TroyBuilt/Briggs-Stratton Pressure washer - no pressure- leaks under pump

I have a troy built 2550 pressure washer with a Briggs and Stratton6.75 engine. When I start it, waterleaks from the bottom and I cannot get any water to the wand. However, when it is turned off I can pull thetrigger on the wand and water will drain from the nozzle.

I can see where the water is leaking under the engine. It is from the item with the red circle inthe attached pump image.
What is this part?
Why would water leak from it instead of being routed to the wand?


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Take it off and see, I'm betting it is corroded and stuck partially open. I would think this is a pressure relief valve without looking it up.

 

I have taken if off, but I am still not sure what it is.
Is the valve in this piece (see below)?
Or is it elsewhere and then is just the outlet?

Is it possible to fox this, or do I need to replace it?

I have looked at the parts diagram but I don't see this piece. The diagram is on page 5 here:
http://brandnewengines.com/pdf/20500IPL.pdf

Below is the part I took off.

 

It is a thermal relief valve. It's purpose is to cool the pump it you leave it running without the trigger pressed. If it is run without the trigger pulled the water will recirculate through the pump and get hotter & hotter this valve will open & let fresh water into the pump cooling it back down. Since it is stuck open you will need to replace it. It is doubtful you will be able to clean it and reuse it. But you should test the pump first no sense buying parts if the pump wont work! So plug the port that the valve fits into and run the pump to see if it will make pressure just don't run it without keeping the trigger pulled as too much heat will destroy the pump. If it still won't make pressure you have other problems and these pumps are not worth spending too much money on better to just replace pump or get new unit.

 

I agree with aj-allen. Have a good one. Geo