cheap fix for "tilt assist" problems?

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darrylsiemer

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I?ve sketched up my guess (ATTACHED) of the internals of the notoriously problematic ?tilt assist? lift cylinder that came standard with many 30-50 hp 1990-2005 JOHNRUDEs (part no. 0434037, list price $625.99). I?ve assumed that it?s basically just a little bottle jack with some high pressure gas (nitrogen) trapped under its piston and hydraulic oil above it. That oil is pushed into the surrounding outside chamber when the piston is raised (motor manually lifted) if the valve connecting the top of the cylinder to the bottom of the latter is ?open? (the lever at the motor?s passenger side pushed backwards).

Questions
  1. Is this how it?s really plumbed?
  2. If ?no?, how is it configured?
  3. If ?yes?, why wouldn?t the substitution of a 1/8? NPT shrader valve (cheap, about $3) for the plug in its bottom (gas) ?fill port? fix most of the problems experienced with it? (doing so would permit a mechanic to easily replenish the nitrogen which inevitably slowly leaks past the seals of such things ?it would also allow him/her to tailor the degree of ?assist? provided to a particular situation.)
 

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Evinrude57

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These were not serviceable units, i never bothered taking them apart because there was no point, no parts available to fix anything. I have looked in all of the OMC literature and there are no instructions, pictures, or diagrams anywhere because they are not meant to be taken apart.

That is the Touch-Trim unit with the cable attached to it right? Most of the time it was just the cable that when bad and the unit itself was fine. You can remove the cable from the Touch-Trim and actuate it with a screwdriver to test it, just be careful not to bend anything.

If it is the unit id imagine there would be a lot of good used ones out there, the lower unit was usually the first thing to go out on those motors and a lot of them got scrapped because of that.
 
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darrylsiemer

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These were not serviceable units, i never bothered taking them apart....

Thanks for the response.

I suspect that these units could indeed be serviced in the fashion I've suggested - there's nothing magic about gas charged shock absorbers & one tank of argon or nitrogen could recharge hundreds of them. The real difficulty is that no one outside of OMC seems to know how this particular gadget was built & it's been unwilling to divulge that info.

I also suspect that the reason so many actuator cables failed is that motor owners assumed that valves were "stuck" when the nitrogen had just leaked down to the point that the motor became too heavy to manually tilt & therefore responded by hammering down its tilt assist release lever.
 
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darrylsiemer

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No one on either of the boating forums I've posted this thing on seems to know how OMC?s tilt assist cylinder is built - lots of reads though. However, if it's as I've assumed, it should relatively cheap/easy to fix & therefore profitable to anyone willing to attempt something different (EBAY/AMAZON sell 1/8 NPT shrader valves for ~$3 plus you'll need a half pint of generic hydraulic oil). Here?s how I would go about doing it:

1) release the motor?s tilt assist (move the lever stern-wise) and ? muscle? its lower end all the way up & tie its power head to the boat?s bow/seat so it can't fall back. Then carefully crack open the trim assist cylinder's upper plug screw to release gas that has gotten past the piston?s seals. Since such gas is likely to have pressurized the outside reservoir, most of the hydraulic oil ?approximately one half pint - is apt to be lost as well (much less would be lost if the cylinder were to be removed from the motor and turned upside down before that screw is removed). Inject approximately the same amount of fresh oil back into that opening with a syringe, apply gasket sealer to its plug screw, and screw it back in. (An additional engineering improvement to OMC?s system would be to add a tiny gas vent at the top of its outside reservoir to prevent such reverse pressurization. Its opening would also provide a more convenient oil fill point ? a $626 gas-filled bottle jack should be ?maintainable?.)

2) carefully remove the lower plug screw (there's almost certainly still some fairly high pressure gas left under the piston)

3) if that hole isn't already threaded for your shrader valve, do so (most tap/die sets include the necessary tap). If it?s necessary to ream it out first, use a 11/32? drill.

4) apply gasket sealer to that valve?s threaded end & screw it in tight

5) pressurize the cylinder with argon or nitrogen until it's able to hold the motor up by itself (i.e., put some slack into your tie-off rope). This will probably require over 300 psi ?beyond the upper range of most gas regulators - which likely means that your fill hose will have to be connected directly to the Ar/N[SUB]2[/SUB] tank?s valve - ?tweak? the latter to pressurize.

