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Thank you Karl, i wish there was something obvious.

We ran the engine with all its cooling system intact at about 1/4 throttle for 30+mins and we did not get over 45degrees,  After checking the tube stack was present and with the knowledge that what was exiting the header tank was coolant and not river water then fairly safe bet tube stack was intact.  

Head scratching time, for curiosity sake i removed the impeller and ran the engine for as long as i dared just to prove the engine would warm up with cooling, that it did, twas near 60 deg when engine stopped.

The calorifier is a large badly insulated stainless cylinder, the coolant seems to be flowing around this from start up not after a thermostat opens, this must be heat sinking a lot of heat from the engine but in my mind with enough running it should still come up to temp, Karl has told me that after a long run on the river the temp still stays at 50deg, so i am thinkinking that the raw water pump has a bit too much flow and although the engine has a thermostat (new one) im not convinced it actually does much to stop engine coolant flow.

plan of action, remove calorifer from system and see how the engine responds to not having it, if this does not prove to be whats keeping the temp down then look at restricting the raw water flow, to let enough through but not to much.

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i removed the impeller and ran the engine for as long as i dared just to prove the engine would warm up with cooling, that it did, twas near 60 deg when engine stopped.

Is that realy good for rubber exhaust hose Mark? I would worry about the inner wall collapsing in on itself with the heat, may not be noticable from the outside till water backs up to the engine.

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9 hours ago, LeoMagill said:

Is that realy good for rubber exhaust hose Mark? I would worry about the inner wall collapsing in on itself with the heat, may not be noticable from the outside till water backs up to the engine.

Not overly no, hence why It was not allowed to run long enough for the hose to warm. exhaust hose holds up a lot longer than you might think, but no not recommended to run it dry.

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Mark and I discussed this last week and I think he may be right with the calorifier. I assume you are getting warm water to the taps? 

The heat loss from an uninsulated calorifier can be high, but there are plenty of these kicking around in boats that don't have this problem. 

The next step has to be to remove the calorifier from the circuit and test without it. This is a case of simply checking things by a process of elimination for the moment. 

We run a Prima 50 in fleet and have no such problems. Actually more that it tends to run a bit warm. However, I also notice that it seems capable of running for quite a while with restricted raw water cooling (due to blockages) at lower revs without getting too hot. We have a stainless tank (adjacent to the engine) and this has a jacket, but it's nothing like a modern calorifier with foam insulation. No real issues with heat loss on the hot water though. 

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I just had a thought! unusual for me I know, but I think you may be onto something with the calorifier because I just remembered I had a very similar problem many years back, and it turned out one of the joints in the heating pipe in the calorifier had seporated so was drawing in cold water somehow, I can't remember the exact details but can remember cutting the old calorifier open and seeing the broken joint on the heater coil, it was an old stainless one I think, I know  I bought a new one and fitted it and the problem was cured,,

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18 hours ago, Mowjo said:

I just had a thought! unusual for me I know, but I think you may be onto something with the calorifier because I just remembered I had a very similar problem many years back, and it turned out one of the joints in the heating pipe in the calorifier had seporated so was drawing in cold water somehow, I can't remember the exact details but can remember cutting the old calorifier open and seeing the broken joint on the heater coil, it was an old stainless one I think, I know  I bought a new one and fitted it and the problem was cured,,

Possible, however this would dilute the antifreeze out of the engine and Karls family would have noticed some non too nice water coming out of there hot taps.

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1 hour ago, MBA Marine said:

Possible, however this would dilute the antifreeze out of the engine and Karls family would have noticed some non too nice water coming out of there hot taps.

Lol Noticed you said Karl's family you are correct in your thinking. i would have not noticed  .As  I would go as far as to say a blue lukewarm  shower would be satisfying :dance:naughty: 

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I have one or two suggestions, but having not seen this boat I may be barking up the wrong tree!

First, people have been talking about the Perkins Prima, but this is not the same engine as the MC42.

Second, I have in the back of my mind (from years ago) that this engine has a partial flow thermostat arrangement, which is why it is mounted within the housing of the circulating water pump.

Third, If the calorifier is "heat sinking" the engine, surely the thermostat would stay closed and prevent circulation, until the engine is up to temperature?

Fourth, When Mark was running the engine, was it in gear, doing some work, or was it in neutral?

