Old boat trim tab hydraulic issue

[MR fisher]

I’m hoping to reach out to the community here to troubleshoot a problem that I am experiencing. I bought a 21’ 1976 Fiberform boat a few days ago. I think that the tabs are original from that time period, manufactured by Boat Leveler Mfg Co. I have spent the past couple of days working through it from front to back solving little issues, customizing, etc. It has been slow, but mostly successful and I’ve learned a ton along the way. My kids are pitching in and they are learning too.

The only issue that has me completely stumped is one with the hydraulic trim tabs. When I inspected the boat with the buyer the tabs operated on and off the water. I’m not familiar with them but it did seem like their range of motion was less than they could be and they maybe moved a bit slowly, but I assumed that all was good. Once I got the boat home and tried to activate them a number of times I was never able to get them moving again. The trim motor makes noises (different sounds whether the up or down buttons are held), but nothing moves.

Once I was able to investigate further I discovered that the port side hydraulic line was leaking at nipple where it is clamped onto the tank. The starboard line seems fine. Although it was pretty stuck on I was able to wrestle the line off. After draining the remaining fluid in the line I cut the line back several inches (there is a lot of excess line) and clamped it back on, but couldn’t get the clamp tight enough (it skipped when tightening) and it continued to leak.

I am headed to the store to see what I can find for a better clamp for that line. I also need to top up the fluid as it is well below the fill line. I’m hoping that once I get the line solidly clamped on and top up the fluid the tabs will function. As I don’t know a lot about this system though I am hoping for some guidance as far as what else to look for, consider, etc.

I have a couple of immediate questions as well. First, what type of fluid do I need? The tank is stamped “Trans. Oil Type A”. Is this saying transmission oil, as opposed to hydraulic fluid?

Is there a better fastener system that I should use than the clamps that are on there right now?

I will dump a lot of related photos in a reply to this post.



Thanks in advance!

 

[MR fisher]

Port trim tab

Starboard trim tab


Controls


Manufacturer label

 

[MR fisher]

Leak location port side



Nipple after removing line




Cut section


Fluid


Trim fluid tank showing fill line and fluid level beneath

 

[MR fisher]

Rubber plug in tank. From what I can see this is the only place to top up fluid. This also shows the line on the starboard side, which doesn't seem to be leaking.

 

[brutus]

Transmission fluid,if there is a leak it will never work properly, once you get all the leaks figure out, bled the system and top off the fluids, should work fine, if not then it’s electrical issues, not sure about that brand, but if it’s electrical google the brand and you might be able to find info. You can always change the pump but they are not cheap, replaced mine few years back and was like 600$ for the pump

 

[MR fisher]

Transmission fluid,if there is a leak it will never work properly, once you get all the leaks figure out, bled the system and top off the fluids, should work fine, if not then it’s electrical issues, not sure about that brand, but if it’s electrical google the brand and you might be able to find info. You can always change the pump but they are not cheap, replaced mine few years back and was like 600$ for the pump

Thanks. Should bleeding the system be simple? Could you give me a quick overview? I've tried to find info online but all I can find out about is self-bleeding trim tab systems.

Also there is a fair bit of extra line gathered in the transom of the boat. Probably at least 18" of excess, maybe more. Is there any reason why I cannot cut this back significantly (I was thinking 8-12") to get a to a fresher part of the line that may create a better seal on the nipple? Does the line length need to be balanced on the two sides of the system?

 

[brutus]

Thanks. Should bleeding the system be simple? Could you give me a quick overview? I've tried to find info online but all I can find out about is self-bleeding trim tab systems.

Also there is a fair bit of extra line gathered in the transom of the boat. Probably at least 18" of excess, maybe more. Is there any reason why I cannot cut this back significantly (I was thinking 8-12") to get a to a fresher part of the line that may create a better seal on the nipple? Does the line length need to be balanced on the two sides of the system?

No need for extra length, bleeding is simple just loosen the clamp, and active up while letting fluid fill up the system, repeat up and down, both sides, some systems don’t need bleeding, all your doing basically is getting any air pockets out of the system, once it stops bubbling and only fluid is coming out your good to go, as you activate just tighten up the clamp, just like bleeding brake lines. You will need 2 person to do it

 

[brutus]

No need for extra length, bleeding is simple just loosen the clamp, and active up while letting fluid fill up the system, repeat up and down, both sides, some systems don’t need bleeding, all your doing basically is getting any air pockets out of the system, once it stops bubbling and only fluid is coming out your good to go, as you activate just tighten up the clamp, just like bleeding brake lines. You will need 2 person to do it

Also, it sure how good this c clamp are going to hold up for pressure, usually hydraulic pressure hose for those, just double clamp everything

 

[MR fisher]

Also, it sure how good this c clamp are going to hold up for pressure, usually hydraulic pressure hose for those, just double clamp everything

Thanks. I replaced with a fuel injector clamp that reduced the leak a lot. The starboard unit seems to be functioning perfectly right now. The port side goes down well but hesitate to come back up. I will try to do a better job bleeding it. I will also add a second clamp. I will update once that's complete.

 

[turbomack]

It's hydraulic to lower the tab and spring to return it to the up position. There is only one hose per cylinder. Mechanical resistance in the hinge might be slowing it's return, once the boat is in the water and moving the water will return it to it's up position quickly, The rubber component of the hose may be embrittled from age. Might be worth replacing the hose and sealing where it comes through the transom. It makes a nasty mess in the water if you blow a line and blast a bunch of ATF into the bay

 

[MR fisher]

I ended up phoning the manufacturer and speaking with a very knowledgeable tech. He suggested a few possibilities, first of which is checking the switch, and replacing the hoses, as turbomack said. Cylinders could also be an issue, but he says the pump itself is probably better than most on the market today, so I should try to figure it out rather than start from scratch. I'm hoping for stop gap solutions for at least the next week to get the boat on the water.

 

[baddogg]

I doubt it is the switch. Lots of good suggestions posted above which I agree with. Fix leak, bleed, refill, should be good to go.

 

[sly_karma]

Try using some Oetiker type ear clamps. Gear clamps aren't perfectly round because of the barrel containing the worm screw, that little unclamped area can result in air and/or fluid leaks. Lots of automotive and marine OEM power uses them, and this is the preferred clamp for PEX water lines in plumbing. The crimpers are a one time purchase and they last forever. Unless they're visibly brand new, you'll want to replace all the hull fuel lines and connections, so you'll need them then anyway.

 

[MR fisher]

First water test yesterday and the tabs performed perfectly! That water resistance must have been key. I'll probably still replace the lines over the winter. Maybe the cylinders also if I have to.

 

[salmonkiller01]

If you’re in Nanaimo I have the whole set of your tabs with wiring, switch, pump and cylinders. Trade for beer

 

[persistent]

Hey salmon killer, are those trim tabs still available? The ones on my 20’ hourston are acting up.

 

[salmonkiller01]

Hey salmon killer, are those trim tabs still available? The ones on my 20’ hourston are acting up.

Sold a while ago

 

[persistent]

Ok, thanks anyways.