How does one use a cooling system pressure tester?

The adapter looks like a composite one. I have the same type (plus a KD universal test type), and I WON’T lend it to anybody, because it can too easily be broken. There are metal adapters, but they cost much more than the composite one.

Quoth hellokit: 'The adapter looks like a composite one. I have the same type (plus a KD universal test type), and I WON’T lend it to anybody, because it can too easily be broken.'
Awww… I was gonna ask.

Quoth hellokit: 'There are metal adapters, but they cost much more than the composite one.'
Perhaps O’Reilly’s lender uses metal adaptors because they don’t break as easily.

It held steady, after I pumped it up a couple of times. I realized that the system includes rubber hoses that stretch: I had to pump up to that give, but after I did that it held without budging for 10 minutes. I’ll keep on watching it but think it’s okay.