Trim tabs don't work.... help!

M

Mastercraft

Well-known member
Joined
Dec 4, 2020
Messages
418
Fluid Motion Model
R-29 S
Trim tabs don't work. Please help!
1) blew fuse
2) replaced fuse
3) trim motors making noise like they run
4) trim tabs don't move

Is it low fluid?
Where is fluid?
Is exact same hydraulic used for something else like engine hatch?
 
Mastercraft said:
Trim tabs don't work. Please help!
1) blew fuse
2) replaced fuse
3) trim motors making noise like they run
4) trim tabs don't move

Is it low fluid?
Where is fluid?
Is exact same hydraulic used for something else like engine hatch?
Click to expand...
It’s my understanding that the same ATF tank is used for both the hatch and trim tabs. Is your engine hatch working?
If both your trim tabs are not working and failed at the same time then some possible issues like seized hinges, blown piston seal, etc. probably don’t apply.
Definitely check the ATF fluid level as a first step.
 
scross said:
It’s my understanding that the same ATF tank is used for both the hatch and trim tabs. Is your engine hatch working?
If both your trim tabs are not working and failed at the same time then some possible issues like seized hinges, blown piston seal, etc. probably don’t apply.
Definitely check the ATF fluid level as a first step.
Click to expand...
Hatch works.
Not sure when tabs quit working.
Recently had prop speed done to trim tabs when bottom painted. I doubt that any mechanical disassembly would have been required of the tabs to apply prop speed..... correct?
 
It is my understanding that on your R29 the same fluid is used for the Bennet Hydraulic Tabs as the engine hatch and if the hatch is open there is not sufficient fluid remaining in the reservoir to then run the tabs. By 2021 when our R29 was built the tabs and engine hatch lift were replaced with electric motors.
 
Stan, when was the last time you used the tabs? I had all 4 of my hydraulic rams replaced this summer, and then my boat sat in the slip for a few months. When i went to use it last month, I had issues with the tabs and some hydraulic fluid leaking on the water surface. They were making a god-awful groaning noise, and not really working right. I think the cold weather and lack of use are the culprit. I'm going to have to have a haul out to inspect them.... so annoying.
 
I don't know when tabs failed. I would try them every couple months. I cruise at 8-11 knots, so they never seemed very effective but they did work before. Yesterday is when I looked into issue, first found blown fuse, then replaced fuse, trim motor runs, no tab movement. I will check fluid. Where is fluid located?
 
It's a pretty simple system. Hydraulic fluid could be low, actuators could be damaged, solenoid valves could be stuck. If motor is running, then check the fluid level with the engine hatch closed. It would be surprising that all four of the actuators are damaged, but could happen. Also look for any leaks in the lines or the actuators. If all else fails then you may have stuck valves ( the round cylinders on the pump). The pump should be mounted on the inside of the transum.
 
I had to replace both trim tab cylinders on my R31 CB a couple of years ago. I then sent the damaged ones back to Bennet and they sent me new ones no question.
I think the key is to cycle them regularly.
 
Bringing this thread to the top.
My starboard Bennet tab will not cycle down (from full up position)The hydraulic pump motor struggles and then stops.

Is that a broken cylinder condition?

Thank you
 
If you know where the trim tab motor is you know where the reservoir is. The bottom portion of the pump assembly is the reservoir. With tabs fully retracted the oil level should be at the line marked on the reservoir. Should be a decal. iI there is no decal 3/4 full will work. It uses ATF (Automatic transmission fluid). You will need a small funnel to fill and an oil absorb rag for spills. Look to see if there is water in the reservoir may have a bad seal in the trim cylinders (seal = o-ring) If the rams are not used they can get stuck from marine growth. In some cases pushing down on the planes while actuating the pump in the extended direction can help release the ram. Once freed actuate the rams in both extended and retracted potions. Look for an oil sheen in the water while doing this to see if there is a bad seal in the ram. There are two solenoids on the top of the pump assembly one is for port (red wire) one is for starboard (green wire) Confirm that they are woking. Place your hand on them should click. Motor runs both directions for up and down. If motor runs, fluid level is correct but no plane movement. Inspect wire connections to solenoids. if solenoids are clicking and no movement try to push down on planes while running the pump ( two person operation ) The fact that you have not used the tabs for a long time and the boat has been in the water. I would suspect the rams are stuck!
 
Thank you BB !
So the last time i went out, I actuated both stabilizers (like I always do) as the boat gets up to speed. I could tell right away that the starboard tab was lagging.l as the boat turned right.

This morning while at the dock I extended the stabilizers and the port one worked fine.

The starboard one only went down half way + a slight oil sheen.

I then brought both stabilizers up.

Tried the port stabilizer by itself. Worked fine. The starboard one did not extend down… no oil sheen. However pump motor struggled and then stopped.
Typically once the stabilizers are either fully down or up - the motor keeps going with no struggling.

I checked the reservoir and it’s 3/4 full.

Motor hatch works fine.

I will go back to the marina with someone and try your idea of pushing / pulling the starboard tab by hand.
Thx !!!
 
The rams have slots for two o-rings on each.

Last time I replaced the o-rings (about $6), I moved the old ones to the outboard position so they'd wipe the ram clean before the new seals pass over the ram. The thought was to, hopefully, minimize wear on the o-rings from barnacles and junk.

There's no noticeable difference in how they operate, we'll see how the new o-rings hold up!
 
Thank you 4um.
In order to replace o rings - do I have to take the boat out of the water ??

I’ll search for a YouTube video to find instructions.

Thx !
 
AGLyme said:
Thank you 4um.
In order to replace o rings - do I have to take the boat out of the water ??

I’ll search for a YouTube video to find instructions.

Thx !
Click to expand...
Yes, it would need to be out of the water.
 
Checked the internet... lots of videos on replacing "O" Rings... so, easy fix thank goodness.
 
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