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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4724
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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How to change seals on a power trim for a 40 HP Evinrude?

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How do you change the seals on a power trim for a 40 hp Evinrude outboard. Mine is a 96 model I think. It is leaking around the cylinder on the pump side. I have to add fluid at least every other time I take the boat out. Also were is a good place to order a seal kit.

I will be happy to assist you. If you have a question or need clarification please post back at any time.
You can order parts from your local Evinrude dealer or a great online site is they sell OEM parts at discount.
I am assuming you are referring to the seals in the trim cylinder. Here is a breakdown of the trim unit.

If you are changing the seals around the trim cylinder you will need a spanner wrench. You can find one at most good auto parts stores. The top of the trim rod is held to the midsection by a large stainless steel pin. You need to remove the cotter pin holding it in place on the port side, then pull using a puller. If the pin has corrosion on it the pin may be frozen and you may be better taking the engine to a qualified shop. Hopefully you are in fresh water!
I've had to grind and drill out the pin which is difficult.
If your leaking is around the base of the trim motor #39, then that is a single O ring #34.
To remove the trim motor you will need to remove the engine from the boat to reach the back screws. When you replace the screws use some gasket maker on the screws. I would recommend replacing the Phillips head screws with a 3/8" head machine screw.
Let me know if you need additional information on this.
Customer: replied 6 years ago.

Thank you for the quick reply. It looks like it will be fairly a simple fix. Yes I fish fresh water. The leak is coming from around the top of the trim cylinder. I have a couple more question for you.

  • Do you have a list for the item #s on the exploded view of the trim unit that you sent.
  • Does the seal kit have just the seals / o-rings for the cylinder or for all of the trim unit.
  • What is the part number for the seal kit? Looking at the model number that I sent you, is the motor a 96 model? I bought this boat from a retired gentleman that is not able to fish anymore. I am just doing some minor repairs to the boat / motor.

Thanks for you help, Have a good day and again thanks for the fast reply.

435567 is the O ring and seal kit. It has all the parts you will need to reseal the unit.
Once you get the large pin out of the trim ram with the engine supported on the trailering legs just tilt the unit down to access the ram. Use the spanner wrench to unscrew the cap.
Take careful note of how the trim ram comes apart. You will be pulling it apart to replace the cap seal.
After replacing the seals before you put the cap on but with the ram in the cylinder, fill it with fresh Dexron ATF. Then install the cap.
Use some good waterproof grease on the pin when reinstalling.
Yes your engine is a 1996.
You can look at the complete parts breakdown with parts pricing at the site.
Jeff G. and other Boat Specialists are ready to help you
Customer: replied 6 years ago.

I removed the cap and remove the trim ram. I then unscrewed the nut at the bottom of the trim rod. I took pictures to be on the safe side for replacing everything. I then removed the piston assy to get the cap off the ram.

Now then I removed the wiper and NOW confused on how to get the seal and backup ring out of the cap. It looks to be a thick washer between the wiper and backup ring and seal.

Question is how do you remove the seal and backup ring? I hope you understand what I am trying to say.

You are referring to the seal in the top of the cap? #21,23,24 in the drawing above? They just pop put, a seal remover or a small screwdriver will pry them out. When you put them back in put some gasket maker on the outside case of the seal. Is this what you are looking for?
Customer: replied 6 years ago.

Yes I am talking about #21,23,24, but my cap looks like it has a thick washer that will not move. I am going to try to attach a picture so you can see what I am talking about. Thanks for respondinggraphic

That is a flexible seal. Get a pick set with the squiggly pick and you will need to get the pick under it and pry it out. The new one is a pain to get in. Put some oil on it prior to installation, squeeze it to elongate it an push and prod into place. Just take your time and don't use any sharp objects to put it in.
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