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Mercury 20hp water pump question Please Help!


jcpjr2004's Avatar
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02-23-07, 04:54 PM   #1  
Mercury 20hp water pump question Please Help!

Hey guys new to the post. I have a 20hp Mercury motor that i recently bought and i was wonderin' if i should replace the water pump on it. I cranked it today with the water hose hooked to it to check and see if water would come out, and it did. However, it took it maybe 10-20 seconds and it wasn't shooting out very hard. Is this normal? i asked the guy i got the motor from and he said that he jsut replaced the impeller last year and it has always took a few seconds before the water would come out. I am just unsure of the pressure it should have. I really want to avoid engine troubles!

Any information would be greatly appreciated!

Thanks,

This is a great site!

 
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Ed Imeduc's Avatar
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02-23-07, 08:24 PM   #2  
Might take it apart and check it. On some of the units its just not the impeller . They have a S/S wear plate and it pays to put a new one in sometimes. With the new impeller.

 
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02-23-07, 09:08 PM   #3  
Been boating with outboards for about 35 years, yes it is normal to take a few seconds for the water to squirt out. It usually is not very forceful but firm and steady, somtimes a little less at idle. Good luck, happy boating.

 
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02-24-07, 09:02 AM   #4  
Hello: jcpjr2004 Welcome to the Boats, Sailing, Pwc's & Navigations topic and the Do-It-Yourself Web Site.

Without any question or doubt, especially if the outboard was purchased through a private party sale, the entire cooling system needs to be checked out and ALL cooling parts replaced. Water pump, (complete assembly) and the thermostat. Also the vertical water tube that brings the water to the engine, all gaskets and seals including the water discharge assembly located in the engine, should be checked.

Failure to do so may cause and/or will cause engine overheating. A very costly repair. An once of prevention is well worth to maintenance costs, even if you cannot do it yourself or choose not to to.

If the repairs are not done correctly the very first time, major mechanical damage can and/or will occur upon engine startup. In such cases, the lower costs to replace the pump will cause major engine damage. In the long run costing far more then saved. Best to have a professional do the work, IMO, than risk any potential other damages.

Usually, but not always, replacing a water pump on any outboard, not all that difficult of a task. Providing one has the hand tools and reasonable mechanical skills, etc.

Basically, all that is needed is to remove the prop housing from the shaft column. The pump is inside the prop housing within it's own housing.

Once prop housing is removed, note how the assembly comes apart and reassemble with new pump impeller exactly as you found the old impeller installed and assembly assembled.

Be sure to note where shifter rod securing clamp is located on the shifters rod inside the props shaft tube. There will be a large round rubber grommet that has to be removed.Inside the housing will be a clamp that holds the two rods together.

It is imperative to re assemble the entire assembly exactly as it is presently assembled. And that shifter rod be re secured exactly where it is presently secured together.

Use all new gaskets and replace the gear lube too. Also note which way impeller is suppose to rotate. Some require a specific direction, while on others it doesn't really matter.

Best bet is to make hand diagrams of each step as you disassemble the parts, once prop housing is removed. If all goes well,the job isn't all that difficult nor complex.

Some variations to the above will and/or may exist. Buy any generic marine shop engine repair manual if you cannot obtain the specific one for that engine. Read and study it well before attempting any such repairs. You'll be glad you did.

Be sure the work area is clean, the shop bench area is cleared and cleaned of any other repairs done prior to anything. Use small containers to hold the removed parts, etc.

The DIY resident boat service & repair professionals may have additional helpful information, suggestions and advice. Check back on your question several times for additional replies.

Kindly use the reply button to add any additional information or questions, etc. to this thread. Using this method also moves the topic back up to the top of the daily list automatically.

Regards, Good Luck & Safe Boating. Sharp Advice. Boating Enthusiast. Web Sites Host, Forums Monitor, Moderator Hiring Agent & Multiple Topics Moderator.

Additional Info Here:
http://forum.doityourself.com/showthread.php?t=146226

 
jcpjr2004's Avatar
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02-25-07, 11:30 AM   #5  
Thanks!

Thanks guys! I guess i will check out just to be safe. Any ideas where i might get a step by step printout of how to change the impeller? Its a mercury 200 20H.P.

I appreciate the help. Again thanks!

 
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02-25-07, 04:02 PM   #6  
Posted By: jcpjr2004 Any ideas where i might get a step by step printout of how to change the impeller? Its a mercury 200 20H.P.

>>>> Buy any generic marine shop engine repair manual if you cannot obtain the specific one for that engine. <<<<<

Read and study it well before attempting any such repairs. You'll be glad you did.

 
Ed Imeduc's Avatar
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02-25-07, 08:42 PM   #7  
Might check out www.defender.com they have the manuals on it

 
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