Leak in Trim Tab Cylinder ???

B

Bill.Secure

New member
We were in some two-three foot waves yesterday and had the tabs at 100% for much of the time (2-3 hrs). Upon returning to the slip there were some globules of black gunk in the bilge and the precoiled hose I store under the starboard cockpit hatch felt oily. This had not been the case when I returned to the slip the previous day.

I went down this morning to see if I could determine the problem. The steering reservoir was full and the trim tab reservoir appeared to be within the two inch approximation specified by the manual, at least at the forward end. I was able to discern an oily feel on the inside of the transom where the lines for the starboard trim tab pass through the transom. There was not a similar oily feel on the port side.

Does my hypothesis of a leak in the trim tab cylinder seem on target? if so, what's the nature of the fix, removing the screws holding the cylinder on and then replacing either the cylinder or the seal? I'm also wondering about the passage of the lines through the transom. Should a leak in the trim tab cylinder have forced the fluid back through the transom?

Although I'm under warranty, I need to understand the ramifications of this type of problem as well as possible to insure the repair is made appropriately. I've got several other warranty items to be addressed, and if possible I'd prefer to wait until the real heat of the summer when boating is less pleasureable.

Bill
Edgewater, MD
 
Bill,
I've not had this type of problem but it sounds like you are on the right track to me. Maybe try having someone run the tabs up and down while you watch the connections and see if you can see a source of the leak. Also check the connections and make sure they are tight.
Ron
 
Not sure about your tabs, but most cyl are outside of the transom--it could be a leak in the hose. But check the resivoir and see if the oil is down. It should be hyraulic oil, not black goo.

I would see how the trim tabs are working--if there is a significant leak, you will see it, and the tab will not work correctly. The rough water may well have brought some other "goo" out into the open--no telling what one finds in bilges!
 
I'll have someone run the tabs up and down while I observe. In looking at the manual. I also need to check and see which model of trim tabs I have. In the case of my tabs, the connection to the actuator is buried inside the transom.

In looking at Bennett's installation instructions, on their standard tabs a metal fitting goes through to the inside of the transom and the connection of the hydraulic lines is visible. On some of their other models, the lines are connected directly to the block at the upper end of the actuator and the connection is buried inside the transom. The hydraulic fluid used is automatic transmission fluid. The reservoir appears to have the required two inches of fluid at the front end (its on an angle).

I'm also trying to figure out whether the tabs are factory or Cutter Marine installed. I'm guessing that at least the actuators are dealer installed as shipping would be considerably easier without the tabs.

I'll post again when after I learn more.

Bill
Edgewater, MD
 
I was not able to perceive any fluid leakage from the starboard trim tab while in my slip moving the tabs up and down a number of times. Today I called Bennett Tabs about the leakage problem I seem to be having. A summary of the conversation follows:

1. The force within the hydraulic system will be substantially greater while underway than while at rest and so leakage might not be observed while at rest. (I had guessed this would be the case).

2. If the actuator (cylinder) was leaking, the results would be seen in the water.

3. The most likely source of the leak is where the hydraulic line connects to the actuator. That connection will leak if it is either too loose or too tight.

4. Removal of the screws holding on the actuator should provide access to the actuator-hydraulic line connection. If that is the point of leakage, according to Bennett it will be very obvious after the actuator has been removed.

5. Typically, trim tabs are installed by the boat builder or factory rather than the boat dealer.

I wanted to have this information and also do a bit more analysis on the Bomar hatch leak prior to contacting the factory about my various warranty issues.

Bill Moseley
Edgewater, MD
 
Bennett was specific in indicating there was a mechanism that provided protection if the pressure became too high. This response came after I asked if the pressures within the system were significantly higher as a result of being underway and in rough water. They may have used the words "limit switch" but I am unsure.

Bill
Edgewater, MD
 
I have had this very problem, but the fluid in my Bennett tabs is automatic transmission fluid, and is red in color. The leak was indeed at the connection to the top of the cylinder. The cylinder must be re-sealed to the transom with 3M 4200 or similar after correcting the hydraulic leak, since the upper mount is near or below the water line.
 
Thanks for your post. You are correct, the fluid used in the reservoir is automatic transmission fluid. The leak is currently fairly small and the boat is under warranty. I've compiled a number of warranty items to be corrected, probably during the heat July.


Bill
Edgewater, MD
 
Back
Top