6BTA OVERHEATING

[BRUCE LAKE]

I have 2x 1995 6BTA engines in my 11mtr cat starboard engine suddenly started to overheat and is now constantly overheating I have checked all aftercooler heat exchanger ect all very clean and were cleaned 18 months ago
I have replaced raw water pump fresh water pump thermostat sender and guage . the engine quickly gets to 210 F in gear at idle runs 200f at idle out of gear coolant full and no leaks the head was new 2 years ago
ideas please thanks
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[Francis Valerio]

I agree with Dan as it can be some kind of obstruction that is preventing proper raw water flow thru your system.

You must confirm the strainer, the thru hull fitting, the actual gate valve or 1/4 turn valve for the raw water intake are FULLY CLEAR of any debris or obstruction and check the thru hull valve to make sure it operates properly and FULL OPENS… If you close every year when the boat is winterized it may not be opeing back up fully even tho the handle shows it

ALL of these must be checked. Years of bottom paint can narrow the openings and then cause debris to be more easily lodged into it.

[Dan]

Bruce,

Confirm external raw water pickups/internal strainers and delivery hose to the raw water pump are clear of debris or marine growth, depending on your environment marine growth can attach to the inside pickup/internal strainer or delivery hose.

Old impeller veins and other debris can also drop back into the delivery hose at rest and be drawn back up to the pump and block it when the engine is running.

Also confirm your raw water pickups haven’t been bottom painted multiple times and restricting water flow.

[Author]

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