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How To: Rebuilding Merc Sea/Fuel Pump

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Old 06-21-2010 | 08:35 PM
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Default How To: Rebuilding Merc Sea/Fuel Pump

Seeing that there have been a few recent threads on the Merc Sea/Fuel pumps I thought I would share the rebuild of mine. And the seals and bearing that I used. I am not a professional so don't flame me to much.
For the record I use electric fuel pumps and just cap these off, but I found out the hard way that they still need maintenance. If I could find an inexpensive HI Performance pump I might switch back to mechanical.

1. I used an Arbor press at work and pressed off the pulley. Make sure you put 1/4" spacers under the pulley so you do not bend it. You need to put the pressure on the inner part of the pulley.
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2. I took a screw driver and punched into the seal and pried it out.
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3. I removed the expansion clip.
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4. I knocked out the shaft: supporting the housing with wood and hitting the shaft with a hammer and a piece of wood in between. The front bearing will come out with the shaft.
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5. I used a punch and knocked the inside bearing into fuel pump cavity. You can wiggle the bearing out through the cam arm opening or gently knock it through the front bearing area.
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6. I then used a socket and extension and knocked the 2 smaller seals out that are between the inner bearing and impeller. They use 2 seals: one to keep the oil in and one to keep the water out.

Last edited by Rookie; 06-22-2010 at 09:32 AM.
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Old 06-21-2010 | 08:36 PM
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Parts These are the bearings and seals that I used. At my bearing supply shop using micrometers we came up with a Metric bearing.
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Assembly Sorry not to many pics. Posting this was an after thought.

1. I put the shaft into the freezer to shrink it so I could get the bearings on easier. I greased the inside and outside of the bearings. Once cold I rested the bearings (6204-2RS/C3 $13.90ea) on wood and then the hammered the shaft through the bearings, using wood in between shaft and hammer. One bearing on each side of the shaft.

2. I then put the 2 smaller seals (CR-7464 $4.95ea) in backside of the housing 1 facing the opposite way than the other.

3. I then hammered both bearings through the front bearing opening. Don't forget to put some grease in the housing.

4. I put the expansion clip back on. (sorry blurry pic)
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5. Finally I put the front seal (7690 $7.85ea) over the shaft and seated it in the housing.
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Old 06-22-2010 | 06:16 AM
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Nice I am sure a lot of guys will be glad to have this!
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Old 06-22-2010 | 06:46 AM
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Very nice

Only one question
"I put the shaft into the freezer to shrink it"

I thought cold made things expand and get bigger
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Old 06-22-2010 | 07:20 AM
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Nice job, thanks for taking the time. Those part numbers will come in real handy too
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Old 06-22-2010 | 08:42 AM
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Originally Posted by 1BIGJIM
Very nice

Only one question
"I put the shaft into the freezer to shrink it"

I thought cold made things expand and get bigger
That sentence read alone is definitely not PG.

I hope you are just kidding. When you machine steel you can not get an accurate measurement until the steel is at ambient temperature. Heat expands, cold shrinks.

I will post my How To: Making a Plexiglass hatch later today. I posted it in the Scarab forum and I'll try to move it over here.
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Old 06-24-2010 | 08:29 AM
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Great thread rookie. I'm just finishing up my pump rebuild also. Did the same thing as you, got the bearings and seals aftermarket thru a bearing supplier.
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Old 07-14-2010 | 01:21 AM
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Originally Posted by 1BIGJIM
Very nice

Only one question
"I put the shaft into the freezer to shrink it"

I thought cold made things expand and get bigger
The only thing that expands, that I know of, in the cold is water/ice. Everything else shrinks.
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Old 05-23-2013 | 03:02 PM
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Thanks for the help! Just used this pictorial to rebuild my sea pump for $32 after tax and overnight shipping.

I also added a valve to the bottom of the housing to drain the oil and check for water intrusion.
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Old 05-23-2013 | 03:43 PM
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Did you use the Merc seal part # 13 and 19. The 2 Merc inner seals (26-90562) work better than the SKF 7464?

http://www.mercruiserparts.com/Show_...%28DESIGN+I%29
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