6) untie the rope & repeatedly tap the shrader valve's sealing pin until enough pressure escapes to allow the motor to completely settle down under its own weight.

7) Test for leaks by tilting the motor back up, locking it by moving its tilt assist lever all the way forward, and putting soap solution on the cylinder?s valves & seals ? if you don?t see bubbles & the motor stays put, you?ve fixed it.

8) charge whatever you think is fair but please tell your customer that your next fix is apt to be both quicker and cheaper.

The really "tough" part about this for a non professional is getting a tank of N[SUB]2[/SUB] or Ar to pressurize with; however, anyone with MIG/TIG (aluminum) welding capability probably already has it.

If anyone decides to give this a shot, please let us know how it worked out.
 

GA_Boater

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Why don't you give it a shot. It's your idea and if the cylinder is totaled, it's your cylinder.

Asking for a guinea pigs to try your ideas is not the way. Try it yourself and let us know how it worked.
 

darrylsiemer

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Why don't you give it a shot. It's your idea and if the cylinder is totaled, it's your cylinder.

Asking for a guinea pigs to try your ideas is not the way. Try it yourself and let us know how it worked.

I'd try it myself if I had a tank of argon or nitrogen to boost it up again. I'm just a typical "customer", not someone who makes his living fixing motors or welding up battered aluminum props/boats.


I've had another brainstorm. Why not just vent the thing, refill with oil & connect its bottom vent to a manual oil pump scavenged from a $15 WALMART bottle jack with flexible tubing?

These things fail (or at least mine did) because the gas leaked past its internal seals - eliminating that gas would constitute a permanent fix.
 

interalian

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I just had a brainstorm too. How about find a small electric hydraulic pump and attach it to your dead cylinder and make power tilt? :popcorn:
 

darrylsiemer

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Thanks Interalian

I'd thought of that too but couldn't locate a cheap little pump. Can you?

Anyway I bought one of those little $12 WALMART bottle jacks yesterday - it's nicely made & works fine as a jack. But it can't be modified as I'd planned (I took it apart & something (oil reservoir) that should come off wouldn't ) so I went back to the internet & found someone on EBAY selling 4 ton portapower jacks complete with oil reservoir and pressure hose for $35 - free shipping. I've ordered one - it's supposed to show up by the 13th.
 

kofkorn

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5) pressurize the cylinder with argon or nitrogen until it's able to hold the motor up by itself (i.e., put some slack into your tie-off rope). This will probably require over 300 psi –beyond the upper range of most gas regulators - which likely means that your fill hose will have to be connected directly to the Ar/N[SUB]2[/SUB] tank’s valve - “tweak” the latter to pressurize.

Please don't try this in any manner if you don't have the proper equipment. Nitrogen and Argon are both bottled at a pressure over 2000psi. Connecting the tank directly to the cylinder will surely guarantee that you blow it to pieces. Standard hydraulic trims cylinder may be rated for that pressure, but the "Schrader" valve you recommend won't be rated for more than 150psi. There is no possible way to control the pressure properly simply by slowly cracking the tank valve. I had the poor experience of being about one room away from a young man who attached a standard air line regulator to a nitrogen tank (He had to finagle some fittings together to get it to fit). He cracked the valve open and lost most of his thumb.

While the theory of what you are thinking of is sound, the equipment needed to do it is not within the reach of most people. Please do not attempt to re-purpose your tilt assist in the manner you describe above.

Best wishes.
 

GA_Boater

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Please don't try this in any manner if you don't have the proper equipment. Nitrogen and Argon are both bottled at a pressure over 2000psi. Connecting the tank directly to the cylinder will surely guarantee that you blow it to pieces. Standard hydraulic trims cylinder may be rated for that pressure, but the "Schrader" valve you recommend won't be rated for more than 150psi. There is no possible way to control the pressure properly simply by slowly cracking the tank valve. I had the poor experience of being about one room away from a young man who attached a standard air line regulator to a nitrogen tank (He had to finagle some fittings together to get it to fit). He cracked the valve open and lost most of his thumb.

