Having to deal with an engine that shuts down repeatedly while mowing can be quite frustrating and prevent you from getting any work done. This can happen for several reasons.
In this article, I talk about some of the common reasons why your Kohler engine dies when hot and practical troubleshooting tips to help you diagnose and fix the problem.
Reasons Why Your Kohler Engine Dies When Hot
Some of the common reasons your Kohler engine dies when hot include:
- Clogged fuel cap vent
- Faulty spark plug
- Damaged ignition coil
- Dirty air filter
- Old fuel
- Old/stale gas
- Stuck choke
Tools You Need for the Job
Some tools you need to have handy before troubleshooting include:
- Work gloves
- Spark tester
- Clean rag
Kohler Engine Does When Hot: Causes, Diagnosis, and Fixes
1. Clogged Fuel Cap Vent
A clogged fuel cap vent is the most common reason an engine dies when it gets hot. The fuel cap vent is a small vent hole in the fuel cap that allows air into the tank as the fuel level reduces to prevent a vapor lock.
When this vent gets clogged, a vapor lock occurs preventing fuel from leaving the tank into the carburetor. This can cause the engine to die when hot.
Loosen the fuel cap to allow air into the tank and start the engine. If the engine runs without shutting down, the fuel cap vent is blocked.
- Clean the fuel cap and allow the vent to dry
- Replace the fuel cap if the problem persists. The cap vent might be damaged or blocked.
2. Faulty Spark Plug
A faulty spark plug is another reason your engine might die when hot. If the fuel vent is okay, the next thing to check is the spark plug.
Your Kohler engine will die when it gets hot if the spark plug isn’t providing a strong enough spark. Spark plugs experience wear and tear over time as a result of frequent heating, cooling, and reheating of the engine.
This destroys the porcelain on the spark plug making it ineffective and unable to produce sparks needed by the engine.
When the engine gets hot, the faulty spark plug will be unable to supply enough spark to ignite the fuel-air mixture causing it to shut down.
A bad/faulty spark plug will have black stains, dry soot, and oily deposits on the ends indicating carbon build-up.
Replace the spark plug with a new one if it is bad.
3. Damaged Ignition Coil
If the spark plug is okay, the ignition coil might be the reason your Kohler engine dies when hot. The ignition coil transfers energy from the battery to the spark plug, enabling it to create a spark that keeps the mower running when hot.
When an ignition coil is going bad, it will work fine when cool but as soon as it gets hot, it will stop supplying voltage to the spark plug causing the engine to die.
You will need a spark tester to check if the ignition coil is damaged.
- Plug the spark tester into the ignition coil and attach the ground wire
- Plug in the coil connector
- Adjust the spark gap to the appropriate measurement
- Start your engine
- If there is no spark, the ignition coil is damaged
The damaged ignition coil should be replaced.
4. Dirty Air Filter
One of the reasons your Kohler engine dies when hot might be a result of trapped air and engine overheating caused by a dirty air filter.
A hot engine needs more air. When the engine starts running and warms up, it needs cool air inflow from the air filter to prevent it from overheating and malfunctioning.
Air comes in through the air filter. When the air filter is dirty, it prevents air from getting into the engine, causing it to overheat and shut down eventually.
Take out the air filter housing at the side of the engine. Inspect the air filter for dirt and dust.
Clean the air filter after removing it from the housing. Clean the housing with a dry, clean rag if dirty.
The air filter gets dirty easily, especially when you are mowing a dusty environment. Checking it regularly before use and cleaning it when dirty can help prevent overheating and other engine problems.
5. Old Fuel
An engine will shut down if there are issues with the fuel and oil supplies, especially as the engine begins to heat up.
Before each use, always check the fuel supply. Fuel that is more than 30 days old in the fuel tank should be disposed of because it will go bad and clog the fuel system with a gummy, sticky material that the old fuel produces. This can cause your engine to die when hot.
Open up the fuel tank and pour the contents out into a container. Sticky residue in the fuel indicates that the fuel is old and should be changed.
- Drain out the fuel tank using a siphon
- Fill the tank with new fuel
- Add a fuel additive like SeaFoam into the fuel tank to clean the engine and fuel system
6. Old/Stale Engine Oil
Old engine oil is another reason for Kohler engines to shut down when hot. Oil should be changed after every 25 hours of operation.
With regular use, heat generated by the engine and friction causes the oil in the engine to darken and become stale. Stale oil will not be able to coat the moving parts of the engine which need lubrication to function effectively.
As a result, friction is increased and the engine begins to overheat. This can cause your engine to die after running for some time.
Insert a dipstick into the oil compartment. If the oil is dark, it is stale and needs to be changed.
Drain out the old oil and fill the tank with new oil.
7. Stuck Choke
If your engine uses auto choke, it might get bound with dirt and restrict airflow in the engine which can cause your engine to die when it heats up.
The choke closes to restrict airflow when the engine is starting up and should open to allow airflow in the mower engine after warming up.
If it is unable to move freely, it will restrict the air, heat the engine, and shut it down.
Visually inspect the base of the choke for dirt or dust that can restrict its movement.
Use a can of compressed air to blow out the dirt. If blowing out doesn’t work, replace the auto choke.
How to Change a Coil on a Kohler Engine
To change the ignition coil of a Kohler engine, you will need:
- Work gloves
- Small plate(to collect screws)
- New ignition coil
Follow the steps below to change a damaged ignition coil:
- Allow the engine to cool, remove the spark plug, and disconnect the spark plug lead
- Disconnect the cables from the battery, black first then red
- Loosen the cover knob to release the air filter and remove the air filter
- Remove the mounting screws securing the blower housing. Take out the blower housing
- Detach the grounding wire from the ignition coil you wish to replace
- Remove the bolts securing the coil and pull the old coil out
- Install the new ignition coil by positioning it and install the mounting bolts
- Pull the coil back and tighten the bolts
- Rotate the flywheel so that the magnets align with the coil
- Attach the grounding wire and reposition the blower housing
- Reassemble the engine
The first thing to check if your Kohler mower engine dies when hot is the fuel cap vent. Then check the spark plug, ignition wires, air filter, oil, and gas.
Examine the following parts carefully to find out the exact cause of the problem and apply the fixes recommended in this article.