Non thumper- compressor seals!

[andy230]

Hello all,

Here's an odd one!  Can anyone help??

My LDV400 (1994, ambulance ) has rear air suspension. Following the compressor failure (not running when ignition is on) I checked out the electrics, and then removed the compressor. Put 12v across it- nothing, so proceeded to strip it. The motor was good (after strip, clean, rebuild) but the compressor piston was really stiff in the bore. The top seal appeared to have swollen slightly. I cleaned up the bore, lubed the bearings etc.

However I think I'll have to replace the seal on the piston. Its an O-ring, covered by a... cover?! Teflon, maybe??  A flat ring, same diameter as the piston about 0.5mm thick and maybe 3mm deep

Anyway.  To cut a long story short, these aren't purchasable spares from LDV.

They wont sell me a seal.  They will, however, gladly sell me a compressor...!!

That, however is madness- a few hundred quids worth of precision engineered metal for a seal whioch would be overpriced at a fiver.

Does anyone know where I may buy such a seal? ? Or am I forking out for a new (or s/h? unlikely I feel!!) compressor. Any ideas?

On an LDV forum, one guy has said he also searched for seals, then bought a new compressor....  The scotsman is determined to fight his way round this!

Thanks.....

a

[Andy M]

Who made the compressor? Does it have an ECU or is it controlled by a simple switch and levelling valve?

If it's marked WABCO and ECU controlled (my ex-employer) you are pretty stuffed; no one ever made spares, it's obsolete and was built in France so goodness knows what supplier or size they used (it was someone in Renaults database but after that ..... big gallic shrug). If it is WABCO, PM me and I'll give you a contact number, they might send you another scrap unit to strip if they have one.

If it's not the above, google a company called Driverite in either Dublin or Winchester. They used an industrial compressor by (I think) Smiths Industries. They might be more willing to supply something less expensive than an LDV dealer.

Another thought, these systems are utterly unreliable. The heat build up in the compressor has defeated at least three big automotive suppliers unless they resort to complex control systems to reduce the duty cycle. If you can fit steel springs you'll be happy in ten years time, stick with the air and you'll be back here in three.

Andy

[andy230]

cheers andy, I was hoping you'd respond 

The pump is made by ATSUGI, an automotive pump manufacturer.  googling them brings up the japanese city of the same name, and some power steering compressors...

ECU controlled, with a ride hight sensor to switch it on and off.  There's also a "drop valve" built into the compressor, which I'd be willing to forego if I save a few hundred quid.

Its a ?teflon? ring over a 19mm id O-ring.  Bore is 23mm.  Agreed its a crap system, but the van is an EOLV (end of live vehicle).  I bought it 4 years ago, and its just kept going.  One more summer from it would be ideal...

Any idea where I can get this teflon ring??  Or other ideas to bodge it?  I fear a notrmal Oring wont last long.  Clearly not meant to be stripped and rebuilt.  And I agree, its a crap idea!  May try to mod a 12v tyre compressor to do same....

Cheers, and thanks!


a

[guest40]

I used a Ford Fairlane unit from a wrecker (breaker) for a slab when the one in my Mitsubishi died. $A1250 for a new one,  or $A630 for a rebuilt unit on change over. What a joke!!
A good quality 12 volt compressor should be perfect for the job. You can then use something like a Norgren normally closed 2/2  soleniod operated M5 ported pnuematic valve as an unloading valve, a M5 hose tail to suit the hose dia and a tee. Make sure you use a sintered silencer in the outlet to stop dust being sucked back into the system. Other brands like SMC can do a similar valve assy. you will need an unloading valve to lower the unit.

[Andy M]

ATSUGI is a new one on me, but anyone who'd talk to us in Leeds was unlikely to be talking to Japan. LDV did some weird stuff, I'll add this to the list 

The temperature inside is a factor, so a Nitrile o-ring won't last long. Connecting a tyre compressor to the ECU will have it confused as the loads will be strange. HT rubber will be a fluorocarbon or Epichlorohydrin (black). Your local pneumatics shop might have o-rings for HT uses but will often be silicone rubber (red). If a red o-ring is a couple of quid, maybe try one.

Does it have a levelling valve or is the ride height set from an electrical sensor? Do you just need it to level or do you need to go to different heights? One height is easier on the compressor.

