Mercruiser 165 4 cylinder running hot

[1987chapperal]

Thanks for the help. I have a 1987 mercruiser 4 cylinder. It runs really well. I got it out to get ready for the summer hooked up to the garden hose and started it. There is no return water coming out of the exhaust ports. So I changed the impeller in the foot new gear oil and all. Started it again still no water coming out of the exhaust ports. So where in the world is the thermostat on the engine. I don't think it's opening. Three months ago it was just fine.

 

[Bt Doctur]

thermostat has nothing to do with water leaving the exaust.

 

[1987chapperal]

So what could be my problem. I was thinking that it was stuck closed not allowing water to flow.

 

[1987chapperal]

thermostat has nothing to do with water leaving the exaust.

So why would my water not be coming back out of the motor and letting it run hot? I was thinking that the thermostat was stuck closed not allowing it to recirculate

 

[Scott Danforth]

How are you testing? Muffs?

 

[1987chapperal]

How are you testing? Muffs?

Yes.

 

[nola mike]

Disconnect the hose entering the heat exchanger from the transom to confirm that you're getting flow from the lower unit. If so, pull the hose from the heat exchanger coming into the reservoir to make sure that you don't have an obstruction in the hx. Basically you need to 1) make sure that your impeller is pumping water, and 2) make sure you don't have an obstruction in the heat exchanger, reservoir, or possibly at the exhaust exit (trying to think if burned flappers could get stuck enough to block the relief ports and prop exit...)

 

[1987chapperal]

Ok I will try those things Tomorrow. How would I clean out the heat exchanger or the exhaust ports?

 

[Scott06]

Ok I will try those things Tomorrow. How would I clean out the heat exchanger or the exhaust ports?

There is always supposed to be some water that bypasses the thermostat to cool the exhaust system regardless of if the thermostat is open or not

Heat exchanger pop the ends off and jam a wire down the tubes, exhaust Id take off the discharge elbow and look in the water passages of the exhaust. The exhaust if run in salt water is a maintenace item and may need replacement.

Dont ket this engine get hot they are known for blowing head gaskets at a slight overheat...

 

[Bt Doctur]

before you go thru all that, remove the inlet hose, start motor, water should exit almost immediately from the hose end IF the pump replacement went ok.If the copper tube did not enter the guide tube no water will make it to the engine

 

[nola mike]

before you go thru all that, remove the inlet hose, start motor, water should exit almost immediately from the hose end IF the pump replacement went ok.If the copper tube did not enter the guide tube no water will make it to the engine

I'm guessing that's what happened. *Completely* obstructing the hx, reservoir, exhaust is possible but seems tough to do.

 

[Bt Doctur]

I`ve heard of people placing the guide tube on the copper tube and miss the pump top