Merc 25hp Impeller Replacement

MJM · 05-08-2008, 07:13 AM

Hello all,

Due to a low volume of water running through the cooling system, I've come to the conclusion that it's time to replace the impeller on my 2002 Merc 25HP 4-stroke. (I hear some people actually replace theirs every year as a preventative measure...I have never replaced this one.)

Anything I need to specifically be on the watch for?

Do I need to drain the gearcase oil first, or will I not be encroaching on that cavity?

Thanks in advance for the advice/tips!

fatlazyless · 05-08-2008, 12:45 PM

The gearcase oil is very seperate from the water pump. It is down at the bottom of the engine, directly in front of the propeller, and the water pump and impeller is about two feet higher up, at the bottom of the engine area.

Definately get a step by step list of what to do from a Seloc manuel, or from an internet outboard repair forum before starting.

You have to remove the entire lower half of the engine to get access to the impeller. If you go to a Napa auto parts store, like the one in Meredith, they may have an impeller replace kit or can order one. They may be able to get you a copy of installation instructions, too. The Meredith Napa is good for marine replacement parts, especially for Mercury.

MJM · 05-12-2008, 07:38 AM

Thanks for the reply - the repair was successfully made, after several hours of being very (overly) cautious, uncertain, etc. Now that I've done it once, it's more like a 20-minute task.

Ready for Summer!

05-08-2008, 07:13 AM	#1
MJM Senior Member Join Date: Jul 2005 Posts: 262 Thanks: 0 Thanked 23 Times in 11 Posts	Merc 25hp Impeller Replacement Hello all, Due to a low volume of water running through the cooling system, I've come to the conclusion that it's time to replace the impeller on my 2002 Merc 25HP 4-stroke. (I hear some people actually replace theirs every year as a preventative measure...I have never replaced this one.) Anything I need to specifically be on the watch for? Do I need to drain the gearcase oil first, or will I not be encroaching on that cavity? Thanks in advance for the advice/tips!

05-08-2008, 12:45 PM	#2
fatlazyless Senior Member Join Date: Apr 2004 Posts: 8,525 Blog Entries: 1 Thanks: 295 Thanked 957 Times in 698 Posts	The gearcase oil is very seperate from the water pump. It is down at the bottom of the engine, directly in front of the propeller, and the water pump and impeller is about two feet higher up, at the bottom of the engine area. Definately get a step by step list of what to do from a Seloc manuel, or from an internet outboard repair forum before starting. You have to remove the entire lower half of the engine to get access to the impeller. If you go to a Napa auto parts store, like the one in Meredith, they may have an impeller replace kit or can order one. They may be able to get you a copy of installation instructions, too. The Meredith Napa is good for marine replacement parts, especially for Mercury. __________________ ... down and out, liv'n that Walmart side of the lake!

05-12-2008, 07:38 AM	#3
MJM Senior Member Join Date: Jul 2005 Posts: 262 Thanks: 0 Thanked 23 Times in 11 Posts	Thanks for the reply - the repair was successfully made, after several hours of being very (overly) cautious, uncertain, etc. Now that I've done it once, it's more like a 20-minute task. Ready for Summer!