Multiple failures of Merc power steering hose

LaRea · September 2021

Starting a new thread: Why would my power steering hose fail three times in three years?

It's the high-pressure hose from the pump to the steering ram. All three times, it failed at the quick-release connector on the ram:

3/2019: slow leak

7/2020: hose blew out of fitting at cruise speed

9/2021: hose blew out of fitting at cruise speed

It's not an issue with the pump or ram. A few months ago, while troubleshooting a separate issue, I replaced the ram and swapped the port/stbd pumps.

I'm using OEM parts: Quicksilver 32-8M0063021. This part is rated for 2250 psi. I think most steering pumps run around 1200 psi.

Aside from the obvious inconvenience and cost ($150 each), this is a dangerous fail. When the steering goes away at 3900 RPM, the boat turns hard to starboard. Imagine that happening in a narrow channel.

So I'm looking for suggestions and guesses.

--Anxious in Alexandria

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Handymans342 · September 2021

Anything made after covid is suspect due to the labor pool and shortage.

aero3113 · September 2021

Could the oil cooler be clogged causing high pressure?

LaRea · September 2021

The cooler is on the ram's output side. That's low pressure -- probably 10 PSI or less. Handy - the one I installed today is date-stamped March 2020, so before widespread labor shortages.

PickleRick · September 2021

Couple dumb questions.

any kinks in any of the hoses going to or from the power steering pumps/ram?

Any chance there is a foreign object like the aluminum seal on a bottle of atf/ps fluid that could be inside the reservoir?

How hard is it to move the outdrive and steering cable by hand back/forth.

I'm trying to figure out what would be causing excess pressure. I highly doubt a power steering pump would put out too much pressure but an obstruction like a hose kink or a sticking steering pivot pin could.

YYZRC · September 2021

Would be interesting to add a pressure gauge. Seems like your failures happen at higher RPMs. How does the pump maintain consistent pressure regardless of RPM (or does it)?

aero3113 · September 2021

Is it possible that you’re using the wrong power steering fluid and it’s too thick?

PickleRick · September 2021

I hope it's not this thick

Willhound · September 2021

🤮🤮🤮🤮🤮🤮🤮

davidbrooks · September 2021

Failure of the PS pressure regulator.

aero3113 · September 2021

davidbrooks said:

Failure of the PS pressure regulator.

He swapped pumps and had the same issue. Would be strange to lose two.

Handymans342 · September 2021

Why not call the Merc engineers??

LaRea · September 2021

@PickleRick - good questions.

> any kinks in any of the hoses going to or from the power steering pumps/ram?

The high-pressure hose is a relatively straight run. No tight turns or constrictions.

> Any chance there is a foreign object like the aluminum seal on a bottle of atf/ps fluid that could be inside the reservoir?

A constriction inside the steering ram would make sense, but the third fail happened with a brand-new ram.

> How hard is it to move the outdrive and steering cable by hand back/forth.

Disconnected steering cable from ram -- cable moves freely. Disconnected autopilot cable from ram - cable moves freely. The port outdrive moves easily by hand, but I haven't verified the stbd outdrive.

And the first two failures pre-dated my recent engine room rebuild, so it's probably not related to that.

@aero3113 I only use OEM fluid (Quicksilver).

LaRea · September 2021

Handymans342 said:

Why not call the Merc engineers??

I guess that's my next move. But you guys take questions on weekends!

davidbrooks · September 2021

aero3113 said:

davidbrooks said:

Failure of the PS pressure regulator.

He swapped pumps and had the same issue. Would be strange to lose two.

Unless they had been replaced by a previous owner with rebuilt PS pumps.

aero3113 · September 2021

davidbrooks said:

aero3113 said:

davidbrooks said:

Failure of the PS pressure regulator.

He swapped pumps and had the same issue. Would be strange to lose two.

Unless they had been replaced by a previous owner with rebuilt PS pumps.

Possible but would think he would’ve had a failure on the other engine also.

Grahamu · September 2021

You had a previous post about stiff and jerky steering, did you fix that problem?

LaRea · September 2021

@Grahamu The jerky feel went away. The steering effort is still slightly higher than I think it should be.

aero3113 · September 2021

LaRea said:

@Grahamu The jerky feel went away. The steering effort is still slightly higher than I think it should be.

The stiffness could be the cause of the hose failures.

LaRea · September 2021

The issue with steering effort came up this spring after the engine room renovation. The first two hose failures happened before that. I don't think the two are connected, but I'm not ruling anything out.

LaRea · September 2021

When the power steering is working, I can let go of the wheel and the boat runs straight. When there's no power steering and both engines are running, it pulls hard to starboard.

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