Multiple failures of Merc power steering hose

LaRea

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

Handymans342

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

aero3113

Could the oil cooler be clogged causing high pressure?

LaRea

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

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

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

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

PickleRick

I hope it's not this thick 

Willhound

🤮🤮🤮🤮🤮🤮🤮

davidbrooks

Failure of the PS pressure regulator. 

aero3113

davidbrooks said:

Failure of the PS pressure regulator. 

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

Handymans342

Why not call the Merc engineers??

LaRea

@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

Handymans342 said:

Why not call the Merc engineers??

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

davidbrooks

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

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

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

LaRea

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

aero3113

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

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

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.