Filling engine with water first time

[biggrhammr]

I just replaced my engine (91 4.3 omc cobra), and wasn't thinking about filling it with water, til I got all done. Question is, I have an extra gasket for the therm housing, should I just remove it, to fill the engine, or is there some trick I don't know about? I know I can fill the water pump hose backwards, but there isn't any way to vent any air out.

Also, I found out in the midst of all this, that I have outdrive troubles, but I'd like to start the engine with the outdrive off. Has anyone ever just stuck water hose in the inlet pipe, with the outdrive off?

 

[kwikkar]

Re: Filling engine with water first time

Short answer yes you can.
I did this test yesterday after my u joints EXPLODED!!

I trimmed a hose nozel to fit in the pump drive hole an turned on the water. You may want to have someone back there just incase it comes out.

Also you dont need to fill the engine with water the impeller pump and your water pump will do that for you.
If you are changing your impeller when you reinstall pump some silicone grease on the rubber so your sure it doesnt tear when you crank it over dry.

 

[biggrhammr]

Re: Filling engine with water first time

Short answer yes you can.
I did this test yesterday after my u joints EXPLODED!!

I trimmed a hose nozel to fit in the pump drive hole an turned on the water. You may want to have someone back there just incase it comes out.

Also you dont need to fill the engine with water the impeller pump and your water pump will do that for you.
If you are changing your impeller when you reinstall pump some silicone grease on the rubber so your sure it doesnt tear when you crank it over dry.

Without the drive on, I won't have an impeller, and if there is any air trapped at the thermostat, it may open too late, or not at all. I've learned if I think I should do something, then I'd better, but I was hoping there was a trick or something. Auto engines will sometimes have a vent you can open, but this one doesn't.

 

[Howard Sterndrive]

Re: Filling engine with water first time

you don't just "fill the engine". Unless equipped with optional "closed cooling", a boat has an open system. Water is free to exit through the risers and exhaust.
So you don't just fill it, you must supply a continuous flow of water.
Couple the garden hose to the the t-stat hsg (the same place the drive impeller normally would), and turn the hose on full. Water will fill the system and flow out the exhaust - through the exhaust bellows. Lots of youtube clips showing people running boats on the trailer with or without a drive
No concerns about air.

 

[Bondo]

Re: Filling engine with water first time

Without the drive on, I won't have an impeller, and if there is any air trapped at the thermostat, it may open too late, or not at all. I've learned if I think I should do something, then I'd better, but I was hoping there was a trick or something. Auto engines will sometimes have a vent you can open, but this one doesn't.

Ayuh,... Yer boat motor is an open system, that fills, 'n vents itself, unlike yer car...

 

[biggrhammr]

Re: Filling engine with water first time

Ayuh,... Yer boat motor is an open system, that fills, 'n vents itself, unlike yer car...

I'm supposed to be taking a vacation from the boat, but I had to get back to this question. I realize it's an open system, but until the thermostat opens, the engine is going to be dry. If water can somehow get to the engine (by not going through the thermostat, then what's the point of it being there (not arguing, just asking)? Once it opens, then the constant flow of water should remove any air and "vent itself" like you said. Once I get back to it, my plan is to break the seal at the housing, and pour water in there anyway (as I could have done that in the time it took to come in and type the question, but, like I said, I was curious if the experienced boaters did it a different way. Maybe I'm being hard headed, but it's just not worth it to me to chance it.

 

[Scott Danforth]

Re: Filling engine with water first time

your thermostat has a bypass for block filling. its not a complete seal, its more like a mixing valve - water is always flowing from inlet thru impeller pump to thermostat housing thru block via circulating pump to manifolds, back to the water your boating in.

you are being hard headed