Alpha One Outdrive Water Pump Impeller Problems

[americanmcss]

Hello to everyone.

I am new to boating (as an owner that is). My family purchased a very nice 1990 Bayliner Capri earlier this year and discovered that the outdrive would not take in water. Long story short, started tearing into the outdrive and found the impeller to be seized to the drive shaft. Both my brother and I are mechanically inclined and know alot of the general do's and don'ts, but we are hoping that there is some trick to getting the impeller off the shaft without doing any damage. We soaked it with a penetrating oil with no short term luck and are hoping that maybe a long term soak will help.

We have a gen one Mercruiser Alpha One serial number 0D326***. We scored a full water pump rebuild kit with the upper and lower housings with seals and gaskets.

Any advice or ideas would be greatly appreciated. Thanks

 

[BF]

Re: Alpha One Outdrive Water Pump Impeller Problems

Hi and welcome... I've changed the impeller in mine a couple times (same year as yours)... I didn't have any problem, and mine wasn't stuck, but if you've got the new impeller, key etc in hand, why can't you just sacrifice the old one and carefully cut it off with a dremel or something? Also, since the impeller is supposed to be turned by the driveshaft (via the key), the fact that it's seized onto the shaft would not in itself mean that the pump wouldn't pump water... unless the reason for it being stuck is that it has been melted/cooked/deformed... I'd change it for sure, but if it is stuck but the vanes otherwise look good, there could be some other problem causing the issue with the cooling system. While it's apart, you can stick a piece of hose onto the water line that normally attaches to the top of the water pump housing and use a garden hose to make sure you get good flow through the engine and out of the exhaust port.

Did the engine have a bad overheat before you found out about the lack of cooling water?

 

[americanmcss]

Re: Alpha One Outdrive Water Pump Impeller Problems

Sorry, I forgot to mention that the impeller was shot... When we found the boat, the P/O said that the boat was ready to go. Before we handed him the cash we checked to make sure that the outdrive would take water and it didnt... so we talked him down on the price quite a bit for our troubles. The engine runs really well and has not been messed with which we insisted on, but we wont know if there is a blown headgasket, of course, until we get water to the block. We have already prepaired ourselves (and our wallets) that an engine replacement is going to happen so no shock there.

We will difinately give the dremel thing a try. Probably safer than a die grinder. Thanks for your idea.

B.O.A.T (Bust Out Another Thousand)

 

[Don S]

Re: Alpha One Outdrive Water Pump Impeller Problems

When I find one stuck, I just use a sharp chisel between the vanes of the impeller and over the key and split the impeller.
Clean the shaft and install the new impeller and gaskets.

View attachment A1 Impeller replace.pdf

 

[americanmcss]

Re: Alpha One Outdrive Water Pump Impeller Problems

Well, we got it apart. Looks like the impeller had traveled north-south on the drive shaft a few times and created a lip that we couldn't see. We had to drive it down as far as we could and then filed the burs on the shaft. A little penetrating oil and it slipped right off.

We got everything put back together with little trouble and had the thing running and pumping water like crazy. We warmed up the engine until the thermostat opened and let it idle with no issues at all. Should hopefully have the boat in the water before the end of the month.

Thanks for all of your ideas and your willingness to help a couple of newbs.