I have a 5HP Honda gasoline pressure washer. It's been a great machine, as in, really great. Anyway the axial mounted hydraulic pump leaks hydraulic fluid like crazy, and I'm not sure where it's coming from. But to get to the question, are those little pumps rebuildable, or do you just by a new one ? I've never been inside one so I'm not sure what to expect, but I'd imagine it's not rocket science.

I don't want to buy a new pressure washer because although I've had the machine for 25 years or so, it still doesn't have a lot of hours on it, and the motor is in excellent shape.

Any advice appreciated.

Everyone I know just drops on a new pump if the motor is still good. Matching shaft size is a key parameter for buying a new one.

Most of these pumps are Chinese specials and they are $75-$100 on eBay/Amazon. If that's what you have, just slap a new one of these on and your good for the next 25 years.

I get good service out of these Chinese pumps. Make sure to anti-seize the shaft because they can be a bitch to get off, which you might find out trying to remove a 25 year old pump. I dump the oil every 25 hours or so. Pretty simple to do and increases the life of these pumps.

If its a name brand pump, like General or Cat, take it off, send it to be rebuilt by the manufacturer or approved rebuilder.