# 20 G over heats



## ric27 (Jun 3, 2015)

After mowing 30 min, in moderately high grass (10") with the deck as high as it will go the tractor loose power like it has over heated. I is full of oil the fan is clear and I have completely cleaned all the cooling fins and the whole motor of accumulated crud. Help


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## ric27 (Jun 3, 2015)

This tractor it a Gravely 20 G with a Kohler Md. M29S twin flathead motor. I just recently purchased it with about 1400hr on the meter. I believe it is an 87 model. The previous owner kept good records of the maintenance. He was good at oil changes, lubing and blade sharpening/replacing, batteries ect, but I noticed that in the service manual in calls out combustion chamber clean out every 500hr. There is no record of this being done in the maintenance ledger. If this has not been done could it cause problems lost power problems after it gets completely warmed up.


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## ric27 (Jun 3, 2015)

OK, I let the motor cool down all the way, changed the oil and went out mowing again. everything seemed great until about 40-45 min then started loosing power again. this is the very same as this morning.


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## PeteNM (Sep 18, 2003)

Welcome rick27!! In the past I've found the same problems as you are seeing and the coil worked. I have a Bobcat that the coil wasn't any help. So, I got new spark plugs and that seemed to fix it. Some plugs aren't so good even if they are new. I keep an extract set of new ones for everything now. Also make sure there is not a problem in the fuel system. edro:


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## ric27 (Jun 3, 2015)

Thanks for the response Pete. So are you saying that a bad coil caused a similar problem on one machine and bad plugs on another?


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## PeteNM (Sep 18, 2003)

ric27 said:


> Thanks for the response Pete. So are you saying that a bad coil caused a similar problem on one machine and bad plugs on another?


It was all on the same Bobcat. When I changed the coil I was kind of shooting in the dark. Bad coil is usually a good place to start, but when that didn't fix it I just tried new spark plugs, they are cheap and it doesn't hurt to have new ones anyway. I had to wind up getting two sets as the first one weren't any good. So, I keep extra new plugs for it now. 

I once had a mower that would act that way and it wound up being the fuel. I would start and fun cold OK but as it warmed up the gas would run less and less cutting the power back. Once I went through the fuel and got it running well, even when hot, I had no more trouble. 

Good luck..edro:


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## TecumsehBriggs (Jun 17, 2011)

I changed the coul on my Ariens S16H that was having problems after running about 20 minutes. It can run all day now.


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## film495 (Nov 1, 2013)

my guess, failing coil. 

if you don't want to pull the head, seafoam engine cleaner or similar product does remove carbon if you follow the directions. you just spray it into the air intake a couple times, then basically let the motor stall out on it, wait a while, then run motor until it stops smoking white out the exhaust and you are done.


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