Service valves are so basic, and we see them with such regularity that we can miss them altogether. But, before I give the tips, I want to address the tech who tells the customer it was “probably the service valve” or “the caps were loose” as a plausible reason for a leak without actually doing a proper diagnosis. Don’t make excuses, find the leak. Now some tips.
1 — Look before you connect: Look for oil around ports before you connect your gauges — every time. If you have a leaking Schrader and cap, you want to know that before you connect your gauges, and eliminate that leak. Keep in mind that a service cap is never meant to be the seal from a leak. It does act as an insurance policy against a tiny leak in a Schrader. If you find a leaking Schrader, replace it.