Farmall 140 Oil Pressure Loss

[diamondjfarmwv]

Good morning all.

My 1968 Farmall 140 is losing oil pressure. Upon start-up, the oil pressure needle centers in the dial reading 0 to 75 lbs. After running the tractor about 10 minutes, the pressure starts to bleed off. After about 20-25 minutes, the pressure needle drops to the first mark above 0 (which I assume is 20 lbs) and the radiator overflow tube just below the cap begins to drip (which I assume is the engine overheating). There is no erratic jumping of the needle, like when an oil pump in a vehicle is going bad--just a slow, steady, even drop in pressure. When I bought the tractor (my first) about two years back, the owner included a gallon of Valvoline 20w50 and a Case IH filter. I changed the oil and filter last summer, after some spring plowing and disc harrowing on 3 acres of compacted clay loam soil. I ran the tractor long and hard from early April through late May this year--probably 50+ hours. I purchased a new filter earlier this week at a local tractor/farm supply store, and the owner suggested using 30w non-detergent, which I did. Yesterday, while cutting weeds in the pasture with a sickle bar, I noticed that I got about 5 more minutes before oil pressure drop and overheating. I'm thinling a new oil pump. What do you fellers think?

 

[DJ54]

I'm thinking the engine overheating is making the oil thin, thus the pressure drop, even with the 30wt. Pull the grill, and check to see if there is chaff/dirt plugging the radiator fins. Check the tension on the water pump belt, it may be a tad loose. May even be the thermostat is sticking some. If those all check out OK, you may be needing to flush the radiator, maybe even have it rodded out. If someone has used well water, with lots of mineral in it to refill the radiator, it will leave deposits in the cores.

 

[diamondjfarmwv]

Good to hear from you again, friend! You and a few others helped me out last winter w/info about a pto-powered spreader and an old Oliver cultipacker. Will do on the radiator fin cleaning. Best to wash from engine side out or other way? Or both? Should flushing help? If so, top to bottom or reverse? And will regular car/truck coolant work? Will check the tension on the water pump belt first as this will be the easiest and quickest. I've had thermostats to stick in old vehicles I had back in the seventies. Thank you for responding and offerings suggestions for repair. Maybe I won't need to replace oil pump/screen after all.

 

[DJ54]

I guess I just now looked at your name..., LOL.. Hope the past advice helped...

Anything in the fins SHOULD be dry stuff. Shouldn't be any oil residue from anything up in front, such as an oil cooler, so if you have a low pressure blow gun, air might be best. And from the inside out first. I've even in the past had dirt collect from moist humid air, and dusty conditions. So you'll just have to look and see what you've got. And yes, I have washed some from the front, as those cores have 3-4 sets of tubes.

You'll have to look in the top of the radiator. Usually if there is mineral build-up, you'll notice some around the edges of the tubes. You should be able to remove the cap, and see good coolant flow once the thermostat opens, if there is even one in there. Maybe start it with the cap off, until it reaches op. temp, and have a look.

An after thought was maybe a collapsed hose, or internal hose failure partially blocking the flow, but there is a pretty short distance between connections, but it is possible I suppose.

Of all the C-113's & C-123 engines i have, even the ones that have been rebuilt, nothing has been done to the oil pumps, and all carry normal oil pressure.

I use the usual 50/50 mix, as straight anti-freeze will run warmer. It got down to -22º here last winter, and all made it through with no freezing problems.

 

[diamondjfarmwv]

Yep. I was the gut that you shared pics of your customized shop with; hope you have it finished and enjoying the new digs.

I've worked on the 140 some this morning. No dirt or other debris on either side of the radiator fins; I can actually see through. Fan belt seems to be tensioned properly. No buildup or residue around neck as I used premixed coolant when I drained and refilled last summer.

I did notice that it was difficult to turn then 4-blade fan by hand. Should the fan turn easily or may this be a sign of a bad water pump. I actually needed to wear gloves and put some elbow grease into it. when I loosened the worm-gear clamp on top, the hose connection nearest the radiator, coolant began streaming out. Is this normal. When I cranked the engine with the rad cap off, the coolant streamed out the overflow tube; when I cranked w/cap on, no overflow. I've drained about a gallon of coolant, and am ready to remove the upper hose to see whether a thermostat is there. Thanks for your help. Will let you know what I find.

This is what I found: the thermostat, lying sideways in the upper radiator inlet; and I found the wire clamp to hold the thermostat inside the rubber elbow hose nearest the inlet on the cylinder head. Guess it's come unlodged. (See photos.) Wonder what would cause this? Maybe the thermostat got stuck and the pressure forced it loose from its sear. Guess I should go ahead and replace the thermostat or could check it with a propane torch to see whether it opens. Appears that you were correct, that the problem was engine overheating, thinning oil, rather than oil pump.

 

[DJ54]

Could be a PO had the thermostat in upside down/backwards, and not letting it seat properly, and not letting the locking ring hold it properly either. With the water pump trying to pump at high RPM's, and it not held in real well, something had to give. You can always do the torch, or boil test and see if it opens. It does look like a newer thermostat. Never had the one out of the 240, or 656, but the one's on the Super C's, BN, A etc, has a brass housing.

I hope that cures your problem..!!

 

[diamondjfarmwv]

Ok. Thanks. Just got back from Steven's Tractor Supply w/a new thermostat. Pin toward radiator, as seated in the last photo, right? With the brass toward the engine, right? Thanks!

 

[DJ54]

Yep... Parts book calls for a 180º one.

 

[diamondjfarmwv]

Great. Thanks. Will double check the temp setting to make sure it opens at 180. Thanks, again, for helping me.

 

[cycle_gator]

Don't want to be negative, but if the problem is overheating, you have likely just fixed a symptom, not the illness. Coolant should have been easily flowing past the dis lodged thermostat. If anything the engine would run too cold, not too hot. Best to look at that water pump again or for signs of oil or exhaust gas in your coolant, like maybe a blown head gasket or a casting crack.