Flowbench Troubleshooting / Manometer reading backwards?

[michaelbarry]

I've been around quite awhile reading but never have made a post so here goes..I have a home built bench that is based off of a SuperFlow SF 600. No electronics, only a vertical manometer for reading test pressure at inches of h2o and an inclined manometer for reading percentage of flow and uses a selectable orifice plate. I have checked it before with a PTS plate and it was dead on the test plate. Today I discovered I'm getting some odd readings, almost like the inclined manometer is reading backwards. I tested three different cylinder heads and got the complete opposite readings of what was expected of them. The best head flowed the worst and vice versa. I've swapped the lines on the inclined manometer from end to end as that was an obvious try, thinking maybe I swapped them without noticing at some point or something and that obviously wasn't the issue, as the manometer tries to go backwards like that. Not sure what I've got going on and looking for a little help. Thanks for your time!

[Brucepts]

Fluid in the lines?

Direction valve leaking possibly would be my thoughts

[michaelbarry]

Bruce, thank you for the reply. No fluid in the lines, one of the first things I did was blow through them with compressed air to be sure. Inspection of the exhaust flow control valve with a bore scope shows that it is seating well also.

[michaelbarry]

An interesting observation that may help is that if I have a cylinder head on the bench and leave both the intake and exhaust valves closed, essentially capping off the bench and turn it on, the inclined manometer (percentage of flow) goes backwards, below zero.

[michaelbarry]

Fellas, I think I found the issue. O-ring was leaking at the high end of the inclinometer. Thank you for the help, Bruce!

[Brucepts]

Good to hear you found the issue!