Thread: '02 Yamaha C90 Power Tilt/Trim Creep Help!

Originally Posted by Lund

Update 2: got my boat back today! Had the o-rings replaced and impellers replaced in both engines. Little more than I thought about $409 but seems like it was a great job. Said both engines and boat have great bones for being 2001.

As I put boat back in garage I noticed one of the old impellers (not changed in my two year ownership) but glad it was replaced!!



Sent from my iPhone using Tapatalk

would make a cool paper weight!

Originally Posted by BabyFinster

I agree with Chris. I am a hydraulic systems guy and if you do not have visible leaks, you have what is called an internal bypassing leak. Fluid is leaking around the piston back to the other side of the piston to the rod side. Some of the fluid is going back into the reservoir, and the other fluid is bypassing around or through torn o-rings or seals coming to the rod side, letting the piston down there for putting your motor down on the ground. You need to replace the seals that and circle the piston. You could have some O-rings leaking in the hydraulic valve but usually it’s a seal on the piston is the problem. The control valves for trim and tilt are what they called normally closed center or all ports blocked valves therefore, fluid leaking around them is usually not issue.


Sent from my iPhone using Crappie.com

So update 2: motor going down much faster. Mechanic before recommended me to get a rebuilt power and trim unit. He said that the O-ring kit doesn’t include one of the needed O rings do you have any suggestions on what to look at? As a rebuilt cost over $1500


Sent from my iPhone using Tapatalk

Originally Posted by RobertFL

A friend gave me a boat 4 years ago that had sat for 7 years unused. It has a 1998 90hp Honda engine. Got it running after soaking cylinders with marvel mystery oil overnight. Trim and tilt worked at first but started leaking down and using fluid. I did not have the tools or experience to rebuild the unit. I sent the TnT unit to Five stars marine in Port Richie Florida for a rebuild. It took some effort to get the TnT off the Honda. I used UPS to mail it to them and they rebuilt it. They hot tanked it. Polished rams and seats, installed new seals and o-rings, charged a little more to replace the "ram caps"..motor was still working so they did not have to replace it.. I did not have them paint the unit. I painted it when I got it back. So far no problems..It was not cheap, think it ended up over $400

Sorry you are still having issues. I just looked at Five Star Marines web site, looks like prices have gone up since they rebuilt mine.. Its possible there could still be a leaky seal/O-ring? Five Star did charge me more than their advertised price since they added some new parts. So far no problems with the rebuild.

Originally Posted by Lund

So update 2: motor going down much faster. Mechanic before recommended me to get a rebuilt power and trim unit. He said that the O-ring kit doesn’t include one of the needed O rings do you have any suggestions on what to look at? As a rebuilt cost over $1500


Sent from my iPhone using Tapatalk

I would be upset that the mechanic attempted to rebuild yours without All the necessary parts. At this point, you have choices....
1. Take the unit back to the mechanic and get the correct o-rings installed like you paid for. (O-ring kits with them all are available through 5 star for $90)
2. Order a correct kit with all the o-rings and replace them yourself.
3. Send your unit to 5 star or other reputable rebuilder for a full rebuild. (5 star is $670 for yours I believe)
4. Buy a used (but good) P/T unit. (Ebay has several currently $500-1000)
5. Buy a new P/T unit (boats.net $3000) Holy cow!

Before I'd do any of that, I'd evaluate what the harm in leaking down overnight is vs. the expense. If you raise the outboard up and engage the tilt lock lever, it should rest there once leaked down and be of no consequence. Does it leak down while on the water and underway? If so it must be repaired.

Good luck!

I'm not a TnT or hydrolic guy.. looking at the first post I see that before the new O-rings were installed the unit was leaking down in 1 hour. Then looking at the parts diagram there are lots of parts in the unit. If the mechanic simply replaced the O-Rings.. he may not have cleaned up the rest of the unit. Some trash may be inside and may be causing the bleed down issue. I like to work on my own stuff but there are some things I just don't know how to do or have the correct tools. I don't have a hot tank or ultra sound cleaner. My TnT unit was leaking from the ram cap seals. Since it was over 20 years old and had never worked on a TnT unit..I sent it to a company that rebuilds them 5 days a week, Tears were shed over the price but I only cried once.

Originally Posted by Lund

So update 2: motor going down much faster. Mechanic before recommended me to get a rebuilt power and trim unit. He said that the O-ring kit doesn’t include one of the needed O rings do you have any suggestions on what to look at? As a rebuilt cost over $1500


Sent from my iPhone using Tapatalk

So it's "leaking" down faster? Or when you trim it goes down faster? If leaking then the "mechanic" didn't do his job. I've NEVER heard of any kind of rebuild kit that includes all but one part. Wouldn't that be silly? Especially if that happens to be the one that leaks the most times?
Agree with NCK, have him repair it correctly and then find a new mechanic.