sea water in crank case - SailNet Community
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post #1 of 19 Old 02-10-2011 Thread Starter
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sea water in crank case

my first question to the forum. raw water getting into crank case. removed oil cooler today. doesnt appear to have any raw water flowing thru it. 2 oil hoses, three fresh water ports (two go to diff parts on the block, 3rd runs into the heat exchanger. when i close off one oil port and blow into other, no air escapes. when same thing with water ports, they appear to be all connected. in fact, heat exchanger conn has one of the block lines teed off from it. how can the oil cooler be my problem? pls, any help would be sincerely appreciated. i live aboard on a very small island with no mechanical help available. tks walt
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post #2 of 19 Old 02-10-2011
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First, check the seal on the RAW WATER pump -- especially if it is 'direct or shaft driven (not a belt driven pump). If the rear shaft seal is leaking on a 'direct or shaft driven' raw water pump, the 'usual' first symptom is water in the crankcase.
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post #3 of 19 Old 02-10-2011 Thread Starter
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tks rich. i chkd the sherwood for leaking seals (ie, water dripping from bottom of housing), but no leaks. the pump, however has not been serviced in a good while. is it poss my oil cooler in fact has no contact with sea water?
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post #4 of 19 Old 02-10-2011
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What is the make and model of you engine.

Generically. there are a few ways that raw water can get into an engine's crankcase
1. Leaking rear seal on a shaft driven raw water pump.
2. Pin hole in the exhaust manifold ... from the wet side to the gas side so that when the engine is shut down the pin hole delivers 'back' to the combustion chamber (through the pin hole, across an open exhaust valve and the water then drains past the 'gaps' at the 'ends' of the piston rings and then down into the crankcase.
3. Oil cooler leak
4. blown head gasket / cracked block on a raw water cooled engine.

Suggest you block the raw water circuit at near the end of the circuit ... ie.: just before the injection elbow, close the inlet valve and pressurize the raw cooling loop with low pressure AIR (not to exceed 15 psi) .... just listen for the 'sound' of where the air is 'leaking' into the crankcase.
If you cant find the leak this way then your probably going to have to remove the components in 1. 2. 3 above and pressure test them individually.

Last edited by RichH; 02-10-2011 at 03:14 PM.
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post #5 of 19 Old 02-10-2011
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How long does it tend to take for you to crank the engine over? i.e. how long do you have to hold down the start button for?

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post #6 of 19 Old 02-10-2011
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How do you know that it is SEA water, and not coolant?

Need to know make & model of engine to assist. Knowing the kind of boat wouldn't hurt either...
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post #7 of 19 Old 02-10-2011
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Quote:
Originally Posted by labatt View Post
How long does it tend to take for you to crank the engine over? i.e. how long do you have to hold down the start button for?
Very good point. Add this as #5 on the list.
#5. Back-flooding through the exhaust system due to failure to rapidly start the engine.
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post #8 of 19 Old 02-10-2011
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Quote:
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Very good point. Add this as #5 on the list.
#5. Back-flooding through the exhaust system due to failure to rapidly start the engine.
Yep... overcranking due to things like a partial hydraulic lock (or for a number of other reasons) can push water down into your crankcase. It comes back through the mixing elbow, into one or more cylinders and then gets compressed down into your crankcase. If it takes more than 4-5 seconds to start, this could be your issue. A couple of things to check for (if, and only if, hard starting occurs). First, after you crank the engine for 5-7 seconds and it doesn't start, STOP trying to crank it. Loosen up the dry exhaust output from your cylinders. If water comes out you've probably found the source of your water. Also, do a compression check between all of your cylinders. If the cylinder closest to the exhaust has lower compression than the rest then most likely you've been having back-flooding issues. Please keep in mind that water in the crankcase is a SYMPTOM of another problem - not the problem itself. You stop the water by tracking down the back flooding issue, which may be caused by things like a clogged vented loop, or a vented loop below the waterline, in your exhaust system.

I would highly recommend getting your oil tested. You can call Mack Boring up and ask them for a test kit. They will ship you a kit, you ship it back to them, and they will fax/mail you a breakdown of everything they find in the oil (what kind of water, coolant, metal, etc.). It's very handy for tracing down problems and they give you a decent description of what causes the levels of contaminants in the testing.

The other thing you can do to verify if it's actually water is the crackle test. Put a few drops of oil on a piece of tin foil and then hold a lighter under it. If it crackles/pops after a bit, there's water in it.

P.S. I agree with putting this as #5 UNLESS you have a hard starting issue, in which case I'd put this as #1 on the list.

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post #9 of 19 Old 02-11-2011
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Where are you finding the water? You can get water with no antifreeze in it from water of combustion. Diesel and gasoline are made up of carbon and hydrogen molecules. When the fuel burns, you get carbon dioxide and water vapor. This water vapor can condense and will show up on oil filler and rocker arm covers, or at least that is were it is usually spotted first. If you use the engine for short periods of time such as docking, it will not warm up enough to evaporate the water.

Here is a possible test method. Take a drop of seawater, put the probes from an ohmmeter on either side of the drop and note a reading. You might try moving the probes around to get a range of readings. Now take a drop of water from the oil and see if you can get about the same readings. It should be considerably less unless there is something in oil that can dissolve in water that conducts current that I am unaware of.

Last edited by LakeSuperiorGeezer; 02-11-2011 at 08:12 AM.
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post #10 of 19 Old 02-11-2011
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There could still be water of combustion that condenses in an engine even if it is ran for long periods if the thermostat is stuck open. Can you hold your hand on the engine after it has ran for a half hour for a few seconds? If so check thermostat.
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