Sea water in engine

[mchendo]

We have a 150 hp speedster done about 80 hrs , we have sea water in intake chamber causing hydro lock of engine. We have tested inter cooler all OK . we have then dried out motor , run on hard stand all OK out water. Back in water run OK , stopped for 15 min , motor hydro lock again. Any comments / help to resolve problem would be appreciated , boat is at remote island ( Cocos) and no dealer rep available. Thanks Hendo

 

[KK40384]

There's only 2 ways that can happen. You're either ingesting it through the intake or it back flows in through the exhaust. If it is a SC engine then you most likely cracked an intercooler. You said it tested ok, how did you test it to come to this conclusion? Also do you have any exhaust modifications?

 

[pwgsx]

I would say intercooler is cracked. The boat would have to be pretty far down in the water for the exhaust to backflow. maybe the manifold for the exhaust is cracked and its getting in somehow????

Did you change your oil on it? You cannot run the boat out of water on the stand that long as well.

 

[mchendo]

Hello , we have the inter cooler back in Australia and have had it retested again and it's OK . We have not done a pressure test on the exhaust manifold and this is one possibility, we have never run the engine on the hard for any length of time only less than a minute, however if the manifold is cracked we can understand how there is water in the cylinders but can't understand how water got into the inlet chamber as thru the 4 strokes the valves won't allow it. ??or have we got this wrong ? Any ideas. Thanks Hendo

 

[mchendo]

Oh I forgot to say yes we did change the oil after the first time the motor hydro locked , the motor was dryer out and run, Hendo

 

[KK40384]

Hello , we have the inter cooler back in Australia and have had it retested again and it's OK . We have not done a pressure test on the exhaust manifold and this is one possibility, we have never run the engine on the hard for any length of time only less than a minute, however if the manifold is cracked we can understand how there is water in the cylinders but can't understand how water got into the inlet chamber as thru the 4 strokes the valves won't allow it. ??or have we got this wrong ? Any ideas. Thanks Hendo

Well you can get back flow into the engine when it is stopped be ause you can't have all valves shut at the same time. At least one or more cyl will have valves open enough to allow water to seep in.


When you say you have the intercooler out and tested ok what do you mean by it? Are you testing this at operating temp or just ambient. That may make a difference. Do you have access to another intercooler? I'd try that as they are fairly inexpensive. I'm still putting my money on the bad intercooler.

 

[mchendo]

We tested the intercooler at Cocos Islands, put about 30PSI on it in a bucket water ,,,negative leaks. Its now back in West Australia where its been tested by dealer and OK. Now going back over thinking about the whole thing, the water seems to be leaking into the cylinders when the motor has been run and then shut down for 10 minutes or more. There is then high volume of water that's spurting out of the cylinders when we crank it with no plugs in. It seems to us now that it is more likely to be a cracked exhaust manifold. I think we will look at this angle and try get locals on island to do a pressure test on manifold.

 

[KK40384]

If you're getting water in the cylinders after it has been shut off then most likely a cracked exhaust manifold is your problem. If that's the case, those can be quite pricy here in the US. I can only imagine what they would cost over there.