LR4 Loud air release sound when air ride deflates

steveC101 said:

Scott, the front end sinking overnight sounds like the front block. Have you tried removing the fuse for a night to see what happens? FYI, I tried the repair kits for both the blocks and compressor and none fixed the problems. I ended up replacing them all. I had the compressor shipped from the UK at about half the price.

Click to expand...

Agreed, sounds like front block to me
This block is the easiest to access

I have successfully disassembled and cleaned the o-rings in mine (silicone spray) - no replacement needed (save $ try cleaning first)

Holds height steady as expected
Start there on yours

douglastic said:

Agreed, sounds like front block to me
This block is the easiest to access

I have successfully disassembled and cleaned the o-rings in mine (silicone spray) - no replacement needed (save $ try cleaning first)

Holds height steady as expected
Start there on yours

Click to expand...

Thanks guys, I will. To be honest, I'm more concerned with the air purge. When I have the time (after the holidays), I'll probably trace the leak down with soap and water. If not, smoke it out. I've just never heard that sound before. Expect on semi trucks and turbo BOVs. It's definitely coming from the air compressor, just not sure what's causing it. Too much pressure in a reserve tank? A clogged check valve? Don't recall seeing a blow-off on it, so I'm thinking it's coming from that block located in the abs box by the D/R. I was really just curious to know if anyone has ever had the same issue. I have access to a lift, but it's a PITA because it's an hour and a half away from a dealer, which means: diagnose, drive(3 hours round trip). Wait for cool down, repair, then drive.

Has your compressor ever been opened for service and desiccant replacement?

Old desiccant turns to powder and clogs things .. including the valve blocks

douglastic said:

Has your compressor ever been opened for service and desiccant replacement?

Old desiccant turns to powder and clogs things .. including the valve blocks

Click to expand...

Yes, I rebuilt it 2 weeks prior to the sound.

DiscoLR said:

Yes, I rebuilt it 2 weeks prior to the sound.

Click to expand...

Maybe remove the compressor insulation and let run so you can try to pinpoint noise location?

Or . . would be annoying, but may need to remove the compressor and retrace your work steps

- Reopen and double check anything you touched on the rebuild
- Check dryer cap and exhaust fittings and tubing for cracks

But do that front block anyway, as you have 2 separate issues I think.
At least you can have some satisfaction for solving the issue of front losing height!

douglastic said:

Maybe remove the compressor insulation and let run so you can try to pinpoint noise location?

Or . . would be annoying, but may need to remove the compressor and retrace your work steps

- Reopen and double check anything you touched on the rebuild
- Check dryer cap and exhaust fittings and tubing for cracks

But do that front block anyway, as you have 2 separate issues I think.
At least you can have some satisfaction for solving the issue of front losing height!

Click to expand...

That's true. Maybe I didn't clean off a gasket properly. Again, maybe I'm not explaining it well. There's a factory purge that everyone hears. Mine is just a loud purge.

Does the sound happen just as the compressor shuts off? if so it could be a stuck check valve releasing pressure through the compressor.

Strizzo said:

Does the sound happen just as the compressor shuts off? if so it could be a stuck check valve releasing pressure through the compressor.

Click to expand...

It happens when the air ride adjusts(like it's supposed to), but much louder. When it auto levels.