Dogbane cooked my 8199G

   / Dogbane cooked my 8199G #1  

daugen

Super Star Member
Joined
Feb 27, 2012
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Location
New Hope PA
Tractor
in between now
My last mowing job of the season was about half an acre of six foot overgrown weeds, affectionally called a "meadow" by the property owner.
Going along just fine, doing the last pass, but going through a thick patch of some large weed that created an enormous cloud of white fluffy material, so much
so that some blew across the road nearby and I bet folks wondered where the snow was coming from. I didn't think much of it, only an hour long job and my Gravely was perfect
going into this job. In a period of ten seconds, I smelled something funny, and then the motor quit like a light switch thrown. I got off the tractor and looked in the rear and just
did a real "oh no". Air intake 100 percent clogged with white stuff, inside of air cleaner clogged, and a pile of seeds off in the corner. Smoke pouring out of the engine but luckily nothing lit off.
What really worried me was looking down at my glass gas filter, and seeing the gasoline boiling merrily away. Not good. It turned over just fine, no strange noises, but no spark.
I think I cooked the coil or the condenser; at the shop now. I asked them to change the oil too, and check the fuel lines; got way too hot in there for my liking.

Since I figured I cooked the electronics, now was the time to install Kirk's electronic conversion kit I have had for more than a year, never getting to it.
Kirk Engines, Inc. >> Garden Tractor Performance Parts

Really hoping I didn't warp a head.
Probably a good time to take the head off and clean in there anyway.
Really annoyed me screwing up one of my favorite pieces of equipment. Just never thought it could happen that quickly. Live and learn.
and I hope I didn't breath too much of it...: Dogbane contains cymarin, a cardiogenic toxin that causes cardiac arrhythmia in humans
Thought it was milkweed, and maybe there was some of that in there too, but next year, I mow at least a month earlier to avoid this.
 
   / Dogbane cooked my 8199G #2  
Sounds like you need to mow a couple times a year if it was 6 feet high. That is what we had when we bought our place and 6 feet high weeds were the low spots. It took a couple of years whacking it down 2-3 times per year to get some grass growing in place of the weeds but now the weeds are all gone except for some occassional thistles that blow in and we cut those by hand when we find them.
We would have to come home about every 30-45 minutes and blow out the radiator and that was running the FEL low to kind of knock over the weeds first.
Sounds like you need some kind of overheat kill switch installed on your mower.
 
   / Dogbane cooked my 8199G
  • Thread Starter
#3  
Gary,
the lady whose property I mow likes to consider this weed infested patch her organic meadow....groan. At least she now realizes that we have to mow it earlier and more often.
Air cooled engine, maybe the fact it's an old fashioned solid iron K series will save it. Dealer promised me an answer this week.
I have another thread "repowering 8199G"....hope I didn't jinx myself! Drew

btw, haven't found anyone that makes a pyrometer for an air cooled; if I have a temp gauge, I'd pay attention to it...Always wanted one.
 
   / Dogbane cooked my 8199G
  • Thread Starter
#5  
an overheat sensor is a good start, and shows Onan had a commercial approach. But...if it's a sensor that trips a light, that's good, but not as good as a gauge, though if it shut down the engine,
that at least provided some protection.
Any idea at what heat limit it tripped? I'd be interested to know how hot they consider "too hot". Thanks.
and sorry, what's a B43 and B48 motor?
 
   / Dogbane cooked my 8199G #6  
A gauge is going to cost you and then there is the ignore factor. Just because a gauge is there doesn't mean it gets looked at.

The sensor could do whatever you want. If you want a light and/or buzzer to come on, that is easy.

If you want it to kill the engine that is easy too. Just connect it to the engine kill wire. On Kohlers do not try to kill the engine and turn on a light at the same time. Many an ignition module has been fried that way. To do that requires a relay.

The Onan B43 and B48 were used on the Gravely 816T and 818T tractors. One engine was 43 cu in displacement and the other 48 cu in.

I have no idea what the temperature trip point is. Whatever it is, it is right.
 
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   / Dogbane cooked my 8199G
  • Thread Starter
#7  
the culprit was found, my coil became a large thermal fuse, melted, shorted out I suppose, or just failed, and off went the engine. Since I supplied the shop with a replacement coil, the bill wasn't too bad. New fuel line from fuel filter back, and had to tighten 8 of the 16 head bolts. Hmmm. Guess that sucker expanded a bit. That tells me they didn't take the heads off, which I wish they had, but it runs just fine. And starts quickly.
I'm going to fashion an open weave furnace filter to fit in behind the stock bumper guard and the intake fan. That might help. And a little more attention paid by the operator.
 

