Odd P38 EAS problem!

Hello. Can anyone please offer an explanation to the following EAS problem before I rush out and buy a new pump please?
My 2000 4.0 P38 was not pumping up quickly back in September this year and so I replaced all the air bags. It was a little better then reverted to slow, then failed to rise at all.
I took the compressor apart and found the piston liner rutted and grooved in one area and so replaced the liner and seal with a kit from Goswin in the Netherlands. Immediately everything was back to normal, but this weekend and after about 800 miles since repair the suspension started going up only slowly and by today wont go up at all.
I took the pump apart again and found the piston and seal very loose within the new liner which was very shiny and slick! Air could obviously pass by the piston it was not a tight fit!
Now before I buy a new pump, could a broken valve/ diaphragm cause these problems? Be fixed by a better performing pump and then cause it to wear so dramatically, so quickly? Or could it be the liner and seal were a poor fit?

Thanks for your thoughts, Robin.

Crabbo said:

Hello. Can anyone please offer an explanation to the following EAS problem before I rush out and buy a new pump please?
My 2000 4.0 P38 was not pumping up quickly back in September this year and so I replaced all the air bags. It was a little better then reverted to slow, then failed to rise at all.
I took the compressor apart and found the piston liner rutted and grooved in one area and so replaced the liner and seal with a kit from Goswin in the Netherlands. Immediately everything was back to normal, but this weekend and after about 800 miles since repair the suspension started going up only slowly and by today wont go up at all.
I took the pump apart again and found the piston and seal very loose within the new liner which was very shiny and slick! Air could obviously pass by the piston it was not a tight fit!
Now before I buy a new pump, could a broken valve/ diaphragm cause these problems? Be fixed by a better performing pump and then cause it to wear so dramatically, so quickly? Or could it be the liner and seal were a poor fit?

Thanks for your thoughts, Robin.

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I have had this problem with the dutch supplied piston seal. Look at the side of the slip ring that holds the seal in place there should be a groove in it. Carefully spread seal and fit a suitabley sized O ring in this groove lubed with a little silicone grease. Then refit piston and rebuild compressor. It should cure your problem.

wammers said:

I have had this problem with the dutch supplied piston seal. Look at the side of the slip ring that holds the seal in place there should be a groove in it. Carefully spread seal and fit a suitabley sized O ring in this groove lubed with a little silicone grease. Then refit piston and rebuild compressor. It should cure your problem.

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Thank you very much for the reply Wammers. I have contacted the Dutch guys today and thay say it must be my valve block or diaphragm and cant be their kit! Odd you should have had the same problem and cured it! I will give it a go, much appreciated.
Robin.

Crabbo said:

Thank you very much for the reply Wammers. I have contacted the Dutch guys today and thay say it must be my valve block or diaphragm and cant be their kit! Odd you should have had the same problem and cured it! I will give it a go, much appreciated.
Robin.

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I would also check the inlet and exhaust valves make sure they are sealing properly. I had an exhaust valve problem and as the piston seal should be forced against the cylinder wall by air pressure, if the valves are leaking what happened to me may have been caused by the compressor running light. It may also be your problem so check the exhaust in particular. Make sure it sits square on the O ring it seats on. And that the support vane does not hold it hard on but is just a few thou off contact at the toe end. The inlet valve should sit flush to head with no percievable gap under its sealing area. Again the support vane should be just off it at the toe. The support vanes are not there to hold the valves onto their seats but to prevent excess flex and fatigue failure. The O ring on the piston keeps the seal pressed onto the cylinder wall. I did mine a couple of months ago and it has been fine since.

Thanks again Wammer. I have dismantled the pump again and will clean the valves. My piston does not have a groove for an O ring beneath the seal as I am told by the Dutch guy that this groove is only on aftermarket pumps and not original as is my case.

Can you tell me if you think an underlying problem could have been temporarily masked/ fixed by the new pump seal and liner only to manifest again as wearing the pump seal so quickly? The wear on the liner is about 1/3 shiny and smooth and 2/3 dull with vertical marks. I realise there needs to be some movement but there is slight space all around the seal, I suspect this is excessive.

Kind regards, Robin.

Crabbo said:

Thanks again Wammer. I have dismantled the pump again and will clean the valves. My piston does not have a groove for an O ring beneath the seal as I am told by the Dutch guy that this groove is only on aftermarket pumps and not original as is my case.

Can you tell me if you think an underlying problem could have been temporarily masked/ fixed by the new pump seal and liner only to manifest again as wearing the pump seal so quickly? The wear on the liner is about 1/3 shiny and smooth and 2/3 dull with vertical marks. I realise there needs to be some movement but there is slight space all around the seal, I suspect this is excessive.

Kind regards, Robin.

