Leaking trim tab actuator

Irie308

Well-Known Member
May 28, 2013
2,578
CT
Boat Info
2004 420 DB, GHS Hydraulic Lift
Garmin 8600/Garmin 1222 plus
AB Mares 10 VSX with 30 hp Tohatsu
Engines
Cummins 450C 8.3 L Turbocharged
I'm dealing with leaks on my trim tabs that are on different locations on both. I know Bennett sells an O-ring kit to service them but I'm not sure about the leak on the one pictured up near the hull. All my research shows that it either leaks at the upper part of the cylinder or tightening or at the piston. Both locations are serviceable however nothing I've found shows common leaks in the area I'm seeing on my port side. Spoke to Bennett and they say it could be cracked. Anyone ever run into this and have to replace the upper unit?
trim tab.jpg
 
Is that an actual leak or just an area where the bottom paint has flaked off? Or did the BP flake off BECAUSE the tab is leaking? Chicken or egg? :)

However, if this a leak... Check on the inside of the transom. It's possible the nipple that goes through the transom is the culprit and just needs to tightened up. Unless, the area where the nipple screws into the tab fitting (the piece touching the hull circled in red) is, as Bennett mentioned, cracked.

There's usually a red drip mark on the inside of the transom, as well.
 
If you have a cracked / leaking hinge, I think I have a couple of spare used ones that are in good condition in the garage someplace, as I converted to the hinges that have the position sensors in them. Looks like yours is cracked, or as others have stated, the hydraulic line nipple is leaking. If you tighten it, be careful, as that is the main reason folks need to replace them after working on them. Easy to screw the pooch on them if not careful.

O-rings can be matched up in the Ace / True Value hardware stores, but easier (and more costly) to buy the rebuild kit with all the o-rings.

If you need one upper hinge, or both, let me know. Yours for shipping costs.
 
If you have a cracked / leaking hinge, I think I have a couple of spare used ones that are in good condition in the garage someplace, as I converted to the hinges that have the position sensors in them. Looks like yours is cracked, or as others have stated, the hydraulic line nipple is leaking. If you tighten it, be careful, as that is the main reason folks need to replace them after working on them. Easy to screw the pooch on them if not careful.

O-rings can be matched up in the Ace / True Value hardware stores, but easier (and more costly) to buy the rebuild kit with all the o-rings.

If you need one upper hinge, or both, let me know. Yours for shipping costs.
Great, thank you! Will go down this weekend and see if it needs tightening in the bilge.
 
I was able to replace the seals on one tab and tightening up the fitting in the bilge for the other did the trick. Pretty easy job to replace the seals. One thing I did find out which I didn't know is that the port switch at the helm controls the starboard tab and visa versa.

BTW thinking about installing the Mente automatic trim tab controls? Has anyone done this on 40+ sized boat. Wondering if its worth the cost. We pretty much run with tabs down fully. Some times I try to find the sweet spot to see if i'm plus or minus a knot but they are almost always fully down.
 
I was able to replace the seals on one tab and tightening up the fitting in the bilge for the other did the trick. Pretty easy job to replace the seals. One thing I did find out which I didn't know is that the port switch at the helm controls the starboard tab and visa versa.

BTW thinking about installing the Mente automatic trim tab controls? Has anyone done this on 40+ sized boat. Wondering if its worth the cost. We pretty much run with tabs down fully. Some times I try to find the sweet spot to see if i'm plus or minus a knot but they are almost always fully down.
Yup, it's that whole "every action has an equal an opposite reaction" thing. The tabs actually control the stern - the bow does the opposite. So if you lift the port stern, the stbd bow goes down. But it's whole lot easier to just think of what you want the bow to do! :)

I haven't used the Mente system (although have heard good things about it). I have used the Bennett version and it works as advertised. I think the largest boat I've ever used it on was probably in the low 30' range. But I'm sure it would work just as well no matter the size of the boat. The system just constantly adjusts to keep the boat at the running attitude you have pre-set.

I think, though, that it's "more" helpful on smaller boats since you tend to adjust the tabs more often given they bounce around more.
 
^^^ #1 100% correct

Smaller / lighter boats are actually harder to control. My current 22 1/2 footer (@3800 lbs dry) with 10x12 tabs is so much harder to control and keep stable than last 25 1/2 footer (@5700 lbs dry) with 12 x 16 tabs.
 
Just an fyi but the entire actuator is only like 125.00 so I typically replace them when they have issues and everything is new.
 
I had one that had a pinhole leak right where your measuring tape it touching the plastic. I had thought it was o-rings and also tried to tighten the cylinder (which did move a bit) and would see a sheen in the water every now and then. One day while it was on the "hard" while I was buffing the hull out I saw a drop of oil right where the pinhole was.

Like Bill, I bought the replacements with the indicator sensor in them, thinking I'd upgrade the buttons at some point to the ones with the lights, but never got around to that.
 

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