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devilray snob
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2,398 Posts
Discussion Starter · #1 ·
Motor: 99 Merc 40 2-stroke

While on my keys trip last week the trim and tilt unit started making high pitched noises as well as popping sounds. I'm guessing a seal is broken inside the pump? The outside of my trim unit pump is also severely corroded. The fluid level is fine.

At first, it would go up and down very slow, but needed to be pushed down by hand with force while being trimmed down to 'help it'. Now the motor won't trim down at all even when I sit on it (this started today).

Do I need just a new pump? Is the ram unit just fine?
 

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Cert. Yamaha technician
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4,330 Posts
If you hear the trim motor running then its the rest of the trim system that has an issue.
honestly it sounds like your low on fluid, or have an air pocket in the system or, you need a new valve body
 

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devilray snob
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2,398 Posts
Discussion Starter · #3 ·
If you hear the trim motor running then its the rest of the trim system that has an issue.
honestly it sounds like your low on fluid, or have an air pocket in the system or, you need a new valve body
I did some investigating. Turns out I was out of trim fluid. BUT HOW? I checked it in January during service and it was full from the plastic cap and was dripping out.

I removed the pump, checked the yellow seal o-ring (which has some minor wear and corrosion in a 1/2" spot) which looked fine. I put some anaerobic gasket on the pump o-ring and re-installed the pump- refilled the unit with ATF+4 and now it works fine!

...but how am I leaking fluid?

I tilted the motor up and down a few times, and I could see where. The trim ram- where the ram enters and exits the top of the trim ram tube- is leaking fluid on the downstroke when the ram is compressed by the engine coming down.

Is there a seal I need to replace inside the trim ram housing?

From this diagram it looks like #2 is what I need?

http://www.boats.net/parts/search/Merc2/Mercury/40%20%283%20CYL.%29/0G760300%20THRU%200T979999/Power%20Trim/parts.html
 

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Cert. Yamaha technician
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4,330 Posts
Can you post a picture of where its leaking?
More than likely its just the seal on the cap. Now im not a mercury guy but most trim systems are essentially the same.
in the parts diagram it shows you can only buy the whole trim piston assembly which is $$$$, when all you really need is $30 in seals.
but your going to need specialty tools for this one, and a bit of experience because an improperly filled system will burn up a valve body.
I know your a do it yourselfer but it would be cheaper to take it to a shop for this one. By the time you find and buy the right spanner wrench you have already paid for the job
 

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devilray snob
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2,398 Posts
Discussion Starter · #5 ·
Can you post a picture of where its leaking?
More than likely its just the seal on the cap. Now im not a mercury guy but most trim systems are essentially the same.
in the parts diagram it shows you can only buy the whole trim piston assembly which is $$$$, when all you really need is $30 in seals.
but your going to need specialty tools for this one, and a bit of experience because an improperly filled system will burn up a valve body.
I know your a do it yourselfer but it would be cheaper to take it to a shop for this one. By the time you find and buy the right spanner wrench you have already paid for the job
It's leaking literally from the cap where the trim ram enters and exits the top of the ram tube.

I actuated the outboard up and down ten times and then re-loosened the fluid fill cap to check the fluid level again - the fluid that leaked out was an aerated pink color instead of solid translucent red. I'm assuming this means there's air in the system being sucked in somewhere?
 

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Brandon, FL
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11,392 Posts
Matty,
A spanner wrench is all you need. The one that I got to change the wheels on my Hitatchi grinder fits my 25's and 70's.

Then take the piece to shop and get the o'rings ($6) when I bought them last winter.

The fluid will change color slightly even when working properly, but not much. You are pushing fluid at high pressure from one chamber to another reservoir that is not under high pressure and it will bubble just a little. But if you are seeing fluid at all, you have a leak and got to fix it before water gets in there.
 

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Cert. Yamaha technician
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4,330 Posts
The oil was frothy because you hit the trim with the manual release valve opened. The only thing you can do with that is drain the system or wait a couple days for the fluid to "de-froth"
 

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Cert. Yamaha technician
Joined
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4,330 Posts
Sorry, I read your post wrong

Yes, you want to get it fixed before saltwater gets in there.
all those small ball bearings, checkboxes and springs are steel
 

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01 Hells Bay Guide.07 ECC LOSTMEN-sold
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1,363 Posts
Matty,
A spanner wrench is all you need.  The one that I got to change the wheels on my Hitatchi grinder fits my 25's and 70's.
Or a small punch on a shallow angle. ;)
 
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