Oil pressure issue with 7140 Magnum

LucasB · Dec 14, 2015

The other day, I thought it dry enough to try plowing. I went 1000 feet and the oil pressure light and the tractor shut off warning lights started to flash, then stopped. it would do this several times. Go about 30 seconds, those lights would momentarily flash then stop. Then another 30 seconds or so, do it again.

It ran just fine previously.

At low idle, 760 rpm no warning lights flashed. so I'm assuming the oil pump and rod bearing are alright. we're thinking a faulty relay or sensor. Any suggestions? also where is or are the oil pressure sending units on the engine?

Thanks- Luke

flying belgian · Dec 14, 2015

i AM GOING THROUGH SOMETHING SIMILAR ON MY McCormick MC 120(CaseIh maxum) I finally got mine narrowed down to the pulley being wore out on the alternator. So belts were slipping on alt pulley which
screwed up the "hertz" being produced. It seams that regulates the tach which also controls the electronic pto switch and the electronic forward, back shuttle. It's been a nightmare for the last 2
years. So first thing to note is tach reading correct all the time? Mine would not register on start up but then if I revved engine and backed it off to idle then tach would kick in. But then as
engine would warm up evidently belts would stretch and start slipping. Then belts would get glazed and slip all the time which led to the pulleys wearing and slip all the time. I am no expert but would
note if your tach is acting right and go from there.

Married2Allis · Dec 14, 2015

Maybe a piece of sludge temporarily clogging the sender or oil line if it's a mechanical gauge?

Steve@Advance · Dec 14, 2015

I'm going to guess it's a bad diaphragm in the sending unit. Engine starts, builds pressure, the leaking diaphragm lets pressure build on the inside of the sender housing, sender thinks "no pressure".

I would check it with a mechanical gauge at varying RPM.

Also check the oil level. If overfull could be contaminated with fuel.

Bob Bancroft · Dec 14, 2015

My 7240 Magnum idles a little slower than it's supposed to. When it's good and hot, if I let it idle down low, the oil pressure light, and warning buzzer will come on. It's never shut the tractor off. But it's usually just momentary anyhow.

I didn't like not knowing what was going on, so I screwed a good mechanical gauge into the side of the block. It's right there where you open the door and check the oil. Of course I can't stare at it while driving, and I don't need to, but I can check it any time, and I do when I'm getting on or off the tractor. It's got about 20 PSI at a hot idle. At speed it's well within the range.

I think there's only one sender, and I believe it's right there along the left side of the block.

Bob M · Dec 14, 2015

I would do as others suggest and stick a mechanical gage on temporarily. My first guess is a problem with the dash panel.

A friend has a 7210 where the gage panel sometimes works perfectly. Other times - and without warning - various warning lights/buzzer come on, all the gages light up in a "zebra pattern" (every other segment is lit), the gear indicator either blanks out or reads several gears off, etc. Then just as suddenly all will return to normal.

Clearly it's a problem with the dash panel display. But for now they simply live with it.

430WLPG · Dec 14, 2015

Early magnums had a low and high pressure
switch on either side of the recovery jug
and on the later ones they just have the
low Switch if you have the high switch you
can just plug it if it is bad

dhermesc · Dec 15, 2015

Don't you love tracking down issues like that? You start out trying to figure out a low oil pressure problem and end up tracking it to the belts.

Oil pressure issue with 7140 Magnum

LucasB

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flying belgian

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Married2Allis

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Steve@Advance

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Bob Bancroft

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Bob M

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430WLPG

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dhermesc

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