Engine Repairing a fire - Walker MTGHS with Kohler CH25S

Boobala

Lawn Pro
Joined
Feb 15, 2015
Threads
200
Messages
7,000
You are on a forum with a percentage of people that are looking for free information who never turned a wrench to make a living. They just think that what ever problem they are having is a common problem and all mowers are the same. They just don't understand they need this information to repair and buy parts. This is the reason I try to keep my answers very generic anymore. They will spend 2 or 3 thousand dollars + to buy a mower but wouldn't spend 60 dollars to buy a service manual to fix it. I get mowers in my shop that people just paint over this important information in which it makes it hard for me to buy parts.

Yeah I know what ya mean about those folks that just " GAS N GO " having no idea about ANY maintenance, including brakes and tires on the family car ! I think some have never even looked at an owners manual . ( I figure they use it for toilet-paper ) I don't believe how many people post , L23xx54 ..LBXXX or some SERIES number especially John Deere AND Craftsman owners thinking its the model number ,and have no idea where to find the information . But then the Manufacturers could alleviate that as they used too with a name designation and decals such as Jacobsen Lawn Queen or Lawn King etc. etc. ....:confused2: ..:laughing: ..:laughing:
 

reynoldston

Lawn Pro
Joined
May 23, 2011
Threads
92
Messages
5,705
I am always skeptical when I get told an engine had an oil fire.
.

Back n the days when I was working on trucks I did see oil fires when they had oil leaks that landed on the exhaust manifolds. Yes oil will catch on fire when it hits a hot exhaust system.
 

JoeM(GA)

Well-Known Member
Joined
Jul 10, 2011
Threads
0
Messages
191
I agree with your thinking and looked closely at the carb, fuel pump, filter and fuel lines. There is enough "lawn dust" for me to see that the fuel system seems intact and functioning properly. At the time of the fire the engine was running smoothly. I did smell what obviously turned out to be burnt oil and was pondering that smell for a short time when the "Hot cylinder Head" alarm went off. I shut it down and climbed out to find a smoky fire on the cylinder head just under the valve cover and alongside the spark plug. What appears to be the sensor for the cylinder head temp probably requires replacement along with some of the attached wire, hence my initial question concerning the shroud.

About 5 years ago I had another fire caused by dried grass which was ignited by the muffler and I understand your comments on grass fires. The fire was located under the hopper close to the blower discharge. The three lessons I learned from that encounter were 1. When your wife runs out to tell you your on fire, believe her. The warning lights will verify that she is right. 2. The area under the hopper should be blown out more frequently and more thoroughly then before. 3. Electrical repair is much easier when you have a manual and the proper solder iron. 4. Wire color-coding abilities are more important then knowing how to count to three :laughing:

I noticed that one of the bolts holding down the valve cover was much darker then the other three-this would be the bolt nearest to the head gasket temp sensor. The temperature on that bolt had to be pretty high at some point in time, which makes me wonder if I have a leaky head gasket or bad head. That bolt tells me that there might have been a "good" heat source in that area. The residue left behind all points to an oil fire and the only place where gas could have contributed would be around the fuel pump hose fittings but they were in very good shape and did not appear suspect.

I need to take a break from this for a day or two while I attend to other needs but I appreciate your observations. I'll be back soon.


I have a PDF of the walker service manual, shoot me your email if wanted

Joe
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
I agree with your thinking and looked closely at the carb, fuel pump, filter and fuel lines. There is enough "lawn dust" for me to see that the fuel system seems intact and functioning properly. At the time of the fire the engine was running smoothly. I did smell what obviously turned out to be burnt oil and was pondering that smell for a short time when the "Hot cylinder Head" alarm went off. I shut it down and climbed out to find a smoky fire on the cylinder head just under the valve cover and alongside the spark plug. What appears to be the sensor for the cylinder head temp probably requires replacement along with some of the attached wire, hence my initial question concerning the shroud.

About 5 years ago I had another fire caused by dried grass which was ignited by the muffler and I understand your comments on grass fires. The fire was located under the hopper close to the blower discharge. The three lessons I learned from that encounter were 1. When your wife runs out to tell you your on fire, believe her. The warning lights will verify that she is right. 2. The area under the hopper should be blown out more frequently and more thoroughly then before. 3. Electrical repair is much easier when you have a manual and the proper solder iron. 4. Wire color-coding abilities are more important then knowing how to count to three :laughing:

I noticed that one of the bolts holding down the valve cover was much darker then the other three-this would be the bolt nearest to the head gasket temp sensor. The temperature on that bolt had to be pretty high at some point in time, which makes me wonder if I have a leaky head gasket or bad head. That bolt tells me that there might have been a "good" heat source in that area. The residue left behind all points to an oil fire and the only place where gas could have contributed would be around the fuel pump hose fittings but they were in very good shape and did not appear suspect.

I need to take a break from this for a day or two while I attend to other needs but I appreciate your observations. I'll be back soon.

As an aside ( which I am rather prone to do ) my workshop is an old farm house on a friends 1000 acres.
They are grazing on land that was previously horticulture so there are drainage ditches everywhere.
They originally rotary hoed some of the slightly flatter but soon realised it was a waste of fuel as the ditches held rainwater really well .
The farm is in a rain shadow and the black fella name means "don't rain'.
Thus a real tractor mounted slasher is of limited use so they mow with a fleet of Cubs when the cattle can not keep up.
After 2 deck fires, all of the mowers now have fire extinguishers fitted.
However when talking about this to a local mower shop they laughed when I suggested fitting extinguisers as an option.
Apparently drink holders, sunnies holders, phone holders & charging ports are far more important accessories.
I do 2 to 3 fire repairs annually, all of them are deck fires from accumulated clippings.
We usually get a few weeks of 100F + days and hat tends to dry out the glass, just a little.
 

FTPing

Forum Newbie
Joined
Jun 17, 2017
Threads
1
Messages
5
Well this is embarrassing-I put this job aside intending to pick it up in a few days but a doctor said my shoulder injury was serious and needed attention. But my focus again switched when my wife was diagnosed with cancer. God was gracious and her cancer was eliminated (hopefully) by surgery, chemo and radiation, and she is feeling great and I am now recovering from recent shoulder surgery and here we are one year later.

My nephew and I pulled the engine last week and removed the shrouds. There was an unbelievable amount of dried greasy grass jammed in the cooling fins and that concoction is what caught fire. We also found a sticker on the engine that called for us to clean that area every 100 hours. Walker does provide access ports to assist cleaning but those ports are high on the block and the impacted materials are low on the block and there is no exit path for the debris when attempting to blow it out with compressed air.

Previously I did find signs of higher temperatures in one corner of the valve cover although the gasket appeared intact. The rear head had similar traits, showing more heat in one corner but with no void observed in the head gasket. The head temperature sensor was toast but since it was in the fire itself we could not tell if the alarm had been triggered by some increased heat source or by the fire itself. The ignition module and wiring appear intact although I'm inclined to replace the ignition module since it got pretty warm in that area.

So I'm thinking that I need a new head temperature sensor and new valve cover gaskets and head gaskets. By adding a new ignition module I should be in pretty good shape.

Your comments and/or suggestions are certainly welcome.
 
Top