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Discussion Starter #1
I had almost finished about an hour of mowing, the last 10 minutes were mowing a fairly heavy patch of grass/weeds, taking it slowly and doing partial passes, and on the last 6" wide pass the engine started misfiring. Not enough to stop moving at decent speed but enough to slow down and hear/feel the difference. Was running like a champ as always till then.

No warning lights, no smoke, just a misfire. I checked oil and coolant before starting and again after parking it, and everything looks good. Air filter and foam surround are clean, plug wires are firmly attached. Full tank of gas when I started so it's not out.

It's the 18 hp version of the 345 with 946 hours on it. Sound like the behavior when a tooth or two let go on the composite cam gear?

I plan on starting it one more time just to be sure it is not a random combination of heat (86 today, but really windy so it feels much cooler) and something else but it sounds like it's lost timing.

I thought I might get lucky but planned ahead so I have the steel gear version already on hand. Just need to find the part list for everything else needed unless you guys can think of something else to try.

I got a whopping 30 hours out of it before it went but I knew it was possible when I bought it so I can't blame the tractor. Just need to fix it. Unfortunately, the grass grows around here like crazy so I will need to get something else because it will be a while till I can get to it.
 

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Probably a YouTube showing how to do it but here is at lease one thread that has some detail on it:

 

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There are several videos available for the gear swap but it is the little details that make or break the job. Don't just look at the video but listen to the dialog. When they give you a hint take it. Daryl has one that is great. He does it on the shop floor without taking off the radiator and all of that shroud. It is amazing how he does it. He mentions the water pump gear but also check the oil pump gear. Any of them can fail and they will all cause the failure of the engine. The water pump is another item to replace if it looks worn since you have to do everything all over again to replace it except split the case.
Google Here is his link.

 

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I think you are right in making sure that it's not something else - it seems you would be really down on power if the cam shifted and I can't imagine running long in such a scenario. Note the failure mode on the ignitor tends to be losing spark on one side which would be consistent with your symptoms.

BTW - I strongly recommend a new water pump when you do change the cam unless you know it has been recently replaced - you have to take it off to get the cam so the work is free so to speak.
 

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There are several videos available for the gear swap but it is the little details that make or break the job. Don't just look at the video but listen to the dialog. When they give you a hint take it. Daryl has one that is great. He does it on the shop floor without taking off the radiator and all of that shroud. It is amazing how he does it. He mentions the water pump gear but also check the oil pump gear. Any of them can fail and they will all cause the failure of the engine. The water pump is another item to replace if it looks worn since you have to do everything all over again to replace it except split the case.
Google Here is his link.

And there's your dinner LOL
 

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Discussion Starter #6
Thanks for the responses. I'll inspect and replace everything while I'm in there.

If I lost spark on one side, I should see a difference between the plugs so I will have a look at them, I had to drive maybe 100' back to the barn after it started acting up. I assume the ignitor is an electrical component, it could have been the heat and hard work it was doing. It was 86 as mentioned but not windy under the hood so it could have overheated,

I've never had one of these apart but thinking back to car work I've done, if I was off with manual distributor timing or a tooth on a timing belt, if I was off a little, it would still run, but not very well.

I will try it again tonight and see what happens.

Where do you guys get your parts for the Kawasaki engines?
 

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Were you able to get it to start again?
 

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Thanks for the responses. I'll inspect and replace everything while I'm in there.

If I lost spark on one side, I should see a difference between the plugs so I will have a look at them, I had to drive maybe 100' back to the barn after it started acting up. I assume the ignitor is an electrical component, it could have been the heat and hard work it was doing. It was 86 as mentioned but not windy under the hood so it could have overheated,

I've never had one of these apart but thinking back to car work I've done, if I was off with manual distributor timing or a tooth on a timing belt, if I was off a little, it would still run, but not very well.

I will try it again tonight and see what happens.

Where do you guys get your parts for the Kawasaki engines?
I doubt you will see any meaningful difference in the plugs given the short amount of run-time. Testing for spark is the way to go. And yes, the ignitor is an, unfortunately expensive, electrical part.

I'm a fan of Pat's Small Engine if you're not in a hurry as they ship slow.
 

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If you have it running, spray some water on the exhaust pipes where they exit the head, if you have a cylinder not firing or not working properly, you will notice a difference when the water spray hits the pipes. If you are brave, you can physically touch the pipes or use an IR thermometer if you have one.
 

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I had a 345 with the 18 HP engine in it. I had almost the exact same symptoms as you, what happened to me was one of the spark plug boots (they were ceramic on mine) just wore out and quit getting energy to the plug. With the engine idling, wiggle those boots, I bet you'll hear a difference.

I also had a really weird one - one of the ceramic centers of the plugs blew out, engine started running like crap... I stopped the deck and idled down to listen to it, to figure out what went wrong this time... and about 20 feet from where I stopped was a little white object. The entire ceramic of the spark plug, electrode intact. And wouldn't you know I was stupid enough to think, 'I better try to pick it up - it might start a fire'. And it's one of those instinctive things that you just reach down and pick it up. It takes about a second and a half for the searing pain to get to the brain...
 

