Overheating issue.

[cosmiccharlie1976]

I bought a 88 sea sprite with a 4.3L mercruiser, alpha 1 gen 1 outdrive.
Took it out and it seemed to overheat but the temp gauge wasn't working. So I did some research and decided to replace the thermostat, water temp sensor, and impeller.
Now I put the out drive into a tub filled with water just past the inlet holes and with the water hose that runs to the thermostat housing off, I start the engine and I have no water coming out. So I put ear muffs on it and start it and I get water coming out of the hose that connects to the thermostat housing. Not sure why the impeller isn't bringing water to the engine.
I'm not sure where to go from here.
Any help is greatly appreciated. Thanks.

 

[kenny nunez]

Whenever you run the drive in a tub you must have the flushout on the drive.
The pump will not be able to raise the water enough. Also you want to keep the exhaust bubbles away from the intake grill.

 

[Bondo]

Now I put the out drive into a tub filled with water just past the inlet holes and

Ayuh,..... Welcome Aboard,.... Impeller pumps are flooded entry pumps,.....

The water level needs to be atleast 2" above the a/v plate, or the pump is still dry,.....

 

[Scott Danforth]

I bought a 88 sea sprite with a 4.3L mercruiser, alpha 1 gen 1 outdrive.
Took it out and it seemed to overheat but the temp gauge wasn't working. So I did some research and decided to replace the thermostat, water temp sensor, and impeller.
Now I put the out drive into a tub filled with water just past the inlet holes and with the water hose that runs to the thermostat housing off, I start the engine and I have no water coming out. So I put ear muffs on it and start it and I get water coming out of the hose that connects to the thermostat housing. Not sure why the impeller isn't bringing water to the engine.
I'm not sure where to go from here.
Any help is greatly appreciated. Thanks.

Unless the whole drive is under water, the impeller is not flooded to prime

Impellers only push water, they do not suck up water...you toasted your impeller by trying to suck from a bucket


So replace your whole raw water pump and get a set of muffs

 

[cosmiccharlie1976]

Whenever you run the drive in a tub you must have the flushout on the drive.
The pump will not be able to raise the water enough. Also you want to keep the exhaust bubbles away from the intake grill.

I actually have the exhaust bellow disconnected so I don't have bubbles. But thanks for the feedback.

 

[cosmiccharlie1976]

I actually have the exhaust bellow disconnected so I don't have bubbles. But thanks for the feedback.

What is a flushout?

 

[cosmiccharlie1976]

Thanks for all the feedback. I will take it to the lake tomorrow and see if the issue is not having it in enough water.

 

[cosmiccharlie1976]

Ayuh,..... Welcome Aboard,.... Impeller pumps are flooded entry pumps,.....

The water level needs to be atleast 2" above the a/v plate, or the pump is still dry,.....

Thanks

 

[cosmiccharlie1976]

Put the boat in the water today and my new impeller was working great. Thanks again for the help.

 

[flashback]

Glad it worked out for you, just keep an eye on your temp, you didn't say anything about the size of your tub and could have injured your impeller.

 

[cosmiccharlie1976]

My tub was way too small. I now have water flow to the water pump. But still overheated so now I'm going to change the water pump. The boat did sit for 7 years before I bought it.

 

[Chris1956]

Clogged exhaust manifolds and risers can cause overheat. When were they last changed? In salt water they last 8-10 years. In fresh water a lot longer, but your motor is 34 years old.

 

[Chris1956]

Also, a lot of those motors had water temp gauges and oil pressure gauges, and a separate warning buzzer for overheat and no oil pressure. These two sensors share the horn.

If your turn the key on and do not start the engine, the no oil pressure buzzer will sound after a few seconds. That is the test for the system. The no oil pressure switch is shaped like a Peppermint patty, and is on the rear of the block. They do wear out.

The gauge oil pressure sensor is also on the block, but is more cylindrical and maybe 3" tall.

The thermostat housing will have two water temp sensors. On will go to the gauge and one to the warning system. If you ground the water temp sensors, you will hear the buzzer or the gauge will deflect (or should). I never had one go bad, but I expect they could.

 

[poconojoe]

Since you are still having overheat issues, are you sure you didn't wipe out the impeller by using a tub of water instead of muffs?
Before assuming it's the water pump, maybe confirm it's not the impeller.

Could also be a clog somewhere as others have stated.
Rubber parts from an old impeller can get lodged in the system causing a restriction.

Same with exhaust flappers (shutters). The rubber part can melt from an overheat and the metal parts can fall down into the exhaust and sometimes even as far as into the drive.
I found one in my lower drive section when I replaced the impeller. A past owner must have overheated the engine at some point and it wiped out the exhaust shutters.

 

[cosmiccharlie1976]

Ok, I replaced the water pump and still overheated. So I checked the flappers and they are totally gone, I found 2 of the 4 metal pcs and some melted rubber. So I already ordered new flappers. If I pull off the exhaust bellow again should I be able to get the missing pcs or can they go somewhere else?

 

[Bondo]

Ok, I replaced the water pump and still overheated. So I checked the flappers and they are totally gone, I found 2 of the 4 metal pcs and some melted rubber. So I already ordered new flappers. If I pull off the exhaust bellow again should I be able to get the missing pcs or can they go somewhere else?

Ayuh,.... Either down through the y-pipe, or up through the exhaust bellows,.....
I've found bits in the backside of a prop before,.....

 

[cosmiccharlie1976]

Ayuh,.... Either down through the y-pipe, or up through the exhaust bellows,.....
I've found bits in the backside of a prop before,.....

Thanks I will take the prop off too and make sure nothing is in there.

 

[cosmiccharlie1976]

Is it normal to see water in the exhaust manifold when the risers are off and looking down into the manifold?

 

[poconojoe]

Is it normal to see water in the exhaust manifold when the risers are off and looking down into the manifold?

I assume the boat is in the water. Correct?

As you know, water seeks it's level.

How high is the water level down there? Is it level with the waterline of the boat?

I believe water will enter through the drive and level itself in the lower part of the exhaust Y pipe.

That's my take, but we'll wait again for the experts to confirm.

 

[cosmiccharlie1976]

I assume the boat is in the water. Correct?

As you know, water seeks it's level.

How high is the water level down there? Is it level with the waterline of the boat?

I believe water will enter through the drive and level itself in the lower part of the exhaust Y pipe.

That's my take, but we'll wait again for the experts to confirm.

The boat was last running on earmuffs and the y pipe of coarse has no water in it there is a puddle inside the port side manifold. It is not complete full but as I look down into the manifold I see a pddle.