Hi all
There is very good advice on this forum and other forums concerning the operation of a clean RPCV.
However if the statement is only "give it a good clean", then there is good reason that when the unit is returned, the expected results may fall short.
I'll try to explain.
I have seen many pictures of partly dismantled RPCV ready for cleaning. While this has remedied many ailments, I have not yet seen a completely disassembled RPCV. If the RPCV is only cleaned from the outside, and the piston is only pushed in and out a few times, it is possible that fine grit from the cleaning process will actually end up inside the cylinder and could cause some binding or stiff operation of the piston.
The pictures of the parts that require cleaning are clearly shown. It's not too difficult to disassemble it all the way, if you have the right tools for the job.
I'll mainly concentrate on the Nozzle body. Most of you are already familiar how to remove the nozzle from the main body.
What I will say is that there is a better way to undo the nozzle without leaving vice grip marks on the valve body. While using vice grips is very affective, it does leave unsightly markings and could even leave very fine metal slithers in your rags, or even a cut finger.
I still use vice grips but I place a double folded fine emery paper over the nozzle to get the extra grip, then I wrap a thin piece of aluminium or steel over it. Place the main body in a vice which has aluminium covers over the jaws to prevent damaging the spanner area.
Then gradually tightening the vice grips hold of the valve body until it no longer slips when turned and the nozzle is removed. It's right hand thread, so you need to turn it counter clockwise when looking into the nozzle.
Observe the bits that fall out, and the orientation of them once it is unscrewed.
You will have a small needle, a long pin, and a piston.
The piston needs to be returned with the small hole visible towards the opening.
The long pin has no orientation, however the small needle point needs to point away from the long pin. ie pointy part of the needle must face towards the nozzle end of the RPCV.
When assembling all components, apply clean oil and hold everything horizontally, otherwise the needle, pin and or piston slide around. You don't want to loose that needle.
Working closely above a white rag will easily show up any small bits that slide out unnoticed.
Driver preparation-Unless your driver is new, you will need to square of the end first, and also tidy up the end if it has flared out from use. You can either do this with a lathe or grinder, followed by a quick buff of the end of the driver to prevent any scratches inside the bore. Do this right and it will work well afterwards.
Anyway to remove the smaller piston from the valve (or nozzle) you unscrewed, (sorry no names for these internal components), you need a driver that fits inside the nozzle (see picture-My driver measures 6.14mm, or 0.242 inch) and give it a gentle tap. Increase force until you start to feel it move the end cap.
With the big piston, pin and small needle already removed, this can be done by screwing the valve back onto the body and rest it vertically between the jaws of the vice.
WARNING- DO NOT TIGHTEN THE VICE, or you will distort the area where the piston slides. Then apply gentle taps until all the bits will fall inside the tube. I've not tried this yet but I think there is just enough room. I will try to confirm with a spare RPCV.
Now you can remove the parts and give them a thorough clean. I can't vouch whether or not any solvents or cleaning agents are safe for the O rings, so beware. I didn't remove mine and I used Carby cleaner, and then quickly applied diesel following the clean. It didn't swell or seem affected by it.
As you can see from the picture, the small piston has a distinct wear mark on one side only. I forgot to take note whether the spring is not flat and it is pushing it to one side. Anyway I use some very fine emery with some diesel on it and tried to clean up some fine score marks. The inside of the valve where the piston slides was also checked if the small piston moves smoothly. A bit of emery around a small rod was moved in and out of the valve body. A good spray with the cleaning agent was applied to remove any grit. Oil was applied for assembly.
Now I did go one step further in pulling things apart, but in hindsight that seemed unnecessary, if you have access to a good cleaning spray and a compressor. I did use a small carburettor jet drill to ensure the small holes were clear. You can see from the pictures that the small piston has a little slotted part inside which is held there with a spring that looks like a helicoil, but is not. I don't fully understand the function of this bit other than maybe to disperse a fine jet of oil and turn it into a stream of oil before entering into the pumps reserve.
Note-I typed this post late one night, and felt it wasn't well written, so I've just edited a bit. It could be better but I think you'll get the gist of it I hope.
