10HP Quincy QR-25 compressor unloads when hot in hot weather

Maybe the hydraulic unloader control on the side of the block? The membranes usually fail by tearing & you would hear an air leak.

MikeB

I am thinking, perhaps the lubricating oil becomes very hot, less viscous, and oil pressure drops, and the hydraulic oil pressure "safety circuit" causes unloading?

Newp. Perhaps find a way to run cooler air over the fins via a mister or water-cooled heads. Just machine some up, Ig. Piece of cake. ;)

It wouldn't cost much to try a load of better oil, eh?

Yes. I could see that happening if the o-rings are hard & leak a little.

Also maybe check the oil filter screen, the big hex plug in the bottom of the sump.

I was impressed with the Quin-cip oil, it would not turn black & much less carbon formed on the valves compared to all the other oils I tried.

MikeB

We have a big pedestal fan to help cool and use synthetic compressor oil. Do check the unloader membrane and hydraulic air valve.

Great minds think alike, we did the same thing.

If this compressor head has an oil pressure system, adding an oil cooler is a trivial thing - They make little cooler cores for power steering on cars and light trucks, or get the smallest automatic transmission size. A few rubber mounts to attach it to the belt cage, attach in line.

Then get the soundproofed closet you have the compressor in some outside air ventilation. Might have to mount a roof jack and a power vent, and then cut a few intakes in the wall behind it.

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