Generator Maintenance and Repair for THOR CHATEAU
This comprehensive guide will walk you through repairing generator maintenance and repair on your THOR CHATEAU. Follow each step carefully and gather all required parts before beginning.
Required Parts
- Generator oil filter – Part Number: Onan 122-0836 (for Onan generators), Alternative: Kohler 25-050-22-S (for Kohler generators), Price Range: $8-$15
- Generator air filter – Part Number: Onan 140-3280 or equivalent, Price Range: $15-$25
- Spark plugs (set of 2) – Part Number: Champion RN14YC or equivalent, Alternative: NGK BPR5ES, Price Range: $8-$12 for set
- Generator oil (10W-30 or 15W-40) – Any quality synthetic or conventional, Quantity: 2 quarts
- Fuel filter (if accessible) – Part Number: Varies by generator model
- Carburetor cleaner – Part Number: Berryman B-12 Chemtool
- Oil drain pan
- Spark plug socket (usually 13/16″ or 5/8″)
- Oil filter wrench
Step-by-Step Instructions
Step 1: Generator System Overview and Diagnosis
The Thor Chateau typically comes equipped with either an Onan or Kohler generator, most commonly an Onan Microquiet or Microlite model in the 2.5-4.0 kilowatt range. These generators are essential for providing AC power when you’re not connected to shore power, running your air conditioner, microwave, and other high-draw appliances. Common generator problems include failure to start, rough running, low power output, or automatic shutdown due to various fault conditions. Before you start any repairs, accurately identify your specific generator model by locating the model and serial number plate, usually found on the generator housing itself. Take a photo of this plate as you’ll need this information for ordering correct parts. If your generator fails to start, first verify that there’s adequate fuel in your tank (generators typically won’t run if the fuel level is below 1/4 tank), the generator circuit breaker is on, and the battery voltage is sufficient (minimum 11.5 volts under load).
Step 2: Accessing the Generator Compartment
The generator in the Thor Chateau is typically mounted in a compartment in the front driver’s side area beneath the cab-over bed section. Access is usually through an exterior door or panel, though some models have interior access. Remove all items from the compartment and use a flashlight to familiarize yourself with the generator’s layout and the location of service points: oil fill/dipstick, oil drain, oil filter, air filter, spark plugs, and fuel lines. Generators run hot, so ensure the unit has been off for at least 1-2 hours before attempting any service to avoid burn injuries. The compartment may also contain other components such as an inverter/charger, propane lines, or electrical connections – work carefully to avoid disturbing these systems. Take photographs of the “before” condition to help with reassembly. Ensure adequate ventilation in your workspace as you’ll be dealing with fuel vapors and engine fumes.
Step 3: Oil and Filter Change Procedure
Regular oil changes are critical for generator longevity – manufacturers typically recommend changes every 100 hours of operation or annually, whichever comes first. Many RV owners neglect this maintenance because they rarely track operating hours. Start by warming the generator by running it for 5-10 minutes, which helps the oil flow more freely and suspends contaminants for better draining. Turn off the generator and allow it to sit for 2-3 minutes. Locate the oil drain plug on the underside of the generator (usually a 1/2″ or 9/16″ bolt) and position your drain pan directly underneath. Remove the drain plug with the appropriate wrench, allowing oil to drain completely (typically 1.5-2.0 quarts). While oil is draining, locate the oil filter – on Onan generators, it’s typically a canister-style filter accessed from the side of the generator. Use an oil filter wrench to loosen and remove the old filter, turning counterclockwise. Clean the filter mounting surface thoroughly with a lint-free cloth.
Step 4: Oil Filter Installation and Refilling
Before installing the new oil filter, apply a thin film of clean oil to the rubber gasket on top of the filter – this ensures proper sealing and prevents the gasket from sticking during future removal. Hand-thread the new filter onto the mounting stud, turning it clockwise until the gasket contacts the mounting surface, then tighten an additional 3/4 turn by hand. Do not use a filter wrench to tighten, as overtightening will damage the gasket and could cause leaks. Reinstall the oil drain plug with a new crush washer if available, tightening to approximately 15-20 ft-lbs (snug but not over-tight). Locate the oil fill cap (usually on top of the generator) and remove it. Using a funnel, pour in new oil – Onan recommends SAE 15W-40 for most conditions, while Kohler typically specifies 10W-30. Add oil slowly, checking the dipstick frequently. Most generators hold 1.6-1.8 quarts. Fill to the “FULL” mark on the dipstick, not above.
Step 5: Air Filter Service
A clean air filter is essential for proper generator operation and fuel efficiency. Locate the air filter housing, typically a plastic or metal box on the side of the generator. The housing is usually secured by clips, latches, or screws depending on the model. Open the housing and carefully remove the air filter element, noting its orientation for proper reinstallation. Foam-type filters (common on Onan generators) can be cleaned and reused multiple times. Wash foam filters in warm water with mild detergent, rinse thoroughly, allow to air dry completely, then lightly oil with SAE 30 weight oil before reinstalling. Paper element filters (common on Kohler generators) should be replaced annually or whenever visibly dirty – attempting to clean paper filters by tapping or blowing compressed air through them provides minimal benefit and may damage the filter media. Install the new or cleaned filter in the exact same orientation as the original, ensuring it seats properly in the housing.
Step 6: Spark Plug Inspection and Replacement
Spark plugs should be replaced every 200-300 hours of generator operation or every 2-3 years for infrequently used generators. Locate the spark plug(s) – most small RV generators have 1-2 plugs accessible from the top or side of the engine. Use a spark plug socket (typically 13/16″ or 5/8″) with a ratchet and extension to remove each plug, turning counterclockwise. Be careful not to drop anything into the spark plug holes during removal. Inspect the old plugs carefully – the electrode and porcelain condition tells you much about engine health. Dark, sooty deposits indicate rich fuel mixture or oil consumption. White, crusty deposits suggest lean mixture or overheating. Light tan to gray deposits with minimal electrode wear indicate good combustion. Gap new spark plugs to manufacturer specification (typically 0.025-0.030″) using a gap gauge. Apply a small amount of anti-seize compound to the threads of new plugs, then hand-thread them into the engine, being extremely careful not to cross-thread. Tighten to approximately 12-15 ft-lbs using a torque wrench.
Step 7: Final Testing and Troubleshooting
With all maintenance completed, you’re ready to test the generator. Close all compartment doors except the one providing ventilation, as generators produce exhaust gases. Turn on the generator using the dash-mounted or exterior switch. The generator should crank and start within 3-5 seconds. Allow it to run unloaded (no appliances operating) for 2-3 minutes while you check for oil leaks around the filter and drain plug, fuel leaks, or unusual noises. If everything looks good, turn on one major appliance (like an air conditioner) to apply load to the generator. Monitor the load – the generator should handle the load smoothly without surging, excessive smoke, or unusual sounds. If the generator runs rough, surges, or produces black smoke, the carburetor may need professional cleaning or adjustment. Run the generator under moderate load for 20-30 minutes monthly to prevent carburetor gumming and keep internal seals lubricated. Record the date of service and generator hour meter reading for future reference.