1992 175hp Evinrude V6 cooling not same on both sides

[MBHeyworth]

On my motor there are two brass 3/8" plugs by the middle cylinders on each bank. These appear to be flushing points for the water jacket, and removing them with the garden hose connected to the flushing port does flow water. However, the port side has a stream of water (shooting out at a good pressure), and the starboard side has a trickle. Running the engine on the muffs results in the same type of flow - good on the port, trickle on the starboard.

Removing the thermostats so that the system is completely open makes no difference. I do sometimes get an overheat alarm at WOT, which may be caused by this cooling issue.

What are these ports for?
Shouldn't I see an equal amount of water from both of them?

 

[boobie]

Re: 1992 175hp Evinrude V6 cooling not same on both sides

They are for a water pressure gauge attachment. You may have some oxidation in the cyl head passages causing this and the occasional over heat. Have seen it before.

 

[MBHeyworth]

Re: 1992 175hp Evinrude V6 cooling not same on both sides

What's the best way to clean the passages?

 

[boobie]

Re: 1992 175hp Evinrude V6 cooling not same on both sides

Pull the head, soak it in muriatic acid for a hour and then flush real good.