1981 mercury 90 tilt trim problems

[gonefishin72]

i have a nightmare on my hands. 1981 sylvan with 90hp mercury inline 6. i had the motor off to replace transom. when i rehooked tilt and trim pump it ran for a bit and then blew the orings out of the bottom of the pump. i took it apart and put orings back in. they looked undamaged. then i realized i hadnt bled the system and thats probably what took out orings. it seemed to be lifting fine but air in the system had to be the problem. so i put it back together and went about the bleeding proceedure. hit the tilt down and it immediately blew the oring at the pump again. Is the whole thing junk now?

 

[Chris1956]

Re: 1981 mercury 90 tilt trim problems

The only o rings I know about are between the pump and the plate that seperates the pump from the control valve. If these are the ones blowing out, replace them and make sure the control valve mounting bolts are tight.

 

[gonefishin72]

Re: 1981 mercury 90 tilt trim problems

yes those are the ones. it keeps blowing the oval oring. is there a way of hooking these up wrong with the hoses? i didnt think so. just 2 bigger hoses and 2 smaller hoses. this thing worked perfectly 2 months ago until i took it loose and put hoses back on. thats when it started squirting oil out between that plate and pump housing. hoping its something simple but not looking that way. is there somewhere i can find a parts breakdown for these units? the way that plate goes in is tricky. different sized ports and such. just wondering if i got something backwards. tried to find another pump online but these things look like theyre pretty much obsolete. have to be on the water in 2 weeks and have to find some sort of solution. very frustrated.

 

[Chris1956]

Re: 1981 mercury 90 tilt trim problems

crowleymarine.com has the exploded parts list for that motor. Those Orings shouldn't blow out. Perhaps the control valve is faulty? Try it without the hoses attached. That will isolate the problem to the control valve. Next connect the hoses, but open the bleed screws on the cylinders.

 

[gonefishin72]

Re: 1981 mercury 90 tilt trim problems

got new orings today. will put them in and try it. it still lifts motor but squirting oil out the side where the spacer plate is.

 

[gonefishin72]

Re: 1981 mercury 90 tilt trim problems

put in orings. still squirting oil. probably bad valve. and out of money! does anyone know where i can get a used pump assembly?