5411 Temperature celebrate or worry?

[Gary_H]

My 5411 cranks first time, runs strong and sounds great, but I'm always worried about cooling. The PO had told me that the temp gage shows higher than it really is by 10 degrees or so. It shows 170. I'm not happy with estimating so I got out my laser thermometer and took some readings. I took a reading on the manifold next to the heat sensor and it read 145 degrees which is perfect. I took another reading on the thermostat housing where the other temperature sensor is and it was also 145 degrees. I was elated because this is where the manual says the temperature should be. But then I took a reading at the cylinder head next to the injector nozzles and it was 185-190. I'm reasoning here that the cylinder head is directly over the combustion chamber and therefore going to show hotter and that the temperatures taken where the factory chose to install the temperature sensors should be the temperature that I should be concerned with. At this point I don't know if I should be celebrating or worried. Any ideas?

 

[kloudie1]

You seem to be guessing correctly! You may be measuring on top in a spot where there is no water jacket or where you are close to the edge of one.. Most probably the temp is correct and you have no cooling problems.. There is a very small chance that you could have restricted flow in the cooling jacket in a small part of the cylinder head but from your measurements, I’d vote on the system being OK.. The only way to tell for sure would be to get a drawing showing the arrangement of the head’s passages and see if where you measured is on or off one.. Not Likely.. Note.. Of necessity, the injector fits into the cylinder head and there is a pretty good heat path through the solid metal around the hole where the injector goes into the head… Again.. 99% guess would be that you have a fine system.

 

[Don S/V ILLusion]

140 seems low from my recollection. You should check out what thermostat is presently in it. Used to have a boat with the 5411 and everyone knowledgeable about that beast told me it's better run hotter than colder.Consequently, I ran a 180 deg thermostat in it for years with good results.

I'd remove it and test it to see at what temp it opens.

 

[Gary_H]

Don, I was looking at the Unversal 5411 manual and it says the operating temperture should be between 135 and 150 degrees. I know that diesels run better at high temps but since this one is strickly raw water cooled I was worried about the seawater salt coming out of solution and crystalizing inside the cooling passages at higher temperatures. I have no doubts that the engine itself would like to run hotter. In the manual when you look at the other models 5416, 24,and 32 they all list an operating temp of 170 to 185 degrees, but they all have heat exchangers.

 

[higgs]

Sometimes too much information is a bad thing. Your engine has heat and oil pressure sensors that are probably working.