D3 Suspension Fault, airline has blown twice

[Disco Fever]

Hi Guys, we have a 2005 SE D3. The compressor was replaced late 2012 at 97,000Kms, all fine until April 2013 we were out 4wdriving with the suspension in 'off-road' height when a very loud bang followed by air noise happened beneath the car. At first we thought it was an airbag, but the car still remained levelled. I turned the engine off and checked beneath the car but couldn't find anything obvious. When I started the car we heard 3 loud shots of compressed air beneath the car and then the amber light appeared with the 'suspension fault' message on the dash. I then got under the car to locate the leak as my wife started the car, I found a large blow out in the black plastic airline under the passenger side following the chassis rail in front of the air tank. The car made it home ok. I removed this long airline which supplies air to the front section of the car and took it to our local Land Rover stealer and ordered a replacement which took 6 weeks due to none in the country. I replaced the airline and all ok until last weekend the new airline blew almost at the same spot. I saw the stealers again to find out why it blows in 'off-road' height, nobody knew why, one technician thinks the compressor could be putting out too much pressure and suggested replacing the compressor again at $1200. I ordered another airline and another 6 weeks wait. Does anyone have any ideas?

[Graeme]

Is the compressor relay sticking? The relay should have been replaced along with the compressor to a heavier duty one. The compressor's mechanical exhaust valve should also have opened before any lines blew so it may be faulty as well. Alternatively the pressure sensor in the reservoir valve block may be faulty.

Edit: Diagnostics wont reveal if the pressure sensor is faulty - a seperate gauge or another sensor will be needed.

Don't get a genuine replacement air-line, just get joiners and some 6mm pressure tube.

[bbyer]

A Land Rover part number for the 6mm push to connect union is STC8580; it is actually a part from the older FFRR's air system but works well for air line repairs on the 3.

You will also need some transport grade air brake 6mm tubing. A Land Rover dealer might have that in bulk, but if not, heavy duty truck repair shops that work on Mercedes, Volvo, Mann, etc should have some.

And yes, you must have a pretty strong air compressor with a frozen relief valve or the air line is touching something hot or rubbing. The bursting pressure of air brake line is supposed to be about 80 bar, (1,160 psig) at 20C; the working pressure is about 27 bar, (390 psig), hence bursting due to high air pressure seems odd.

I would favor heat or rubbing when in off road height, and since the break is in near the same place as previous, perhaps ....

http://www.disco3.co.uk/gallery/albums/userpics/15405/wiki1_John%20Guest%20Push%20In%20quarter%20inch%20 DOT-A%20Union761151b8b165121f24da2ad39a17d24d.jpg

[Disco Fever]

Thanks heaps guys, We have a truck parts supply in the industrial area, so I will call around and ask for a 6mm joiner. The airline isn't rubbing on anything and well clear of any heat items such as the exhaust system. The relay was replaced when the new compressor was installed, so looks like relief valve faulty. Our Land Rover stealer said they will measure the pressure of the system when I repair the break.

[bbyer]

Shops that sell hydraulic fittings and hose as well as metric and imperial fittings are also a source of suitable DIN spec metric air line and fittings.

I have ordered fittings from these guys based in Mordialloc Victoria and they will have friends elsewhere.

General Pneumatics Pty Ltd (http://www.generalpneumatics.com.au/html/s01_home/home.asp)

General Pneumatics, GP TRUCK PARTS, GP, TRUCK PARTS, TRUCKMASTER, DUMPMASTER, GENERAL, DRAIN VALVE, SUZI COIL, DOT FITTINGS, BRASS, (http://www.generalpneumatics.com.au/Products/Products/Products.asp)

The attachment is a two page pdf spec re airline. There is a table at the bottom of the second page re the transport grade DIN spec stuff.

[gghaggis]

If you need air line or connectors, you can order them from me (I keep spares to go with the EAS kits we sell).

You need to be careful with the type of airline you order - some of them de-rate very rapidly at over 40degC!

Cheers,

Gordon

[Disco Fever]

Hi everyone, the car went in last Thursday to our local Land Rover stealer service department. They replaced the blown airline + the 70A compressor relay (as for some reason wasn't replaced when the new compressor went in 14 months ago). They performed an air pressure test on the system plus checking valve blocks, etc and said everything was normal, couldn't fault the system. They also cleared the logged fault codes due to the split airline. This has me a bit worried now hoping they would have found something wrong. This is the 2nd airline replaced in 8 months. I will take a photo of the blown airline section and post it soon. Thanks again for your help.

[bbyer]

You comment re the new relay being installed makes me wonder if the old one was at times sticking closed.

All the overpressure and temperature shutdowns and computer shutdown instructions do the same thing; tell that relay to open up so the compressor is depowered and will hence shut down.

If for some reason on occasion, the relay would not open when told to, then I suppose something somewhere else would have to give.

Maybe the problem is resolved. You will be the first to know.

And thank you for the update and please continue to keep us in the loop.

I am always very suspicious when LR develops a hardware or software fix and then throws in some "extra" part with no explanation other than to also install it.

For me, even though I still have the old style air compressor, when I heard about the "free" relay being added into a compressor replacement kit and or software update, I bought the new relay and replaced same just because of my above suspicions.

I think the old adage is Never say you are Sorry, and Never Explain.

DISCO3.CO.UK Photo Gallery - LR3 Air Suspension fuse 35P ECU Manual Shut Off Switch/Underhood Fuse and Relay Box drawing (http://www.disco3.co.uk/gallery/displayimage.php?album=3778&pos=6)