1987 Mercruiser 3.0 / Alpha One - No water to Engine

[g_speran]

Hello All,
So after about 1 year of sitting, I went to start the boat. The engine runs fine starts, idles etc. However after about 5-10 minutes of running, I noticed more then usual smoke. Therefore I Shut off the engine and have been waiting for it to cool down. I removed both the Engine Block Drain plug and The Exhaust Manifold plug and noticed no water was coming out of those. They were bone dry. I was originally using a garden hose connected to "water muffs" that I have always used and worked. The water is coming out the muffs without any issue
So I am trying to troubleshoot the issue now and isolate if it is a circulation issue within the engine or if it is the water pump in the outboard. Therefore my question is: Is there a way to bypass the outboard water pump and directly connect a garden hose to "some" hose on the engine to see if water will actually circulate when I try to start the engine again?

 

[Alumarine]

Yes, there is a 1/2" id hose that runs from the transom to near the thermostat housing.
It looks like a heater hose on a car.
You can connect to that.
You should remove the drive first. Throttle in forward and remove 6 nuts.

 

[mr 88]

or you can disconnect the same hose from the lower unit that goes to the water pump or thermo housing and put the muffs on. Fire up the engine and see what kind of flow your getting from the impeller in the out drive. That may be cooked . Your thermostat may also be stuck in the closed position. BTW you posted this in the Mercury forum and I boats has a Mercruiser forum, which is below this one.

 

[fishrdan]

When was the last time the raw water pump was rebuilt/replaced? That's where I would start as water has to go through this pump, before the engine will get any water.

marc c mentioned the hose that runs from the transom (gimble housing) to the thermostat housing (between valve cover and carb), remove it from the thermostat housing, Attach muffs, turn on house water, start the engine, then see if there is water pumping through the raw water pump. I'm guessing there won't be water flowing, or poor flow, and it's time to rebuild/replace the raw water pump.

It's possible to service the raw water pump by dropping the lower, but kind of a pain. Easiest to pull the whole drive, then split it on the work bench. If there are any vanes missing off the impeller, you'll have to find/remove them as they will block water flow.

 

[Bondo]

So I am trying to troubleshoot the issue now and isolate if it is a circulation issue within the engine or if it is the water pump in the outboard.

Ayuh,.... If the motor is dry after runnin' it, the impeller in the drive Ain't movin' water to the motor,....

The 1st place to look in any overheat situation, is the Raw Water Pump, 'n it's impeller,....

 

[kenny nunez]

Just as Bondo said the pump in the lower is the first place to inspect. While the pump is being replaced closely inspect the plastic cover that the copper tube connects to. If that cover is melted then it also has to be replaced. If it has to be replaced be careful not to break any of the 4 bolts that secure it, they are too far in the housing to drill out and the drive shaft housing will have to be replaced. Inspect the water passages for pieces of the pump impeller which could be in the thermostat housing. Back flush the water supply hose also. Good luck

 

[rickasbury]

maybe some little critter has built a nest up in the water line like a mud dauber or something- if it's been sitting, for sure the first place to look and sounds like time wise, should be replaced anyway!