Alpha One Gen 2 Water Pump Kit 817275Q05

kbeckman

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I have a 1996 Alpha One Gen 2 Sterndrive, and when it was new it would cause the engine to overheat. After quite a bit of back and forth with Mercruiser, they determined that the plate under the impeller was warped, and allowing air to get sucked into the water flow. The fix was to seal the upper gasket with RTV, and it has been fine ever since then. I have faithfully replaced the impeller every few years, and just RTV'd it.

This year, I took it to an actual Merc dealer, and he researched my issue and said I needed a kit 817275Q05. This kit has the gaskets bonded to the plate, and looks like it might be a fix for me.

Does anyone have access to the bulletin about this?

Also, going forward, do I buy this $120 kit every time I need a water pump?

New Water Pump.JPG
 

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Bt Doctur

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I would say no. The biggest problem with these is the seal for the driveshaft. If it is even slightly overheated the plastic expands the base plate upward causing a suction leak and an overheat. All you need to do is make sure the SS plate does sit flush with the housing and is not being raised up from the driveshaft seal
Using permatex aviation sealant works well also..
 
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achris

More fish than mountain goat
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There are a few checks I'd be doing before making any conclusions about your problem. I'd do a volume check on the pump. I'd also put a section of clear hose in the water line coming from the drive. If it is sucking air, then that's how you'd determine it. One of the biggest issues I see is people not FOLLOWING THE MANUAL!!! when re-assembling the pump. You MUST use the alignment pins, and the small V-seal on the top of the housing needs to be set correctly WITH THE RIGHT TOOL! Either of these done wrong will allow air to be sucked in.

If you have an expanded drive shaft seal carrier, you'll feel it when you set the base plate down. One thing I do is to set the plate down without the gasket (can't do that anymore with the new plates with the bonded gaskets :facepalm:), if the carrier is damaged, then the plate won't sit down properly. Easy fix, replace the carrier. One of the full kits includes a carrier (I think it's the one you have). Once you have a new carrier in, and are using the pins and the seal height setting tool, them all you need replace each 3 or so years is the impeller and the gaskets. If the base plate needs replacing, then just replace along with the impeller... No need for a full kit every time... :)

Chris.........
 
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kbeckman

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There are a few checks I'd be doing before making any conclusions about your problem. I'd do a volume check on the pump. I'd also put a section of clear hose in the water line coming from the drive. If it is sucking air, then that's how you'd determine it.
Chris.........



This is a long story:

I bought this boat new, and babied it for the 1st 20 hours. I boat on Lake Michigan, and it's almost never calm. 1-2' waves are a nice day, but every once in a while I could open it up. What would happen is the RPM's would go up to 4200, and I could trim it up to 4400. Speed was around 48 MPH with a 17 pitch prop. After a couple of minutes, the RPM would start dropping. If I throttled back, I could then go WOT again for a few minutes. If I left the throttle wide open, the RPM's would drop until the engine quit.

The dealer couldn't really find anything wrong, and blamed it on incorrect timing, an intake leak, bad plugs, bad ignition, but nothing fixed the problem. Again, it was a rare day that I could really test it, so this went on all summer. Finally one of the times I was out, the engine quit, and dieseled. The restart was VERY hard, and it took quite a while to get the engine started again. It seemed like gas was boiling out of the carb. I took it back to the dealer, and it seemed like it was only running on 7 cylinders, as it took quite a bit to get it to plane, and top speed was way down. They could find nothing wrong. A week later I took the boat back again, and asked them to do a compression test, and low and behold, one cylinder was dead.

At this point they also figured out the water pump problem, and said the fix was to RTV the upper gasket on the impeller.

I thought that the engine was toast, and Mercruiser would replace it, but they did not. They even refused to replace it, and even told me to stop calling them, as they were not going to change their mind. I pointed out that the only reason the engine would lose RPM's is that it was overheating. The gauge never went above 190, and the over temp alarm never sounded, so in their mind it never overheated. The dead cylinder was a bent valve, and Mercruiser paid for a new valve job. I continued to push for an engine replacement, but got no where.

