Help Diagnosing Issue

[VegetiveSteam]

Timing is controlled by the flywheel key. The shaking engine is probably loose or lost engine mounting bolts. The Kohler Courage is a dog and has several problems. Read up on it online and definitely check the top cover engine bolts for tightness under engine shroud.

The thing to remember is the Courage single cylinder was the dog. The unfortunately same named Courage twin was a very good engine and was in many ways simply a Command twin with solid lifters.

 

[PTmowerMech]

First time poster here, thanks in advance.

I'm running a Husqvarna RZ5426 with a Kohler SV735 (Courage 26hp 725cc). I purchased it new years ago and have maintained it well. This season something has changed. Let me describe the symptoms and tell you what I've looked at already.

Symptoms:

1. Runs a slight bit rougher than normally. By this, I mean that the engine shakes more than years past, but it isn't much.
2. Starts fine and runs for a good 15 mins; Then the engine will wain when under a strain, to the point where it dies. This can be mitigated somewhat by disengaging the blades and releasing the handles so that it idles in neutral.
3. If the engines does shut off, it can easily be restarted, but runs best if let set to cool down.

What I've looked into:

1. I've checked the oil level; it is full but not overfull. Oil is clean from a recent change.
2. There is no smoke in the oil fill pipe as would be the case if a head gasket was leaky.
3. The carb was taken off, apart and cleaned. No trash was in it.
4. Gas is fresh, and fuel filter was replaced last year. Fuel pump was tested and is pumping as it should.
5. Air filter is new for the season and not clogged.
6. Battery is 1 year old and holds at 12.8v.
7. Spark plugs have spark. I did disconnect each spark plug momentarily to see if each cylinder was firing. I did this quickly so the engine wouldn't run too long...just a couple of seconds. Each cylinder ran fine.
8. I cleaned the debris was the engine block fins, thinking it was a cooling issue. one side seems clogged with grass, but there was no oil leaks anywhere on the block, and I looked hard after taking covers off.

The only defect I did find was a crack in the muffler.

Okay, there it is. Any suggestions of what I should look into next?

I'd suggest removing and inspecting the fuel solenoid. Sounds like it could be malfunctioning and about to go out.

 

[PTmowerMech]

First time poster here, thanks in advance.

I'm running a Husqvarna RZ5426 with a Kohler SV735 (Courage 26hp 725cc). I purchased it new years ago and have maintained it well. This season something has changed. Let me describe the symptoms and tell you what I've looked at already.

Symptoms:

1. Runs a slight bit rougher than normally. By this, I mean that the engine shakes more than years past, but it isn't much.
2. Starts fine and runs for a good 15 mins; Then the engine will wain when under a strain, to the point where it dies. This can be mitigated somewhat by disengaging the blades and releasing the handles so that it idles in neutral.
3. If the engines does shut off, it can easily be restarted, but runs best if let set to cool down.

What I've looked into:

1. I've checked the oil level; it is full but not overfull. Oil is clean from a recent change.
2. There is no smoke in the oil fill pipe as would be the case if a head gasket was leaky.
3. The carb was taken off, apart and cleaned. No trash was in it.
4. Gas is fresh, and fuel filter was replaced last year. Fuel pump was tested and is pumping as it should.
5. Air filter is new for the season and not clogged.
6. Battery is 1 year old and holds at 12.8v.
7. Spark plugs have spark. I did disconnect each spark plug momentarily to see if each cylinder was firing. I did this quickly so the engine wouldn't run too long...just a couple of seconds. Each cylinder ran fine.
8. I cleaned the debris was the engine block fins, thinking it was a cooling issue. one side seems clogged with grass, but there was no oil leaks anywhere on the block, and I looked hard after taking covers off.

The only defect I did find was a crack in the muffler.

Okay, there it is. Any suggestions of what I should look into next?

I'd suggest removing and inspecting the fuel solenoid. Sounds like it could be malfunctioning and about to go out.

 

[MrLarkins]

Ran it again today. Issue persists.
To VegetiveSteam: I took your suggestion and check the heat from each side of the exhaust...both cylinders are putting out the same heat.
To Rivets: the crankcase bolts are all tight.
To PT mowerMech: when I turn the key and before the engine cranks (accessory spot), I here the 'click' of the solenoid in the carb. What else can I do to 'check' it?

I'm going to take a video of the issue occurring and post it for your inspection.

What else?

 

[MrLarkins]

Starting up <--video link

Mower issue: it dies when warmed up. <--video link

 

[bertsmobile1]

buy a pair of red in line spark testers and install them
When the engine is running properly they will glow red/ orange
Watch them when the engine is faultering
If one ( or both ) start to flash then you have an electrical problem
If they remain constant then only flash when the engine get to a slow idle you have a fuel problem
If you can get your hands on an alternative fuel tank hook it up directly to the carb and see if the problem goes away
Either or both
The first step is to work out if the problem is electrical, fuel or mechanical
As for mechanical, tat would be things like a valve guise or seat coming loose
Valve guides are easy to check because the valve lash will be different every time you check it

FWIW I have a fuel tank I got off an old Tecumseh flat head engine that I use as an alternative fuel supply
You can usually pick them up for peanuts as trash & treasure sales, boot sales or mower wreckers .
A customer with motorcycles pinched the tank off one of them and I have even had a customer who used the tank off their push mower

 

[MrLarkins]

OK, I ordered a pair of red inline testers. Delivery is Tuesday. I'll get back to everyone then. Thanks

 

[VegetiveSteam]

When it's warm and acting up like in the video, how does the engine run if you just let go of the levers and sit still? And if it seems to straighten out while sitting still what does the engine do if you move the throttle to idle?

 

[Hammermechanicman]

Starting up <--video link

Mower issue: it dies when warmed up. <--video link

Sounds like it is starving for fuel.
Fuel pump?
Tank vent?
Hot carb boiling fuel?

 

[MrLarkins]

When it's warm and acting up like in the video, how does the engine run if you just let go of the levers and sit still? And if it seems to straighten out while sitting still what does the engine do if you move the throttle to idle?

From a cold start, it takes around 10min before it begins acting weird. Once I hear the engine take a turn for the worse, I can keep it running by turning off the blades and/or letting go of the handles (to neutral). But after 10min of doing that, it'll die even if I back off and reduce the throttle.