My bukh runs to cold
I am now thinking the head and exhaust manifold may be some of thr cause by restricting the flow to the themostat
Maybe im wrong but 45 c is not right
For a diesel

Hi HG

From a Yanmar website

A salt water cooled engine operates at about 55degC / 130degF. This means it is quite easy to keep your hand on the cylinder block while the engine is running. If the temp goes over this the salt will precipitate out of the water and restrict the water galleries at an unacceptably fast rate. Because of this the alarm operates at 62degC / 144degF

Regards Don

Thanks for that Donk
Id very much like to obtain 55 c if i could

HG, How did you measure the engine temp?. I don't have a gauge only a light and alarm, but I would
like to know the temp. The alarm will tell me if it's too hot but not if it's too cold.

My DV20 runs at 55-60c as measured on VDO Black Vision Temp gauge with the VDO sender we have previously corresponded about. This temperature range is right at the bottom of the scale on the gauge. The scale is also compressed in this temperature range. The questions accuracy.
However, experience has taught me that when the temperature gets above 70c under load I should start worrying and look at the system.

Hi HG

I found a owners manual on the net for a dv24 and it says 50-70 so you are not to far from the low end

have you tried it under load (motoring) to see what it runs at and are you confident with the accuracy of your guage

Regards Don

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Donk107 said..
Hi HG

I found a owners manual on the net for a dv24 and it says 50-70 so you are not to far from the low end

have you tried it under load (motoring) to see what it runs at and are you confident with the accuracy of your gauge

Regards Don

That is under load Donk 3/4 throttle tied to the marina the 45 c is the max I got it went lower hovering around 40c

I had a lot of trouble trying to fit my pencil anode in . Initially I machined it down so it would fit in and recently I removed the throttle bracket so I could clean out the anode port so the standard size anode would fit which leads me to think it might be worth taking the head and exhaust manifold off and clean refurbish them ,guides, seals and a valve grind.. I think Ill put it on my to do list .
The trouble being a mechanic is you visualize every moving part i in your head when there running .
But on the bright side it wont need doing again for a while if I do it and its another inch or two that Ill know on the boat .
Jabberwok I also used a temp probe that I had as well as the VDO gauge and sender.

Is your thermostat working? If it was open all the time I would expect a lower temperature. Never run the engine without the thermostat in.
Second thoughts. You have put in a water pump up grade - this might be forcing more cold water through the block and cooling it. The other day I did have a problem with my system and I flushed it out with fresh water. I was interest to see the flow rate of water through the thermostat when it was shut. I used about 3 metres head of water and a good flow of cold water was going through the thermostat which I assumed would be shut.

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Jabberwock said..
Is your thermostat working? If it was open all the time I would expect a lower temperature. Never run the engine without the thermostat in.
Second thoughts. You have put in a water pump up grade - this might be forcing more cold water through the block and cooling it. The other day I did have a problem with my system and I flushed it out with fresh water. I was interest to see the flow rate of water through the thermostat when it was shut. I used about 3 metres head of water and a good flow of cold water was going through the thermostat which I assumed would be shut.

Thermostat is band new bought off T Norris .
I just think my old Bukh was only used mostly for very short runs and after finding that calcified restriction inside the old water pump on the out let side of the pump I really thing the motor needs a really good clean inside vinegar wont cut the mustard .
Maybe a short soak in hydrochloric acid might clean her out. but its must only be done for a very short period of time as the acid could damage the o ring on the cylinder liners
I would like to see the water cooling galleries inside the exhaust manifold.



this is before I cleaned it having not seen the internals of the exhaust manifold I have no idea what they look like

With a blockage in the block I would expect an increase in engine temperature.

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Jabberwock said..
With a blockage in the block I would expect an increase in engine temperature.

What my thoughts are that the cooling water from the water pump goes onto the engine block via the Y tubing behind the fly wheel



To the right of the alternator adjusting bracket the inlet tubing focuses on the rear cylinder to assit cooling it and there had two paths out of the engine
one is to the thermostat after it opens and if it had any restrictions getting to the thermostat it would then be directed out of the Y tube and to the top of the thermostat housing and out to the engine pipe . Which I believe is happening to my motor . Some of which I probably caused adding a higher flow water pump
off a Bukh DV 24.

To me I have two choices get more flow to the thermostat and or reduce the flow out of the Y tube which bypasses the thermostat

.Found a thread with this quote
Dont try to run raw/salt water cooled engines above 120...they'll scale up the water jackets

it also said live with it low temp I mean

Photo below cleaning with phosphoric acid
Some phosphoric acid is eating the salts out of the cooling system in the manifold. Most holes were completely clogged: advice get fresh water cooling with a heat exchanger, though the holes in the heat exchanger are smaller than those in the engine and they can also get clogged! Tough choice!