After that, my boat worked fine, but never acheived 48 MPH again. The best it would do was 42 - 43 with the 17 pitch prop, and my WOT RPMs dropped to under 4000. I had to re-prop to a 13 pitch to get my WOT RPM's back to 4400.

Since then I have always RTV'd the upper water pump gasket, and have run it WOT many, many times. I didn't really need the 48 MPH, so I gave up on it. It's been a nice reliable boat, and have lots of hours fishing Lake Michigan with it. The engine has idled for 18 years trolling for Lake Trout and Salmon. It have NEVER let me down on the water.

There is a 2nd half to this story, if you are interested.
 

achris

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I'd like to hear the rest of the story, mainly about this 'air leak'... and so I can get a full handle on the situation, what is the engine serial number? (So far all I know is that it's an 8 cylinder engine and it has an Alpha One Gen II drive, which does mean it's either a 305 or a 350, but I know nothing of the fuel or ignition systems, hence the request for serial number.)

Chris........
 

kbeckman

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kbeckman

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I'd like to hear the rest of the story, mainly about this 'air leak'... and so I can get a full handle on the situation, what is the engine serial number? (So far all I know is that it's an 8 cylinder engine and it has an Alpha One Gen II drive, which does mean it's either a 305 or a 350, but I know nothing of the fuel or ignition systems, hence the request for serial number.)

Chris........

Engine was 0F606xxx That's a 1995 5.7L, w/2BBL carb. Drive is an Alpha One Gen 2 with a 1.47:1 ratio.

Well, as I had previously posted, the boat has never let me down on the water. I went to do an oil change this fall, and found water in the oil. Compression was low on cylinder #5, and a teardown revealed a cracked head:

image_212263.jpg

This must have happened this fall, but I did not notice the oil was milky on the dipstick, and the level was not increasing. This was also before there was a freeze. I have always done my own winterizations, and follow the service manual by draining the block. I then fill up the block with -100 degree antifreeze, which isn't listed in the manual, but I wanted some corrosion protection.

The block seemed OK, cylinder #5 showed rust:

Old Engine #5 003 sml.JPG

Given the engines previous history back in 1996, I opted for a new long block, and already replaced it. I won't know until spring how well the new engine works. I'm hoping to put any cooling issue to rest as well. I will also not know for a while if I get my 48 MPH back. The engine I got was similar, but has a roller cam rather that the original flat tappet.
 
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kbeckman

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I found my original notes about the water pump that I wrote in 1996. This was the issue as explained to me by Mercruiser:

1) The plate that the impeller in the stern drive sits on, that has a housing around it that pumps water to the engine warps and allows air to enter.

2) The lower part of the stern drive had too much paint applied at the junction between the lower section of the stern drive and the upper section of the stern drive, right where the impeller assembly is. This creates to large of a crack between the two, that air can enter.

Here is the bulletin:

http://www.boatfix.com/merc/bullet/95/95_13.PDF

I will see if I can find some 1 1/2" clear hose to try this. I want to make sure my new engine is getting proper cooling.
 

Bt Doctur

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1 if the plate does not sit flush you have an air leak .It may not sit flush because the plastic is melted and pushing it upward.
2 pure bull dung
 

achris

More fish than mountain goat
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1 if the plate does not sit flush you have an air leak .It may not sit flush because the plastic is melted and pushing it upward.
2 pure bull dung

Agree, particularly with #2... Complete BS.
 

achris

More fish than mountain goat
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There is no plastic. This is an Alpha One Generation 2, so all stainless steel. I had occur exactly what is described in this Mercruiser Bulletin:

http://www.boatfix.com/merc/bullet/95/95_13.PDF

How else would you explain the symptom, bulletin and fix???

There is plastic. It's the seal carrier that sits below the pump face plate. There's also something quite important in that bulletin that a lot of people seem to be overlooking... "Install the water pump alignment pins".... If you don't use the pins, guess what... You suck air at high speed and your engine overheats!

Chris.......
 
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