Fixing old high pressure washer

[DennisCA]

Decided to make a dedicated thread for this.

Before christmas I brgouth this home, for 40 euros I thought it was worth the price of the motor if it's not salvageable. But I would like a working high pressure washer of better quality than the usual consumer level stuff.

Water intake on bottom, four pistons of some kind that build pressure, the high pressure output is on the top. It doesn't seem to be going from one piston to another for sequentially higher pressures, but to all four at once and then to a combined high pressure side.

Brass construction, can't see no cracks.

Motor off:

I did find how the valve that returns the water to the stream works, it was actually shown in the previous photos. Orange colored part, hex shaped.

Removed the cylinder heads, doesn't look very nice inside...

Vacuumed it out

Took apart a 2nd cylinder, similar but better shape

Both seem to have rusted out in the middle around the center holes. The center hole is threaded and I think the cylinder is attached via the hole.

The pistons look like they might be plated with something that has started to release. I think hard chrome.

Cylinder tops looks OK. Next step is to contine disassembling all the cylinders. Some kind of rubber washer.

 

[DennisCA]

After taking it apart further I can say that the pistons don't look good on the ends, they are plated, probably hard chrome. But it has started to flake off at the top which has been the most exposed part. The piston marked as 1 is the most corroded.

The pump becomes smaller and more manageable the more parts I remove:

This is the return from the relief valve (hex shaped part), first place I find a crack.

Worst piston, nr 1

3 and 4 look something like this. 2 looks the best.

This is the cast iron part (or is it steel) that sits between the brass cylinder and the pump body, looks OK, some sort of plastic seal there, this part is in contact with the oil in the pump and I'm guessing it's to make sure the oil doesn't leak out and it also lubricates the cylinder which looks to be in good shape further down.

The brass cylinders look like this. Inside there is some kind of piston ring that seems to be a whole ring and I guess it does the job of keeping water out. edit: It's some kind of hard rubber.

On cylinder 2 which otherwise looked the best, the ring looks like this.

So on cylinder 1 the piston is most corroded although it doesn't seem to have spread all the way around the seal yet. This is the cylinder the seller claimed was leaking. Based on the pictures, it feels like cylinder number two should be the one that is leaking. But it could be that the seller was wrong. I haven't actually tested it as I don't have any outside water to test with during the winter.

What next...

-I will try to remove the ring, hopefully it is some rubber that has become hard and not metal. Then we'll see if it's possible to get a replacement, too much to hope it's a standard part?

-Then I wonder if there is something you can or should do with the pistons. I don't think replacement parts are available. Or if something needs to be done. Maybe it will work for a while, but now it will only get worse, I think.

-Was wondering if you could have cut off only the damaged part and turn a replacement part in some form of plastic. But it may not be a suitable material, but maybe it is?

-Right now I am also trying to remove the bottom cover of the pump so I can clean out the innards and maybe remove the pistons entirely but that lid is stuck like hell even though I removed the bolts. I think the gasket is holding it in place. I am wondering if I need to apply heat...

 

[DennisCA]

Part is out, hard and breaking apart. Anyone know what kind of seal this might be? Standard part?

 

[tigdlo]

-Then I wonder if there is something you can or should do with the pistons. I don't think replacement parts are available. Or if something needs to be done. Maybe it will work for a while, but now it will only get worse, I think.

I'm not sure what grade but pistons and cylinders in some water jet cutting pumps are made from stainless steel, you could machine the old ones down to make an external thread to screw a stainless cover on.

 

[tigdlo]

Anyone know what kind of seal this might be? Standard part?

I'm not trying to be funny but it will be a pressure washer piston seal. Measure the groove width and ID and the piston OD to get the size.

 

[eddie49]

Part is out, hard and breaking apart. Anyone know what kind of seal this might be? Standard part?

Not sure why, but the word that comes to mind is "Viton".

 

[DennisCA]

I'm not trying to be funny but it will be a pressure washer piston seal. Measure the groove width and ID and the piston OD to get the size.

Right so that's their literal name, figured they would've had some name like stefa seals that means nothing.

