Purchased Northern 29 (built 1981) equiped with Universal Atomic Diesel Model 5411, cools with raw fresh water that flows to wet muffler (no radiator). Previous owner stated firm belief that exhaust tossing a cupful of water every 30 seconds or so was part of boat design. Doubtful, last year an investigation revealed inner lining of exhaust hose had collapsed and water bypass was fully blocked. Both deficiencies repaired plus replaced water pump with new improved pump, I think from Moyer Marine. However, repair guy couldn't get water to go up and over the highly-placed anti-siphon tubing so by-passed it with a much lower tubing lacking anti-siphon. This year, I discover water in the oil. Replaced contaminated oil. Re-attached anti-siphon tubing to rule out water being drawn in from wet exhaust. Started engine, then immediately opened raw water valve and monitored engine temperature and water discharge. Didn’t observe water discharging but exhaust didn’t sound dry. Engine temperature rose above spec parameters (70C VS 66C max) after 10 minutes, so shut off engine. Checked oil- milky look dead giveaway for water and confirmed approximately half a quart of water had been added to the fresh oil by unknown route during the 10 minutes. Refilled engine with fresh oil to spec. I've ordered in a new head gasket and shim from Discount Marine Source with plan to have a person competent at such things to take off the head to inspect the gasket and do a replacement. Is it reasonable to think a failed head gasket could introduce a half quart of water in ten minutes? If not the head gasket, what would you suggest? I'm also perplexed why a new improved water pump doesn't efficiently get water up and over the original design anti-siphon tubing which has been confirmed to not be blocked.
Water in Engine Oil of Raw Water Cooled Universal Atomic Diesel 5411
- Thread starter Media again
- Start date
I have had problems with new raw water impellers for that engine that are minutely too narrow (diameter is OK and hub is driving the rubber blades ) .. This allows a lot of bypassing around the sides of the impeller and very low flow.. I don't see a heat exchanger ...? Is that engine raw water cooled? It looks like there is a hot water tank plumbed into the system.. Check that the water heater valves are open (some folks have block valves for winterizing) and the raw water is not being restricted. The water coughing out of the muffler is an indication that the cooling pump is working.. it should look like a half pint or so chugging out every 5-10 seconds at idle. A leaky head gasket is one of the causes of water in the oil but it would be good to troubleshoot the raw water cooling system from the inlet (including the thru-hull) all the way to the muffler, thermostat, flow through the water heater and mixing elbow water injection flow on the muffler included.
Before you remove the head you might want to check pressure in water jacket with engine running. I understand your engine is raw water cooled but similar engines with heat exchangers and coolant typically have radiator caps with, say, 7 psi ratings. Just thinking out loud here, your water jacket pressure should be similar or less. Maybe read pressure in temperature gauge port.
Status Update: Removed Head Gasket to find that it was intact but someone had applied a sealant on top of the gasket, suggestive that they were trying to solve a water problem. Sent engine to a diesel shop. Mechanic diagnoses that the water ingress to oil was occuring in the fuel injection unit. Replaced fuel injection unit. Mechanic determines the engine needs to be rebuilt. Rebuild is in progress. Then they will test the engine.
@Media again i just completed my rebuild. I hope yours runs smoothly. It will give your boat a new life.
I would love to know the path that cooling water can find it's way to the injection pump and then into the engine oil. If your mechanic has given you an explanation, please share.
Me too. I actually wrote a comment on this just after it was mentioned. Then decided that maybe it was not in my place to degrade the so called mechanic, so I deleted my post. However as now it has been mentioned, can you "Media again" get that explanation from your mechanic.