Alpha one drive questions.

[Chemdawg]

Hello everyone. Over the winter I rebuilt my Alpha one outdrive. All new seals, etc.... I pressure tested it and vacuum tested it, and it worked out great. I also replaced both bellows and shift cable, and bellows for that. I put the outdrive back on today, and did a reverse type flow test. I took the hose off the thermostat housing, and ran water through it to the outdrive.


So here's my questions. I had water coming out the shark fins, prop, and where the front bolt is by the shift linkage, there is a hole behind the bolt that water was coming out of.

Are these all normal places for water to go in or out?

 

[crazy charlie]

Re: Alpha one drive questions.

"Reverse type flow test" ?? Am I missing something?? Why didnt you put a set of muffs on it?? Charlie

 

[Bondo]

Re: Alpha one drive questions.

Hello everyone. Over the winter I rebuilt my Alpha one outdrive. All new seals, etc.... I pressure tested it and vacuum tested it, and it worked out great. I also replaced both bellows and shift cable, and bellows for that. I put the outdrive back on today, and did a reverse type flow test. I took the hose off the thermostat housing, and ran water through it to the outdrive.


So here's my questions. I had water coming out the shark fins, prop, and where the front bolt is by the shift linkage, there is a hole behind the bolt that water was coming out of.

Are these all normal places for water to go in or out?

Ayuh,.... Sounds 'bout right,....

 

[Pete104]

Re: Alpha one drive questions.

Your VACUUM test did NOT work out Great! An Alpha or Bravo, for that matter, will not hold vacuum!

The so-called reverse flow test should only allow water @ the pick up holes in the lower unit, where normally a person would attach his muffs. Water coming from in front of prop ain't good, that's all exhaust!

I bet you hooked up the hose and cranked water pressure, which eventually blew a gasket in the pump housing & that's why you are getting water everywhere it shouldn't be!

 

[Chemdawg]

Re: Alpha one drive questions.

Couple of things. This boat is a huge project. I'm working on interior, etc... So right now I have alot going on. The electrical is a work in progress. I am rebuilding the dash, so before I can fire the motor again, I have to finish the last of the wiring. I know it runs, because it was running and out on the lake before the end of the year. I tore all dash apart, before winterizing it. I'm hoping that by the end of the week, the dash will be ready to go, and the electrical will be finished. Hence why I didn't put on the muffs and fire it.

So... The last poster... I'm confused. If you apply air pressure to a sealed system, and it holds, then if you apply a vacuum, it should also hold. From everything I've read over the last two years, you are supposed to do both. Now Bondo said that it sounds about right where the water is coming out. I'm not sure, that's why I was asking. I believe it is correct for the water to come out of the prop. When I run the motor with the muffs on, I have water coming out of the prop. I've never had an issue with water mixing with the gear lube, and vice versa.

So honestly, I'm not sure what to believe right now.....

 

[achris]

Re: Alpha one drive questions.

Hello everyone. Over the winter I rebuilt my Alpha one outdrive. All new seals, etc.... I pressure tested it and vacuum tested it, and it worked out great. I also replaced both bellows and shift cable, and bellows for that. I put the outdrive back on today, and did a reverse type flow test. I took the hose off the thermostat housing, and ran water through it to the outdrive.


So here's my questions. I had water coming out the shark fins, prop, and where the front bolt is by the shift linkage, there is a hole behind the bolt that water was coming out of.

Are these all normal places for water to go in or out?

Hey Dawg, we need to clarify a few things.

Please define 'reverse water flow test'. Never heard of it.

When you say you took the hose off the thermostat housing, which hose? Also when you said you put water though it, through the hose or the thermostat housing?

'I had water coming out of the shark fins'... ???? What shark fins?

Chris.......

 

[achris]

Re: Alpha one drive questions.

Your VACUUM test did NOT work out Great! An Alpha or Bravo, for that matter, will not hold vacuum!...

Bollocks!!! When I reseal a drive I expect it to hold at least 12" of vacuum.... Even an old drive should hold at least 6".

Chris.....

 

[UncleWillie]

Re: Alpha one drive questions.

Pumping water into the T-Stat housing is not Back Flowing.
It will go out the Exhaust manifold the normal direction and eventually pour out the prop and the bypass port near the shift linkage. All Normal Forward flow.

My only concern would be pumping a lot of water through the exhaust manifolds without the engine running and half the exhaust valves in the open position. The manifold design should prevent you from water flooding the cylinders. But something to consider.

The oil seals are designed to keep the oil in when under pressure.
They will hold a moderate vacuum but nowhere near as much as they will pressure.
If your drive has a Drive Oil Monitor/Overflow bottle on the engine, the drive is vented to atmosphere and never sees any pressure or vacuum in normal operation. If it will hold 3 psi of pressure when dismounted, you are good.

Shark Fin = Drive Skeg under the prop???

 

[achris]

Re: Alpha one drive questions.

...Shark Fin = Drive Skeg under the prop???

Also a brand name of one of those stupid bits of plastic people bolt onto the anti-cavitation plate thinking it will make the boat better.... :facepalm:

...The oil seals are designed to keep the oil in when under pressure.
They will hold a moderate vacuum but nowhere near as much as they will pressure....

Which is I guess why the manufacturers use 2 of them mounted back-to-back.... One keeps the oil in, the other keeps the water out... You need to run a pressure test to check the ones that keep the oil in, and a vacuum test to check the seals that keep the water out...

Chris....

 

[Chemdawg]

Re: Alpha one drive questions.

Sorry for not clarifying very good. The shark fins are the ones on the lower outdrive. They are where I stick my rabbit ears on. The hose I'm talking about is the one that goes into the tstat housing that goes across the top of the engine through the transom to the outdrive.

I was thinking if I pushed low pressure water through there, I could see if the gasket/oring was leaking between the outdrive and bell housing, etc.....

I hope this helps. But honestly, I think my questions are being answered. I used a hand vacuum pump and it held at 10 in/hg when I tested the outdirve. I pumped it up to 15 psi of pressure and it held that too. I'm not talking about just for 5 min, I'm talking about for a full day. So I think the seals are doing their job.

Thanks for all the info.