water in engine

[Bill]

I just spent the weekend working on my Universal M-25 (on a 1984 Catalina 30) to fix damage caused by water getting in to the engine. I had sailed for three days the weekend before and had no engine problems. I arrived at the boat this weekend, turned the key and heard "clunk" instead of the engine starting. Water had gotten into the cylinders. Everything seems to working fine now (after replacing the head gasket and changing the oil 3 times) but I am interested in how this might have happened. I have read about the probable causes and I think that somehow water siphoned back into the engine from the exhaust system. I would like to check any possible problems so that this won't happen again. Any suggestions?

 

[Dave]

Here's A Thought

If the anti siphon valve on your raw water intake failed. It's possible a siphon could have started though the raw water intake to the raw water pump, to the heat exchanger, to the mixing elbow, to the aqua lift muffler, then backup the engine exhaust into the cylinders.

 

[Jack Swords]

Water sucking back into engine

This is a potentially serious problem. I can think of two instances where water can be in the engine. When the engine cools it can suck seawater from the waterline that is injected into the exhaust line that cools the exhaust. There is an anti-siphon device on this line that opens up when the engine is not running and lets air in to prevent siphoning. Check it and perhaps clean it out. Another possibility is cranking the engine without it starting...the Aqualift muffler fills with water (water pumps are turning as you crank motor) and then the water goes up the exhaust to the engine. The engine must fire to expel the cooling water. If you crank the engine several times, shut off the raw water seacock, then reopen it when the engine is running. I assume the water is salt water and in that part of the circuit.

 

[Windwalker]

Quick fix to raw water siphon problem

Close your raw water through hull. Really a good idea anytime (but don't start without opening it). It will put an instant stop to any siphoning through that source until you get your anti siphoning valve figured out. Only other source is water backing through your exhaust hose (much less likeley). Good luck!