Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

I have a 1995 Mercruiser Alpha-1 drive (stern drive serial # F699850) (on a 3.0LX engine), bought new, fresh water use only. Power trim hoses are original. Braided metal outer sheaths on them are breaking up (braid wire is fraying) from flexation metal fatigue, tiny prickly bits of braid wire sticking out? Rubber hoses inside are still sound, there are no fluid leaks. I was thinking I should replace them (all 4 hoses) as PM before the sharp wire bits puncture the rubber hoses. I have a marine railway at my cottage, easy to pull the boat to do this, but no trailer and so not so easy to bring boat to a mechanic. I have read elsewhere that changing them can be a nightmare due to seized fittings, access issues etc, and have also read that the wire bits are unlikely to puncture the hoses, just leave them alone, don't worry about it. Question 1: Are the 4 hoses reinforced inside (ie fabric cord in the rubber? Will they withstand chafing/puncture from the tiny outer wire braid shards if I delay making this repair? Question 2: A marine mechanic, possibly wanting to scare me, said the hydraulic oil inside is under 2,000psi pressure and will spray everywhere when I start loosening the hoses. Is this true? I don?t want to pollute the lake, which is just a few feet from the outdrive when boat is on railway. Question 3: Does it matter whether outdrive is all the way up, or down, or mid-travel, when I do this replacement? Question 4: For this Alpha-1 drive do I need to brace the lower unit or tie it up to prevent it swinging down when the hoses are removed? Question 5: For this model of Alpha-1, is it still true that I can just install the new hoses dry/empty and then simply cycle the drive up and down a few times to fill the hoses and automatically purge the air, ie no need to manually purge air or fill the lines with fluid? Question 6: Will I need to remove the mercathode block on this unit to get at the connectors? Question 7: Any other advice, please? Anything else I should be aware of? Question 8: Does anyone know what torque I should use when installing new lines to avoid over-torqueing and stripping the connectors/fittings? Thank you kindly!

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Welcome to iBoats . . .

This is not all that hard, just buy the 4 hoses and put them on. Support the outdrive while you are working on it, so you you don't loose too much fluid. Get a flarenut wrench so you can loosen and tighten the fittings easily.

Then you will have to cycle the outdrive up and down about 5 times to bleed the lines. Re-fill the reservoir as needed.

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Phipp said:

I have a 1995 Mercruiser Alpha-1 drive (stern drive serial # F699850) (on a 3.0LX engine), bought new, fresh water use only. Power trim hoses are original. Braided metal outer sheaths on them are breaking up (braid wire is fraying) from flexation metal fatigue, tiny prickly bits of braid wire sticking out… Rubber hoses inside are still sound, there are no fluid leaks. I was thinking I should replace them (all 4 hoses) as PM before the sharp wire bits puncture the rubber hoses. I have a marine railway at my cottage, easy to pull the boat to do this, but no trailer and so not so easy to bring boat to a mechanic. I have read elsewhere that changing them can be a nightmare due to seized fittings, access issues etc, and have also read that the wire bits are unlikely to puncture the hoses, just leave them alone, don't worry about it. Question 1: Are the 4 hoses reinforced inside (ie fabric cord in the rubber? Will they withstand chafing/puncture from the tiny outer wire braid shards if I delay making this repair?

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It's possiable as amything is, replacing them is probably a good idea

Question 2: A marine mechanic, possibly wanting to scare me, said the hydraulic oil inside is under 2,000psi pressure and will spray everywhere when I start loosening the hoses. Is this true? I don’t want to pollute the lake, which is just a few feet from the outdrive when boat is on railway.

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No, they are only under pressure when the engine is rumming.

Question 3: Does it matter whether outdrive is all the way up, or down, or mid-travel, when I do this replacement?

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That would be yes and No, Yes it makes a difference because there will be pressure but not much. Best to keep the drive down to lessen the pressure.

Question 4: For this Alpha-1 drive do I need to brace the lower unit or tie it up to prevent it swinging down when the hoses are removed?

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Yes/No, keep the drive down to lessen the pressure

Question 5: For this model of Alpha-1, is it still true that I can just install the new hoses dry/empty and then simply cycle the drive up and down a few times to fill the hoses and automatically purge the air, ie no need to manually purge air or fill the lines with fluid?

