Pontoon tilt / trim...

[ScotB]

I have a 25' toon with 50HP merc Bigfoot. The tilt on the motor automatically lowers @ 1500 rpm & above. We are located on a chain of lakes with lots of shallows and this "so called helpful feature" from Merc is a pain. There are shallows and under bridge areas where the toons are inches away from bottom.

I understand this isn't really a toon question. But Bigfoot is common on toons so I'm hoping someone else has dealt with this problem successfully. Is anyone aware of a internal part in the trim motor or pump that could be changed to eliminate this?

Thanks

 

[Jeep Man]

When you say it " automatically" lowers, do you mean that the pump kicks on or does it lower slowly. If the pump starts then you have an electrical problem. If it lowers slowly then you have a leak. At this point, more info is needed.

 

[MinUph]

This is what my Honda manual says. Maybe your bigfoot is the same?
--
If an excessive amount of throttle is
. used when operating in forward gear,
the motor will return to the transom
angle adjusting rod.
(Gas assisted tilt type).
If the motor trim angle is more than
20? and the control lever is moved
more than 40? forward/rearward from
the N (neutral) position, the power
trim warning system will be activated
(refer to page 65).
(Power trim/tilt type).

 

[ScotB]

Not a powered lowering. Just a pressure release of fluid within the pump. If the range of the tilt is broken down into "bottom 25% trim" and "top 75% tilt" I would say it automatically lowers to the top of the 25%.

I hope that makes sense?

 

[HotTommy]

On my 150 HP outboard, there is a smaller tilt piston and a much fatter trim piston. This is needed because it takes far less force to lift (tilt) the motor than it does to withstand the constant push of the motor when underway. Perhaps your trim system is simply too small to resist full power from the motor, so the piston just leaks down. Rather than say it those words, Honda may have decided to describe it as a feature rather than a deficiency.

 

[ScotB]

Thanks Tommy

It can't be a "too much power" issue. Since it only takes 1600 RPM to cause the problem. I would completely understand if Merc had the auto-lower at higher RPM to prevent motor damage.

Anybody aware of Mercury reps cruising these boards that could chime in? It appears to be the original lift unit that came with motor

 

[Jeep Man]

Thanks Tommy

It can't be a "too much power" issue. Since it only takes 1600 RPM to cause the problem. I would completely understand if Merc had the auto-lower at higher RPM to prevent motor damage.

Anybody aware of Mercury reps cruising these boards that could chime in? It appears to be the original lift unit that came with motor

Scot, I would suggest that you have a moderator move this thread over to the Mercury repair section for more results.

 

[Gouda]

Not sure what year your's is, but up until yesterday I had a 07 40 Bigfoot. I never had that happen, but mine would not allow me to trim the motor up if exceeding about 1500 rpm. I could trim in down further, but had to slow way down to raise it up. I had the tile and trim pump fail about 3 years ago, an expensive repair. I never understood their reasoning. Part of the reason that motor is gone.

 

[mla2ofus]

Maybe the Merc engineers are trying the impossible, to out-engineer idiots!! Or maybe to protect a weak spot in design due to cost cutting factory bean counters!!
Mike

 

[cootshobbyfarm]

Sounds like they built a relief valve into the trim cylinders.

 

[Silver Eagle]

Check your Hydraulic fluid .It may be too low. Google it, there's a video on how to replace it.