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CrazyCooter
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I agree with you.....I was planning on swapping 4.10s for my 37s, but I like it better as is. No notable difference in temps with either stock or 37s.
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houseofdiesel
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Oil temps should never be more than coolant temps if the cooling system is engineered properly. I run 37"s on all my SD with 3.31 - 3.73. Older trans with less gear sets have a harder time carrying loads. As the newer designs have multiple gearsets carrying the load, displacing the energy resistance, they can handle more load without getting hot and burning torque converters and gears. The torque provided by the diesels at a lower RPM also means you don't have to lower the gears at the same rate you would with a gasser.
This is an extreme example for a truck that I have built to carry max loads up any grade in the US regardless of ambient temps and never have to worry about my oil getting too hot. It's amazing cause it allows the cooling system to work as it was engineered.
ShadowsPapa
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The oil is exposed directly to the bottom side of the pistons and hot cylinder walls. The oil is also heated greatly by the sheering forces it's exposed to in the bearing areas. This increases the oil temperatures above what people accept as normal.
Oil will be more hot than the coolant as it comes off the bearings and the backsides of the pistons.
The oil should be cooled once it leaves those areas, but depending on where you take the oil temperature, it may be higher. It could hit 280-300 in small quantities for short periods.
According to one engineer -
An ideal oil sump temperature range is between 215*F and 250*F. If your sump temperature runs hotter than this range, you should add an oil cooler, or upgrade your oil cooler, if you already have one.
My oil temps have been above that of the cooling system - but not often. Even when towing the oil temps were close to that of the coolant.
UTRZRDOG
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I get what everyone is saying about the oil being too hot however, below are two different articles about oil and water temps. Looks to me that 240-250 oil temp is not all that uncommon and not such a bad thing. I am not saying anyone is right or wrong just pointing out a couple of articles that I have read over the last few days about oil temps.
As a general rule of thumb, after the car is warmed up, oil tends to be a few degrees warmer than the coolant (usually 10-15 degrees Fahrenheit). However, it takes much longer for oil to come up to temperature than coolant.
For a dual-purpose car, engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water's boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings.
As for ultimate power potential, the general consensus among most racers is that hot oil and cool water make more power in most engines. Cold engine oil causes excessive frictional drag on the bearings and cylinder walls. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees. Even on a short-duration, drag-only combo where oil is frequently changed, I would not want to routinely see under-200-degree oil temps.
A full-synthetic oil will withstand sump temperatures in excess of 300 degrees, and for hard-core professional racing, some oval-track race teams are experimenting with ultra-thin, specially formulated, race-only synthetics operating at 350 degrees or even higher.
Also remember that a high-end engine is built as a total combination. Piston-to-wall clearances, piston ring end-gaps, and bearing clearances are specifically tailored to match the engine oil's characteristics and intended operating temperature.
As a general rule of thumb, after the car is warmed up, oil tends to be a few degrees warmer than the coolant (usually 10-15 degrees Fahrenheit). However, it takes much longer for oil to come up to temperature than coolant.
For a dual-purpose car, engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water's boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings.
As for ultimate power potential, the general consensus among most racers is that hot oil and cool water make more power in most engines. Cold engine oil causes excessive frictional drag on the bearings and cylinder walls. A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees. Even on a short-duration, drag-only combo where oil is frequently changed, I would not want to routinely see under-200-degree oil temps.
A full-synthetic oil will withstand sump temperatures in excess of 300 degrees, and for hard-core professional racing, some oval-track race teams are experimenting with ultra-thin, specially formulated, race-only synthetics operating at 350 degrees or even higher.
Also remember that a high-end engine is built as a total combination. Piston-to-wall clearances, piston ring end-gaps, and bearing clearances are specifically tailored to match the engine oil's characteristics and intended operating temperature.
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CrazyCooter
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Every light vehicle and motorcycle I've driven with full gauges, the oil runs at least 10° warmer than the coolant when it's tied into the cooling system. My Peterbilt ran the oil around 160° unless it was under a big load, but it never reached coolant temp. Could be that it had a gal of oil per L of displacement, the manufacturer speced out an oversized cooler, or I just never ran it hard enough using it in RV towing service?
This Jeep just runs hotter in coolant and oil than any healthy vehicle I've ever driven.
This Jeep just runs hotter in coolant and oil than any healthy vehicle I've ever driven.
houseofdiesel
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How I'd want it. I'm running a cooler with 3x the volume of the Bulletproof Engineer one. I've never seen more than 212 oil temps fully loaded, on a grade, in the hottest SW US conditions on a 500 rwhp truck.
CerOf
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So, 214/186 at 18psi.How I'd want it. I'm running a cooler with 3x the volume of the Bulletproof Engineer one. I've never seen more than 212 oil temps fully loaded, on a grade, in the hottest SW US conditions on a 500 rwhp truck.
What’s max boost on that?
what’s the JT’s max boost?
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