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Yes you are correct

Question 6: Will I need to remove the mercathode block on this unit to get at the connectors?

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Maybe, this all depends if you can remove the lines without breaking them off. Use PB blaster and let them soak. Also use line boxwd wrenches to help/Quote]

Question 7: Any other advice, please? Anything else I should be aware of?

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May need some heat but take your time.

Question 8: Does anyone know what torque I should use when installing new lines to avoid over-torqueing and stripping the connectors/fittings? Thank you kindly!

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Just snug them, you can always tighten them a slight bit more.

Almost forgot :welcome: to iboats

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Question 1: Are the 4 hoses reinforced inside (ie fabric cord in the rubber? Will they withstand chafing/puncture from the tiny outer wire braid shards if I delay making this repair?

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They are pretty sturdy hoses, But anything can still happen to them at anytime.

Question 2: A marine mechanic, possibly wanting to scare me, said the hydraulic oil inside is under 2,000psi pressure and will spray everywhere when I start loosening the hoses. Is this true? I don?t want to pollute the lake, which is just a few feet from the outdrive when boat is on railway.

Click to expand...

While running the trim pump in the up position, it will produce and hold around 2400-2600- PSI within the system. Just momentarily tapping the trim button down once the drives are all the way up will lower the PSI down to the 400 psi range and is considered good practice to always do once the drive is up.

Question 3: Does it matter whether outdrive is all the way up, or down, or mid-travel, when I do this replacement?

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Best to have the drive all the way down so that all the fluid in the trim rams will flow back into the trim pump reservoir lessening the chance of an oily mess.

Question 4: For this Alpha-1 drive do I need to brace the lower unit or tie it up to prevent it swinging down when the hoses are removed?

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You'd be fine with lowering the drive all the way down, then pull the anchor pin out and use the anchor pin behind the bell housing to support the drive from hanging all the way down.

Question 5: For this model of Alpha-1, is it still true that I can just install the new hoses dry/empty and then simply cycle the drive up and down a few times to fill the hoses and automatically purge the air, ie no need to manually purge air or fill the lines with fluid?

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This is true.

Question 6: Will I need to remove the mercathode block on this unit to get at the connectors?

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You should be able remove the hoses without needed to remove the block.

Question 7: Any other advice, please? Anything else I should be aware of?

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As AllDodge mentioned, Use PB blaster and let them soak. the longer the better, so start now. Have lots of rags and a canister to direct any left over oil flow from the hoses if there's any is left.

Question 8: Does anyone know what torque I should use when installing new lines to avoid over-torqueing and stripping the connectors/fittings? Thank you kindly!

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Don't believe there is a torque setting in the service manual. Just know when to stop.:faint2: Hope this helps, good luck.

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Many heartfelt thanks to tpenfield, AllDodge and FunTimes for your quick and detailed and thorough replies, and for your welcomes to this new member. You have given me the confidence to tackle the replacement myself, but I will probably wait till next spring, and meanwhile put some PB-Blaster or the LiquidWrench equivalent on the 8 fittings when I pull the boat for the winter, next month, so they can soak and loosen up over the winter. By then I suppose this thread will be closed/dormant, but I have the sense now that I know what to expect. Extra thanks to FunTimes for the hint to pulse the drive down briefly to relieve pressure in a drive-up system. Makes perfect sense but I never thought of it. I will try to remember to do this in future. Cheers, Phipp

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Phipp said:

but I will probably wait till next spring, By then I suppose this thread will be closed/dormant,

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Just know that while this thread will go dormant over time, The forum rules will allow you to bring it back up as needed for things like more info, an update of how it all turned out for you is always nice to see for future forum lurkers.

Forum rule #12. Please do not post to threads that have been inactive for more than 3 months UN-LESS you are the original poster. We have very active forums and any thread that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old thread. This is considered a hijack. Please start a new thread of your own.

Re: Whether, and How, to replace frayed external power trim hoses- Mercruiser Alpha-1

Yup, the OP can light up their own thread at any time . . .

When I replaced my trim hoses, I went with an after market brand ( Sierra, if I recall ) as they were significantly lower in price. They did not have the stainless steel mesh jacket on them, but seem to work just fine.

If the boat has been used in fresh water, then the fitting threads should be in good shape. If salt water, then maybe not. I had to buy a new trim cylinder, because the threads disintegrated in the salt water after about 15 years of age.