I suspect that my NRVs are pretty tired, given how much air seems to leak out of the exhaust port when the compressor is off. It seems that we can't get new NRVs from anywhere. So, I wonder if we could use something like these with a groove turned in each hex to take a big fat O-ring to hold it firmly in the block?
Gordon forgive me my ignorance but what is there other to NRV's than renewing O rings?
Tony.
Renewing the O rings doesn't work, because the soft brass cone wears down and they don't sit square on the seat any more, and it all starts to leak badly.
Aha, is this a result of O rings totally worn out so the brass parts getting hit, I mean servicing too late?
The brass is the hard material in this case so thats what wears. Might well be better material options. At a price. Usual automotive cost-material-design compromise I imagine. Whole valve block is a fairly standard way of doing such control for its era but the usual industrial rated way of doing things would have been too expensive so i imagine the engineers had to work hard to get the price down to something reasonable. Those sort of compromises tend to bite after 10 or 15 years.
Personally I'd look for a screw in valve with fully threaded housing rather than modifying one to be trapped by an O ring. Looks easy enough to modify the hole size and tap appropriately.
Wonder if it would be practical to duplicate the whole unit with modern, miniature, " join the blocks together" style electro-pneumatic parts. Pressure might be an issue as many of the less expensive ones top out under 100 psi. Distributor price for that sort of valve seems to be of the order of £30 to £50 a pop which will be too much but careful direct from China shopping might make it work. Order of £250 for all new, industrial quality, drop in replacement would certainly attract me should I have more problems.
Clive
Thanks Clive for this explanation.
Clive603 wrote:
but the usual industrial rated way of doing things would have been too expensive so i imagine the engineers had to work hard to get the price down to something reasonable. Those sort of compromises tend to bite after 10 or 15 years.
Reasonable? The LR price for RVH100030 (valveblock only) is €1450.- ex VAT
One might expect something for that money.
Ferryman wrote:
Reasonable? The LR price for RVH100030 (valveblock only) is €1450.- ex VAT
One might expect something for that money.
Wouldn't have been anything like that price in bulk to LR ready to bolt on as the car comes down the production line. Parts have always carried a monster mark up relative to actual cost as part of a vehicle. Always used to be reckoned that it would cost you around 4 times as much to build a vehicle from parts as it would to buy. Thats DIY with no labor costs, no factory overheads no yadda yadda to pay either. Just dealer mark-up. Wild guess is ex-factory from whoever makes them is £300-£600 range for small batches. Equivalent in series production price could well have been under half that. Given that its obsolete technology and small market, can't see they would sell many at that price. Of course you do have to factor in the LR "hello Mr Parts Customer, here is your green box now turn round and bend over" bit! LR direct show around half that price for pattern or 2/3 rds for OEM in different colour box which isn't stupidly shabby considering what folk have to pay for similarly complex parts for vehicles that are in production. In many ways we P38 pilots are spoilt because so many parts are flat out cheap by modern standards. Certainly what folk are paying for bits on ordinary VW, Fiat, Renault, Honda and the like scare me.
Still be interesting to see what a functional equivalent from modern standard units would come out at?
Clive
I've often considered replacing the valve block with 4 individual valves - one for each corner... the biggest problem I can see is that even though you can get dual inlet/exhaust valves designed for air suspension, the wiring would need looking at, as the EAS system uses a single inlet, and exhaust valve for the whole system... whereas newer air suspension systems appear to have a dual purpose valve for each corner.
I have had a few thoughts about adapting the wiring from the EAS ECU to drive the system to allow for individual valves at each corner, and do away with the valve block completely - but haven't had time to actually do anything about it yet.
You'd just replace the ECU with something equally more modern. There's bugger all to it.
Not wishing to be a party pooper, but would your vehicle still have type approval/MOT/Insurance after you modified a rather fundamental system?
Can anyone point me in the direction of these solenoids which have both intake and exhaust?
Morat wrote:
Not wishing to be a party pooper, but would your vehicle still have type approval/MOT/Insurance after you modified a rather fundamental system?
Probably not but would anyone notice? I doubt the average MoT tester would even know what should live inside the EAS box and people still manage to get through the test on coils.
Purists 'look away now' but what happens if you seal the NRVs in with silicone or (oh-oh !) epoxy resin ?
The problem with adding a customised (ie. non-OEM/pattern) block is that in theory you have 'modified' the suspension system,
which may be 'of interest' to your Insurance Company: Anyone knows what happens if/when you tell then you fitted coils ?
gordonjcp wrote:
Renewing the O rings doesn't work, because the soft brass cone wears down and they don't sit square on the seat any more, and it all starts to leak badly.
I've not seen inside these beasts, but could new brass cones be machined?
I just 'borrowed' these two pics from Paul's P38A valveblock guide. Are these the buggers we are talking about?
Give a ring at Dunlop for spares?
Yes, and I did some (necessary) research myself after my daft question and those are the ones; In context (Step 7):
Even if the o-rings are exactly the right size (and the 'right' material) in a well-worn block they will most likely leak.....(?)
Wonder what the possibilities are for re-doing the seating in the block? Well worn in this case translates to about 3/8 of not very much actual material wear and there is plenty of free movement on the springs so taking a gnats nubbin or two out ought not to alter the seating pressure enough to stop it working fine. Heck standard model engineer practice with leaky valve seats on their baby (and not so baby) steam locos is to sit a ball bearing on said seat and whack it with a hammer. Said to work for both steel ball and O ring types.
If you have decent machine shop facilities for small parts re-making the valve cones after modifying the design of the unit so it can be put back together looks to be no great issue. Just fiddly. I could do it if I had to, even make a new block from scratch if really pushed, but it all seems more trouble than is worth. That said I've not taken a good look at the valve units so it might be rather easier than I think.
Clive
I don't think the seat wears so much as the cone that the rubber bit goes around. All three of mine have about half the cone eaten away.
Hafta get my hands on some worn ones and see what can be done about making and fitting new cones then. Its not rocket science, just has to be turned smooth and true. Sorting out how to ensure that it all goes back together is probably a bigger issue. Maybe stainless steel would wear better than brass as being harder.
Deterioration is due to the itsy bitsy bits of brass that are worn off over time by the O ring rubbing on the cone becoming embedded in the O ring surface acting as a sort of grinding block. Once wear starts it just keeps getting worse due to the bits that come off hanging around to grind more off.
Clive
I must admit looking at the pictures I did think that it shouldn't be too difficult for someone with a lathe to turn up some new cones. Looks like you may have a little project in the making Clive......