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Question about engine driven raw water pump

1

1973browning

Contributing Member
"I couldn't help reading t

"I couldn't help reading the post about the 454 swap and saw chiefalen's post about the bravo engine driven raw water pump setup. Question: Can a raw water pump be installed using the same principle of pulling water through drive in an alpha one r/mr standard drive? And if the raw water pump was removed from alpha one, would the external engine driven pump be able to pull water through drive in order to cool the unit and exaust system? What are the pros and cons if even possible! Thanks, Tom"
 
"volvo also has the same setup

"volvo also has the same setup a external pump pulling water thru the drive and then thru the motor back out the prop.

Some guys have done this setup with omc's and i bet it may work with a pre alpha or any alpha, my question is why would you want to.

So the reply is yes it would work.

But also, why re-invent the wheel, and spend all kinds of money, cause it ain't cheap that external pump. Then you have to mount it exactly straight with a pulley lined up exactly straight, and have a pulley on the crank or re-invent a 1 piece belt to fit your motor.

You will also have a alternator to turn with a belt."
 
"[b]"And if the raw water

""And if the raw water pump was removed from alpha one,"

Ayuh,... If you pull the raw water pump from an Alpha drive, the drive will be Open to the water,+ quite literally, it'll fall apart...

Even if a motor mounted raw water pump is used for cooling,...
The raw water pump in the Alpha must still be maintained...."
 
"Bondo with all due respect, [

"Bondo with all due respect, Open to the water,+ quite literally, it'll fall apart has me a little perplexed, and I disagree. How will it Fall apart?

No doubt it would be more costly, adding hoses & a pump there are VP/PCM GM Engines that have engine driven pumps that can be used, the belt isn't a big deal, and if you remove the flow restriction plate from the impeller housing, impeller(and key) flow wont change, albeit I'd rather have the drive mounted pump versus the engine mounted as I think there's less chance of the engine mounted to run dry.

As long as water still is being pulled through the drive (and I think this is what you are referring to) AIDing in cooling the bearings (in addition to the oil) it's all good. I wouldn't convert to a separate pickup for that reason. IF I had a high HP engine, I'd add a pickup and engine mounted to maybe BOOST water supply, but.. I dont know if that would be needed."
 
"Even though this is not somet

"Even though this is not something that needs to be done,

It could be done very easily,

1. Get a motor mounted impeller set up and hoses off a Inboard ski motor.

2. make adapter with gaskets that would seal the lower water hole with a NPT barbed fitting and remove the upper plastic housing and modify with a barbed fitting and a flexable hose such as one as strong as the hose from the transom to the outdrive. Route it so it will not rub on the drive shaft.

Remove water pumkp base and remove all unecessary plastic and retain seals. Make a stainless steel plate to secure seals and remove the three studs and use smaller to tighten seals in place.

Done!

Here is my idea, Although it may not be practicle but I think it could be done easily.


375483.jpg
"
 
"Agree..... why re-invent the

"Agree..... why re-invent the wheel?
And Bondo makes a great point!

Three issues that come to mind for me:

1)The lower unit vertical shaft seal is integral with, and is just underneath, the Alpha pump body!


2) The Alpha drive uses the cooling water for upper gear unit cooling due to porting and since there is no "pump type" oil exchange between lower/upper as there is with all Volvo Pentas.
(volvo pumps cooler lower oil to the upper)

If you were to add the engine mounted raw water pump, the original Alpha pump must remain, and the water would then be diverted over-board.
It can also be "T" 'd into the thru-hull intake of the engine mounted sea water pump. (I've done this, and it works)

3) If you were to successfully circumvent the Alpha raw water pump (and create a safe oil seal), the NOW suction hose ID and the NOW suction porting, etc, of the Alpha drive is now too small and restrictive for the suction of the engine mounted sea water pump.
Hydraulic Dynamics of "suction" vs "pressure"!

IMO, in the long run you'd be better off to leave the Alpha pump and discharge the Alpha water over-board after it has provided cooling for the upper unit.

