Mercruiser Tilt/Trim

[rbarnesjr]

I purchased a 21' Wellcraft w/ twin 120hp I/O Mercs back in December and was trying to get it ready for warm weather and I noticed the outdrives do not go all the way up or down. One of the trim pumps was replaced and probably wasn't bled. Question 1 is what is the easest way to bleed the systems? Question 2 is the pumps say 10W30 Motor Oil only but the person who has it used transmission fluid. Is this OK? Thanks in advance!!!

 

[CROOSET]

Re: Mercruiser Tilt/Trim

Hi, I had a similar problem with a Mercruiser leg ...as far as i know the Oil was probably ok if the viscosity was the same .. I use oil from the local Car shop as viscosity is same<br />for the trim pump in the Merc ..if not it will probably become either very sluggish or blow a seal somewhere ..re the travel a) sure there is nothing stopping the legs ? B) to bleed system can be quite complicated as you have to do either the suck or push sides first..I would contact Mercury ..the Manuals are very very good for Mercruiser ..otherwise it should be straight forward ...

 

[CROOSET]

Re: Mercruiser Tilt/Trim

Hello again, just realised you ARE talking I/O here ..In case of travel ..your trim position sensors sensors might need adjusting or renewal. These are the round black plastic things high on both sides of the Gimbal ring they may need to be re-set..basically the sensor is turned so that the travel is longer see the postion of the screw on the sensor and just turn it slightly..use your own intuition re the settings then try the trim ..re the bleeding of the rams ..<br />1 Up/Out ram - Disconnect up hose front front<br />2 Put hoses in container ( for the spillage )<br />3 Run trim pump in UP direction until solid stream of oil shows..<br />4 Refill trim pump ..<br />Bleed In/down<br />1 Discconnect down hose from rear connection in hydraulic connector..<br />2 Plug holes in connector ( use same thread scre or pay for the plug 'kit' #22-38609<br />3 Run trim UP until cylinders are fully extended.<br />4 Remove plugs and momentarily run trim in DOWN direction until no air bubbles..<br />5 Reconnect everything<br />6 Lower unti to full down ..refill reservoir and run up-down several times checking reservoir each time <br /><br />Good luck...but its not that bad to do <br />One tip USE A GOOD SPANNER NOT AN ADJUSTABLE..those small fittings on the hoses and hydraulic connector are SOFT and TIGHT !

 

[CROOSET]

Re: Mercruiser Tilt/Trim

Hello again, just realised you ARE talking I/O here ..In case of travel ..your trim position sensors sensors might need adjusting or renewal. These are the round black plastic things high on both sides of the Gimbal ring they may need to be re-set..basically the sensor is turned so that the travel is longer see the postion of the screw on the sensor and just turn it slightly..use your own intuition re the settings then try the trim ..re the bleeding of the rams ..<br />1 Up/Out ram - Disconnect up hose front front<br />2 Put hoses in container ( for the spillage )<br />3 Run trim pump in UP direction until solid stream of oil shows..<br />4 Refill trim pump ..<br />Bleed In/down<br />1 Discconnect down hose from rear connection in hydraulic connector..<br />2 Plug holes in connector ( use same thread scre or pay for the plug 'kit' #22-38609<br />3 Run trim UP until cylinders are fully extended.<br />4 Remove plugs and momentarily run trim in DOWN direction until no air bubbles..<br />5 Reconnect everything<br />6 Lower unti to full down ..refill reservoir and run up-down several times checking reservoir each time <br /><br />Good luck...but its not that bad to do <br />One tip USE A GOOD SPANNER NOT AN ADJUSTABLE..those small fittings on the hoses and hydraulic connector are SOFT and TIGHT !

 

[rbarnesjr]

Re: Mercruiser Tilt/Trim

Thanks for the info!!!<br />Any idea how to flush the tranny fluid out of the system so I can put the recommended oil in?

 

[jocko_nc]

Re: Mercruiser Tilt/Trim

What is the make of the pump unit? I know Mercury Marine uses a lot of Oildyne.<br /><br />The Oildyne 108 literature specifies hydraulic oil, particurarly ATF. 150 to 300 SUS at 100 F viscosity. I do not know how motor oil rates in viscosity, but I think it is a bit thicker than that. Where did that recommendation come from? The gump is likely a tiny gear pump, but you do not want to cavitate.<br /><br />For any hydraulic system I'd stick with ATF. There is a good reason we don't put motor oil in our automatic transmissions. High viscosity is death to pumps.<br /><br />Jocko.

 

[rbarnesjr]

Re: Mercruiser Tilt/Trim

I do not know the make of the pump. It has a sticker on it that states "10W30 Motor Oil ONLY" on it. It is the pump with the motor mounted on top of a rectangular cast tank. It is a 1974 model boat.

 

[jocko_nc]

Re: Mercruiser Tilt/Trim

I see. I assumed it was a newer model. I guess the sticker says it all then! This system must have been designed around a heavier oil.<br /><br />In general, ATF is a high grade hydraulic oil suitabe for mobile or industrial use.<br /><br />Jocko

 

[rbarnesjr]

Re: Mercruiser Tilt/Trim

I spoke with a mechaninc of 40 years who happened to be knowledgable of the type of problem I have. For all who may want to know Type F tranny fluid actually works better than the motor oil. Motor oil pits the metal over time where tranny fluid does not. It is also better on the seals. Type F must be used as it does not foam and has an equivilent boiling point to the oil. Dextron type fluids foam easily. Also received an email from the guy I bought this from and the hydralics are from a newer ('80s) boat. <br /><br />Thanks

 

[daveswaves]

Re: Mercruiser Tilt/Trim

Just a thought, but you may need to bleed the trim cyl and its entirely possible that the last person who did it put the hoses on backwards. The mercruiser manual has a detailed description of how to bleed and which hose goes where, worth the money. My system sounds similar to yours and calls for # 20 motor oil. Someone had put #90 in mine and mixed up the hoses. Flushed it out, put in #20, bled it down and has been working trouble free for 2 years.