 

[carbon]

It doesn't seem to be going from one piston to another for sequentially higher pressures, but to all four at once and then to a combined high pressure side.

Ive never seen a pressure washer that the water goes from one piston-cylinder to another, usually they share a common water inlet and then pump to a common outlet.

Low pressure seals tend to be made of softer material than the high pressure seals, which are mostly fabric impregnated and are fairly rigid. Not all manufacturers do this but the brown colour of the pressure seal would indicate to me a fabric impregnated seal.
Don't install any new seals with the pistons in that condition. With the pumps I deal with most of the pistons are now ceramic sleeves and the problem with corrosion is now eliminated

Not sure why, but the word that comes to mind is "Viton".

Sealing rings for hoses and quick release couplings tend to be viton for better heat and detergent handling.

 

[DennisCA]

Looking closely at the seal but cannot see any signs of fabric in it personally.

I was hoping to try them out as is with new seals. If I could get a few years of operation before having to deal with rebuilding the pistons (which feels like an operation that I am not certain it would result in success) I would like that. So far the corrosion in 3 of the 4 cylinders has not reached the seals and only partially in the case of cylinder 1.

 

[Erie Fred]

To me at least, that looks like a airless paint pump.
Graco is the big name over here.

 

[awemawson]

Have you asked the maker Norcar?

They seem to be still in business and making professional pressure washers for street cleaners.

 

[DennisCA]

Yeah but no response.

 

[DennisCA]

Took some measurements of the seals and they're probably these (non english link)

SIL 32x42x7,3 U-manschett PU

Används som Kolvstångstätning

www.kullagret.com

32x47x7.3 mm rated 400 bar

 

[Turbo]

Unless you replace those corroded pistons you will be wasting your time rebuilding that. Because all 4 pistons share a common output side any one bad piston will affect the output pressure of the other 3. You have 3 bad pistons so the output pressure will be very poor. If you fit new seals to those pistons they will get torn up very quickly!

As carbon said, the piston seals are specific to pressure washers in their material & construction. It is likely that those seals will be specific to that manufacturer. I would guess that Norcar bought the pumps in from a pressure washer manufacturer such as KEW or WAP so you would need to find out in order to source the seals & pistons.

If it were me I'd save the motor & scrap the rest. Looking at the construction I'd guess that the pump dates from the 1980's so the liklihood of finding spares is basically zero.

 

[DennisCA]

I'm gonna try fixing the pistons first before I give up on this.

I don't believe you are correct about the seals and I think the ones I found are the correct ones. From my experience older equipment is more likely to use standardized parts than modern equipment.

Of the corrosion, only one of four has the corrosion gone far back enough to touch the area that the seals touch.

 

[winchman]

Have a look at the non return valves on each cylinder as this is the usual cause of issues,

 

[carbon]

Some of the softer more flexible seals in pressure washer pumps are NBR rather than PU

 

[carbon]

Any shiny bands around the piston circumference indicate were the seal has rubbed on the piston over the years. Any damage in that area will leak. In the case of the really corroded one this will damage a seal in a few strokes rather than years

 

[DennisCA]

Yes that's the only one where the corrosion has gone that far. Too bad you can't find a ceramic sleeve in 32 mm.

Seem to max out at 22mm, if so one could've remachined the ends of the pistons to accept ceramic sleeves, since that seems to be how modern piston pumps work, the pistons seem to be hollow sleeves held on with a bolt.

A nice theory anyway...but a moot point in the absence of suitable parts.

e:
It is possible to buy hard chromed ground rods in the right size.

Kolbenstange hartverchromt Ø 32mm f7 Länge 100-2000 mm | eBay

Kolbenstange Ø 32 mm. Längentoleranz: +/-1 mm. Technische Daten.

www.ebay.de

 

[Gareth J]

Curious design. Maybe that's how they all were back in the day. Any information regarding pressure and flow rate? Been looking at a new pressure washer recently. Assembled my own last time but hoping to find someone local who can supply something ~150bar, 15lpm, 3.7kw single phase. Anything less seems a bit weedy.