I have a 28ft ODay with a universal atomic diesel 11 horse raw water cooled engine, that has been in salt water since it was built in 1982. What hull speed should I expect the boat to go without it starting to over heat. If I go 6 knots the temp starts climbing over 175. Does anyone know what hull speed this engine would push when it was brand new, and what the temp gauge should be at?
Diesel engine in 28 ft
- Thread starter O Happy Day
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Your engine shouldn't overheat regardless of the hull speed or RPM of the engine. The temp range in the manual for my universal M25 is 160 to 190 but the thermostat is 160 and if my cooling system is correct (not restricted with debris) it will hold rock steady at 160. You need to check your raw water system to see if you have enough flow, clean out your heat exchanger of salt buildup and zinc residue and any other debris in there. Then see if your injection nozzle connections to your exhaust pipe are restricted. Check the search function, there might be a manual for your engine posted here or an owners manual that should have the temperature specs. Also make sure your anti freeze reservoir is filled and you aren't losing coolant. Any loss suggests a leak in the heat exchanger or the hoses. You might also need to replace your raw water impeller if it is old and worn out. If your temperature rises above the thermostat setting with RPM's it means the cooling capacity of the raw water system is not taking away enough heat, so you either don't have enough water flow or the efficiency of the heat exchanger is compromised. Think of it like this, as the RPM increases so does the speed of the raw water pump and the fresh water pump so you are circulating coolant faster with RPM's and pumping more sea water through the heat exchanger. So the cooling should remain constant with RPM's just like in a car, as you go faster more air is passing through the radiator and more coolant is flowing through it and you don't expect to see the temperature rise as you go faster. If it is rising something is wrong and that usually means work and some dollars to fix it.
I have a universal M-12 diesel (11 hp) in my 1984 O28. With a clean bottom max RPM's are 3200, she moves along around 6.4 knots. I normally run her around 2600 which moves her along about 5.5 knots and she stays around 160 degrees.
I have an 83 O'Day with an M12 that is also raw water cooled, NO heat exchanger, radiator. I'm moored in down east Maine with rather cool water all 2 weeks of summer (!!). Beginning of season it sits at 100 degrees, never gets up to thermostat temp due to raw water temp. But round the end of July, barnacle build up in water intake 'screen' slows water flow and the engine actually gets up to thermostat temp, about 165 I think, opens up, temp drops, thermos closes, and continues to cycle as you would expect. Sometimes, round the end of August it'll start running hotter than I like (180+) so I go down and clean screen and we're back to 100. My 2 cents. No RPM gauge, and I don't try to run it up against the governor.
The 5411 is designed to run on the cool side compared to the larger engines in that family. But if it can maintain 155-160 at loaded speed, it should be just fine. I have seen them run at 165 without any brine problems. The 5411 is a pretty simple system with water coming from the sea cock/strainer to the mixing tee, to the pump, to the block-head-manifold/thermostst, then overboard.
My first check would be to make sure that I was getting good flow. If the flow is weak, check the the impeller. If the flow is ok and it is still climbing, check the thermostat. The thermostat should be should be directing water back to the mixing tee during cooler operating temps. If the thermostat is hanging up, the engine would act that way because it is send hot water back for another loop through the system.
It's hard to say without being on the boat with you. Has the system been jury rigged over the years? Are the cooling passages clean? Is corrosion taking over? No broken impeller pieces clogging the system? Strainer clean?
http://downeasteryachts.com/wp-cont...Model-30-operation-and-maintenance-manual.pdf
Diesel engines should be ruin at around 180 degrees, bit with sea water coming on salt water that will scale up the engine. That's why the 140 thermostat. That same engine in a tractor would be running 180.
If your impeller and flow are all good, you have some scale and need an acid flush.
I'm running a Universal 5411 that I got for "free" in my Columbia 36. Somewhat underpowered but it works. It will run at about 170 at cruise speed, but we're in fresh water so that's ok.
If your impeller and flow are all good, you have some scale and need an acid flush.
I'm running a Universal 5411 that I got for "free" in my Columbia 36. Somewhat underpowered but it works. It will run at about 170 at cruise speed, but we're in fresh water so that's ok.
Sorry I didn't realize it was raw water cooled without a heat exchanger, even though you clearly said so in your original post. You can check your thermostat by taking it out and putting it in a pan of water on the stove and heating the water to see if it opens Ok. A meat thermometer can give you the temperature of the water when it opens.