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Joined: Dec 30 2015
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Interesting results...

I won't tell you how long it takes for my Viair 444C to fill the p38 tank ;)

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Joined: Jan 07 2016
Posts: 169

Physics type eh? Kinda suspected as much from the Resonance comment.....
I ran my re build 2 more full cycles and it's times dropped by a minute to 100Psi and 1: 30 to 125, so certainly wearing in.
Tested the pump on Bolt: 5:00 to 100 Psi. 8:15 to 125 Psi. Seems pretty good.
Very glad I tested the Borrego's pump....
I stopped the test at 5:45 and 30 psi.......Piston seal virtually knackered!
I gave the Borrego the the freshly re built pump.
Now, to order another seal kit for the knackered one.
I think I can now remove, refresh and re install one of these in about 15 min.....Simple once you do it a few times inna row!

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Joined: Jan 07 2016
Posts: 169

Martyuk wrote:

Interesting results...

I won't tell you how long it takes for my Viair 444C to fill the p38 tank ;)

Awww, Come on, Now you have to......If only to make us jealous, but mostly to give us an idea of what it can do!
Is yours the 2 cyl jobbie?

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Bolt wrote:

I think I can now remove, refresh and re install one of these in about 15 min.....Simple once you do it a few times inna row!

Sounds about right but one thing I haven't seen in any of the write ups on how to do it is one thing I always do. Before putting the crank back on I screw the grub screw in a little so it will only go on with the grub screw against the flat on the shaft. I know one owner who rebuilt his compressor but didn't so the grub screw was bearing on the round part of the shaft and not into the flat. Then went on holiday to Scotland so roughly 500 miles later, in the Scottish highlands, it dumped him down to the bumpstops. Took ages to work out what the problem was (by remote control over the phone) as the pump seemed to be running but not getting even warm. Taking it off and trying it showed it wasn't generating any pressure as the motor shaft was spinning but not turning the crank. Next problem was that he only had a few tools with him and a set of Allen keys wasn't in the toolbox.....

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Joined: Sep 14 2016
Posts: 462

With the strip under the reed valve its natural position is slightly open so its feasible that this arrangement leads to faster opening and more time / area for the inlet valve so you get more air in than you lose by the valve being slightly open for the initial phase of the compression stroke.

If I recall correctly reed valves of this sort are quite slow in operation under inlet pressures, primarily because you need to have enough pressure differential to actually bend the thing so it opens. Only 14 psi max available and you want it open at the lowest possible differential pressure to maximise cylinder filling. With the small gap air will start flowing immediately after TDC. Flow through the small gap will be quite fast reducing pressure significantly in that region and to some degree reducing it over the whole port area which will help the valve open. Given that inlet reed valves usually seem to operate with restricted openings I suspect that air flow speed related pressure drop is a fairly important factor in helping keep them open and maximise efficiency.

No doubt there is some maths somewhere.

Clive

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Joined: Dec 30 2015
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Bolt wrote:

Martyuk wrote:

Interesting results...

I won't tell you how long it takes for my Viair 444C to fill the p38 tank ;)

Awww, Come on, Now you have to......If only to make us jealous, but mostly to give us an idea of what it can do!
Is yours the 2 cyl jobbie?

Nah, it's single cylinder, but it's a beast...

I am actually probably going to have the tank emptied tomorrow as I'm chasing a leak on the tank side... I haven't been bothered doing it so far, but it is getting to the stage where it annoys me...

I'll time it when I get it up and running and get the 0-50/100/150 psi times. From memory though it was somewhere around 5mins to fill the tank completely.

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Joined: Sep 02 2016
Posts: 491

Whilst I appreciate all that Clive but the pressure differential happens as soon as the piston is going down of course (?), It is probably more important that ithe valve closes as the piston comes back up and seals it ? And it may just be as mentioned above that with the long strip on top the valve simply opens further (than it does if the short strip is on top) and that improves the overall air throughput (?)

Either way it may be one of those situations where they carefully calculated all the parameters.... but then just used LR-style 'trial and error' instead ?!

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Joined: Sep 02 2016
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Marty: I looked at the Vlairs once but recall they were noisy (?). In the end I went for an L322 unit instead (Wabco) which fits in the spare wheel/well (in a felt-lined cradle with a foam lid... ).... but you can still hear it inside the car !

