Fixing old high pressure washer

[carbon]

I was wondering if I should use an o-ring to seal the face, but I think a flat face will work

If you want to use a seal, a copper washer will work. A lot of pressure washer pumps that have ceramic pistons use one on the pressure end of the piston

 

[DennisCA]

Finally some machining. The two tapers fit nicely. I did not touch the compound between cutting the internal and external tapers, I ran it in reverse for the external taper and cut on the back side.

Still more features to turn yet and then the screw on cap which will become the piston face.

 

[DennisCA]

First cylinder almost done, along with a redesign, a simplification. Now I use a threaded rod that goes through it all.

I had trouble doing the fine single point thread, crappy chinese carbide threading tools have been fighting me since day 1. I then lost the small screw into the chip pan when replacing a broken one. Couldn't find it again... I gave up for a week or so. I ground a new threading tool from HSS once I finished up some side projects to be able to do that well enough. But alas I had fumbled the part bad enough with the old insert tool I did not have enough material left.

So I redesigned. I make the "top lid" deeper, drill a thru-hole and tap it to M10. The screw is deleted and replaced with a stainless M10 rod that now hold everything in place. Much easier to make. I am not sure if I ought to tig weld the stainless top to the lid or not. Risk of distortion and I think loctite 2701 might suffice. So first one down anyway... And I got the new seals.

 

[Turbo]

First cylinder almost done, along with a redesign, a simplification. Now I use a threaded rod that goes through it all.

I had trouble doing the fine single point thread, crappy chinese carbide threading tools have been fighting me since day 1. I then lost the small screw into the chip pan when replacing a broken one. Couldn't find it again... I gave up for a week or so. I ground a new threading tool from HSS once I finished up some side projects to be able to do that well enough. But alas I had fumbled the part bad enough with the old insert tool I did not have enough material left.

So I redesigned. I make the "top lid" deeper, drill a thru-hole and tap it to M10. The screw is deleted and replaced with a stainless M10 rod that now hold everything in place. Much easier to make. I am not sure if I ought to tig weld the stainless top to the lid or not. Risk of distortion and I think loctite 2701 might suffice. So first one down anyway... And I got the new seals.

Whatever you use, weld or loctite, you need to make sure that the top cannot come loose. I've seen that happen on a pump & the results were not pretty!

 

[DennisCA]

I have a high amount of faith in Loctite 2701, but not as much as a weld. Loctite 272 IIRC is the strongest stuff out there, but not available in europe.

 

[DennisCA]

I am impressed at the depth of cut my lathe can make with the right insert. My lathe is a south bend 9 clone. This shows two cuts taken on the hard chromed rod that will become the pistons, using an WNMG insert for aluminum that is a lot sharper than the regular inserts. I got the whole rod down to length in four cuts total. I also rehoned the aluminum insert on a diamond grinder after it got dull.

Almost done with all four new pistons.

 

[DennisCA]

All pistons are completed and I have begun reassembling the pump but I believe I need some kind of tools, like spreaders to be able to reassemble this thing.

Due to space constraints the pistons need to go in first. Then the very strong springs need to be hooked up. Then I need to insert the shaft and later the lower cam. The problem are those springs. Too strong for me to bend apart in order to fit in the shaft and cam. I would need to expand both as well.

I don't have big hopes for finding something suitable to buy, at a reasonable (DIRT CHEAP!) price so I think I am looking at making my own tools again, damn.

Photo from disassembly.

Last photo of pistons before final reassembly using loctite. I made it so I could use this lever tool from an iscar parting tool kit to also tighten the top lids in place. I also added hylomar blue on the contact surfaces as extra insurance.

All cylinders have new seals and I've tested the check valves using compressed air and they all seem to work.

 

[carbon]

If the cylinder bolts are threaded into the area where the springs are then possibly use some slightly smaller bolts to go through these holes and use 4 bars to pull the springs apart on two opposing pistons. If space inside is limited then thread the short bar to eliminate the need to fit nuts inside. Also use something on the outside surface to spread the load on the casing.

 

[DennisCA]

I threw this together, one was enough to get the shaft by. I will need to make another to expand both sides so I can drop in the cam. But it seems to work. Just rant out of M10 nuts.

 

[brightspark]

a stroke of luck today . the high pressure hose started leaking in the middle its rotten on my power washer a new ones about 50 quid ..8 years ago a bloke got rid of his power washer and on the roadside so i grabbed the hose and lance as it was in good condition . tried it on the power washer and both ends were the correct fittings and it works perfect

 

[DennisCA]

Oh a question. Since it's getting near, what kind of oil would one run in this. Will regular motor oil work, or should it be a straight oil with no additives or detergents?

 

[carbon]

Usually a mineral based oil is recommended for most pumps. Some use sae 90 and some use sae 15w40

 

[DennisCA]

OK I made two tools for pressing apart the springs and, I think this must be a first, it worked like I had planned.

So now all plungers/pistons are back in place. This is the part of the reassembly I figured was going to be the hardest. Reassembly of the rest of the pump should hopefully be easier and faster. Need to get some oil.

 

[Turbo]

Oh a question. Since it's getting near, what kind of oil would one run in this. Will regular motor oil work, or should it be a straight oil with no additives or detergents?

As carbon said, either a 15/40 or 90 mineral oil. The Karcher HDS machines used the 90 grade in their 3 phase machines & 15/40 in their single phase but both pumps were the same design.

 

[DennisCA]

Well the pump is coming back together

Think I got the wrong oil though, SAE 30 was what I got when I asked.

I've been using Hylomar Blue for gasket material. I found this residue on the motor, only thing that affected it was acetone. It looks like they used Hylomar blue or something very similar from factory too.

I actually got the motor mounted and the whole thing back in its "frame" and some of the plumbing back too. But forgot to photo that. Near to being able to test this. The plan is to just connect to a hose at first and also not hook up the return valve. I was thinking of fitting a valve and slowly shut off the water pressure and see if the return valve works. If it does I should be able to connect everything up, then I just need to get myself a spray gun.

 

[carbon]

The plan is to just connect to a hose at first and also not hook up the return valve

With the return valve connected to the outlet manifold disconnect it from the inlet of the pump. Install a blank in the inlet manifold where the flexible pipe would be connected, then adjust the return valve to the lowest setting. When the outlet hose is then blanked or shut off the water should exit from the return valve. An 075 nozzle is a little on the large size but an 07 nozzle is a little small for the specifications of this pump, an 075 with reduce the pressure slightly but should be the better choice as it wont wear the return valve as an 07 nozzle would. For me I don't rely on any machine pressure gauge to set the operating pressure, I always use an amp clamp when setting the operating pressure, then usually set it at about 0.5 amps below the motor rating.

If the oil is to light it will more than likely foam and expand to much when in use for a while, if this happens use a heavier oil as @Turbo example

 

[brightspark]

i had ep 90 in my old power washer

 

[Turbo]

For me I don't rely on any machine pressure gauge to set the operating pressure, I always use an amp clamp when setting the operating pressure, then usually set it at about 0.5 amps below the motor rating.

That's a very sage piece of advice.

Very few pressure gauges are accurate & if there is a detergent injector fitted in the system it causes a restriction, increasing the pump pressure. If your pressure gauge is fitted after that it will read a good bit below the actual pump pressure.

Not so easy to do on an engine driven unit, you have to jet it according to the pump output.

 

[DennisCA]

I don't believe the return valve on this pump is at all adjustable however

 

[DennisCA]

Status as of this morning