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Author Topic:   Hydraulic fluid for '89 Mercury 200 tilt/trim unit
andygere posted 09-20-2004 01:13 PM ET (US)   Profile for andygere   Send Email to andygere  
The shop manual for my 1989 Mercury 200 specifies Dexron II, type F or type FA automatic transmission fluid for the tilt and trim pump. My local auto parts store had plenty of Dexron III, but no Dexron II. Are these fluids compatible, and will the Dexron III work?

The bigger problem may be finding out where the fluid went, but I have to put some in before I can figure out how it got out.

Nausiat posted 09-20-2004 01:34 PM ET (US)     Profile for Nausiat  Send Email to Nausiat     
Sounds like they just want any tranny fluid since Dexron and Type F are normally not considered compatible fluids..

Can't say for certain, but in any other oil, such as TCW3, the nigher number is backwards compatible with lower numbers, I expect the III is compatible, but better in some way, then II..


andygere posted 09-20-2004 03:19 PM ET (US)     Profile for andygere  Send Email to andygere     
What is really unclear, is if any of the acceptable fluids can be used together. For example if Type FA is in there and I add Dexron III, is that a problem? I have no idea what fluid is currently in the system, and don't know how sensitive this application is to fluid type.
andygere posted 09-22-2004 01:00 PM ET (US)     Profile for andygere  Send Email to andygere     
Did some more research, and found the Dexron III is fine. Filled the reservoir and found a major leak around one of the the pivot shaft seals on the trim unit. The good news is that the pump and motor work fine. The bad news is that it will take some labor to replace the seals since the whole tilt/trim unit has to come off to drive the pivot shaft out. This one is a job for the pro's, she goes into Moore and Sons on Monday.
Clark Roberts posted 09-23-2004 07:32 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Try some "automatic transmission fluid conditioner" available at any auto supply store... add an ounce or so and work trim so as to fully distribute and chances are that the offending seal{s) will swell a bit and leak will go away! It has worked for me... good luck... Clark... Spruce Creek Navy
jimh posted 09-23-2004 08:48 AM ET (US)     Profile for jimh  Send Email to jimh     
You can buy the Mercury brand hydraulic fluid in a convenient container for about $4 at your dealer.
andygere posted 09-23-2004 11:17 AM ET (US)     Profile for andygere  Send Email to andygere     
Clark, I considered this, and didn't know if there would be ill effects on the pump. Does it tend to solve the problem for a long time? This leak is a pretty good one, and it drains the reservoir in just 2 full cycles of trim range. I might give it a try, but since I'm planning a cruise the weekend after next (with a 22 mile open water crossing) I may just bite the bullet and have it done. It's a good opportunity to get some other maintenance done, but it will probably hurt $$!

Jim, my Mercury shop manual suggests using ATF or the Quicksilver product, but a quart of ATF is less than $2, and the local auto parts outlet is open 'till 9, seven days a week, vs. my Mercury mechanic who is never open when I'm not at work.

jimh posted 09-23-2004 01:19 PM ET (US)     Profile for jimh  Send Email to jimh     
I agree with you on the ATF fluid if you need a large amount and plan on watching much of that leak out. If you just need an extra pint to carry onboard, the OEM branded products are not that expensive, and the container is more convenient for pouring into the oil reservoir for the hydraulic system.

I don't know the impact of mixing different fluids in a hydraulic system.

andygere posted 09-27-2004 09:25 PM ET (US)     Profile for andygere  Send Email to andygere     
Update on the leaking trim system: My mechanic called and told me that he has to replace the tilt ram since it has internal pitting on the sealing surfaces. This is the part of the ram that is submerged, but there are no outward signs of corrosion on the exterior of the unit, and I replace the zincs annually whether they need it or not. It makes me wonder if I have a stray current problem, however it is a 15 year old motor, so who knows. Perhaps the hydraulic fluid was contaminated with sea water from a leaking seal, and that's how the pitting happened. I am asking to see the part so I can try to determine the cause of failure. Thanks for the help offered in this thread.


Clark Roberts posted 09-28-2004 08:04 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
ANdy, I have used auto trans conditioner for years and never had any problem. I use Dextron III in all my hyd systems (including hyd steering) except power jack plate which uses 30weight non-detergent motor oil....
andygere posted 09-28-2004 11:10 AM ET (US)     Profile for andygere  Send Email to andygere     
Thanks for the confirmation on fluid types. I put Dextron/Dexron III in the system, and it worked fine until it all leaked out, which was pretty quickly. It sounds as though my problem was caused by pitting of a sealing surface as opposed to a dry or shrunken seal, so I'm betting that the trans conditioner wouldn't have solved the problem. I'm tempted to keep a small bottle on hand for any future leaks that may develop.
andygere posted 09-30-2004 04:21 PM ET (US)     Profile for andygere  Send Email to andygere     
The repair required installation of a new tilt ram. The part cost $697--Ouch! The cause of the leak was pitting on the alloy that eventually broke through to the o-ring seating surface. When that last little chunck of metal let go, whamo, big leak. My (very good) Mercury mechanic said has has seen a few similar failures on the older Black Max models, but none on the more recent motors. He suspects it is a material problem since there was no other evidence of corrosion anywhere else on the tilt/trim system, and the other failures he's seen have been nearly identical to mine. I saved the part, and will post a picture for the experts out there to weigh in on.

The good news is that Namequoit is back in the water ready for her upcoming fall cruise.

Clark Roberts posted 10-02-2004 06:14 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Never thought of it before but maybe a complete fluid flush every few years would be good preventive maintenance and insurance for trim and tilt hyd units. These babies are so expensive to replace/repair! Auto companies recommend brake fluid replacement and auto trans fluid replacement at various intervals because of water absorption and heat breakdown. Most trim/tilt units are self bleeding and can be drained of fluid by removing the hyd. manual release screw completely and running the pump motor but a check of your specific trim/tilt's drain procedure will calrify. Happy Whalin'... Clark... SCN
jimh posted 10-02-2004 08:03 AM ET (US)     Profile for jimh  Send Email to jimh     
Was the 1989 Mercury tilt/trim assembly which failed used mainly in fresh water or in salt water? Was the boat kept on a trailer or in the water?

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