Overheating issue.

[flashback]

Yes in my limited experience a manifold will hold water unless you pull the drain plug.

 

[poconojoe]

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.

So, the boat is out of the water and just a little residual water puddle in the bottom.
I've never had to look down there myself, but that seems to make sense.

 

[cosmiccharlie1976]

So my next step is replace the flappers and retrieve any obstructions in the exhaust.

 

[cosmiccharlie1976]

Thanks again for all the responses, I really appriate you guys.

 

[Chris1956]

There should not be any water in the exhaust passage of the manifold. It should stay in the outer water jacket (hence the name).

The trailing ends of the risers rust away first. This can let water dribble into the manifolds, thru holes or voids. Water in manifolds can easy get into engine, which can destroy the engine.

 

[Chris1956]

Flappers are not really important. They will stop water from backing up into the manifolds, if and only if you make a quick change from high speed to no speed. That maneuver is not one you should make for a variety of reasons.

Fix the manifolds/risers first.

 

[cosmiccharlie1976]

This is what my riser gaskets looked like when I took the risers off. Why would they make them restricted on 2 sides of the water jacket? I am thinking that I will replace them with gaskets that are not restricted.

 

[Chris1956]

Your motor should have water hoses to each manifold and each riser. There is a ball and spring device under some of the hoses that helps direct water flow to risers(if I remember correctly). The gaskets were chosen to assist this circulation system.

Use the gaskets recommended for your motor, and use MerCruiser ones. They are thick silver, and are a lot better than the green paper ones. You might lap the manifolds and riser mating surfaces with sandpaper on a piece of glass. It will help them seal better. Leaks at that gasket often let water into the engine.

 

[cosmiccharlie1976]

You are correct, the thermostat housing has a hos going to each manifold and riser and also has the ball and spring thing. So I will order the correct gaskets. Thanks.
So now I have established that their is nothing wrong with the manifolds and risers and no obstructions, good impeller, and new water pump. I still don't know what is causing the overheating, unless it was the flapper parts I pulled from the bottom of the y-pipe.
I will get back to it on Monday put the new flappers on and put the manifold and risers back on and try again.
I was trying to find a diagram of the water flow but wasn't finding anything that I thought matched my motor. I want to hook a garden hose up to the engine to verify I have flow throughout the motor.
I know where the water comes into the thermostat housing and goes to the water pump. But how do I verify flow threw the motor to the risers?
Thank you so much for the help. I don't know anybody that knows about boats. I've had a few boats but never had overheating problems.

 

[Chris1956]

Gee, Have you established that the manifolds are not clogged? Exactly how did you do that?

You can pull the hoses off the manifolds and risers and see the water flow, when motor is on flusher. What you cannot see is if water flows thru them.

Exhaust Flappers will not fix your issue.

 

[Bondo]

You are correct, the thermostat housing has a hos going to each manifold and riser and also has the ball and spring thing. So I will order the correct gaskets. Thanks.
So now I have established that their is nothing wrong with the manifolds and risers and no obstructions, good impeller, and new water pump. I still don't know what is causing the overheating, unless it was the flapper parts I pulled from the bottom of the y-pipe.
I will get back to it on Monday put the new flappers on and put the manifold and risers back on and try again.
I was trying to find a diagram of the water flow but wasn't finding anything that I thought matched my motor. I want to hook a garden hose up to the engine to verify I have flow throughout the motor.
I know where the water comes into the thermostat housing and goes to the water pump. But how do I verify flow threw the motor to the risers?
Thank you so much for the help. I don't know anybody that knows about boats. I've had a few boats but never had overheating problems.

Ayuh,...... Are the balls, Just touchin' the housin', closin' off the water,..??

They don't need much pressure, but the balls need to properly seat into the housin',....

Run without 'em, leads to overheatin' at idle,.....

 

[cosmiccharlie1976]

Gee, Have you established that the manifolds are not clogged? Exactly how did you do that?

You can pull the hoses off the manifolds and risers and see the water flow, when motor is on flusher. What you cannot see is if water flows thru them.

Exhaust Flappers will not fix your issue.

I checked the manifolds by removing them and putting water through them.

 

[cosmiccharlie1976]

Ayuh,...... Are the balls, Just touchin' the housin', closin' off the water,..??

They don't need much pressure, but the balls need to properly seat into the housin',....

Run without 'em, leads to overheatin' at idle,.....

The balls are just touching the housing and the springs feel good. I guess I don't know what good really is but they seem like they're not too tight.

 

[cosmiccharlie1976]

Maybe something was a small clog in the manifolds and I freed it up. I will put it back together on Monday and see how she runs. I will update on Monday.
Thanks

 

[cosmiccharlie1976]

Well, I put it back together and it is still overheating while hooked up to the ear muffs. And 1 manifold is hotter than the other. So I am taking off that manifold and trying to blow some air though it and make sure it clear.
I also might try and take out the thermostat to see if that is faulty. Any thoughts
I do have water coming out the exhaust behind the transom. When I feel the water hose that goes to the water pump it is pretty warm. I was expecting that hose to be cool.

 

[Chris1956]

Thermostats do fail. However, if one manifold is warmer than the other, I would expect that one to be clogged.

Did you ever figure out how old the manifolds and risers are? If original and used exclusively in freshwater, that can be near or at the end of their life. If saltwater, they last 8 years or so.

The raw water hose should be the temp of the water supply to the flusher.

 

[cosmiccharlie1976]

I have no idea how old the manifolds are. But there is no signs of rust in the exhaust section. Plus replacing the manifolds will cost more than I paid for the boat, which would be an acceptable expense if I new they were bad but they seem good.
I assume by flusher you mean water pump?

 

[cosmiccharlie1976]

Now I took off the manifold again and I have great water flow going through it and through the riser and no water seeping in the exhaust section. The thermostat opens as it should. Why am I still overheating?

 

[nola mike]

Put the boat in the water today and my new impeller was working great.

How did you verify this?

 

[cosmiccharlie1976]

How did you verify this?

Took off the intake hose that connects to the thermostat housing and had lots of water coming out.