If you've got a levelling valve and better still a small reservoir, pull the fuse on the ECU, fill the reservoir to 3 bar/40 psi with a tyre compressor and go for a drive. If you can do half an hour/20 miles and still be roughly level the tyre compressor is up to the job and you just need to rig a pressure switch to trigger it to run. If it won't, the duty cycle is beyond a tyre compressor. The duty cycle is something like 3 minutes on, 17 off if you want it to live. If anything leaks the tyre compressor will run to destruction, but hopefully you'd hear it.

If you've got a height sensor you need to either fix the ECAS (google ATSUGI ECAS?) or build a new system. That's when I'd talk to Gliderite/Driverite or go looking for some steel springs. If you decide to design a system mail/pm me and I'll do you a schematic and some part numbers an automotive distributor might recognise. Parts for this will run to over £200.

ECAS sensors are much of a muchness, so any 12V compressor unit could work. A Rangerover or BMW unit might get you going, but you'd need to find the wiring diagrams for that particular item before you'd know how to power it, level it and so on. I could get diagrams for WABCO units if you can find a unit, but I'm guessing a pneumatic fix will be simpler.

I'd take the compressor ring to someone like Scattergood and Johnsons or Thorite here abouts, the sort of distributors in the yellow pages under pneumatics. It's a long shot but somebody else might use the same thing.

Andy

[guest146]

Andy send me your vin number or reg number. We have good working relationship with our LDV agent i will get them to make a real effort. I do know that Mercedes have a compressor for the brakes on the vario so i am guessing several others may do including range rover. As said you need to know if it just pumps or is it a combined level unit. Maybe a quality tyre compressor as i don't think it will pump all the time but just when you load it  and it needs to compensate.


http://cgi.ebay.co.uk/Discovery-TD5-Air-Suspension-Compressor_W0QQitemZ330316981948QQihZ014QQcategoryZ31348QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Ken

[andy230]

Gents!  Thank you very much for your help with this.  This forum is truely great.

A bit more info.  I reassembled it last night, with various stop-gap o-rings, original seals etc.  It would appear that in fact while the seals may be shot, the motor may also be goosed.  Even with an imperfect seal, as you load it up (ie finger over the outlet) the motor really struggles, slows, and eventually stops.  So if it is trying to pump agains 100-odd psi, that is clearly not going to happen.  So its going to be a new compressor anyway.

Kurt: an alternative part may well do the trick.  Like the one Ken posted, a landie/ range rover one may suffice.  Worth a bash if its cheap, and I could probably get the fittings to work (with a bodge, and a bit of araldite!)

Andy:

Does it have a levelling valve or is the ride height set from an electrical sensor? Do you just need it to level or do you need to go to different heights? One height is easier on the compressor.

Pre-set level, measured with a (?potentiometer) on the back axle, linked to the ECU.  Incidently, the ECU just switches on/off a solenoid to work the compressor.  It also has an air tank of 10L, with a max of 11 bar (160 psi)

If you've got a levelling valve and better still a small reservoir, pull the fuse on the ECU, fill the reservoir to 3 bar/40 psi with a tyre compressor and go for a drive. If you can do half an hour/20 miles and still be roughly level the tyre compressor is up to the job and you just need to rig a pressure switch to trigger it to run. If it won't, the duty cycle is beyond a tyre compressor. The duty cycle is something like 3 minutes on, 17 off if you want it to live. If anything leaks the tyre compressor will run to destruction, but hopefully you'd hear it.

I suspect it may have a bit of a leak (thus possible failure of the compressor!) but it was ever thus.  May well use my tyre compressor as a stop gap so I can use the van.  Someone else suggested this.  But agreed, its going to be hard on the compressor!  Tho I may just switch it on & off manually until I get one switched via the ride height sensor / tank pressure sensor.

....build a new system. ....Parts for this will run to over £200.

ECAS sensors are much of a muchness, so any 12V compressor unit could work. A Rangerover or BMW unit might get you going, but you'd need to find the wiring diagrams for that particular item before you'd know how to power it, level it and so on. I could get diagrams for WABCO units if you can find a unit, but I'm guessing a pneumatic fix will be simpler.

Andy for info and, but the ECU just switches on a relay, so may be more simple than that.  I know someone (oviously with a better "downstream" system than mine on a Merc Vito), who just tops it up every now and again with an airline.  Not going to go that route, but you see the principle.

