i had a working p38, now i don't

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luckymark

Active Member
Posts
227
Location
new malden, surrey
I had a working p38, it needed a bit of tlc and then it went for an mot, it passed although my friendly mot man did let slip that he had an appointment at Specsavers in the afternoon! so i decided to sort it all out, i fitted new air bags, new shocks, new radius arm bushes, new anti roll bar bushes,new drop links, fixed the windscreen washers, cured the leaking washer bottle, rebuilt the compressor and last but not least thought that i would change the seals in the valve block, up until this point the car was still working fine although it was now on a sorn, some might say that changing a few rubber seals is an easy job, i would disagree, especially as iv'e changed mine and now the bloody thing don't work, i read all the how to's, thanks Wammer's, and did only one valve at a time, what could go wrong you ask? iv'e no idea is the answer! as far as i can work out there's air coming out of the exhaust port, as far as i understand it, thanks Wammer's, that means a problem with the nrv's ? i checked them twice and can't see anything wrong, could it be the new seals or do i need to look at something else?
 
What are the symptoms? I'm guessing you have suspension issues?
Does it do anything? Any warnings on the dash? Do you have any diagnostics?
 
Wazzajnr said:
What are the symptoms? I'm guessing you have suspension issues?
Does it do anything? Any warnings on the dash? Do you have any diagnostics?
Click to expand...
The compressor runs constantly, but the suspension wont rise, there are no warnings on the dash and the normal lights come up, its telling me that its trying to reach its normal height from the access height which it has always done, i don't have any diagnostics
 
My best guess would be a duff compressor then. Or a seriously bad air leak. Or a combination of the two.
Mine used to take forever to get up to height but after replacing the compressor seal and cylinder it's up within a couple of minutes even after sitting for months.
I would check compressor output first or just get a refurb kit anyway.
Once that's done, it's time to get the soapy water out to find the leaks if it still doesn't work.
Loads of videos on YouTube on how to fix the compressor and cheap kits on bay of E.
 
luckymark said:
The compressor runs constantly, but the suspension wont rise, there are no warnings on the dash and the normal lights come up, its telling me that its trying to reach its normal height from the access height which it has always done, i don't have any diagnostics
Click to expand...

Sticking your thumb over the compressor outlet might be worth a try as Wazzajnr says. It should take a reasonable amount of pressure to push your thumb off.

Or ff you leave the door (or the tailgate) open with the car running for 10 minutes the air-tank should refill but it won't try to raise or lower the suspension. Then shut the door / tailgate and it should lift up.
 
Iv'e checked the compressor as per Wammers how to and that appears to be fine, it has been rebuilt and was pumping up the suspension just fine, iv'e tried letting it run with the door open for twenty minutes and then closing it but i still can't get it up! the problem has started since i changed the seals in the valve block, i,m still thinking along the lines of nrv's as there seems to be air coming out of the exhaust port when the compressor is running, wish i'd left it alone but i won't give up until iv'e sussed it out
 
@kurtjohnson10 had some nrv's for sale last week, might be worth a PM to him.
If the compressor is working but the air is escaping, it's never going to work.
Run it with the doors open and lots of water with lots of fairy liquid in around the valve block and you should find your leak. Once found, should be a relatively easy fix.
 
I think its got something to do with the nut behind the wheel(me) it was working fine, although it was a bit slow to rise and would gradually drop if left for a couple of days, before i attempted my rebuild, oh well tomorrows another day, so i'll have another play around with it if i can be arsed!
 
When you put the rear bags in did you inflate them before you let it off the jacks because the rear ones can get a kink in them and not inflate properly and break the bottom seal and there fore will run the compressor constantly and leak out as fast as you put air in.
the cure is to jack the body up to lift the wheelto the point where the wheels are nearly off the ground and try inflating the bags and if your lucky that will take the kink out of the bag. if your unlucky the bottom plastic mount will have broken and you will need a new air bag.
 
If when compressor is running air is coming from exhaust port. Diaphragm valve is duff or solenoid is not being pulled to seal it.
 
New bags have been on for a couple of months and have been working fine until i touched the valve block, i think Wammers has hit the nail on the head, i'm racking my brains about the diaphragm, no laughing at the back, but iv'e got a nagging doubt i may have put the diaphragm in upside down!! going to strip it again this evening and check
 
luckymark said:
New bags have been on for a couple of months and have been working fine until i touched the valve block, i think Wammers has hit the nail on the head, i'm racking my brains about the diaphragm, no laughing at the back, but iv'e got a nagging doubt i may have put the diaphragm in upside down!! going to strip it again this evening and check
Click to expand...

Check for correct fit and don't forget the spring, that is vital.
 
+1 on sorting the diaphragm valve first. Look here on PaulP38 page, and about halfway down the page are nice pictures showing which way round the valve goes. The flat centre of the diaphragm needs to be able to seal on the brass insert.

The slightly further down the page is a picture showing the correct orientation for the NRV's.

If you still can't sort it out you are welcome to pop over to Langley at the weekend (assuming you have alternate transport). I have a special cable I made for bench testing the valve block & driver packs. This makes it much easier to "soapy water test" the underside of the block.
 
Gentlemen (i use this term loosely!) thank you for all your advice and offers of help, i have found out the cause of the problem. It was as i thought, the " nut behind the wheel " was to blame all along. Suffice to say that some idiot having taken great care to keep everything clean and only do one valve at a time and not wind up with any spare parts at the end of the rebuild (this is a favourite trick of mine) had put the diaphragm in upside down!!!
 
luckymark said:
Gentlemen (i use this term loosely!) thank you for all your advice and offers of help, i have found out the cause of the problem. It was as i thought, the " nut behind the wheel " was to blame all along. Suffice to say that some idiot having taken great care to keep everything clean and only do one valve at a time and not wind up with any spare parts at the end of the rebuild (this is a favourite trick of mine) had put the diaphragm in upside down!!!
Click to expand...

Always listen to uncle Tony, you know it makes sense. :D:D
 
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