View Full Version : rebuilding Trim Cylinders?

07-14-2008, 09:49 AM
I am assuming this is a DIY project? Will I need any special tools? Has onyone done this themselves? Can you share any advice?

Thank you in advance.


07-14-2008, 09:52 AM
Gregg hvae you looked into just replacing it with a new one I replaced one about two years ago and I think it was only about 90.00 bucks

07-14-2008, 12:43 PM

new cylinders are alot more, according to what I've found. $300 per side. I just bought the rebuild kits from WM @ $22/side.

Looks like i have my weekend planned!

I'll let everyone know how it goes if they're interested.


07-14-2008, 12:56 PM
Gregg I may have been mistaken The trim cylinder I replaced was for my trim tab sorry about that

07-14-2008, 12:57 PM
not a problem!

I won't deduct any points for that one. :)

07-14-2008, 02:08 PM
Gregg you may take a look here just to see if they have a cylinder to fit your needs


07-14-2008, 02:11 PM
thank you! per website, complete cylinders start at $199 ea.

I'l go the rebuild method. more money left over for gas!

07-14-2008, 03:13 PM
Let me know how this goes for you. I have a leaky one that needs to be looked at. I have rebuilt hydraulic cylinders before on forklifts and they were a PITA, and they worked after the repair, so I guess that's a plus. :grin:

07-14-2008, 03:16 PM
will do...

I'm pulling the boat out friday, early afternoon. Hope to be in the water on Saturday!

07-14-2008, 04:52 PM
Check out SEI. They have cylinders.



Sorrento 25
07-14-2008, 05:31 PM
Please keep us posted on the cylinder rebuilds! I've been wanting to do this myself.

07-14-2008, 05:45 PM
You can rebuild them. It's easy. I've done it and you need no special tools. It's so easy a Four Winns owner could do it. Heck even a Larson guy could rebuild them.

There is a special tool to remove the end caps. However mine were a bit corroded, so I bought new caps. Used water pump pilers to remove the old since they were heading for the bin. Fabricated an installing tool from flat stock. Drilled holes to match the holes in the end caps and put screws into the holes in the flat stock that matched the holes in the end caps.

Only special thing to remember, as with all hydraulic systems, is too keep everything very clean! Mercruiser manual outlines the bleeding process once you reinstall the cylinders. My rebuilding kits, from Mercruiser, don't get the cheap substitutes, also had instructions. I posted the instructions elsewhere on this site.

Best regards,

07-14-2008, 06:37 PM
"You can rebuild them. It's easy. I've done it and you need no special tools. It's so easy a Four Winns owner could do it. Heck even a Larson guy could rebuild them."

hehe! That's reassuring, 'cus I'm a caveman.

The instructions indicate to use a pipe wrench. It looks like all you need is the proper size "spanner wrench" to fit the holes you describe.

I'll be certain to keep things sanitary. I looked for other threads here on trim cylinders, but was unsuccessful. The instructions on bleeding the system would be helpful.

Do the tabs and outdrive use the same pump resevoir?

Do I need full photo disclosure of the process?


07-14-2008, 06:59 PM
You're right. I didn't post the full instructions, just a parts diagram here (http://clubsearay.com/forum/showpost.php?p=102905&postcount=10).

I'll check the manual and see if I can get the scanner to play nice.

Best regards,

sea salt
07-14-2008, 07:03 PM
Do the tabs and outdrive use the same pump resevoir?


07-14-2008, 08:28 PM
I have to now rebuild the cylinders on my trim tabs (or, my dealer might do it). When my boat came back from the SR factory after they replaced my hull, they somehow had put a 10 amp fuse where a 20 is supposed to go for the tabs. Unknown to me, the fuse blew while I was on the water and when the dry stack forklift lifted my boat, it bent the tabs and blew out the seals in the cylinders. I know its the seals because I had hydraulic fluid on the outside of the boat, at the cylinders. Glad to hear its not a big deal. This hull doesn't like not having tabs.


07-15-2008, 08:13 AM

The rebuild i'm doing is for the trim cylinders on the outdrive, not the trim tabs. Although, the process may be similar?

Frank, those procedures would be greatly appreciated! Thank you!

Seasalt, that's what i thought. Just wanted to verify. I think the trim tabs use ATF, while the trim cyclinders use 10w-30.

Thank you all!


07-15-2008, 07:11 PM
Here you go, Gregg.

Bleeding air 1 (http://home.comcast.net/~fc3other/BleedingTrim-1.jpg)
Bleeding air 2 (http://home.comcast.net/~fc3other/BleedingTrim-2.jpg)
Disassemble 1 (http://home.comcast.net/~fc3other/TrimCylinder-1.jpg)
Disassemble 2 (http://home.comcast.net/~fc3other/TrimCylinder-2.jpg)
Reassemble 1 (http://home.comcast.net/~fc3other/TrimCylinder-3.jpg)
Reassemble 2 (http://home.comcast.net/~fc3other/TrimCylinder-4.jpg)


Note that when I bought my rebuilding kit, directions were enclosed. I bought the Mercruiser kit, not a Sierra or third party one.

Best regards,
Frank C

07-16-2008, 05:23 PM
Frank C,

Thank you for posting the procedures.

I'll let everyone know how it goes this weekend...


07-17-2008, 07:59 AM
ShipShape TV just did an episode on this but of course the Guy from Bennet said it's better to replace them instead of rebuild them.

07-20-2008, 10:15 AM

Well, it wasn't the trim cylinders at all...

When I pulled the boat out of the water, I went to pull the drain plug and noticed that the trim cylinders were not attached at the bell housing!?!?

Nylok nuts, washers and bushings are missing. Luckily the pin was still present.

Off to 4 different marine stores to get all the required parts. What an easy fix. Sorry, no pics!

I was able to clean bottom side of junk, as well as blast off the zebra mussles off the outdrive, then clean/wax the hull from the rub rail on down!

Thank you all for your help and encouragement!!!!