my ar383 leaks oil from the little round window on the pump, is that bad?

Diagnosis

The oil leaking from the sight glass (the round window) on your AR Blue Clean AR383 is a critical failure indicator. This window is designed to allow you to monitor the oil level and color; it is not designed to be a leak point. When oil escapes from here, it typically means the internal pressure within the crankcase has exceeded the seal's capacity, or more commonly, the pump shaft seal has been compromised. The root cause is almost always "water contamination." The shaft seal is the primary barrier preventing high-pressure water from entering the oil reservoir. Once that seal fails, water is forced into the oil chamber during operation. This creates an emulsion—a milky, creamy mixture of water and oil—which increases the volume of the fluid in the crankcase. Because the fluid now exceeds the capacity of the pump, the excess pressure forces the milky oil out through the weakest point: the sight glass seal. If you see a "mayonnaise" consistency or a milky white color in that window, your pump is currently operating without proper lubrication, which will lead to catastrophic bearing failure and a seized pump if not addressed immediately.

How to Fix It

To resolve this, you must replace the shaft seals and flush the contaminated lubricant. You will need a pump seal kit compatible with the AR AAA-series pump and a fresh quart of non-detergent SAE 30 pump oil.

1. Drain the Pump: Place a catch pan under the pump. Unscrew the drain plug located at the bottom of the crankcase. Let the milky fluid drain completely. If the oil looks like a milkshake, you will need to flush the pump twice.
2. Remove the Pump Head: Using a socket wrench, remove the bolts securing the pump head (the manifold) to the crankcase. Carefully pull the head away to expose the pistons and the shaft assembly.
3. Extract the Failed Seal: Locate the shaft seal behind the pump head. Use a seal puller or a small flat-head screwdriver to carefully pry out the old, worn rubber seal. Be careful not to scratch the metal seating surface of the crankcase.
4. Install New Seals: Clean the seal seat with a lint-free cloth. Press the new shaft seal into place using a seal driver or a socket of the exact same diameter, tapping it gently with a rubber mallet until it sits flush. Ensure the seal is oriented correctly (lip facing the water side).
5. Replace O-Rings: Replace all O-rings on the pump head manifold to ensure no external leaks occur once the pump is reassembled.
6. Reassemble and Fill: Bolt the pump head back onto the crankcase, tightening the bolts in a star pattern to ensure even pressure. Fill the crankcase with fresh, non-detergent SAE 30 oil until the oil level is exactly halfway up the sight glass window.
7. Test Run: Run the machine for 30 seconds and check for leaks around the sight glass and the shaft seal.

If That Didn't Work

• Inspect the Crankshaft for Scoring: If the new seal leaks immediately, the metal shaft itself may be scored or pitted. Use a fine-grit emery cloth to lightly polish the shaft. If there is a deep groove where the old seal sat, the shaft is compromised and the entire pump assembly must be replaced.
• Check the Sight Glass Gasket: If the oil is clean but still leaking from the window, the sight glass itself may be cracked or the perimeter gasket may have perished. You can attempt to seal the edge with a high-temp RTV silicone sealant, but replacing the sight glass assembly is the professional fix.
• Verify Pressure Settings: If the pump leaks shortly after a seal change, your Unloader Valve may be stuck closed. This creates extreme back-pressure that can blow out a brand-new seal. Test the unloader by ensuring the trigger is pulled or the bypass is functioning.
• Replace the Entire Pump Head: If you find cracks in the manifold casting during disassembly, seal kits will not help. You will need to order a complete replacement pump head assembly to restore the pressure seal.

Heads Up

• Oil Type is Critical: Never use standard automotive motor oil. Automotive oil contains detergents that cause foaming in pressure washer pumps, which leads to cavitation and rapid wear. Only use non-detergent SAE 30 oil.
• Avoid Dry Running: Never run the pump without water. Running the pump "dry" for even a few seconds creates immense heat that hardens the shaft seals, making them brittle and prone to the exact leak you are experiencing.
• Winterization: If you live in a freezing climate, always use pump guard or a similar antifreeze agent. Frozen water inside the pump head will crack the casting and blow out the seals from the inside out.
• Check Oil Monthly: Check the sight glass every 10-20 hours of use. If the oil looks cloudy, change it immediately to prevent the bearings from grinding down.