CONTINUOUSWAVE

Q1: who sells new seals for a 1987 Yamaha 70?

Q2: who sells new cap with seals installed for a 1987 Yamaha 70?

Q3: is there cross compatibility between the 1987 parts and later years?

BACKSTORY: [A 1987 Yamaha 70-HP outboard engine has a] trim unit that likes to squeal when it reaches near the bottom, the last 20-percent before fully down. I notice some fluid dripping from the starboard trim piston. The trim "unit" is labeled 6H1. I think newer [trim "units") are [labeled] 6H1-10 or higher. I think [the leaking starboard trim piston] is the cause [of the squeal or vice versa].

Give Andy at SIM Yamaha a call. He might be able to source them.

http://www.simyamaha.com

Good talking with you last night Thomas.

You have the old style trim unit and key parts are no longer available, even from SIM, unless he's has a cashe of NOS parts.



Once the trim caps have corrosion under the seal they are no longer any good and time to replace since they will leak fluid. There are 2 style caps and one has just the seal seated into a recess, the other has the same seal setup, but below that there's a second groove with a nylon split washer and r-ring and I believe that's what you have.



If it's leaking past both of those, you may also need the oring and nylon split washer on the piston itself, picture below.



This is a typical rebuild kit (Yamaha does not offer a kit). I'm not overly happy with the trim seals, but aftermarket is the only way to purchase the tilt ram seal since Yamaha does not offer it and wants to sell you a $700 part when it's only a bad $12 seal....



Here's a pic of a bad trim cap. You can see the additional groove below where the seal seats. That groove is for the nylon split washer and oring.




Here are some various OEM and aftermarket ram endcaps for various Yamaha trim units. If there is any damage to the shiny trim pistons (rust, nicks etc) this will damage new seals if installed and the piston should be replaced. You can try a newer style cap as the threading is the same, but I'd also to the oring and nylon split washer on the piston itself.





You also mentioned your trim motor noise and that could be:
1. The motor is failing internally
2. There is air in your system from the leaks and the air causes cavitation bubbles causing the pump to make noise.

Based on the pic you texted me (below). You have the older trim motor that uses 3 wires - black, green and blue.



1. Black is negative
2. Blue is tilt/trim up when B+ is applied
3. Green is tilt/trim down when B+ is applied.

Newer trim motors are 2 wire.

If you decide to service the unit, be advised there are special endcap tools required. DO NOT buy cheap tools and only use the type with pins that engage all 4 detents in the trim ramp cap and do not use an impact tool to remove. It's best to hold the unit in a vise and have someone help hold the tool inplace while you unscrew with a breaker bar. At times they are so bad you have to enlist the help of a pipewrench and at that point they are throw away caps.

Hope this helps.

D-

Thanks for the thorough reply. I have just three more questions.

Q4. I think you mentioned that both the new and old trim caps have the same thread pattern. I am unable to find an style trim cap. Can you confirm that I can use a new style trim cap instead?

Q5. Is the same tool used to remove both the new and old trim caps?

Q6: Is the hole spacing the same on both?

198715ss wrote:Thanks for the thorough reply. I have just three more questions.

Q4. I think you mentioned that both the new and old trim caps have the same thread pattern. I am unable to find an style trim cap. Can you confirm that I can use a new style trim cap instead?

Q5. Is the same tool used to remove both the new and old trim caps?

Q6: Is the hole spacing the same on both?

The ideal tool is the 4 pin, they have 2 and 3 pin options, but I find they shear pins when applying lots torque, which older units require after corroding on. DO NOT use an impact gun, use a long ratchet and make sure they pins stay fully seated in the trim cap detents. The pins are replaceable, but once the cap detents are stripped, you're all done and may have to use a pipe wrench.





D-

Thanks for the guidance. New tool and parts are on the way. Hopefully I will have no leaks next week.

I have reassembled and bled [the Yamaha] trim unit, and it is now working great.

The tool recommended above [and seen in Figures 9 and 10)] to remove the end caps worked great.

One point to note for other owners of a 1987 Yamaha 70 trim unit: the 1987 caps are not compatible with the newer caps. The caps from 1987 have a much shallower threaded area and also have a groove in the back to retain a large spring inside the trim piston.

I was able to reuse the old cap. I replaced the O-ring and dust seal; those parts were stocked at my local Yamaha dealer.