Ken:

Andy send me your vin number or reg number. We have good working relationship with our LDV agent i will get them to make a real effort. I do know that Mercedes have a compressor for the brakes on the vario so i am guessing several others may do including range rover. As said you need to know if it just pumps or is it a combined level unit. Maybe a quality tyre compressor as i don't think it will pump all the time but just when you load it  and it needs to compensate.

That would be great, but I fear horrific cost, as I will likely need a motor too....  Would be great if you could try tho??  Its L928 JFS, LDV 400, ambulance body.

I may take a punt on that range rover/Landie/Disco part on Ebay, however it is the WABCO that Andy was decrying!!  However, anything will do just now.  Its not a quality vehicle, so doesnt need quality parts!!!

Cheers guys.  I owe you all a beer!

a

[Andy M]

Just to really confuse things, the height sensor is inductive! It's a coil with a cam mounted centre. A square wave goes in and is modified by where the coil is. Advantage of this is that it's temerature insensitive and the same unit can be mounted either side. Depending on whose view point, another "feature" is you can't buy one at RS components.

Simple check to make sure yours isn't a potentiometer is to put a meter on and move the lever. The inductive type has the same resistance regardless, you can only see it work with an Oscilloscope.

Good Luck and get back to us if you need more info.

Andy

[andy230]

Thanks all

Will see what Ken says, otherwise will go for a new compressor care of -->

http://zebra-parts.co.uk/shop/product_info.php?cPath=2_3_18&products_id=130

Looks like it will do the trick, tho will need to come up with a lowering valve as suggested by Kurt.  Sir, can you elaborate on what I need to do??

thanks a million-million!

a

[johnr]

you could just leave the duff unit in situ, with all its sensors and pressure switches, and then add another 12v one somewhere else in the system and just wire it into the feed to the old motor.

[andy230]

Hi John,

Yes, that was my plan.  Although it has made me think that I may be able to use the down solenoid on the old compressor unit if I leave it in situ.  But I'll have to have a think to see if that requires a good seal on the piston....

Mind, maybe araldite round the old bore/piston would solve that problem!!

Sounds like a plan tho.  Thanks!

a

[Steve Lake]

ye gods, and i thought the system on my xanthia's was wierd!!

Got an oscilloscope if you need one :-)

Anything to earn a beer off Andy

[guest146]

Andy

I looked through our manuals and found the pages you need. it will be on that Cd I sent you but if you cant find it send me you email and  I will send the PDF file to you . To check for spares I Will need you vehicle details.  You made me wonder when you said you put a battery to the pump motor and nothing happend and then you took the compressor to bits??

Ken

[andy230]

Hello Ken (and anyone else still reading!)

I have the manual, thanks.  That CD is invaluable.  But I think I may have an answer.  Maybe not a great answer, but an answer nonetheless!

I noticed a schrader valve on the compressor, at the (comperssor) cylinder head. Not sure if this is ambulance-specific (ie. in an emergency?) but the compressor looks the same as the manual so I think probably not.

Anyway. I re-assembled the whole assembly, plus air dryer. I connected my (12v, 300psi!) tyre inflator to this schrader, and it works (on the bench). Moreover, I can still use the down solenoid in the compressor cylinder head.

So I'm going to give it a try, connecting the motor wires (from the ECU and compressor solenoid) to the tyre pump, and just run this as a compressor and see how it goes.

I will also buy another compressor, either the "zebra" one I posted, or a landie/ range-rover part and probably some fittings, and just try to plumb it into the schrader on the existing compressor and keep the functional down solenoid and obselete compressor.

Will post on this thread and let you know how I go. Both with the tyre pump (which may have a rather short and inglorious life inder my bonnet!) and the new pump (if necessary).

Thanks a million for your help guys.  Just kicking ideas about is a big help.  And not spending hundreds of pounds on new LDV parts.

Necessity is after all the mother of invention!

a

ps. Ken:

You made me wonder when you said you put a battery to the pump motor and nothing happend and then you took the compressor to bits??

Yes.  On the bench, 12v across the motor wouldnt run it.  So I started investigating as to why.  Unfortunately the motor shaft and the compressor crank are 1-piece, sealed bearings, pressed up and cant be dis-assembled.

[guest7]

My head's hurting again!



GC