I finally pulled the compressor out of my 2001 Disco to overhaul and test.

There's lots of places to buy the standard kit with new o-rings and piston ring. Are they all the same or is one vendor better than another?

It was pretty corroded inside, so I want to replace the piston/connecting rod. Can someone point me to a source for that? I've seen some online for other vehicles. They look the same, are they all pretty much the same?

If I can get the compressor working, new air bags are next.

Thanks for the help,

Sean

 

I think you can either replace the o-rings, or the entire compressor. You might have a hard time sourcing the piston itself.

 

I ordered the connecting rod today from here:

https://bestofparts.com/parts/for-la...j-2003-2_29014

It comes with a new piston ring, so I asked about the shaped o-ring, and they are throwing that in for free! I don't need new screws or zip ties, so I should be all set.

I'll let everyone know how it works out.

Thanks,

Sean.

 

So I got everything working, here's what I did for those interested. The pics are not great, but I'm including some for reference.

There are lots of videos online for the Wabco compressors, I found these two very helpful for what I was doing:

I put the rear frame up on jack stands at around normal suspension height to take any pressure off the air springs.

I removed the compressor box from under the driver's side of the Disco and set it on some plastic boxes I had. There's enough slack in the lines to pull it out and work on it. Make sure you take pics before disconnecting everything so it's easy to hook back up. I took picks of the electrical connectors and the air lines. Even though the axles were pretty much down to the bump stop, some air came out when I disconnected the air lines.


The compressor comes out of the box pretty easily. I removed the head, and the inside of the piston chamber was pretty corroded and rusty.


I removed the rivets that hold the cover on the piston chamber and removed the piston/connecting rod. The center bearing was rusted and didn't turn at all. Now it made sense why the compressor wasn't working. I removed the piston and tested the motor by connecting some jumper cables to the battery, then connecting some test leads to the jumper cables. I attached the test leads to the connector plug of the compressor, and it fired up and ran quickly and smoothly. So I was pretty sure if I replaced the piston I would be good.

It took some searching, but I ordered a replacement piston rod at the link above. They threw in a new shaped O-ring for free, yay!

I took the opportunity to dry out the silica beads in the oven. The video above discusses how to do that, super easy. My beads weren't too wet though.

I also tried to clean out the piston chamber the best I could with some fine sandpaper and microfiber rags.


Here's the new and old piston rods for comparison.


I installed the new rod. It's pretty obvious which direction it attaches, but you can see the proper install in the video. The screw that holds the piston rod to the motor is reverse thread! Thank goodness the video mentioned that or I probably would have stripped the thing when taking it out!


Replaced the piston cover with some new pop rivets (bought a pop-rivet gun at Wal Mart, and some longer rivets at Home Depot). The rivet flanges were not as large as the original, but they seem to be holding nicely. Re-installed the head with the new shaped O-ring. I tested the compressor again with the Disco battery, and it seemed to run fine (sounded like a compressor). Cleaned up the box the best I could and put it back together.


Before reinstalling the box under the Disco, I opened the rear door to make sure the compressor wouldn't try to kick in. Re-installed the box and reconnected the air lines and electrical connectors.

I started the Disco, nothing. Tried a couple more times, making sure all of the doors and hood were closed properly. Nothing. Ugh. Tested the SLS relay (video here: ) and it tested fine. Checked the SLS fusible link fuse and it was bad. Duh, the wire was obviously gone. I figured it burned out after the compressor seized up. I was impatient, so I borrowed the Aux fusible link (they're both 30 amp) and plugged it into the SLS location. (I replaced the Aux one later that night.)

Started up the Disco, opened the window and got out. I could feel the compressor going, then heard the jack stands starting to move a bit. The air springs aired up in 15-20 seconds. Yay! I measured from the ground to the bottom of the wheel well, 82.5 cm. That height held for a few days, so I think my air springs are good, and no leaks in my connections. I'll probably buy a new set as spares just in case the old ones start leaking.

I also tested off road mode a few days later. The rear raise up to 86.5 cm, exactly 40 mm as it says in the owners guide. So off road mode seems to be working great too.

I was on the fence about just going to the Terra Firma 2" lift and ditching the SLS, but after spending about $50 to get it working, I'm very happy with it. We'll see how long it lasts.

Hope this helps someone. Any questions, just let me know.

Thanks,

Sean.

 

This is an awesome write up. Thank you.