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Ok. Maybe as i said the piston seal goes like this because it is running light. (No pressure to push it against cylinder). Check your valves make sure they are sealing in particular the exhaust. I put a piece of silicone tube to outlet and sucked to make sure it sealed onto the O ring. Also the O ring it seats on is better stuck in with a little silicone rtv. You must make sure this valve seals properly. If you then get pump working and cannot stop air from it with your finger. Next thing to look at is diaphragm valve. If when pump is running there is any air at all coming out of exhaust outlet this maybe split. Easy to replace this item. If you find the diaphragm is intact next port of call is the diaphragm solenoid valve. The one with two blue wires to it. This must be energised when the pump is running. What it does is supply air pressure from the tank to underneath the diaphragm via the 4mm pipe to push diaphragm up onto exhaust outlet and seal it. This then sends air via an 8mm pipe through drier then back into valve block and out to tank via 6mm pipe colour coded Violet.
When you have done all that the tank should fill. Did you just change the piston seal or did you also change the cylinder. There should be no grooves or marks in that at all. I have had them were the hard anodising has worn through. Try polishing inside it with a little brasso if it shines anywhere you have lost the hard coating and it needs replacing.

Wow! Thanks Wammers. I bit the bullet and bought a new compressor today and replaced the old one as the old liner was very badly scored in one area and lipped in one place deeply, so I reckoned maybe the piston was not running symmetrically in the new cylinder as in the old and caused the damage.
Everything is working perfectly for the moment but time will tell! I will probably try and replace the O rings in the valve block next.
Your thoughts and expertise are much appreciated. Regards, Robin.

Hi all,

Unsurprisingly I now have exactly the same problem ! I replaced my piston seal a couple of months back and all was ok initially. But it got gradually worse at inflating especially in the cold, and today I got the air supply fault message. Put my finger over the inlet (with filter removed) and could feel air coming out of there.

So stripped the pump and have found the "new" piston seal (from the Dutch) is not making contact properly with the cylinder, there is an air gap around the circumference of it. The seal is quite hard, not a lot of flex, and I guess that's why it's worse in the cold.

Have had a good play blowing here and there and think inlet and exhaust valves are ok, just this crap piston seal. I can't see a place to put an o-ring under it though, does that mean I've got to get a new pump ? To be honest, the seal is that hard that i can't flex it out enough to check for a groove. What a load of ****e that was, is there anywhere that sells a better seal ?

Thanks, Rick

I've had the exact same problem with the dutch seal and there's at least one member of RR.net that reported the same.
In my case I fixed it by wedging a small screwdriver between the seal and the metallic ring, to force the seal to "open" and increase it's diameter. But I know it's only a temporary fix as I've done this about one month a go and I've just came in from doing it again

I'll going to contact the vendor and spread this information as much as I can. P38's are troublesome as they are and we don't need a sh*ty parts seller to help

Yep that's the same as mine then. I've just ordered a different one from fleabay, this time from a UK manufacturer. It's yellow in the picture so I guess potentially a different (hopefully better) material than the grey one from the Dutch.

Will keep you posted on how good it is once it arrives...

Same here! Unbelievable! After only two weeks. And the compressor was filled with sooth like powder that I believe was disintegrated seal material. I was too lazy to demand my money back and invented ways to blame myself, buy I will now.

dannys said:

Same here! Unbelievable! After only two weeks. And the compressor was filled with sooth like powder that I believe was disintegrated seal material. I was too lazy to demand my money back and invented ways to blame myself, buy I will now.

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Powder is French chalk from inside airbags.

wammers said:

Powder is French chalk from inside airbags.

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Pretty sure there is no french chalk in Arnott Gen 2's or any other nationality of chalk

Datatek said:

Pretty sure there is no french chalk in Arnott Gen 2's or any other nationality of chalk

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Don't know about that. But the powder deposite found in all EAS valve blocks, the shuff that blocks the exhaust filter comes from somewhere. There was certainly evidence of chalk inside the OE bags i changed last year. Unless it's desicant residue, but hardly think the desicant is in powder form. Unless it breaks down over time. It certainly ain't fairy dust.

wammers said:

Don't know about that. But the powder deposite found in all EAS valve blocks, the shuff that blocks the exhaust filter comes from somewhere. There was certainly evidence of chalk inside the OE bags i changed last year. Unless it's desicant residue, but hardly think the desicant is in powder form. Unless it breaks down over time. It certainly ain't fairy dust.

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I am pretty sure it came from my disintegrated seal. Same color, dull-blackish, was not there the first time I opened the compressor to replace the seal. And, the seal had indeed disintegrated, and it is dull-black in color...

dannys said:

I am pretty sure it came from my disintegrated seal. Same color, dull-blackish, was not there the first time I opened the compressor to replace the seal. And, the seal had indeed disintegrated, and it is dull-black in color...

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Ok misunderstanding then. I refer to the white powder deposit found in the EAS system. Don't think this Dutch seal is as good as they say it is judging by the number of fails.