They are Voss connectors and have small o-rings on them. Get the full kit and do the lot.

 

Alright, I tightened the leaking connection and it’s not blowing bubbles any longer. But I’m only getting about 190 psi before the compressor is getting too hot and turns off.

Would it be wise at this point to either clean the center valve block or do the seals on the compressor piston and cylinder?

 

If you have the latest software, about 200psi will be the new max pressure. Used to be about 250 but that was lowered to extend compressor life. If you rebuilt eh compressor you must do the piston, cylinder, cylinder gasket (where it meets the body). That is what wears out, not much else. The cycler will be tight fit when new but wear to match quick enough. But if too tight, you may want to very carefully sand the piston seal. I had one that was SUEPR tight and left it, it meat a quick death. And never lubricate it - I did once, bad idea.

With that said, have you pressure tested the reservoir? As you figured, slow to fill can be an underperforming compressor or a leak at ANY place in the gallery. A leak at the front and rear valve block will cause a slow filling reservoir. And a hole in them is not uncommon at all.

 

I don’t have the ability to pressure test the tank. But, I let the truck build up some pressure and let it sit overnight. There’s still plenty of hissing when I crack the bolt on the front of the reservoir. I consider that a basic test.

I am throwing another parts grenade at this and trying a rebuild of the compressor piston and valve seals.

 

Always a good move if you haven't done it before or if history is unknown.

 

Test that "center" valve block, or front valve block in the bumper, can leak internally too. Unplug the EAS relay, measure the height, let it sit overnight, then measure it again. If BOTH front corners lost height, that block is leaking internally. If one side drops, you're losing air in that corner.

eBay has suppliers that sell o ring kits for the valve block. The rebuild procedure is pretty simple. The front valve block has been the culprit for a out 1/2 my leaks. I
did a rebuild of my OEM valve block and it lasted 4 years. The aftermarket ones barely last 1 year.

It does sound like your compressor is on the way out, but testing for the valve block is simple and free.

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Okay let’s do some updates!

I rebuilt the compressor with new piston seals and o-rings for the cylinder head and drier connection. I’m still got the C1A20 (that would be a good personalized plate!) code. Gallery pressure barely hitting 200psi. I swapped the relay for another one, and I undid the connections for the intake and exhaust, and the gallery pressure was managing to hit 212psi and up even right on startup. I was getting as high as 240psi. However, the system still faults with the same error. Sometimes right on start and sometimes about a minute after. I can continually clear the code and then after three times or so the truck runs without the error. Eventually, it comes back on after the compressor cycles a few times.

I think the compressor is a Hitachi copy. There’s no original Land Rover branding on the outside. I am unable to undo the fittings (the actual 17mm nut) for the intake, exhaust, and the other valve. It looks like they’re fused to the body. So, I don’t think I’ll be able to service those.

Running the compressor without the connections for intake and exhaust yields more gallery pressure (and a cool exhaust sound!). I’ll check the intake filter. However, I think there’s a leak in the center valve block. I don’t get any corner drops overnight, but I feel like the compressor is fighting a trickle back leak. Tank hisses if I crack the front valve open even after sitting for a few days.

I’ve ordered the o-ring kit for the center valve block. I’ll examine the tank if I get a chance. But I feel like if the center block doesn’t fix it, I’ll end up getting a new compressor. It sounds like mine is about to bite the dust.

 

Final update:

I bought a legit Hitachi compressor and the problem is solved. No more errors. I noticed that the gallery pressure remains at 200+ after the compressor shuts off which tells me the old compressor had a stuck open exhaust valve. I wish I had known gallery pressure is supposed to stay high after compressor turns off! I would have saved myself so much time.

I Tim Taylor’d myself by redoing the o rings in the front valve block causing the valve block to then immediately fail. So I had to buy a new one. I thought I’d be helping future me, but I only caused more problems. If it ain’t broke, don’t fix it!

Also, I got a great deal on the Hitachi. Check Amazon for the ones that are opened or gently used. Mine had been opened but never used and it was half price.

 

Good to hear. And a familiar story, aftermarket compressors have caused issues before.

But FYI, gallery pressure is designed to l Al down. In fact, the compressor “fart” that happens before or after operation dumps gallery pressure so the compressor can fire up. That small thing can not fight 200psi from a standstill. Part of the software update was to lower startup gallery pressure limit. Meaning if gallery pressure is still too night before compressor start, it will dump air if needed. And other reason you don’t always get a fart before startup, just sometimes. But basically the gallery is not air tight anyway, it will bleeds back through the compressor.