AC tractor sump: Cool Pool or French Fry Cooker? K thermocouple DIY

motoman

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  • / AC tractor sump: Cool Pool or French Fry Cooker? K thermocouple DIY
IMO the oil sloshing around in the air cooled engine pan should run from 212F to 250F, but can still lubricate at well above that, say out to 320F. The additives start disappearing at the high temps, and around 390F oil will vaporize and ignite (flash). The term "breakdown" is undefined, but may be viscosity reduction or loss of additives. This forum is full of oil talk, and may be everyone's favorite topic. So it's time to retreat into this thread which is " how hot is the oil?"

Pictured below is the $3 "K" thermocouple probe which can be inserted into the oil dipstick tube for temperature readings. This does not replace the dipstick. It uses the K wires to transmit the temp to your hand held digital thermometer. Cost: K wire $.25/ft and K connector $2.50. The K thermocouple is very accurate unlike the "typical" oil temp (fluid) sensor and gauge.
 

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motoman

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  • / AC tractor sump: Cool Pool or French Fry Cooker? K thermocouple DIY
AC tractor sump...K thermocouple DIY


HOW TO. Brake line is used for the metal probe (.200" OD). The length is determined by tractor dip stick length. The probe tip should sit in hot oil. If cable is used the jacket and filler materials must be stripped out and cut off so the insulated K wires can thread thru to the tip for termination. Then a ball end is made consisting of the intermingled K wires and the brake line tip. Remove the galvanized plating at the tip before heating-bad fumes. This unit was gas welded. The ball seals the probe so oil is kept out. Some means is required to keep the probe depth accurate ( plastic sleeve - cannot drop into sump!), and a strain relief should be added to stiffen and protect the K wires as they leave the tube.

Before weld the K wires should be pushed into the tube so no insulation is above tip
 

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motoman

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  • / AC tractor sump: Cool Pool or French Fry Cooker? K thermocouple DIY
AC tractor sump...K thermocouple DIY

IN USE Crankcase pressure stopped me from taking readings with the Intek 24 running-messy splatter. Readings are taken immediately after shutdown. The thermometer reading is not instantaneous like the head reading. Total insertion time is about one minute while readings increase about 5 degrees and then stabilize before dropping off.


WARNING and REFEREE. At high ambient under heavy load the pan oil temp can be your benchmark or warning. Get nervous at 280F like I do, and also see if 280F on an existing dashboard gauge is accurate. So far my Bedee reads 15F-20F higher than the K (at 220F). If 280F is real and climbing you should worry about your head(s) temp which is no doubt higher. High sump oil temp cannot help cool pistons (and indirectly the head).
 
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