Quick question on running engine outside of boat

[jimrockireland]

I set up my engine (1983 Mercruiser 305/5L MCM228 S/N 6275628) to run outside the boat. I ran water from a garden hose into the inlet hose on the underside port side of the engine (right where the power steering cooler is attached). I hooked up the fan belt to drive the water pump and started the engine. I let it run for about 1 minute and saw no water coming out of the exhaust manifold risers. I was afraid to run it longer because I could feel the risers getting hot. How long does it take to get enough water in the engine to see it coming out of the exhaust manifold risers?

 

[alldodge]

Re: Quick question on running engine outside of boat

If the block was empty of water it could take a bit longer but not much. Even if it takes a bit longer it will take a few more minutes at idle before it heats up enough to cause heat damage.

I hope your outdrive was off (probably the reason to connect water where you did), because if it wasn't and you have an alpha drive you will need to replace the impeller.
Connecting the hose where you did, just turn the water on without starting it and you should see some come out the exhaust. Make sure you have a fairly leak proff connection, city water should supply sufficient pressure.

 

[jimrockireland]

Re: Quick question on running engine outside of boat

The engine was empty of water since it has not been run for a year and the sterndrive is off. I was wondering if I didn't let it run long enough for the thermostat to open. I'm going to try and run it with the thermostat out.

 

[alldodge]

Re: Quick question on running engine outside of boat

The engine was empty of water since it has not been run for a year and the sterndrive is off. I was wondering if I didn't let it run long enough for the thermostat to open. I'm going to try and run it with the thermostat out.

The thermostat only controls the amount of water circulating through the block, it will not stop the water going out the exhaust. The block does need to fill back up before it comes out. Sounds like your good, just need a bit more time

 

[djmakko]

Re: Quick question on running engine outside of boat

Let water run without starting e engine it should come out! Once you see it out the exhaust start it up.

 

[jimrockireland]

Re: Quick question on running engine outside of boat

Thanks for the info on the thermostat. I did remove the thermostat housing to fill the engine up with about 5 qts. of water. I then replaced the housing -started the engine - and ran it for awhile with the hose going. I chickened out again after about 90 seconds. The risers and exhaust manifolds were getting too hot to touch. I'll try just running the hose with the engine off and see how that goes. I DID NOT have a very leak proof hose connection. I thought the water pump would suck the water in, but evidently it doesn't work that way. I'll work on making the hose connection less leaky, That sounds like my problem.

 

[alldodge]

Re: Quick question on running engine outside of boat

Thanks for the info on the thermostat. I did remove the thermostat housing to fill the engine up with about 5 qts. of water. I then replaced the housing -started the engine - and ran it for awhile with the hose going. I chickened out again after about 90 seconds. The risers and exhaust manifolds were getting too hot to touch. I'll try just running the hose with the engine off and see how that goes. I DID NOT have a very leak proof hose connection. I thought the water pump would suck the water in, but evidently it doesn't work that way. I'll work on making the hose connection less leaky, That sounds like my problem.

Your correct, the engine water pump just circulates the water, it does not develop any suction to pull the water up into it. After making a good connection their shouldn't be any problems.

 

[tpenfield]

Re: Quick question on running engine outside of boat

When I first fired up my Mercruiser outside the boat, I recall that it took a couple of minutes for the water to come out of the exhaust. The cooling system along with the exhaust manifolds does hold a fair amount of water, and If you do not have a tight connection to the garden hose, then it may not be getting enough water to make it through the engine and fill everything up.

I ran my engine with a somewhat loose fitting to the garden hose, since it had the sea water pump on the engine to draw in the water. If you are relying on the water pressure alone, then you should have a tight connection to the supply hose (garden hose)

 

[jimrockireland]

Re: Quick question on running engine outside of boat

Definitely a cool video. I tightened up my water inlet connection and it worked fine. Thanks for all the help and info.