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Joined: Jun 23 2019
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Hi I am thinking of overhauling the EAS pump & I watched ED China ON WD's, & it looked straightforward.

So is it as straightforward as it looks?
Anything i should be aware of?
Is it OK to just undo the outlet pipe, or do I need to release pressure from the system via some other way?
Where is the best place to get the kit to refurbish the pump?

Always a good site with some great reads.

Thanks

John

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It's very simple and straightforward, there's two things you need to be aware of. When putting the crank back on the shaft, make sure the grub screw bears against the flat on the shaft and be careful when putting the new liner over the seal. It needs to go on at an angle and then twisted straight otherwise you will ruin the new seal. Yes, you can just undo the pipe, there won't be any pressure behind it because of the non return valves in the valve block.

Kit here https://www.ebay.co.uk/itm/Range-Rover-P38-EAS-Air-Suspension-Compressor-Piston-Liner-Seal-Repair-Fix-Kit/282534660124

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Joined: Jun 23 2019
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Many thanks

John

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Joined: Jun 23 2019
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Hi when you say---
make sure the grub screw bears against the flat on the shaft

I am not sure what you are referring to. Do you mean the grub screw that you remove to take out the piston? I presume that there is a round part of the shaft & a flat part, & if you screw it to the flat side it holds it in position.
This may be more obvious when I get it off?
John

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You got it, there is a flat on the shaft that the grub screw needs to bear on. If the grub screw is screwed in part way then the crank will only slide onto the shaft with the screw against the flat so then you just tighten it.

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Joined: Jun 23 2019
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Thanks

J

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Joined: Dec 30 2015
Posts: 1175

Bolt wrote:

Martyuk wrote:

Interesting results...

I won't tell you how long it takes for my Viair 444C to fill the p38 tank ;)

Awww, Come on, Now you have to......If only to make us jealous, but mostly to give us an idea of what it can do!
Is yours the 2 cyl jobbie?

OK, so it took a few more days than I had hoped to get around to tinkering with the EAS, but finally got a look at it today, now the weather has cleared up a little bit.

I had the tank empty, and the times are in... this is with a single Viair 444C compressor:
0-50psi: 49s
50-100 psi: 1:09s (total from empty: 1:58s)
100-145 psi: 1:13s (total from empty: 3:11s) 145 psi (ish) on the gauge was to the pressure switch turning the pump off.

So a shade over 3 mins to fill the tank from empty, with a door open etc.
The 444C is rated to 200psi, and 100% duty cycle at 100psi.

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Joined: Aug 19 2019
Posts: 166

Marty, how difficult is it to fit the Viair? It looks like a good upgrade. Is the original pump wiring heavy enough without mod's?

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Joined: Dec 30 2015
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It wasn't the worst thing in the world... I had previously had a second P38 compressor fitted, which I mounted on a steel adapter plate next to the EAS box. I used the studs in the bodywork where the ABS pump would fit on a LHD vehicle, and then used standoffs from that for the second P38 compressor.

When I upgraded to the viair, I re-drilled the plate and used some anti-vibration mounts, and it's now situated there pretty happily. I extended the inlet feed around to into the EAS box with the filter head on it, so it takes air in from the EAS box, rather than just in the engine bay, as mine gets fairly dusty!

Control wise - I took a feed off the positive for the standard P38 compressor, and wired that to a relay. The relay contact then has a separate 30A fused feed (which in my case comes off the auxiliary battery in the loadspace). So when the factory compressor 'turns on', it triggers the relay to power the Viair.

I still have a P38 compressor in the EAS box, but it isn't connected - as it's really along for the ride with the Viair... it's there just as a backup incase the Viair fails at any point, then I have a 'get home' solution. The air feed from the Viair goes through a NRV and T's into the feed from the P38 compressor.

The standard p38 compressor is unplugged, so it doesn't run under normal circumstances.

I'll try and get a couple of pictures at some point...

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Joined: Dec 30 2015
Posts: 1921

Ask him about the airline in the boot!

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Joined: Aug 19 2019
Posts: 166

Thanks Marty. Yes, I suspect the airline in the boot might be for airing tires back up after off-roading. A more heavy duty compressor would be ideal for that.