OMC 5.7 Overheating. HELP PLEASE

[Dan249]

1988 four winns horizon 210 is overheating in the lake.
i have replaced the impeller in the out drive, water pump, thermostat, back flushed the inlet.
When I hook up to the hose on land I do not overheat. Any ideas?

 

[Master mechanic]

Elbows clogged... flapper / shutter fell down the pipe. You have 2.

Heat exchanger clogged up.

You backwashed the the long hose coming in from the transom ?

 

[Dan249]

I back flushed the long hose yes.
I did not check the heat exchanger/oil cooler or the elbows.
Will try that today, thank you so much. I am new to the boat world.

 

[Master mechanic]

We all here will assist if need be.

 

[Dan249]

I took off the exhaust elbow and only the pin is in the pipe, flapper/seal is gone on one side. Haven't checked other side yet. Thanks for the advice and I will use this forum again maybe sooner than later.

 

[Master mechanic]

You got to fish it out of the pipe.