So, I've had this compressor for a few years. I've had my fair share of problems with it too. The last major issue was the crank case housing cracked where it bolts to the motor. After re-assembling a new one it wasn't compressing that well and after really looking over the second stage cylinder I could see some wear, so I started looking for a new cylinder. I ended up getting a used, fully complete second stage assembly from AirVenturi that looked better than mine. After tearing it down and cleaning/polishing both reed valves and their mating surfaces I re-assembled it all. At this point it would build pressure to 3300-3500psi but then it would start detonating the oil (I think that's what I'm hearing), creating a short irregular knock and then black discharge to the bottom of the filter tower. This was also on a fresh set of AV high pressure seals (about $35 worth)
Might next thought was to swap lube oils although the one I've been using had been working fine. I ordered some Seco 500 thinking this was going to cure the current issue. Nope, still has that intermittent rattle/knocking at high pressure. Pulled the cylinder off and the high-pressure seals still looked like new. This is where I'm at now, so now I'm thinking maybe it has something to do with the discharge pressure leaving the first stage side going to the suction of the second stage. I'm wondering if the first stage isn't sending enough pressure, which I think is actually acting like a back pressure to keep any oil from migrating easier across the second stage seals that is ending up on top of the high-pressure piston and then doing a little detonating.
A couple of years ago out of curiosity and troubleshooting I actually measured the discharge pressure of the first stage and if I remember correctly it was somewhere around 350-400psi.
I tried this again recently, but I really didn't have the correct gauge, but I could tell it wasn't going to be anywhere near 350psi. But the air flow volume seems pretty good. As soon as I get an in-range gauge I'm going to test it again.
Just wondering if anyone else has ran into this issue and found out the first stage being the issue. I may pull it apart today and check the rings but they looked fine when I replaced the crank case housing. Sounds crazy I know but I'm about at my wits end this time.
Might next thought was to swap lube oils although the one I've been using had been working fine. I ordered some Seco 500 thinking this was going to cure the current issue. Nope, still has that intermittent rattle/knocking at high pressure. Pulled the cylinder off and the high-pressure seals still looked like new. This is where I'm at now, so now I'm thinking maybe it has something to do with the discharge pressure leaving the first stage side going to the suction of the second stage. I'm wondering if the first stage isn't sending enough pressure, which I think is actually acting like a back pressure to keep any oil from migrating easier across the second stage seals that is ending up on top of the high-pressure piston and then doing a little detonating.
A couple of years ago out of curiosity and troubleshooting I actually measured the discharge pressure of the first stage and if I remember correctly it was somewhere around 350-400psi.
I tried this again recently, but I really didn't have the correct gauge, but I could tell it wasn't going to be anywhere near 350psi. But the air flow volume seems pretty good. As soon as I get an in-range gauge I'm going to test it again.
Just wondering if anyone else has ran into this issue and found out the first stage being the issue. I may pull it apart today and check the rings but they looked fine when I replaced the crank case housing. Sounds crazy I know but I'm about at my wits end this time.