One other option may be a drive shower but cooling is acheived at planing speeds.
IOW's, where is your upper unit cooling when the drive shower does not yet have enough water force?

."
 
"Thanks men for the input, I g

"Thanks men for the input, I guess I was dreaming a little but just wondered if there was another way to cool drive and exaust. The pumps don't last to long in the alpha ones. Are you not supposed to change it every season? And it is kind of delicate in nature to overheat and melting. Anyway, I liked all of your ideas that you had and appreciate your input. I guess you are right too Ricardo about the suction vs. pressure issue because the engine mounted pump would probably create way to much suction and probably wipe out seals etc. Did not think of that at first! lol And kghost, thats pretty cool and yes unpractical. lol Also thanks chiefalen and Bondo. I did not know that the alpha one internal pump had to be maintained with external motor driven pump in place. Anyways, I was attempting to find a way to create a more reliable raw water cooling setup. And finally Brian, that is what I was referring too and I will respect your advice on the issue. I guess the moral of the story is to make sure your drive does not get blocked with seaweed, you change the water pump as required, and you don't run the engine on the boat in your driveway without the proper muffs and of course water flow out the back. lol thanks, Tom"
 
"Tom, You are correct.... the

"Tom, You are correct.... the Alpha raw water pump "impellers" are more prone to taking what is called a "set", and consequently do not survive as long as many other impellers do! Winter lay-up (with the impeller still in the pump) is what usually takes it's toll on these!
Just change it annually at the beginning of the season, not during winter lay-up!
(some do this as part of their winterizing procedure... I'd not advise this)

Re; the suction thing..... the suction of an engine mounted pump may not necessarily damage any of the Alpha pump hoses, but with enough restriction, may collapse a hose....... thus causing issues.
The porting is just simply too small, IMO.
BTW, if you were to do the engine mounted sea water pump, any suction hose should be the re-inforced type to prevent collapsing!

Just to be clear.... while using the engine mounted pump, the Alpha pump supply can be diverted once the water has exited the upper unit (actually the Gimbal Bell).
This means maintaining the Alpha pump, but not necessarily using it for engine cooling.

."
 
"[b]"Bondo with all due re

""Bondo with all due respect, Open to the water,+ quite literally, it'll fall apart has me a little perplexed, and I disagree. How will it Fall apart?"

Ayuh,.. As noted by Ricardo, without the pump base, the oil cavity is Open to the water,+ the vertical shaft won't be supported...
Then of course, the pump base is tied down by the pump cover, so just runnin' it as designed is Better in my book...

With all due respect,...
Feel free to jump my a$$ when necessary,...
I'm Well aware that I'm not always Right....

The Worst days of my life are the days I Don't make a Mistake....
'cause those are the days I musta not Done enough...
wink.gif
"
 
"[b]"Feel free to jump my

""Feel free to jump my a$$ when necessary,..."

Bondo, if your Avatar gives any indication of where your A$$ may be located, I think that we'd simply step on it.... and maybe accidentally! LOL

."
 
"Thanks Ricardo and Bondo, I u

"Thanks Ricardo and Bondo, I understand a little more than I did before thanks to you guys!
I guess I will have to run it as intended and keep it shall we say, simple! lol Unfortunately, nothing about boats is simple as I am finding out the hard way. lol Tom"
 
"Bondo, forgot about the base

"Bondo, forgot about the base sealing the lower case upper bearing and that someone might remove it not knowing, if I did it I would leave it just remove material from the metal separator to allow more flow, but now more thinking and as mentioned the engine mounted ones flow more water (bigger in/out ports and bigger impellers and more vanes).. hm.. Happy almost Spring to ALL !!!"
 
"I hear you Brian, and you can

"I hear you Brian, and you can't blame me for trying! lol It's dropping like a rock in the Philadelphia area as we speak. Sure would be nice to see some flowers and grass growing. Tom"
 
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