deer 725 Kawasaki motor FD501V died ideas?

[laurencen]

had this deere f725 many years, bulletproff I figured but started it yesterday half rmp and backing onto lawn heard a klunk in motor and died, now does not even attempt to fire, pulled plug right side clean, no compression and plug is firing, pulled left plug oily, crank over spitting oil too messy to see if it has compression.

best guess im thinking canshaft drive is shot, pulled valve covers no sign of valve dropped or broken spring, will try to crank it over and see if valves move, looking for ideas, read older motors had plastic gear and prone to failure but do the symptoms lead to this as a possibility

thanks for any guidence, will start tearing it down when I bting it back from the cabin

 

[Richard001]

Well the "KLUNK" is the clue. I'm guessing that the big end of the connecting rod is not longer attached to the crankshaft.

Richard

 

[laurencen]

thanks Richard, since posting here is what I found, no compression in any cylinder, one is pumping in out drt the other is spitting oil, the crank is in one piece as fan turns on top and PTO turns on bittom, no movemrnt at the rockers

im thinking if it was a connecting rod it would be making noise when cranking which there is not ans obvious no compression, it spins easily with or without plugs installed

will start removing motor tomorrow then tear into it

 

[5030]

Tell us what you discover please...

 

[oldnslo]

The Plastic gears failing that I have seen had following symptoms

On one governor gear broke ran at idle or uncontrolled high RPM. Simple repair and back in service

On Two oil pump drive gear broke in both cases this damaged the main bearings and blocks were scrap.

Either two three engines timing gears went and cam stopped turning but no damage to any of these engines.

Was a lot of discussion on could the timing gears jump a tooth and cause valves to get smacked by piston. I would suspect you would have noticed if one of the valves was not returning and rocker arm was loose and flopping around.

I don’t recall ever reading about head or valve damage from plastic gears but certainly would admit I think it could be possible.

 

[laurencen]

here is my findings, camshaft gear is stripped badly, next to no teeth on the gear, waterpump gear lost 2 teeth, oil pump and governor gears are OK first look, case full of teeth, have not removed heads but the pushrods are straight and the valves are not sticking of stiff to move.

all parts less the camshaft were stocked locally at the Brandt Deere dealer less the gear/camshaft it should be in tomorrow, cleaning up the housing today why the heck use a plastic gear for this application? given the load and heat cycles it sees over a few thousand hours of use.

it must have made many rotations even without teeth as most all teeth are missing, anyone know if the valves are clearance on the pistons when this happens?

here are a few pictures of the parts as they are removed,

 

[5030]

I would have NEVER purchased the replacement parts from a Deere dealer as the markup on Deere parts is extreme. I would have went to a site like Jack's small engines and bought them there or Stens or anywhere but a JD dealer. The gears look rough to say the least and engine builders use plastic gears (or structural fiber gears) to save money as they are much cheaper to produce and most people would just install a new engine anyway. Jack's has them (new engines) as well.

 

[laurencen]

hi 5030, I would have liked to find one other than Deere but on the internet any cam gears I found were either not in stock or unavailable, most all that had them would not ship to Canada and after the 35% exchange, duty and shipping were $400cdn anyway. the gaskets and waterpump gear was under $60 again Canadian dollars all parts are local so no shipping.

looks like my parts will be here tomorrow afternoon for pickup so we may have it back up running on the weekend, we will definitely keep the supplier you mentioned on file for future

 

[laurencen]

just checked Jack's the timing gear is no longer available, Id be upset if they had them for $150 at least in this case its fixable and not throw away, this time around, had this machine for a good 10 to 12 years, only other thing I have replaced was the fuel pump, it got thro 2 new OEM pumps within a few months then I installed a electric pump, it really does not owe me much

 

[oldnslo]

Double check your water pump while you have it apart. Some models of water pumps could leak internally into crankcase before showing anything external. This would lead to scored bearings from lack of lubrication. I do not recall which Kawi models or Deere models had this design.