Compression dropping?

[Umckibben]

2006 225L Merc Optimax
Serial number 1B254885

2 years ago in May '17, I had compression tested on the motor, 105, 110, 110, 120, 105, 105, fast forward to this May '19, had compression tested again, same place, 85, 85, 95, 95, 80, 80, all cylinders reading quite a bit lower, the tech thought it was a different compression tester, but they haven't gotten back to me yet to confirm, the motor is ok at idle doesn't seem any different from two years ago, should I be concerned? Am I on the brink of catastrophe? Any input appreciated.

[Savage]

Why do you keep having compression test performed, are you experiencing problems???

[Umckibben]

Was considering selling in '17 but decided to keep the boat, there was some concern from the service center and myself that I had 1 cylinder 15# higher, I had the wp impeller changed and figured while I was there I'd get the test done again just to see if it had changed at all

[Savage]

I would say that the gauge and the gauge operator are different.

Motor should be warm.
With the throttle wide open.
With a fully charged battery.
Counting the same number of revolutions on each cylinder.

[Fishfreq]

I would say that the gauge and the gauge operator are different.

Motor should be warm.
With the throttle wide open.
With a fully charged battery.
Counting the same number of revolutions on each cylinder.

Exactly what Savage said. Last test sounds like the throttle wasn't open or only cranked it 3-4 revolutions. Important thing is it's consistent. How many hours on this boat? Do you use the recommended cocktail in your gas every fill up, including carbon remover? I've had compression go down from carbon build-up around the ring lands back in the day before I used Yamaha Ring Free Plus.... in my Merc.

[Umckibben]

I can't speak for the tech running the test, it was the same tech each time though but different gauge, motor has around 360 hours

I do use quick kleen "most" of the time, maybe I'll look for a carbon remover?

[Savage]

Click on this>>>>

Performing Compression Tests

[EuropeanAM]

Click on this>>>>

Performing Compression Tests

+1

THOSE are the correct methods for performing a compression test.

[Umckibben]

I'll touch base with the tech, thanks guys for the input!