PDA

View Full Version : When to do Impeller Service? Alpha 1 Gen II



RickSE
05-21-2003, 12:56 PM
I have 104 hours on my 1996 Alpha-I Gen II. Should I service the impeller? I've heard some people say you should do this every 100 hours.

Also has anyone bought Merc. parts from BAM Marine? Any problems is so?

MOP
05-21-2003, 01:40 PM
My general rule is to change out at 100 hours if you do clean running, guys that run in silt and sandy conditions 50-75. Guys like me that trailer and have pumps in the drive which dry out during non usage should follow above but never go past one season. People will argue, I only have 25 hours. I have seen so many low hour impellers that had started to crack near the hub that I am a firm believer in changing them. My 16 has 58 hours in three years and three new impellers, same housing and plates. I carry the last one as a backup. Drive pumps are a pain especialy Mercs but it is still cheap insurance. No water No fun day and maybe other problems if not caught in time. Another plus if you goop your bolts well and clean the threads it comes apart real easy.

krakmeup
05-21-2003, 04:04 PM
Good post, M.O.P. Completely agree, hours AND age are a factor - non-usage is the biggest killer many times. On my big boat, I boat ~200 hours in ten months every year (twin gas merc 260's with Jabsco raw water pumps in salt water), and I can let mine go nearly the 200 because of such frequent use, but typically 50-75 or once per season is what I tell most boaters.

RickS, YES change it, it's cheap insurance! It is amazing how much these boats can take when maintained properly. Good luck! (Always carry a spare...)

Air 22
05-21-2003, 04:35 PM
You guys got it right..You should inspect the entire unit atleast once a year. Take impeller out of housing look for any cracks or chunks missing. Also inspect caseing..if it has grooves and looks worn replace it as well as impeller. Use an old impeller on a new casing won't pump as well as a new impeller. They need to wear in together. I replaced mine first timer on my 454MAG no sweat 30 min. Installed a new housing and impeller $103.00 purcased from a local shop that carries Merc parts. You can call any Merc service center or better yet e-mail MAD Poodle Scott propably can get you the best price on Merc parts(Madpoodle@aol.com)
Salt water use will shorten the life as it will on any boat parts etc....

RickSE
05-21-2003, 06:33 PM
Thanks guys. Hard to believe mine has lasted so long, 8-years on the original impeller. I figure I'd better change it since my 8-year old OEM fuel pump just blew out.

I'm assuming it's a fairly easy R&R from the manual, split the case and the impeller is right there.

I can get the kit for cost from my dad's place, just need to get the right one.

RickR
05-21-2003, 07:28 PM
Rick
http://www.marinemechanic.com/site/page159.html

BTW:
There is a bolt under the trim tab
Do not lose small o-ring between the upper and lower unit (gear lube passage)
Do NOT overtighten water pump housing!

Rootsy
05-21-2003, 07:42 PM
One good thing about the GEN II floppy vane impeller is that unless you just plain run it totally dry for a good bit it won't come apart generally! UNLIKE the older style of the GEN I... the one in my GEN II lasted 5 years and finally got weak at WOT allowing my motor temp to creep up. This due to my lack of water supply from the old well which got her running dry and hot. The Gen II has a SS housing whereas the gen I uses a plastic housing with SS sleeve... much much much better and more robust design.

I agree with replacing it each season. better safe than sorry...if you worried about startup friction..smear a bit of soap on the inside of the housing. This will help lubricate the impeller as well as making it easier to assemble.

MOP
05-21-2003, 08:57 PM
2 more cents! The over tighten thing is important, 1/4 tun past seated. As you pull the housing apart look to see which way the blades are turned, many have put them back in the opposite direction. What usually happens is one or two will flip the right way, you get it back together only to have an overheat which sends many off looking for another cause. Use non hardening gasket compound or in fresh water proof grease on all bolts, run a tap in all holes and clean all threads. When you put it up use spline grease on the vertical shaft splines a light coating not to much. Look for a post on props!