Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

nearpar

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
143
If I were to remove the inlet 3/4" hose from the out drive at the thermostat housing and replace it with a garden hose from my tap and use this for the engine cooling without running the engine would I fill up my crank case with water ?

Probably would burn up the impeller as well I guess?
 

Silly Seville

Senior Chief Petty Officer
Joined
Dec 5, 2009
Messages
798
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

If I were to remove the inlet 3/4" hose from the out drive at the thermostat housing and replace it with a garden hose from my tap and use this for the engine cooling without running the engine would I fill up my crank case with water ?

Probably would burn up the impeller as well I guess?

No, you will not introduce water into the crankcase, and yes you will smoke an impeller if the engine is turning the drive without water available to the water pump. If the engine was not running...well then, it would be irrelevant.

What exactly are you trying to determine about your engine by performing this task. Give us the details and we can be more helpful.

BTW, I should edit my statement to read...if you have a failing exhaust manifold/riser or gasket, then yes, you will introduce water into the crankcase by way of the open valves in the head.

Again, we need details.

Cheers!
 

nearpar

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
143
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

Well to tell you the truth I already done this last week not thinking that I could burn up the water pump in the outdrive. I also had water gushing out the number two cylinder. The reson I done this was an easy way to test the engine without using the muffs. I got a gallon of water into the oil pan as well. However I have suspected a leak ( cracked block or exhaust manifold ) for sometime. I finally pulled the engine a couple of days ago and removed the exhaust manifold and I do not see any cracks. I will put the caps back on and fill it with acetone like I have seen here on the forum and try that.
 

Oshkosh1

Ensign
Joined
Jun 8, 2009
Messages
968
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

Well to tell you the truth I already done this last week not thinking that I could burn up the water pump in the outdrive. I also had water gushing out the number two cylinder. The reson I done this was an easy way to test the engine without using the muffs. I got a gallon of water into the oil pan as well. However I have suspected a leak ( cracked block or exhaust manifold ) for sometime. I finally pulled the engine a couple of days ago and removed the exhaust manifold and I do not see any cracks. I will put the caps back on and fill it with acetone like I have seen here on the forum and try that.

I, I, I don't even know what to say!...:facepalm:
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

How is that easier that putting on muffs? You have lots of things to fix now.
 

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

If you ran the water to the motor without running the engine it COULD have allowed the crankcase to fill if there was a defect in the manifold or the elbow or the gasket between them. It could also happen if there is a crack in the block.
You have stuff to check.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,478
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

Running the hose into the thermostat housing should not result in water in your engine assuming the exhaust exit is clear. As others have said, you have either cracks in your block or exhaust manifold.
 

nearpar

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
143
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

Ok probably will not do the Garden hose to the thermostat thing again, since I risk burning up the impeller. However I can't believe how easy it was to remove the engine. I had the the engine out in less than 60 minutes ( much easier that a car...lol ) I will be taking this apart and checking for cracks. Probably will not be going back in the boat anyway as I have a spare motor in very good condition to put back in. I will change the impeller on the drive over the winter and install everything this spring. I know I have to line everything back up again the gimble assembly looks great so no worries there. Any advice as far as re-installation is concerned ?

Thank you in advance.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,478
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

before you take it apart, do a pressure test on the cooling section.
 

nearpar

Petty Officer 2nd Class
Joined
Sep 4, 2010
Messages
143
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

I will do that thank you very much ...
 

mxcobra

Chief Petty Officer
Joined
Jun 27, 2011
Messages
526
Re: Hooking a graden hose directly to Mercruiser 120 water pump inlet from Drive

i ran mine with a garden hose just like that to check for leaks in the system- worked great for me...
 
Top