Can anybody explain a tilt/trim system to me?

[bigbluebirdy]

Hi folks,<br /><br />I have a 1985 Mercury Black Max with power trim/tilt. I have only one switch that is labeled "power trim". I am under the impression that this acts as a switch for both trim and tilt. My motor tilts (up and down) just fine, but while under way, it does not respond at all. In other words, once it's down and I'm moving, I can't trim it at all. Only under slow speed and stopped can I move it. Here's the question and tell me if I'm crazy. Are tilt/trim units independent of one another? Are they different hydraulics, one to tilt the motor up and down and one to trim the motor in and out? If so, is it feasible that this could be done with my one switch? Or, are they one in the same tilt is trim, trim is tilt... If my tilt works, that means the trim works, etc. (This is what I've been told.) The shop told me that I need a new power trim unit ($946.00), that you need to replace the whole thing. This is what leads me to believe that the units are seperate. They are not talking about replacing the trim and the tilt... are they? Also, when I get the manual(on its way), will I be enlightened or do they not normally contain tilt/trim? Sorry this is long winded and full of questions, but this has been driving me crazy. Any info or input would be greatly appreciated. Or you can just slap me and tell me I'm an idiot. <br /><br />Thanks in advance,<br /><br />Chris

 

[Dennis4b]

Re: Can anybody explain a tilt/trim system to me?

Hi Chris,<br /><br />I have a 1988 Black Max, but most (all?) tilt/trim systems I've used work pretty much the same.<br /><br />Between the engine and the transom (above the lower unit) is the tilt/trim unit, which consists of a cilinder with hydraulic fluid, a housing and an electric motor. There are 2 small pistons that come out say 5-8 inches to push the engine up (trimming it, it just pushes, they're not attached, the engine weight and gravity do the rest), and a large piston connected to the engine which can tilt it all the way up.<br /><br />The way it works is that when you say trim it up, first the small pistons will extend and push the engine, and when they reach their highest point the third, bigger, piston will take over (due to the design of the trim unit). When you tilt it down, first the third bigger piston will retract until the engine "hits" the smaller pistons, and then they slowly retract as well trimming the engine down.<br /><br />The trimming part (small pistons) happens much slower than the tilting part (big piston). However it is all in the same motion, you only need one up and one down button.<br /><br />To troubleshoot:<br />Pressing either up or down should engage the trimming motor (try both, when the engine is all the way down the down button will probably not engage). It's a distinct whirling sound. If the outboard is not running, you will definately hear it. <br /><br />If you do not hear it, see if you hear a click sound from the appropriate relay. If your engine is the same as mine, the relays are in the engine itself, starboard side (where the wiring is), all the way near the carbs, above each other.<br /><br />The one with the green wire trims down, the blue wire trims up. You can try bypassing the relay by applying ground anywhere to the engine ground and touching the right side of the relay (left side somehow goes to engine plus) with for example a jumper cable connected to a battery plus (or engine plus). This should engage the trim motor.<br /><br />If not, it could still be a connection problem, but if you're unlucky it's inside the electric motor and you have to take it off somehow and maybe replace it, but probably fix it. Still, you don't have to buy a new entire trim unit!<br /><br />If you do hear the whirling sound, but nothing really happens, it could be that it's out of hydraulic fluid. You can open the fluid compartment WITH THE ENGINE TRIMMED ALL THE WAY UP (and verify this with your manual in case it's different from mine!!!!!) and it will not be pressurized.<br /><br />A good test is then to see if any fluid leaks from anywhere. If the fluid leaks out of the unit, you'll have to rebuild the hydraulic part of the unit, which is a pain because hydraulics need to be assembled in a CLEAN environment, dust, sand, water, etc are fatal.<br /><br />Let's get some more symptoms and I'm sure other people here will have some good ideas!

 

[Dennis4b]

Re: Can anybody explain a tilt/trim system to me?

Read your question again <br /><br />If it does not trim when running (how do you know for sure?) but does trim when stopped, it's one of those annoying intermittent problems. They don't require the unit to be replaced usually.<br /><br />Bad contact, not enough power under load, safety feature stopping trim (thinks its too high?), could be a lot of things. Other people here will definately be more knowledgable <br /><br />PS be careful not to trim too high when running, let alone get it to tilt, engine in gear running and catching air will kill it really fast, never mind water pickup etc.

 

[Bob_VT]

Re: Can anybody explain a tilt/trim system to me?

Chris, save yourself a bundle of money. Buy the manual and troubleshoot the system. ALL the wire ends must be cleaned with sandpaper and tight. The probable cause to the sporadic operation is a bad connection. If the trim motor works, it works full time. Don't get talked out of $900+ if the motor works. I would imagine your mercury has tilt controls on the motor too. If that will tilt at a slow speed your okay, if the control at the box works you are still okay. Get the book, do it quickly! Nice weather is close!<br /><br />[On a brighter note I was out on Lake Bomoseen on Monday and that darn wind pounded the H*** out of me]<br /><br />Bob

 

[clanton]

Re: Can anybody explain a tilt/trim system to me?

If the electric motor is running and outboard will not trim up, it is low on fluid, or bypassing fluid inside pump. If it will hold trimmed out position underpower the check valves and relief valve should be ok. If the motor is not running when trimming up under load, check relays for dirty contacts, motor brushes, shorted armature. Merc trouble shooting guide says check battery, motor.