Alpha One gen 1 water impeller "issues"

[cavscout35]

I recently purchased my first running boat about a year after I came home. It is a Marathon weekender 21'. So to the point, I researched the Alpha One 200hp GM 305 c.i.d. and pulled all info I could find on the outdrive. I took it out for maybe 4 hours and everything ran great (especially since the boat sat since 2007) brought it home to flush it, and no water was making it thru. I took it apart to find the impeller totally exploded. No worries, I have friends that have boats and repair knowledge about them, and I was an auto/diesel mechanic before I joined the Army, no big deal RIGHT??

I got the manual, I got the tools, and followed instructions to the letter, I am also on my 3rd pump kit in as many weeks. It got to the point where I would replace the appropriate parts in the appropriate manner to reassemble hook up the muffs crank the motor and look over the back just in time to see NO water flowing out shut it down pull the muffs to find smoke coming from my water intake. Rinse, repeat, to find a melted impeller.

I am not claiming to know anything more about these things than what is in the 3b manual (that I've read 8 times)

HELP!!!

 

[Don S]

Re: Alpha One gen 1 water impeller "issues"

I took it out for maybe 4 hours and everything ran great (especially since the boat sat since 2007) brought it home to flush it, and no water was making it thru. I took it apart to find the impeller totally exploded.

Were you on muffs? Or does your boat have a flushing system on the engine?

If there is no water going to the pump through muffs, it will take out a pump impeller in short order. You don't say what kind of kit you had, but a burned up impeller normally melts and distorts the pump housing and base as well.

 

[artificialreef]

Re: Alpha One gen 1 water impeller "issues"

I did the same thing you did. Bought a boat and thought its just another combustion engine, no problem. WRONG. You will find the marine mech world is a whole new learning curve for you. My motors had good compression when i bought them and got it home and got it running on muffs to watch the temp gauge on one go straight to 180 degrees and i shut her down. I changed the nonexistent impeller (and housing) but do not recall if the manual mentions doing a pressure test. I found that on this forum and luckily did it before i reinstalled the drive (it was leaking like the haitian navy)and I now run at a cool 160 degrees. Did you do a pressure test before putting it back on? There are directions on making your own tester with some hardware store parts on here. I have gained an incredible amount of respect for the professional gentlemen on here willing to help. Best of luck and be prepared to be humbled.

 

[artificialreef]

Re: Alpha One gen 1 water impeller "issues"

Forgot to mention, i also installed new pump bases as well and did the cool running motor just for good measure. Was told the motors hadnt run in 2 to 3 years. The good one was missing 1 or 2 fins so glad i did that one too.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

I took it out for maybe 4 hours and everything ran great (especially since the boat sat since 2007) brought it home to flush it, and no water was making it thru. I took it apart to find the impeller totally exploded.

Were you on muffs? Or does your boat have a flushing system on the engine?

If there is no water going to the pump through muffs, it will take out a pump impeller in short order. You don't say what kind of kit you had, but a burned up impeller normally melts and distorts the pump housing and base as well.

I started on the muffs, but then had to attach a flush kit directly to the motor

 

[Don S]

Re: Alpha One gen 1 water impeller "issues"

I started on the muffs, but then had to attach a flush kit directly to the motor

Not sure what you mean by that, what kind of flush kit?

If you ran it on the flusher on the engine and without muffs, that's why you keep loosing the impeller. No water to the impeller.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

I did the same thing you did. Bought a boat and thought its just another combustion engine, no problem. WRONG. You will find the marine mech world is a whole new learning curve for you. My motors had good compression when i bought them and got it home and got it running on muffs to watch the temp gauge on one go straight to 180 degrees and i shut her down. I changed the nonexistent impeller (and housing) but do not recall if the manual mentions doing a pressure test. I found that on this forum and luckily did it before i reinstalled the drive (it was leaking like the haitian navy)and I now run at a cool 160 degrees. Did you do a pressure test before putting it back on? There are directions on making your own tester with some hardware store parts on here. I have gained an incredible amount of respect for the professional gentlemen on here willing to help. Best of luck and be prepared to be humbled.

No I did not perform a pressure test, how does one go about that? Oh I'm humble pie, when it comes to these outdrives and counter rotation and all that, I know nothing, and freely admit it. All i know is whats in the manual and even then some of it is greek to me!!

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Not sure what you mean by that, what kind of flush kit?

If you ran it on the flusher on the engine and without muffs, that's why you keep loosing the impeller. No water to the impeller.

It is a flush kit from a car that I pulled the temp sender and hooked up right to the intake manifold and turned the hose on. I started the motor and let it run for maybe 10mins to flush the salt out

 

[Don S]

Re: Alpha One gen 1 water impeller "issues"

It is a flush kit from a car that I pulled the temp sender and hooked up right to the intake manifold and turned the hose on. I started the motor and let it run for maybe 10mins to flush the salt out

Don't do that, that is why you are burning up impellers. Just hook it up on muffs, the the water also cleans the salt out of the pump, and keeps the pump lubricated and cooled. Something that doesn't happen with your flush kit.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Oh no, sir!!! By that time I already had the lower unit off and on the bench. Sorry if i forgot to include that.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Don't do that, that is why you are burning up impellers. Just hook it up on muffs, the the water also cleans the salt out of the pump, and keeps the pump lubricated and cooled. Something that doesn't happen with your flush kit.

