Power Steering Leak - 5.7 Mercruiser

jplayland

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Jun 1, 2011
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21
I bought a 1986 Four Winns 21' Open Bow a month or so back. On the test drive the steering was a bit choppy, noticed low power steering fluid. I filled it up after buying the boat and the next two trips were perfect. On the next trip it was pulling left hard. If I let go of the wheel the wheel would actually turn itself hard left (I mean hard, like a hard turn trying to dump someone off a tube.) I found the fluid was low again and assumed the system had air in it before. Worked perfectly again for one trip. At home I was checking the fluid levels and again found it dry. I ran on muffs filling and steering until it was full (almost two quarts.) After the next trip again the reservoir was empty.

I noticed a fair amount of "oil" milk in the bilge water and now assume that is power steering fluid. After reading other threads I checked the hose ends on the pump and steering ram (is that what you call it?) No leak. Is the cooler below the engine in the bilge area? I see a larger line coming from the "ram" to below the engine and a smaller one back to the pump from below the engine. I assume these are going to the cooler? I would have to remove the seat to reach down there to check for a leak.

I did notice some fluid on the bottom of the power steering pump. It overflowed once when I was refilling, so I'm not sure if the fluid is the leak or if I have to pull the seat out. The only other spot I noticed anything was on the shaft of the ram there was some oily substance, but I assume that is just grease to lube it. Any advice?
 

dubs283

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Jul 27, 2005
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5,058
Re: Power Steering Leak - 5.7 Mercruiser

what are you using for fluid??

atf is usually what is used so if the color of the fluid in the bilge is red or pinkish, then yes the ps system is leaking somewhere

the cooler is a definite possible culprit, usually one of the lines is leaking at the barbs going into the cooler, should be enough hose to trim off the bad part and reattach
 

jplayland

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Jun 1, 2011
Messages
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Re: Power Steering Leak - 5.7 Mercruiser

The first small bottle (1/2 quart or so) was from prestone, I think it was red. The rest (2 quarts) was the O'Reilly Power Steering, regular quart bottles like oil. The O'Reilly stuff was clear/amber. I didn't notice any pink, but that fluid may have leaked early on before I knew to look.
 

dubs283

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Re: Power Steering Leak - 5.7 Mercruiser

your best bet is to get some oil 'sorb mats for the bilge and get it as clean and dry, free of oil as possible

fill the reservior with atf (red) then leave an oil mat under the cooler and run the engine, if you see the atf on the mat then you know one or both of the hoses is leaking

if you still lose a lot of fluid but have no obvious leaks into the bilge i would suspect a faulty cooler (internal issue) and it probably needs replacing
 

jplayland

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Jun 1, 2011
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Re: Power Steering Leak - 5.7 Mercruiser

Is the cooler down below the engine in the bilge area as I assumed?
 

dubs283

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Jul 27, 2005
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Re: Power Steering Leak - 5.7 Mercruiser

yes, in line with the cooling water supply hose
 

Lilbrit

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Sep 8, 2013
Messages
1
Re: Power Steering Leak - 5.7 Mercruiser

yes, in line with the cooling water supply hose

I had this on my Yanmar fitted with Mercruiser Bravo 3X drive.

It will be one of the power steering cooler oil pipes pulled out of the oil cooler body allowing both seawater and power steering fluid to get into the bilge. The coolers cost a small fortune to replace so I repaired mine and it solved the problem.
 
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