A Leaky Pressure Washer

My son picked up this Briggs & Stratton pressure washer for very little.

The I.D. label on the chassis is mostly obliterated, so I can't tell what the model number is.^[1] The engine^[2] runs nicely, but it seems that the pump has a bad leak when it's in operation.

To be investigated. This may be interesting.

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It Leaks Alright! -- TUESDAY, JUNE 6, 2017

With the machine not running, but the water supply connected, there's a wicked leak from between the output manifold and the pump head.

The next thing I need to do is to actually run the machine in spite of the leak, just to check whether the pump is otherwise operational. If the pump fails to put out, regardless of the leak, then the washer is a write-off. If pump operation appears to be more-or-less normal, then a repair attempt is worth pursuing.

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'Performed that test, and the pump appears to work. I imagine that the leak is providing a fair bit of pressure relief, and impairing the pump's output pressure somewhat.

Pump Removal

Three M8x40mm hex socket head screws w/flange nuts hold the pump and engine together. You need a 6mm hex key and a 13mm open end wrench to remove them. The pump comes away readily from the engine's keyed shaft.

The pump has a label on it that reads:

MTPV90736
197137
Order 5209923
0511094746

for whatever that's worth.

Here's a view of the leaking spot. The leak is right at the centre of the photograph.

It looks like an O-ring may have blown out. It's time to carefully open up that section of the pump and see what's there.

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And here's the trouble.

An utterly ruined O-ring and a broken screw. I suspect that the pump had a freeze-up incident.

The O-ring is one thing; the broken screw is another matter entirely. The odds of my successfully extracting the broken off screw end are slim to nil.

We'll see what can be done here.

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An attempt to drill out the broken screw only resulted in a broken cobalt drill, so I carved the casting away to get rid of the broken off screw end entirely.

I drilled and tapped what was left of the casting beyond the end of the screw, and came up with a longer M5 screw to replace the broken one. The repair looks like this.

I didn't have an exact replacement metric O-ring, but I had fractional inch O-rings that were close in size. So, I replaced all four O-rings with 9/16" x 3/4" O-rings, so that at least the assembly would close up evenly, with slightly oversize o-rings squashed inside.

Anyway, that worked. The pump no longer leaks, and it operates quite powerfully.

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Notes:

[1] With the help of Google Images I may have deciphered the machine's model number; it appears to be 020288-0, or something very close to that. That makes it a 2008 vintage machine. It's not doing too badly for its age.

[2] Engine is Briggs & Stratton model number 10J902, type 0139 E1. Spark plug is Champion RJ19LM, 13/16" hex, 0.030" gap.

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