While the theory of what you are thinking of is sound, the equipment needed to do it is not within the reach of most people. Please do not attempt to re-purpose your tilt assist in the manner you describe above.

Best wishes.

Thank you for the common sense reply, kofkorn. This shouldn't be a 'hold my beer" moment.
 

guy48065

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The nitrogen bottle, regulator & correct HP "schrader" valve & no-loss fitting is common stuff wherever performance shocks are built or tuned. Maybe OP can buddy up with somebody on a race team.

My setup (obviously I remove the blowgun for high-pressure use...):
N2setup.jpg
 

darrylsiemer

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It's me again. OMC has totally defeated me on this project. It turns out that they apparently "glued in" the 5/32" hex-headed set screws ( there are three, not two of them) that originally served as fill points for their tilt assist cylinder's nitrogen & oil. I broke a "fresh" Allen wrench and a hardened 1/4" drive hex bit trying to get one of them out. In other words, OMC deliberately made the this thing "unserviceable"

It's this kind of US engineering expertise & decision-making that makes me look forward to China's getting into the outboard motor business too.

I really appreciate constructive comments like the one immediately before this reply .
 

flyingscott

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It's me again. OMC has totally defeated me on this project. It turns out that they apparently "glued in" the 5/32" hex-headed set screws ( there are three, not two of them) that originally served as fill points for their tilt assist cylinder's nitrogen & oil. I broke a "fresh" Allen wrench and a hardened 1/4" drive hex bit trying to get one of them out. In other words, OMC deliberately made the this thing "unserviceable"

It's this kind of US engineering expertise & decision-making that makes me look forward to China's getting into the outboard motor business too.

I really appreciate constructive comments like the one immediately before this reply .


It's like that because it becomes a liability issue for the company. When people try to open them up and get hurt first thing they want to do is file a lawsuit.

China is in the outboard business and they are not impressive.
 

jakedaawg

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Try heat. Heat that old pressurized cylinder up. Use oxy/acetylene, get those fittings red hot. Maybe they'll come out. Maybe it will blow up....try and see.
 

jakedaawg

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As far as chinese motors go....try finding parts for a hangkai in the states and then you can brag about their repairability.

"Boating is Inexpensive" said NO ONE EVER! LOL
 

interalian

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Try heat. Heat that old pressurized cylinder up. Use oxy/acetylene, get those fittings red hot. Maybe they'll come out. Maybe it will blow up....try and see.

I was thinking more along the lines of shooting it with a depleted uranium round out of a Howitzer...
 

darrylsiemer

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I figured that mentioning the probable virtues of a China-made OB motor

Mod EDIT: Not needed commentary removed.

No such motors are available off-the-shelf in my neck of the woods which means getting a new water pump impeller for one (what else is apt to wear out?) would mean getting it at the same place you would have get the motor itself, probably EBAY or AMAZON. A check of those websites indicates that a brand new 6 hp Hangkai sells for less than OMC wants for just the "naked" OEM OMC hydraulic cylinder that got this discussion going - having a pro install one of the latter for you would probably jack that bill up to over $800.

What does "LOL" mean? Is it supposed to be funny?
 
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guy48065

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I figured that mentioning the probable virtues of a China-made OB motor

Mod EDIT: Not needed commentary removed.


MOD EDIT - Unneeded comments from the peanut gallery!
 
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flyingscott

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You know what, for all the time you spent trying to jury rig this thing up. You could have went and found a parts motor for under $500 taken the parts off that you needed, you could then take the rest of the parts off of that motor and sold them. If it's a 40-50 hp then you have you could have possibly gotten T/N/T off of a donor motor and been far better off. After selling the rest of the parts especially the lower unit you could have possibly fixed your motor for free or close to it.


Long before I would buy a 6 hp Chinese motor I would find an older johnson/evinrude or mercury/mariner 6/8 hp and had a FAR better motor than anything china is putting out. I would have more confidence in a 1968 OMC 6 hp than I would ever have in any of the 2017 chinese motors.
 

interalian

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My grandfather would have called the OP a "glutton for punishment". I can get behind the idea of trying to repair something rather than spend money on a new part - it's my Yorkshire ancestry - but there's a limit.
 
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