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I had a 345 with the 18 HP engine in it. I had almost the exact same symptoms as you, what happened to me was one of the spark plug boots (they were ceramic on mine) just wore out and quit getting energy to the plug. With the engine idling, wiggle those boots, I bet you'll hear a difference.

I also had a really weird one - one of the ceramic centers of the plugs blew out, engine started running like crap... I stopped the deck and idled down to listen to it, to figure out what went wrong this time... and about 20 feet from where I stopped was a little white object. The entire ceramic of the spark plug, electrode intact. And wouldn't you know I was stupid enough to think, 'I better try to pick it up - it might start a fire'. And it's one of those instinctive things that you just reach down and pick it up. It takes about a second and a half for the searing pain to get to the brain...
That would have made an awesome YouTube Video. :)

Yeah, I've done stuff like that before too.... More often than I really care to think about. :D
 

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Carefully remove each plug wire while it is running to see if it dies when one side is pulled. If neither side kills it then it just about has to be internal.
 

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Discussion Starter #13
Thanks for the replies. Work has been crazy so I haven't tried it yet, will do so tomorrow.

Plugs are still there and wires attached so I haven't blown the center out.

I have an IR thermometer so that's a good idea.

Need to find my insulated gloves so I can pull a plug wire while running.

Will report back after I get a chance to look at it.
 

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I think it's vapor lock.
Had similar issues with mine before I made some changes and haven't had a problem since.
 

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Years ago I was mowing the two acres in the rear of the 20 acres and the grass was about one foot tall. I had the mower deck at it's highest limits, and the '99 JD 345 with the 20 hp Kaw was huffing and puffing it way until it just died...engine stop. I raised the hood and grass clipping completely cover the radiator screen and the engine was hot. I let it set for a hour and went back to mowing. The engine again quit and I decided that I was abusing the 345 beyond it's mowing capabilities. I went to the garage and power washed the 345 and installed a new air filter and all is well, and that was about 600 hours ago and the mighty Kaw still runs today as it was new.
So, don't get too excited about tearing into the engine for a rebuild when it just might need a rest from the heavy thick grass mowing.
However, do as the others have said on here. Start the 345 and remove the spark plug cap on one side and see if the engine dies... it should run on one cylinder. Do it on the other cylinder and see if the problem is enteral, and not a outside problem.
 

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Discussion Starter #16
Thanks for the additional replies. It fired right up tonight and seems okay. I didn't cut with it but the problem was there without the PTO engaged previously, I'll probably cut again sunday so we will see how it goes.

There is a little misfire at what I'll call cold idle but I never checked that before so it could have always done that.

I pulled the plugs and they were evenly colored, electrode was unworn, and they looked normal. However, they were Champions so I installed OEM NGK's.

I did notice that the boot around the very end of the plug wire was cracked but the boot snapped onto the plug nicely. Are those coil packs with integrated plug wires?

I read that the cam gear usually goes between 1000 and 1200 hours so I was thinking it was getting close to time. However, I wasn't going to tear into till I knew what was wrong for sure.

I live in prime farm country so the grass is usually thick but the 345 hardly ever has debris collect on the radiator screen. My wife's LX 188 screen loads up terribly on the same yard, finding some automotive door sill trim or something like the 345 screen seal for the LX 188 is on my list of things to do.

At the moment, tragedy temporarily averted, but we will see what sunday brings. Seems to be stuck in the upper 80's right now, we went from frost to summer in a week, haha.

Thanks again.
 

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So this is one of the things I did to my 1998 345 after having issues with excessive heat and vapor lock. This thing only has 665 hours on it and runs like new again.
I added a fuel return line from just before the carburetor back to the tank. I purchased the tank restrictor, grommet and Tee along with 6 feet of fuel line.
John Deere did this on the 1999 345's due to vapor lock problems.
There is a channel molded in the tank for it. I just had to drill a 1/2" hole.
Before I made the change, the fuel line was hot regardless of the ambient temp. Now, it is just warm to the touch after over an hour of mowing and no more re-start issues.
I also added a duct like my 2005 gx345 has and helps blow air down and back to the engine.
In my opinion, the fuel pump really heats up the fuel and since there is no where for it to go, it causes vapor lock.
Here is a pic of the return line. It's the lower line.


2460598
 
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Discussion Starter #18
I think that is a good idea and worth doing for sure. The only thing that sticks in my mind is that I've had this tractor for 2 years mowing the same yard and I have to believe it's been that hot before.
 

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John Deere realized there was a problem and added the return line for that reason. They eventually removed the shields from the front of the engine and added a duct like on my gx345 and did away with the return line. There is no where for the heat to escape on the early 345's. I was surprised to see how different the early FD590V is compared to the FD611V. I never actually looked that close at them until I bought this '98 345 and had to diagnose this problem.
Another thing JD did was remove the mechanical pump and add a vacuum pump on the back of the engine.
 

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Discussion Starter #20
I cut for an hour last night with the temps the mid 80's but a nice breeze with no issues. Low speed idle is still loping but it runs well otherwise. If I have another issue, I'll install that return line.

Thanks
 
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