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Need help with weird problem. 79 228 Mercruiser draws water at shutdown and Hydro locks

R

Robk11

New member
Have a pair of 1979 Mercruiser 228 GM 305's . Very randomly the Port motor will suck lake water into the motor when shut down. This causes the motor to hydro lock. I then have to pull the plugs and blow the water out. This motor has a split sea water cooling system . Coolant in the engine and sea water through a heat exchanger . The Starboard motor never does this and as I said it happens instantly and randomly . May be every twenty start and stop cycles. The fluid in the cylinders does not have any coolant in it. Any Ideas what can couse this?
 
Bt Doctur said:
is the motor dieseling at shutdown,idle speed at shutdown, engine temp at shutdown?
Click to expand...

No the motor runs like a clock, 140 Deg. F at shutdown . No dieseling or kick back I can see. This he second time the motor has drawn water into the cylinders. The first time the boat was lifted out of the water for bottom coating . The second time today . At the fuel dock. Idled in and shut down the motor. Went to start it and it's locked up with water only in the starboard bank. of plugs
 
The only test is a pressure test.
Use your imagination and close off all water out and pressurize water in of the entire assembly.

A smoke test can be done, if smoke comes out of carb/intake........leak.
 
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