470 trim pump leak

[1977 SILVERLINE]

Oil keeps leaking from this plug on my 470 trim pump. The plug is difficult to remove and I have changed the oring twice but it keeps blowing a chunk out of the oring and begins to leak heavily. Any ideas why this keeps leaking. Thanks.

 

[Bt Doctur]

reverse valve not adjusted properly

 

[ROY WILLIAMS]

Oil keeps leaking from this plug on my 470 trim pump. The plug is difficult to remove and I have changed the oring twice but it keeps blowing a chunk out of the o ring and begins to leak heavily. Any ideas why this keeps leaking. Thanks.

the trim pump creates a higher pressure ...remove the trim cylinders on the outdrive .. then lift up the out drive is a very good movement or trim cylinders are looking the in/out buttons moving the pistons ..
then remove the oil,,,, tank see if its dirty ..many have to change the oil or leaks to get water in the oil ..