Jinma 254 overheating with oil spray

[Bob Rooks]

It's always been ran at low speed with lots of idle.......

Aha! Diesels really don't like that. Combustion temps and pressures are low, lube oil temp is low, increased liner wear, etc.

 

[Bob Rooks]

I am not sure that it is oil. It smears like oil and is a pain to wash off. The only symptom it will show when overheating is #1 spraying oil from exhaust. #2 engine noise gets louder ( no knocking tho ) #3 while running if you pull the radiator cap it will boil over. Radiator cap is in good shape to my knowledge. Cap has been replaced with the same psi as original.

#3 suggests that the thermostat is stuck open, which can also contribute to overheating because the coolant doesn't spend enough time in residence in the radiator to permit proper heat transfer, and gradually exceed the radiator's ability to cool.

 

[pmsmechanic]

To me it sure sounds like a blown head gasket or a cracked head. Do you have an infrared thermometer? They are cheap enough. It would be interesting to know the water temperature when the radiator is "boiling over". If the water temp is under 212F while "boiling over" I would tend to think a head gasket leak or a cracked head.

I saw a water pump once on an overheating 391 Ford that had all the water pump fins broken off. I've also seen the water pump impeller spinning on the shaft. That was an interesting one. No overheating at an idle. Just moving down the road. The plastic impeller gripped the shaft enough at an idle to cool the engine but at speed centrifugal force would pull the plastic impeller away form the shaft.

The sooty oil is most likely diesel slobber caused by not getting the motor good and warm for a period of time. My guess is that the engine needs to be worked hard for about 2 hours and the slobber would go away. I had the same trouble after one cold winter of pushing snow which really doesn't bring the motor up to operating temperature. The first time I rorotilled a garden in spring there was slobber running out of my exhaust pipe for a short period of time.

All the best in figuring this out!

 

[orezok]

However, remember that anti-freeze is more than just protection against freezing. It lowers the freeze point of water but it also raises the boiling point. Since a proper coolant mix is more dense than plain water it is able to absorb and carry more heat energy than plain water. This allows the engine to operate at higher temps than if using just water.

Sorry, but that is not correct. Please research before commenting.

The specific heat capacity of ethylene glycolbased water solutions is less than that of pure water; in a 50 percent solution, ethylene glycol's specific heat capacity compared with pure water is decreased at least 20 percent at 36 degrees and about 17 percent at 200 degrees. Propylene glycol, another common coolant, has an even lower specific heat. Assuming a 100-gpm (gallons/minute) coolant flow rate and an energy loss through the coolant system of 189.5 hp, the water temperature increase would be 10 degrees, the ethylene glycol water mix would gain 20 degrees, and propylene glycol would gain 33.3 degrees.
Compensating for the reduced heat capacity of coolant/water mixes would require circulating more fluid through the system. Assuming a fixed amount of circulating fluid and radiator capacity, running 100 percent water would be the most efficient coolant in terms of its ability to conduct heat with minimal temperature rise. In other words, of all common liquids, water requires the most heat energy to change its temperature.

 

[piper184]

The comment about raising the boiling point was from memory of reading the chart on a jug of anti-freeze, admittedly many years ago. I just did a quick search and the Wikipedia entry backs that up. However, I did not know about the resulting loss of specific heat capacity. At first impulse it would seem counter-intuitive that higher boiling goes with lower heat capacity, but I stand corrected on that point.
So it would seem that if you were watching the radiator with the cap off, water would boil over at a lower temp than a coolant mix, but a mix would need a faster flow rate and presumably a larger radiator to provide the same cooling to the engine at any given power output?
Where I live a 50:50 mix of EG and water is imperative if you don't want to be buying new parts each spring. The other end of the spectrum, not so much.
In any case it will be interesting to find out what the OP's cooling problem really is.

 

[Bob Rooks]

The problem with using straight water for coolant, aside from the obvious corrosion issues, is that it flashes on the liners in the areas where the piston rings flip (top and bottom of stroke) creating air pockets and eroding the liners, and not carrying heat away. Straight water is also subject to cavitation. Straight water simply is not "wet" or "slippery" enough. That's why there are coolant additives to use with straight water, such as Nalcool and it's counterparts. On the extreme side, there is Evans coolant, but it won't fix mechanical issues.

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