Water pressure gauge

[cane72]

Good morning.

98 Mariner 225mag efi 3.0L serial#0G626858.

my water pressure gauge seemed off so I wanted to test it out. I set my air compressor at 25psi and made an attachment with tubing to my gauge. Blew 25psi of air and it read 20psi on the gauge (picture attached). Would this be an accurate test or should I test it a different way?

This is one of the old prism gauges so I’m sure they are far an in between, is there a direct replacement? Looked some up and saw that some are not rated for 3.0 litters from 98 and up, why is that?

thanks for any guidance.

[JOE54]

analog not real; accurate anyway , not seen that rating,,30 psi is way plenty for 3.0 engines

[SilverFox579]

Not at all uncommon to see 5psi loss from your compressor to fitting on your air line. I'd say your water presure gauge is fine.

[EuropeanAM]

Should be fine to use.