Fresh water flushing of Mercrusier with alpha one drive

[Davidsgara]

Hi everyone I’m looking at setting up fresh water flushing for my Mercrusier that has an alpha one drive.

I have been looking at posts but have no definitive answers.

I have the boat moored in salt water so muffs will not work.


Can anyone please answer the following?

I’m concerned that with a Perko or valve system the water pressure will be forced against the water impeller in the alpha drive?

How does that work? Won’t you burn out the impeller?

Also how would it flush out the drive?

Do I run the engine while flushing?


Sorry about all the questions but I wanted to make sure what system has worked for you?

 

[alldodge]

I’m looking at setting up fresh water flushing for my Mercrusier that has an alpha one drive.



I have the boat moored in salt water

Assuming this is a raw water cooled motor and not a closed cooled one

Your not going to be able to flush the drive so long as the boat sits in the water.

If you want to flush the motor, this can be done but will not be able to run the motor without rigging some over the side water connection for the drive, and have a fresh connection for the motor.

Any flushing is helpful, but it is not going to be much. Could connect a fitting between drive and thermostat housing, then flush

 

[Davidsgara]

Thanks AllDodgeyes it’s raw water cooled.

i was thinking of setting up T valves just to flush the engine see attached.

Do you think this would work ?

 

[harringtondav]

I'm assuming you have a raw water cooled engine, not a heat exchanger. I've never done this, so this is my best guess.

Disconnect the raw water hose from the thermo hsg and use a splice barb to extend a section of hose overboard. Then clamp a short section of hose onto the thermo hsg and clamp a female hose connector to this short hose. Then connect a fresh water hose to the connector. Open the fresh water supply about 1/2 way and start the engine. The raw water pump will relieve itself overboard.

While you're at it you can check your raw water pump's output per the attachment. View attachment Pump output 1.pdf

 

[alldodge]

As harrintondav mentioned, you could install some Tee's and start the motor which would allow drive water over the side, and fresh in the motor. If it was me, I would just install one Tee fitting, connect a hose, then just turn the hose ON and let it run for a bit.

Starting up the motor will not flush the block much if any. The reason being, is the thermostat needs to heat up enough to open. If it does open it usually doesn't open much or for long in neutral

 

[Davidsgara]

Would the location for the Tee fitting be ok as per the picture I previously posted ?

Thanks

 

[harringtondav]

Starting up the motor will not flush the block much if any. The reason being, is the thermostat needs to heat up enough to open. If it does open it usually doesn't open much or for long in neutral

It takes a while on muffs. Like 15-20 min at idle before my Alpha II comes up to temp. But it eventually does.

 

[alldodge]

Would the location for the Tee fitting be ok as per the picture I previously posted ?

Thanks

Yes, or anywhere on the hose

It takes a while on muffs. Like 15-20 min at idle before my Alpha II comes up to temp. But it eventually does.

Agree, my point is as soon as the thermostat starts to open, the cold water will hit, and it closes back down, it will not stay open

 

[Scott Danforth]

You could get a super flush SC400 and simply hook the hose up. Motor does not need to run

My former boss had one on a 5.7 350 mag / Bravo set up (moored in salt water)

I used it on my 5.0/ alpha in the sea ray

 

[Bt Doctur]

Those things are nothing but snake oil

I have the boat moored in salt water so muffs will not work.

Not entirely correct, you can raise the drive ,install the muffs, lower the drive, turn the water on and run the motor

 

[Davidsgara]

Has anyone got any pictures of their set-up ?

 

[Bt Doctur]

Considering the standard hook up is to remove the block drains and plumb in 2 lines, cut the manifold hoses and install T`s
and then figure out how to drain everything to keep the block from freezing.. Not to mention corrosion , rust, sand and crub plugging up the fittings and not getting the flush action you were looking to have.
Just look at the clogged ports in the pic.

 

[Davidsgara]

Hi BT Doctur

so do you think I should just not worry about flushing with fresh water?

Its to difficult with the extended swim platform to try and get muffs on.
Thanks

 

[tpenfield]

Do you have a source of fresh water out at your mooring :noidea:

 

[Davidsgara]

Hi Tpenfield

Yes I have fresh water at the jetty the boat is moored at.

I just can’t access the leg to enable the muffs to be fitted as the leg is way under the swim platform.

Any advise would be appreciated.

Thanks

 

[Davidsgara]

This is what my local boat shop is saying about using a tee into the raw water system after the leg.

“Hi the system works same as Mercruiser option the fresh water backs up to the pump with engine at idle impeller just spins. When engine shut down some water will pass the impeller to backflush. “

What at do you think?

thanks

 

[achris]

Load of crap. Once the impeller is turning it WILL push salt water into the system. The only way to do it with the engine running is as has already been suggested, redirect the water from the drive pump overboard, and have freshwater going into the engine where the water from the drive pump would have been going...

Chris...

 

[Davidsgara]

Thanks Chris

what of if I just set up a tee connector and use the hose pressure to flush the engine?

will it actually flush the engine or just the risers and exhaust?

cheers

 

[Davidsgara]

What about this set-up?

 

[achris]

Dead-heading pumps is never a good idea. Just running the water through without the engine running will only flush the manifolds and elbows.

I feel you're looking for a 'simple' way to do what you want, but there isn't one... To completely flush the engine, block included, you're going to need to direct water from the pump overboard... There's no easy way around that...

Chris...