On the plate of the thermostat is a small hole with a little rubber bobble, like a float valve, which allows water to pass in the opposite direction, when filling the engine with coolant. If this little bobble has broken off, it can allow enough water to pass, even through that small hole, that will prevent the engine from warming up.

When this thermostat was put back, was it the original, or a new one? Was it seated properly in its housing, or has it ended up cocked over to one side, under the gasket? This can easily happen, so may be worth another look at it.

It still remains a mystery why this engine has obviously over heated in the past.

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Never thought of that Mark! I never used anti freeze so I wouldn't have noticed, but I do remember the water tasted rank even when boiled, I pressume I'd have been drinking boiled river water for a while! I do know fitting the new calorifier fixed it,, as Karls calorifier sounds really old could it just be the heating coil furred up and restricting the flow, Karl may have anti freeze in the sysyem now but we don't know if the previous owners did, know how hard Norfolk water is, it might be a possibilty,,

 

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6 hours ago, Vaughan said:

I have one or two suggestions, but having not seen this boat I may be barking up the wrong tree!

First, people have been talking about the Perkins Prima, but this is not the same engine as the MC42.

Second, I have in the back of my mind (from years ago) that this engine has a partial flow thermostat arrangement, which is why it is mounted within the housing of the circulating water pump.

Third, If the calorifier is "heat sinking" the engine, surely the thermostat would stay closed and prevent circulation, until the engine is up to temperature?

Fourth, When Mark was running the engine, was it in gear, doing some work, or was it in neutral?

On the plate of the thermostat is a small hole with a little rubber bobble, like a float valve, which allows water to pass in the opposite direction, when filling the engine with coolant. If this little bobble has broken off, it can allow enough water to pass, even through that small hole, that will prevent the engine from warming up.

When this thermostat was put back, was it the original, or a new one? Was it seated properly in its housing, or has it ended up cocked over to one side, under the gasket? This can easily happen, so may be worth another look at it.

It still remains a mystery why this engine has obviously over heated in the past.

I did not go back over Karl's work as such, the thermostat that he replaced was with a new one and he test it worked before fitting, he told me the new one opened faster than the old one when dunked in hot water, Vaughan you have me thinking here, Karl has said that they removed the water circulation pump as that is where they 1st looked for the stat but it was not there, it's location is behind a square plate on the port side of engine towards the fwd end, is there 2 stats? or should there be? 

The fact that the coolant seems to circulate the calorifier from start up would be a cause that the engine is slow to warm up but after 4 plus hours of cruising you would expect even the biggest of calorifiers to come up to temperature unless the tank has such great heat loss that the engine cannot keep up with the demand,  now it has been said that the water from the taps is warmer in the summer, well the ambient temp of the tank would be on average 18ish degrees but this time of year closer to 5 degrees.

Engine not run under load on my test, the boat is moored on a floating pontoon and people do not take kindly to having their moorings stability tested!!  Now I have tested the engine temp with a infrared thermo tester we know the gauge is reading fairly true as the boat is well used we can say that under load the temp still stays low.

 

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  • 4 months later...

Quick update for any body following

 We un winterised her at the weekend

 We had sail down the river she never really got above 40 , which i already new , that it wouldn't.  As i have not done any thing yet :naughty:

So on the return journey we  turned  both seacocks to decrease the flow of water to the engine  checking the exhaust pipes too make sure they were not getting to hot . We noticed it did go above 40 c  and get to it quicker.  With the wind and the current  being strong on the return leg , i managed to increase the revs above what i normally would  travel at  . Which i don't usually do . The temp gauge went above the normally 40 and was heading for 55- 60 :dance ,We ran out of river :dance.   So a trip over Breydon  water in the summer is called for :bow.

 

Not pointing any fingers but with it being a EX hire fleet boat i just think it was probably working harder , then i have ever worked her . Hence lukewarm water has never been a issue.

Ill keep you posted.

 

 

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You will never cure this problem by closing the seacocks on the raw water inlet. You are just creating the same effect as a blocked weed filter!

The heat exchanger has to have a good flow of river water going through it. It is then up to the thermostat to control the temperature of the engine. The heat exchanger, of course, must be clean, clear and not furred up.

This has nothing to do with old use as a hire boat. The Perkins MC42 is a low revving, long reach engine which is well able to cope with a bit of river work.

I fear we cannot help you much with this unless you want someone to "get their hands" on this engine and have a good look at it.

 

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