Flushing Evinrude 9.9

driver0606

Seaman
Joined
Sep 9, 2015
Messages
56
Hello. It would seem an easy job to fit a hose connection to the thermostat housing on a 1988 Evinrude 9.9. Would it work as a fresh water flush without running the engine, please?
 

tphoyt

Master Chief Petty Officer
Joined
Jun 10, 2010
Messages
899
Unless the thermostat was open it wouldn’t get you anywhere.
 

driver0606

Seaman
Joined
Sep 9, 2015
Messages
56
Thank you for your replies.

The motor is on a tender and has to be flushed at the end of the day in port when its back sitting on the swim platform. Its not practical to run it in a bucket. There is no thermostat, but the motor runs at a reasonable temperature. The water passages seem reasonably clear inside but perhaps there is some water pressure/flow lost or part blockage at an imperfect seal at the top of the copper tube coming up from the (new) water pump. To replace this top seal will probably cost more than the motor is worth. My questions are -

1) Without a thermostat and not running, but vertical, can the motor be flushed through the thermostat housing without the water going into the wrong places and causing damage?

2) If the seal at the top of the copper tube where it goes into the engine block is leaking, can the leaking water cause any damaage?
 

tphoyt

Master Chief Petty Officer
Joined
Jun 10, 2010
Messages
899
I understand your situation now.
I don’t think you would get the same amount of result but I don’t think it would hurt anything either.
Honestly if the boat is in use daily I wouldn’t worry about that much.
A fresh water rinse is good before storage but if using daily the benefit is just not there in my opinion.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
^^^^agreed^^^By the time cooling water gets to the thermostat, it is on it's way back out to sea. So any fresh water you put in there is mostly just going to go back to sea, but supposedly some might be able to backflow through the system. But to do so, it has to get through the stationary water pump.

Your concern seems to be damage. Well, you are coming up with an untested theory, so probably no one can answer 100% for certain. My opinion is it won't "hurt" anything, but won't do much good either.

Any reason you can't run it with muffs on the water intake? Either way, any benefit will be a "feel good" for trying.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
That's a salted or fresh water 33 year oldie motor ? If flushing it frequently with a water hose thru the thermostat housing will end screwing the block's thermostat threads the sooner or latter along boring yourself very fast performing that awkward flushing procedure.

Check if on the exhaust's cover front there's a plated nut which is the flushing port, will need to buy a flushing adapter to flush the motor thru it. As there's no thermo the motor won't care at all if flushed ON or OFF.

How do you know or suspect the motor is losing water thru the upper water pick up tube's grommet ? if losing water will also lose top water pressure coming from the water pump.

Happy Boating
 

driver0606

Seaman
Joined
Sep 9, 2015
Messages
56
Thanks guys. I will give up on the idea of flushing thru the thermostat housing, and running on muffs makes too much noise in the marina. Being on a tender its used very little and I do flush in a bucket before the winter. I think the grommet may be damaged because I hear they can be fitted badly and fold over, partially blocking the flow. Sometimes the engine has seemed completely blocked and I can clear it by wriggling a long piece of wire up the long tube from the pump end. I have had the bottom unit and the cylinder head off and they are relatively clear of deposits. Which is the exhaust's cover front, please, and will my 1988 model have the plated nut flushing port?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Check if said motor has a dedicated flushing port, probably that model year lacks one ? The pic corresponds to a 96 year oldie motor..

Flushing Adapter.JPG

To repair the WP water pick up only need to order the upper grommet water tube part code 0330426 and a lower powerhead gasket part code 0325721, both for $ 19.00.

WP Water Pipe.JPG

Had same issue due to having an errotion on that precise corner shown, applying Mega Gray Silicone stopped the WP water pressure loss out...

Happy Boating
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
On the matter of exhaust noise using muffs, you might put the motor in running position with the muffs and hose attached. Check periodically to make sure they remain in place, as you probably would anyway. Monitor operating temp.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
On the matter of exhaust noise using muffs, you might put the motor in running position with the muffs and hose attached.
Can't possibly attenuate a high motor's noise when on muffs, it's a natural screamer, can cover the prop's exhaust with a rag previously dampened in water to lessen the noise but not cancel it..

Happy Boating
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
If flushing is a huge chore then just buy another motor every 5 years.----No effort involved.----Many folks use that approach.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Can't possibly attenuate a high motor's noise when on muffs, it's a natural screamer, can cover the prop's exhaust with a rag previously dampened in water to lessen the noise but not cancel it..

Happy Boating
Don't want to block exhaust outlet. Run it lowered in the water (at the dock), with the flusher and hose operating under water. Exhaust operates normally.

I've done this with an inboard, using a toilet plunger fitted with a hose inlet -- shallow brackish slip, with the plunger handle held in the sand. Obviously not for noise, but to flush the engine without pulling the boat. Seasonal thing. (wintered the boat over in it's slip, using and engine compartment heater).
 

driver0606

Seaman
Joined
Sep 9, 2015
Messages
56
Thanks guys, for all the input. I don't have a flushing port, so guess I will have to get the bucket out again. And hand out earplugs and/or beer!
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Water needs to be well above the pump. As a rule of thumb, you might dunk it about half way up the shaft. If you are getting exhaust noise with your bucket, chances are you do not have enough water.
 
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