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   / Dogbane cooked my 8199G
  • Thread Starter
#8  
I'll take a pic of the new coil installed later today. It's bright yellow and sticks out like a sore thumb. The new Bosch coil I have on my Cub Cadet 125 is an attractive metallic blue, this thing is dayglo yellow.
I have plenty of Gravely paint...and I need to inspect the engine closely to see what paint I burned off anyway. All the shrouding was taken off and everything inside cleaned out. So I'm back in operation; I really missed the thing
because it has a ball hitch on the back and I don't have one yet on the Kubota tractor.

I think the governor is getting very tired. Hunts and rolls a fair amount at idle and is set too low now, it will stall when cold. I have a digital tach on it, what should the low and high rpm settings be? My understanding is full throttle/WOT should produce 3300 under no load/light load, but I'm now only getting 3200. I never liked to run at full speed, no need really, but now while mowing, I push it all the way up, and it was running in the 3150 to 3200 rpm range. I use to have 100 more rpm and I think I want it back... The low speed hunting can be eliminated mostly by a little higher idle speed, which I will do next. The governor renewal is what I will research next.

I've put 180 hours on the Gravely in the three years I've owned it. Some of that is high load, high heat operation, doing field mowing. But the hour meter is still under 800, so that helps. All those loose head bolts concern me, and why if they were loose weren't the heads taken off and new gaskets reflected in the parts list? I thought this was a good time to do that, but apparently my overheating period was short enough that I didn't damage anything more than the ignition parts. Fine with me.

I was considering putting three rib front tires on the Gravely, to give me better side traction on slopes when mowing. I use the Gravely to mow those areas I won't take the larger tractor and finish mower. Has anyone you know installed these? Wondering if it would leave tracks on damp lawns. Unit is mostly used off the lawn so those front turf tires aren't all that hot on hills. I grew up with tri-ribs on a JD B, and they rarely lost grip from my memory.
 

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   / Dogbane cooked my 8199G #9  
I have yet to see a governor wear out on a Kohler. As a matter of fact on the KT series, to get at the governor, you have to tear the engine down and split the cases.

Too lean a mixture will cause hunting and also too low a RPM. I would adjust the idle mixture and idle speed if the idle speed is too low.. If you rebuilt the carb, I would double check the float height. Those Kohler carbs are finicky about float height.

Assuming the carb mixture is OK and it is still hunting at WOT, then I would adjust the governor sensitivity. See the Kohler manual for how to adjust that. To get the max RPMs usually adjusting the throttle cable at the engine usually takes care of it. Gravely went so far as to limit the throw of the throttle lever at the dash. They did that by shortening the slot in the dash but I thought that was only done on the G series tractors.

Gravely normally set their engines to run at 3200-3300. A slightly lower max RPM extends engine life dramatically.

As far as the ribbed tires are concerned, I would try a front weight rack first. The 800/8000/G series is very light in the front and it needs some weight. At least put a set of front wheel weights on it. That might be enough to take care of your problems.

The Carlisle Mutitrac C/S is about as good as it gets in a turf tire. Compared to the original tires or Turf Master or Turf Savers, they give me at least 2 times more traction.

I strongly advise people to not mow sideways on a hill unless they have a ROPS. If that tractor were to roll over on you, it will kill you. That tractor weighs about 1000 lbs or 1/2 a ton. The same with climbing a steep hill. Being so rear heavy, it is again conceivable that the tractor may flip on you. I have had a 816 almost roll and flip on me. Then I learned to only mow downhill on steep slopes.
 
   / Dogbane cooked my 8199G
  • Thread Starter
#10  
Richard,
you are a remarkable resource of info, thank you.
I found when doing heavy field mowing that last hundred rpms helped, just seemed to not bog as much; clearly I was taking all the hp out of the engine. Only time I have to use full throttle, normally I like to keep it much slower, and when doing the occasional normal grass mowing with it, probably run in the 3100-3200 range, or whatever the little digital tach thinks I'm running. But it always has fresh Rotella 30W in it which I watch like a hawk. Burns, drips very little oil, more dripping. I think the seal between the engine and trans is unhappy, and someday I will have to split it all and will do a serious redo then. For now I'll hike up the idle and check the air mix. It backfired on me with a big pop, so that sounds like things are a little lean as you suggested. It was just tuned up, with carb adjust, when I overheated it, and now with the new hybrid electronics on it, maybe it needs some fine tuning again.

Still finding little bits of the cottony material on the mower.
 
 
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