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TAMD 74 Water in oil

Mike Broshar

New member
I'm new to this forum. We purchased a 2006 Cruisers Yacht 455 with TAMD74 diesels with 135 hours this past fall. Closed cooling system with raw water and heat exchanger. When we took the boat out the first time, the starboard engine was smoking after running on plane. The next weekend, when we took the boat out, we were idling and the high temperature alarm sounded. We shut down the engine and went back to port. Checked the impeller on the water pump (which was okay). Added coolant (was low). The next morning, we went to the gas dock at idle speed to pump out. After pumping out, could not start starboard engine, and burned out starter. Had starter repaired. Our local mechanic had VP rep look at boat (local mechanic unfamiliar with diesel engines). Got engine running and ran (not under load) for 30 minutes. Mentioned vapor lock. Took boat out a week later and the engine overheated as soon as I started to go beyond idle. Some loss of coolant.

Had a local diesel mechanic look at it. Took an oil sample and found 10% water, but no coolant in the oil. Also traces of iron and phosphorous. Recommended removing the oil pan to see what's in there. The local mechanic works on trucks and not able to work on marine engines. I need to find a mechanic to look at the engine (in East Dubuque, IL). I think the closest VP Marine mechanic is in Kenosha, WI.

Any thoughts on how water would get in the oil?
 
If you have freshwater in oil, first place to look is OIL COOLER. If oil cooler element is compromised (cracked/rusted/delaminated or broken o-ring) it will allow mixing. However, oil pressure is higher than raw water pressure, that is most likely why you are only seeing 10% mixing. You should also have oil loss thru raw water side (and out thru exhaust), did you notice any of that (maybe smoking on plane you refer to)? How do your engines look on the outside, clean or rusty?
 
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As for overheating, you have to verify that there is good raw water flow at the hose that enters exhaust elbow, and that exhaust elbow itself is not corroded shut and is still able to flow the cooling water out of the system. The fact impeller is intact means nothing if there is a clog somewhere afterwards in the system
 
Thanks for the replies.

Have not experienced any oil loss. Will look at the oil cooler. The engines both look very good from the outside. No rust and very clean.
 
Overheat with coolant loss and oil contamination could indicate a head gasket failure. Is the coolant visible in the bilge after it leaks or is it 'disappearing'? Overheating at idle is also not that common due to the 'normal' cooling issues of heat exchanger, after cooler, impeller, exhaust elbow etc. Again this would be more common due to a head gasket type issue, or maybe a failed water pump on the coolant side, or maybe a stuck thermostat. A quick check for a head gasket failure is to bring the engine up to temp (thermostat open) and then look into the header tank for air bubbles. Make sure the tank is full as this makes spotting the bubbles easier. This is not an 'absolute' test, but is easy to do and if you see bubbles you will know that you need a leak down type test to check where the bubbles are coming from. You can check the thermostat by removing it for a test run. Whilst it is out you should also be able to see how strongly the water pump is circulating the coolant through the header tank etc.
 
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