Simple Out Drive Pressure Testing

[dpb]

Useful to do during service as you change oil to give heads up of any problems.

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Drain the leg and then replace the drain plug.

Connect auto car tyre pump with gauge to fill hole.
If you can get hold of a mercruiser drive oil filler pump they have the correct thread for the Volvo DP drives. Cut of fitting and connect to air pump with bits of plastic pipe.

Manual says test to about 3 psi, if holding take to 16psi.
1psi drop from 16psi allowed in three minutes. Need to rotate prop shaft to see if that provokes a leak.

I have tried rigging up a Pela oil extraction pump in a similar way to test under vacuum but not so easy to do and only confirmed that I dont have a catastrophic leak.
At least the pressure test gives you an idea of how the seals are bearing up.

 

[oGaryo]

Sorry, but obvious question, is it wise to take to 16psi if the manual says 3?

 

[dpb]

Sorry, but obvious question, is it wise to take to 16psi if the manual says 3?

Sorry, did not make clear,
Manual says start with 3 then if OK go to 16 for 3 minutes.
Not quite sure what the point of going to 3 first is as there is no time given for that.

 

[Beamishken]

Think the idea is to pause at 3 psi to see if any leakage at low pressure as lip seals can hold with a higher presure behind them due to the pressure forcing them to grip the shaft but might leak at lower pressure due to not being compressed on the shaft
Obviously in service the pressure in the drive will rise slower than being pumped up than it will with the increase in temperature

 

[DavidJ]

Thanks
great reply!