Engine Repairing a fire - Walker MTGHS with Kohler CH25S

FTPing

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Oil leaked from the rear valve cover onto the cylinder head and caused a fire. This is the valve cover with the fuel pump mounted to it, I'm lucky the gasoline was not involved. Anyway I'm trying to remove the engine shroud to assess the damage but it appears that I might have to remove the engine, which seems a bit extreme. Can the shroud be removed without pulling the engine? Any help is appreciated.

I'm new to this forum and I apologize if missed any prior discussion on this topic.
 

Boobala

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Sorry about your misfortune, can you supply some more info about your machine ( if still available )
please see the example and post what you can ...

GET INFO.JPG click to enlarge .
 

reynoldston

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Oil leaked from the rear valve cover onto the cylinder head and caused a fire. This is the valve cover with the fuel pump mounted to it, I'm lucky the gasoline was not involved. Anyway I'm trying to remove the engine shroud to assess the damage but it appears that I might have to remove the engine, which seems a bit extreme. Can the shroud be removed without pulling the engine? Any help is appreciated.

I'm new to this forum and I apologize if missed any prior discussion on this topic.

I have worked on several garden tractors in my shop with that style engines that I have had to remove the engine shroud. Yes you will need to remove the engine if its like anything I have worked on.
 

bertsmobile1

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It will depend upon how long the PTO shaft is.
Some Walkers have enough space after you unbolt the PTO from the flywheel, some don't.
In any case you will have to remove the front pulley so start with that, followed by the shaft ( 4 bolts ) then see if there is enough space.
Walker being a better maker usually specify engines with blow out ports in the blower housing if it can not be removed for cleaning.
So if your has a pair of small removable covers over each head in the blower housing, it can not be removed with the engine in situ.
 

FTPing

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Yes-I do have a Walker mower with the Kohler CH25S engine and with blow out ports in the blower housing, and on further inspection it appears that there is not enough room to remove the shroud without removing the engine. Drats!

I'm also not finding any real evidence that the oil came past the valve cover gasket as I first thought, and I'm wondering if the head might be the culprit. I have one discolored valve cover bolt that indicates there was a lot of heat in one corner, lower corner. Still investigating ...
 

FTPing

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Mower - Walker
Model - MTGHS
Date Mfg - 1998
Engine - Kohler
HP - 25
Model - CH25S
 

bertsmobile1

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I am always skeptical when I get told an engine had an oil fire.
It is bloody hard to get light fuel oil to burn let alone lube oil.
Usually it just smokes but rarely ignites.
Grass clippings, fine grass dust, dust itself and fuel will readily combust.
Of all of the fire damaged engines I have fixed, No 1 was fuel, leaking from the tank, leaking from the carb
No 2 was clippings , even had a couple where the clippings caught from the heat off the spark plug

Thus I would suspect the carb float first
Walkers with the big hoppers covering the engine bay are a bit hard to keep clean as it is difficult to properly access the engine bay without fully removing the hopper which is a PAI , particulalry if it is 1/2 full.
 

Boobala

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Mower - Walker
Model - MTGHS
Date Mfg - 1998
Engine - Kohler
HP - 25
Model - CH25S

Folks here appreciate the info you put forth , NOW , if only ALL those seeking help would do the same , ....
 

reynoldston

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Folks here appreciate the info you put forth , NOW , if only ALL those seeking help would do the same , ....

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.
 

FTPing

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I am always skeptical when I get told an engine had an oil fire.
It is bloody hard to get light fuel oil to burn let alone lube oil.
Usually it just smokes but rarely ignites.
Grass clippings, fine grass dust, dust itself and fuel will readily combust.
Of all of the fire damaged engines I have fixed, No 1 was fuel, leaking from the tank, leaking from the carb
No 2 was clippings , even had a couple where the clippings caught from the heat off the spark plug

Thus I would suspect the carb float first
Walkers with the big hoppers covering the engine bay are a bit hard to keep clean as it is difficult to properly access the engine bay without fully removing the hopper which is a PAI , particulalry if it is 1/2 full.

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.
 
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