If your pump bolts to your motor, Unbolt it and when you slide it off you will find a shear pin on the shaft. Hope this helps.

Three things in order of easiness. First I'll assume that the pump head is driven by a swash plate on the end of the motor, all in an oil bath. Open that up and dump out the oil. You'll be replacing the oil with just about any sort of motor oil; no need to be picky.

EDIT: everything about unbolting and refilling that oil filled housing will be awfully terribly thoroughly nastily messy.

The pump body has to come apart. Since there's no pressure it is very likely that a relief valve is stuck, seals are dirty, or seals are shot. If its been apart, almost everyone working without a manual puts the new seals in backwards.

If the pump shaft seals (rubber wiper washers on a hard base where the 3(?) plungers work back and forth) are even slightly ragged, replace them and take close note of which way is up!

Take every single o-ring and plunger out of the pump body, clean it with a good rag, and grease it with a silicone waterproof grease. If it moves, clean it. You will probably find a long thick steel plate crimped to the aluminum pump body. Slide it out (stiff!) and clean/lube everything behind it. When you take assemblies out of the valve body they may fall apart but don't worry about that, just clean, lube, and put them back in the proper order.

Take notes. Take pics. Get rid of every single bit of grit and lime scale, and it should be headache free.

If it still won't pressure up it may be time to buy a new pressure release valve, but that's last resort.

This post was edited by cold_weather_is_evil on Thu, Apr 3, 14 at 1:09