more time)
I.e mow till it quits, check oil level, then disconnect the sensor and try to finish the lawn.

 

[djg james]

My log splitter oil sensor occasionally acts up even when the oil level is fine, especially if I toss a large log on and it bounces the splitter. Maybe with the thinner hot oil, it’s not getting good read.
Easy to rule out the oil sensor. Just disconnect the wire (after confirming oil level one more time)
I.e mow till it quits, check oil level, then disconnect the sensor and try to finish the lawn.

Sounds like something to try. I will.

 

[blades]

some times the oil dip sticks are not right and you end up with less oil than the senors says it needs. Have a pressure washer like that, could not keep it running for very long. Friend told me about the dip stick issue, put more oil it and runs fine now. just another thought. yes the oil senors can be finicky all by themselves.

 

[Sidecarflip]

Had a Kowalski sane as yours on a ZTR I just traded in on a Kubota DIESEL powered mower and I always kept the cooling fins clean, removed the shroud and blew them out a few times during the mow season. I also kept the valve clearance within spec all the time.

Both the Kowalski and the Kroler are basically disposa-engines with pot metal blocks and no cam bearings, only crank bearings. They are purposely designed to last maybe 1500 hours, possibly 3000 hours (if you change to oil and filter a couple times a year and only use quality oil like Rotella T6 and nor cheap garbage and a good oil filter as well.

I mowed acerage with mine, why I traded it on a Kubota diesel front mount mower. They ain't cheap, they retail (base model) for around 25 grand and go UP from there depending on what accessories you buy. You can get them with a 60 or a 72" 3 blade deck. side or rear discharge, power brooms, snow blower or plow blade and you can get an optional full climate controlled cabin or dedicated bagger if you desire that and JD makes and sells a similar model with a Yanmar diesel engine. A fully optioned one will set you back, north of 30 grand. You can find them used but used don't last long. They sell like hotcakes. The one I bought used was from a local fair board, a trade in when they got a new one. My dealer maintained it for them. Mine is 2wd not 4 because I don't mow hills at all, it's flat here but even the 2wd models have a differential lock.

They are all hydrostats and it's basically a Kubota B series tractor with the engine facing backwards and the mowers and optional accessories are all shaft drive. No belts and the mower blades are all driven via right angle oil filled gearboxes. Mine has the optional air ride seat as well.

ZTR's really have no trade in value. I paid north of 6 for my Cub Cadet 60" Tank model years ago with a 25 horse Kowalski and got on trade in 1300 bucks which I considered good. Not much resale value in them and like I said they have pot metal blocks, disposa motors. Good resale on the Kubota or JD diesel powered front mount mowers. Mine set me back just under 9 grand and I was tickled to get it. and the Kubota diesel engine will be humming along, long after your Kowalski disposa motor craps out and replacement V twins aren't cheap today. Even a Predator disposa V twin will set you back over a grand.

All depends on your wallet, how long you expect a mower to be viable and it's trade in value. On the one I bought, I expect to get at least what I paid for it or close, when I trade it in. Kubota's hold their value exceptionally well, mowers or tractors, no exceptions and Kubota diesel engines last forever (if you take care of them and I do. My Kubota farming tractors have many thousands of hours on them with just ordinary maintenance, Same applies to the Kubota diesel powered mower I bought this spring. It has 1300 hours on the meter and should last at least another 3000 hours probably a lot more, with normal maintenance. Kubota builds a bullet proof engine. It will be humming along, long after your Kawasaki or Kohler engine is at the scrap yard. 1300 hours is close to end of life for them whereas my Kubota is just getting broken in.

My philosophy is, buy it once and cry a little or buy many and cry a lot. I know how Kubota builds stuff, I've ran Kubota tractors and now Kubota hay tools for decades with zero issues. Once you go from a gasser to a diesel, you won't ever look back and the Kubota as well as the JD diesels just sip fuel. When I ran the gasser, it took almost 5 gallons of weasel pee to mow all the lawns. With the Kubota diesel it takes around 1.5 to 2 gallons of off road diesel. if you are really set on a diesel, Kubota produces a line of diesel powered ZTR's as well and so does JD.

Me, I'm sold on a front mount mower. One, it rides better and 2, I can see what I'm mowing plus the deck flips up for easy cleaning and / or blade changes and 3, I can mow under our low hanging pine trees without getting bloody arms from low branches sticking me.

The asking price is high but they will outlast 2-3 gasser powered units and no belts to deal with either. Once you run a front mount mower, you'll never go back to a mid mount. Grasshopper also makes one and they have a Kubota diesel engine in them as well. Kubota engine and transmission.

So long as your wallet can stand the initial bust, you'll be good to go and no corn fed unleaded weasel pee either.

 

[Sidecarflip]

So, how many hours on the Kowalski? you probably need to adjust the valves, both Krohler and Kowalski recommend a valve lash adjustment at 500 hours or sooner. and I bet your fuel is boiling in the carb bowl as well and causing vapor lock. Once I went liquid cooled diesel, I lost all the disposa motor issues.

Like I said, not for everyone because of the price of admission but for some folks like me, the diesel powered unit is a fantastic unit.

 

[djg james]

Last week, I ran the mower for two 20 minute sessions on the same day without any problems. Just wanted to get the yard finished up.