Oh no, sir!!! By that time I already had the lower unit off and on the bench. Sorry if i forgot to include that.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Now one of my dive buddies is saying that it may be the bearing beneath the water pump base. There is a little slop to it and I can visibly see the bearing race moving when I turn the shaft. How would this effect the waterpump when installed? I think I'm getting in a bit above my paygrade here.

 

[stonyloam]

Re: Alpha One gen 1 water impeller "issues"

no water was making it thru. I took it apart to find the impeller totally exploded.

Did you find ALL of the impeller pieces? If not, they could have gone into the cooling system and be blocking things, most likely in the thermostat housing.

 

[mnypitboat]

Re: Alpha One gen 1 water impeller "issues"

Since you are running the engine off a flush kit, without the outdrive attatched, and you still have a no flow situation, then you need to start there. Personally I would pull the engine water pump off(pretty easy, its just a Chevy small block). Pull your thermostat. Then try running a hose into the openings and see if you get water flow. If you are getting flow, then replace them both. If you are still suspect of other blockage, then pick up a cheapo water pump from a mid 80s Chevy Caprice. Leave your T-stat out and test water flow.


This is temporary though. You will need to get a regular marine water pump and a new t-stat, especially if you are in salt water, once you ahve established whether there is any other issues. This is a cheap test. Those pumps are only about $30.

You need to get the engine flowing before you attempt to tackle the outdrive. Once confirmed then you can move on to getting the outdrive to flow. If it sat as long as you say, and whoever had it oout last was in salt water and didnt flush it properly, you could have all sorts of issues, including manifolds etc.

 

[stonyloam]

Re: Alpha One gen 1 water impeller "issues"

Now one of my dive buddies is saying that it may be the bearing beneath the water pump base. There is a little slop to it and I can visibly see the bearing race moving when I turn the shaft. How would this effect the waterpump when installed? I think I'm getting in a bit above my paygrade here.

Just a guess here, but I would think the bearings would not cause a significant problem. The efficiency of the pump would depend on how well the pump veins contact the pump housing, and I suspect the bearing play would have little effect. IMHO if you replace the impeller and housing with OEM Mercruiser parts the pump should work OK.

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Did you find ALL of the impeller pieces? If not, they could have gone into the cooling system and be blocking things, most likely in the thermostat housing.

Yes I found all the pieces to it after some digging around thru the WHOLE powertrain, and I pulled the thermostat and put the housing back together sans thermostat, and stuffed a garden house in the upper part of the outdrive where the pipe goes from the water pump and turned on the hose (didnt start the motor at this point). I have great flow thruout at that point. so I would guess that the problem lies in the waterpump down?

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

Since you are running the engine off a flush kit, without the outdrive attatched, and you still have a no flow situation, then you need to start there. Personally I would pull the engine water pump off(pretty easy, its just a Chevy small block). Pull your thermostat. Then try running a hose into the openings and see if you get water flow. If you are getting flow, then replace them both. If you are still suspect of other blockage, then pick up a cheapo water pump from a mid 80s Chevy Caprice. Leave your T-stat out and test water flow.


This is temporary though. You will need to get a regular marine water pump and a new t-stat, especially if you are in salt water, once you ahve established whether there is any other issues. This is a cheap test. Those pumps are only about $30.

You need to get the engine flowing before you attempt to tackle the outdrive. Once confirmed then you can move on to getting the outdrive to flow. If it sat as long as you say, and whoever had it oout last was in salt water and didnt flush it properly, you could have all sorts of issues, including manifolds etc.

A curiosity redneck-ish question: do I really need to run a tstat in this motor. I understand fully the function of it in a car, and being in FL, usually ditch the tstat if any problem occurs. Can I get away with doing that in a boat motor?

 

[MarkSee]

Re: Alpha One gen 1 water impeller "issues"

....ditch the tstat ...Can I get away with doing that in a boat motor?

Not recommended. Boat motors need to run at certain temperatures for optimum performance, longevity and fuel economy.

Mark

 

[dubs283]

Re: Alpha One gen 1 water impeller "issues"

A curiosity redneck-ish question: do I really need to run a tstat in this motor. I understand fully the function of it in a car, and being in FL, usually ditch the tstat if any problem occurs. Can I get away with doing that in a boat motor?

if you understand the reason for a t-stat in an auto, then it should make sense in a boat engine - the reason is the same

you can do whatever you like, but the engine is designed to have a t-stat and not properly maintaining your boat engine will cost you in the long run

read below -vvvv

 

[cavscout35]

Re: Alpha One gen 1 water impeller "issues"

if you understand the reason for a t-stat in an auto, then it should make sense in a boat engine - the reason is the same

you can do whatever you like, but the engine is designed to have a t-stat and not properly maintaining your boat engine will cost you in the long run

read below -vvvv

Yes, sir understood. taking the day off of playing with it, I have some tools and a marine mech friend coming on tuesday. I will update, and appreciate all the help. This isn't over. "I have not yet begun to fight!!"