Somewhat OT: Repairing a Pressure Washer Pump?

For those who want the condensed version, here are the questions: 1) Should I repair or replace the Comet ZWD 4030G pump on my pressure washer, or should I replace the whole pressure washer? 2) If repair is practical, what are the most likely components that need to be replaced, and/or what should I be looking for as I tear it down and reassemble?

Here are the details: I did some searching on the forum, thinking I had seen this discussed, but couldn't find anything relevant. I have a pressure washer that has given good service over many years, but now the pump is not working. I thought Ihad seen some "general wisdom" that it wasn't worth repairing or replacing the pump. But as I have priced new pressure washers, I have discovered that this one is at the higher end of non-commercial units -- its specs are 3000psi at 4gpm. The 3000psi is commonly available even under $500, but the 4gpm pushes the price up to the $1000 range.

The pump is a Comet ZWD 4030G. A replacement pump will cost $350 or so. I have a complete parts schematic, and repair kits for the valves, seals, and pistons are available (around $50 for each of those kits) -- if I only needed to service one of those components, I could possibly get this working again for $50. The problem is, I've never been into one of these before, so I'm hoping someone here can give me some pointers on whether it is worth attempting a repair, what the most likely problem points are, etc.

Having taken apart and repaired several HP pumps there is nothing difficult about any of them. But thats me, if you are not comfortable with disassembly of stuff without detailed manuals and the like, then don't do it. To replace the valves in a typical 3 cylinder pump its about $50-80.
A comon problem of NO pump pressure is the unloader valve getting stuck with particals, or the valve and seat erroding. if thats the case another $50-100. Until you pull it apart these are only electronic guesses.

My philosophy on it? Its already broke so try to fix it. Worst case scenario is you have to go buy a new replacement pump. If nothing else you learned what a high pressure pump looks like inside. Sounds like a win-win to me however I've been disassembling everything I've touched since I was five.

I was once told by a previous boss, "If it's not working and the alternative to giving a teardown and inspect is total replacement, what do we have to lose other than a few minutes for the teardown? If you can fix it great, if not we aren't out anything!"

That's been a philosophy I have adapted. It has saved me a lot of money and I've gained a lot of experience from it.

To give credit, thanks Mark--MR Chassis.

Go for it, and good luck. Might just be dirty and cost you a couple O rings.

Ben

For a new pump, I would use Water Cannon for a supplier. If its a belt drive, there should be lots of pumps that will fit.

The unloader/pressure relief is a good place to start before you tear into the pump. You can disconnect the line from the unloader to the inlet side of the pump and see if the water is bypassing there.

I'm with post # 4 & # 5. Have a look, it's not working now, it can't get worse.

Paul

Oh I use these for work and finally gave up trying to repair all but the simplest of problems. Granted, I'm not the most mechanically inclined person, but the plain fact is that usually a number of things wear in short order, and it takes more experience than I have to find all of them when you have the thing disassembled. So you fix the obvious, and place more pressure on the next-weakest part which fails next time out. And so on.

There are servicing companies and repair people around who can get it all done. They cost in between doing it yourself and buying new, of course. But it's a chore that has caused me so much aggravation that calling them is well worth it. The last annoyance i encountered is a design that required a gear-puller of a type I have never seen before, and could not find or buy without knowing what it was. Just to get the case open so I could get access to the motor.

One thing is that many pressure washers are manufactured in Italy and sold under different names. An odd mix of English and metric components and fasteners. You didn't say if yours was gas-powered or electric, but if it's an Italian electric motor, beware the solenoids. . . .

Sorry to be slow in following up. Thanks for the responses. I guess I should have said up front that I will definitely be taking the pump apart, one way or another. I have not had a chance yet to work on it, but I will report what I find when I do.