Mercury Mercruiser power steering pump replacement

[miktwalker]

I had to replace the power steering pump on my 1998 5.7 Mercruiser. I found these pumps are the EXACT same match as the original OEM pump. The casting part numbers stamped on the pump are identical. These are approximately 50.00 at your local auto parts store. Swapping your original OEM reservoir is very simple and straightforward. Much better option than buying a 650.00 pump from Mercruiser. Just make sure you swap your original valve and spring from the Merc pump to your new pump. Here are the part numbers. Hope this helps.

Napa 20-7920
Car quest 20-661
Saginaw pump sp17250

 

[alldodge]

Agree, but ........

The but is the pressure relief valve is of a different size. There is no issue with using the auto part to replace the marine pump, but ...,,, keep the original pressure fitting which screws into the back of the pump and the high pressure line connects. If you do not do this then there will be less pressure which is needed for a boat

 

[scorpion230ltd]

Is it the valve and piston and spring that all need to be swapped?

 

[scoflaw]

I've had no problem at all just using the chevy truck pump as is. Saginaw went from standard to metric fittings in the 80's, so pay attention to that.

 

[alldodge]

I've had no problem at all just using the chevy truck pump as is. Saginaw went from standard to metric fittings in the 80's, so pay attention to that.

If that went on your power quest I don't see how that would work. It is lighter then my formula but the pump did not work very well, was hard to steer on plane

 

[scoflaw]

Worked fine, ordered one for a 90 gmc pickup. My issue was a rotted resovoir, but used the complete unit. No difference in performance at all.

 

[alldodge]

Guess we just agree to disagree

Marine 1500 psi max
Manual shows 1150 to 1250 psi normal

http://www.boatfix.com/merc/servmanl/14/14a6.pdf

Race track and such have links showing how to increase pressure of the standard pump

I tried a new truck pump and did not keep the valve. After install it was hard to steer on plane. Bought a new marine pump and I'm back to easy steering. Maybe I did something dumb, or maybe there is a difference. Maybe my boat is just heavier and needs the extra pressure

Hope your info does the same for any others reading the thread

 

[miktwalker]

Is it the valve and piston and spring that all need to be swapped?

Like Alldodge said, make sure to swap your psi fitting from your original pump too. You’ll probably need to mount your original reservoir to the new pump. Pay attention to the black o rings that seal the reservoir at the psi fitting and mounting bolts. The o rings are easy to get out of position when assembling. Suggest cleaning out the reservoir along with the catch magnet and flushing the system with new fluid. (Very easy to do, feed new fluid to the psi fitting with a 3/8 hose. Catch the old fluid in a container with the return hose then manually move steering stop to stop to flush.) Mine called for dexron III which is unavailable but Mobil 1 makes a synthetic ATF that is a substitute (superior) for dextrin III. Hope this helps. Also after everything is together, bleed the system using the fill technique above.