I recently moved and relocated the compressor. Upon restart , after replacing 2 quarts of correct oil, it ran for about 40 seconds before shutting off. I found the low oil switch had tripped. press reset and goes for 3-4 seconds then shuts off.

VR5-8 champion

VR5-8 champion oil switch

Does the low oil unit have anything that could be clogged or air bound? Did laying it down to move effect anything? ( I drained the oil before I laid it down )

Any help would be appreciated, by Tom from New Hampshire.


Presuming you actually have the correct oil and level of oil, does it run longer after it sits awhile?

I’d guess after a while, it will get whatever it’s looking for, and stop tripping.

Meanwhile, and again if you’re certain the oil level is correct, bypass the oil switch until starts working and un-bypass or replace it if you decide it’s broken (possibly in transit, maybe just died.) Good luck, Doug from s.d. ca.


Yes 2 quarts per the specs. It also shows halfway on the site glass.
yes it does run longer if you wait a while, Tom.


Well, I’m standing by my original idea of bypassing it.

It’s what others have done, and as long as it doesn’t run for extended periods unattended, it’ll be OK as long as you keep the oil up.

I don’t really understand how it works, and worse, there are old and new versions of it – and they are expensive at 160 to over 200 bucks.

Let us know if it starts working after a time, or you just give up on it, or you find out anything more about it, Doug.


Well, if you take the air line off the back of the switch and spin the cap off, there is an aluminum plunger with two o rings on it.

You need to ether replace the o rings or the completed assembly.

I had one but just used it on a job and am looking for a new one, that’s how I ended up here but anyway that is the fix.

I would urge you not to bypass the low oil switch,  by Zemmit


Based on the symptom in the original post, this isn’t an issue with the o-rings. (Air leaking out of the little bleed hole on top of the housing would be a symptom that o-rings could fix).

I’ve attached a picture of the schematics for this sensor/switch.

Schematics for sensor switch

VR5-8 schematics for sensor switch from Jason Scott

If the symptom is that it switches off after a few seconds of running, then the problem is that the rod on the float (#2 in the diagram) is not stopping the piston (#10) from pushing on the electrical switch (#16) when head pressure builds up. There could be a number of reasons for this, but all of them should be fairly simple.

First, the bowl fills with oil through cross-drilled holes in a small pipe. Are those holes plugged with sludge? If so, the bowl will never fill and the float cant be lifted.

If the bowl can fill with oil, does the float actually float? It could have been cracked and will no longer float.
If it floats, then it might simply have something blocking it from rising up into the machined housing. Make sure there isn’t any debris in there so that the float can rise all the way to the top. This will stop that piston from moving far enough to trip the switch, and your problem is fixed!

This should be a fairly easy problem to fix. Good luck!

I guess I should add one more possible reason this could be failing… if the piston spring (#13 in the diagram) is broken or missing, the piston/plunger will never fully retract. If it can’t retract, then the float CAN’T rise with the oil level, and it will trip like this indefinitely. I’ve seen a broken spring in these before, and it can cause this issue.

Jason Scott