On this weeks cutting, yesterday, I got 50 minutes out of it before it cut off. Cool day outside, but had to let it set for 30 minutes before restarting and half throttle back to the garage. Today, I ought to get the yard done. Then I'll look into it more.

I forget who asked about the fuel system. It has two tanks that Tee into a line running to the filter and then to a vacuum? fuel pump. After that, I can't trace the fuel line without taking off the cover again. Which I will be doing since there were lower sheet metal shrouds I didn't take off and clean before. Looks clean through the holes, but I remove to make sure.

Does the fuel pump have an impulse line that could be collapsing when it gets hot? Rural King didn't have any fuel line so I'll get it from the local auto parts store. I'll change the section around the engine that gets most of the heat and the impulse line if it has one.

Someone also asked about the engine revving. I had said it runs smoothly, but that was wrong. The engine does surge without any load (PTO disengaged) and is more noticeable at half throttle. Is that the spark plugs? I'm picking up a pair of new ones to have on hand.

The mower only sees less than 100 hours a year of use, so buying a new one at this point is not feasible.

 

[blades]

Surging is almost always a fuel supply issue. on rare occasions it could be the governor.

 

[Ridgehiker]

my wood chipper has a 19hp Kawasaki motor and there is a fuel shut off solenoid on the bottom front of the carb, it would act up after it set for a year, this year i unscrewed it and threw away the needle and spring and left it unhooked, maybe your mower has one as well, try to remove the spring and needle and see if it runs better

 

[Ridgehiker]

any update?

 

[sean donato]

Surging of the governor is a carb low side or transition port issue in the carb, possibly a fuel starvation issue, but wouldn't be the typical issues seen.
The fuel pump on that is a std crankcase pulse operated fuel pump. Used on many engines. Easy and cheap to replace. Doesn't matter what brand you get, I usually buy the Briggs branded ones, just the cheapest out of the lot. Same company makes them for every one.
The main jet shut off needle is easy enough to diagnose, but It's symptoms should be very repeatable ie, same thing happens the same time frame,same way etc. Ridge hiker gave the basic way to test it. I prefer to remove it and use a plug, to each their own.
Another though for overheating could be the oil cooler, some were just basically heat sinks at the oil fikter, other were actual little coolers that used air from the flywheel fan for cooling.
Whatever the issue, its got to be something fairly simple. These engines go for a very long time despite what some blowhards want to say, and are quite simple to work on.

 

[djg james]

any update?en't done

I was just going to respond tonight. Parts came late today and I haven't done anything yet. More rain tomorrow so I wanted to knock down the high stuff first. I'll work on the mower tomorrow. I only got 30 minutes of mowing today before it quit. Let it cool for 2 hours and then tried to resume mowing. Started right up with a little sputtering and when I engaged the blades, it immediately died. Started it back up and when I put it into full throttle it died. Manage to get it restarted and ran it half throttle back to the garage.

 

[djg james]

Surging of the governor is a carb low side or transition port issue in the carb, possibly a fuel starvation issue, but wouldn't be the typical issues seen.
The fuel pump on that is a std crankcase pulse operated fuel pump. Used on many engines. Easy and cheap to replace. Doesn't matter what brand you get, I usually buy the Briggs branded ones, just the cheapest out of the lot. Same company makes them for every one.
The main jet shut off needle is easy enough to diagnose, but It's symptoms should be very repeatable ie, same thing happens the same time frame,same way etc. Ridge hiker gave the basic way to test it. I prefer to remove it and use a plug, to each their own.
Another though for overheating could be the oil cooler, some were just basically heat sinks at the oil fikter, other were actual little coolers that used air from the flywheel fan for cooling.
Whatever the issue, its got to be something fairly simple. These engines go for a very long time despite what some blowhards want to say, and are quite simple to work on.

See my above response. Now it sounds like a fuel pump to me. Not that I have any experience with fuel pumps. I bought an AM and will install tomorrow. You mentioned "crankcase pulse operated" pump. Is that the same as having an impulse line like a chainsaw?

I'm not sure it has an oil cooler and if it does, what kind. I've been looking over the parts list and can't seem to find one.

I agree, this engine is built like a tank, best I've ever had. and am hoping it's just something simple.

Thanks for your help

 

[sean donato]

Yes the fuel pump is operated on the same principal as the fuel pump in a saw carb. Should have 3 lines on it, fuel in, fuel out, and the pulse line. Usually held on by 2 bolts.
From your parts list, it doesn't appear that a oil cooler was an option, so one less thing to worry about. Usually there's an adapter plate between the engine block and oil fikter with short lines going to a radiator looking cooler, or a finned aluminum heat sink looking type cooler. The lower hp v twins didn't have them.

 

[djg james]

I just don't get it. They pushed back the rain until late afternoon, so I decided to try mowing some more of my yard. Mower started up fine and ran for at least 20-30 minutes before the rain came. Got it back in the garage without any problems. The only noticeable problem was the surging at half throttle.

If it were the fuel pump it shouldn't run fine for 30 minutes, I would think. The only thing I can think of is the impulse line heats up and then collapses.

I have a new pump, plugs, change back to a larger fuel filter, air filter and fuel lines. I'll change them all just in case.