Impellor Replacement - 4.3L Merc

Dave R · 01-17-2008, 11:42 AM

I'm 99% sure you have an alpha drive based on previous threads. It's not a difficult job to change the impeller on an Alpha, and it's certainly a DIY project. There's a common misconception that having the pump in the drive leg versus on the engine (like a Bravo) makes the job really complicated. It's not true, IMO (I've replaced both Alpha and Bravos impellers).

Here's a link to the procedure: http://www.mercstuff.com/waterpumpinst.htm

eye spy · 01-17-2008, 02:18 PM

I needed new imp. last year took it over to guy on 106 with shrink wrap boat out front of house. He replace imp, lower unit oil, service drive, and installed new gasket on drive. Just over 100.00 bucks for everything. His phone is 603-267-7223 charges 50 per hour for work 1/2 cost of lake Winn dealers.

MV1 · 01-19-2008, 11:55 AM

Remember, there are two main Alpha Models out there. Alpha I-R which uses plastic pump housing and a "Stiff Vane" impeller which should be replaced every 2-3 yrs. This drive was used till 1991. Then there is the Alpha I-MR which is still used. This drive has a completly different pump with a metal housing and a "Flopy Vein" impeller. Some manuals list this as a lifetime impeller but still should be checked whenever drive is dissembled for any reason...either way you still should have a service manual of some kind before doing work.

MV1 · 01-19-2008, 01:25 PM

Sorry, need to correct my last post. Both Alpha I-R & MR use stiff impeller and Alpha Gen-II use the metal cover, flopy vane pump.

01-17-2008, 02:18 PM	#2
eye spy Junior Member Join Date: Dec 2006 Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts	boat I needed new imp. last year took it over to guy on 106 with shrink wrap boat out front of house. He replace imp, lower unit oil, service drive, and installed new gasket on drive. Just over 100.00 bucks for everything. His phone is 603-267-7223 charges 50 per hour for work 1/2 cost of lake Winn dealers.

01-17-2008, 11:42 AM	#1
Dave R Senior Member Join Date: Jul 2004 Posts: 2,985 Thanks: 246 Thanked 744 Times in 444 Posts	I'm 99% sure you have an alpha drive based on previous threads. It's not a difficult job to change the impeller on an Alpha, and it's certainly a DIY project. There's a common misconception that having the pump in the drive leg versus on the engine (like a Bravo) makes the job really complicated. It's not true, IMO (I've replaced both Alpha and Bravos impellers). Here's a link to the procedure: http://www.mercstuff.com/waterpumpinst.htm

01-19-2008, 11:55 AM	#3
MV1 Member Join Date: Jan 2008 Location: Meredith Posts: 25 Thanks: 0 Thanked 4 Times in 3 Posts	Remember, there are two main Alpha Models out there. Alpha I-R which uses plastic pump housing and a "Stiff Vane" impeller which should be replaced every 2-3 yrs. This drive was used till 1991. Then there is the Alpha I-MR which is still used. This drive has a completly different pump with a metal housing and a "Flopy Vein" impeller. Some manuals list this as a lifetime impeller but still should be checked whenever drive is dissembled for any reason...either way you still should have a service manual of some kind before doing work.

01-19-2008, 01:25 PM	#4
MV1 Member Join Date: Jan 2008 Location: Meredith Posts: 25 Thanks: 0 Thanked 4 Times in 3 Posts	Sorry, need to correct my last post. Both Alpha I-R & MR use stiff impeller and Alpha Gen-II use the metal cover, flopy vane pump.