Massey 135 Diesel Oil Pressure

UAFitter · Jun 11, 2015

Good morning,

I have a new to me 135 diesel, which I am generally pleased with. When started from cold, the tractor shows 60 psi oil pressure, but as I use it (running a mower) the oil pressure gradually drops to around 25 at speed. I have changed the oil (Rotella 15w40) and filter, but have not seen any change in this behavior. The filter is the element type, and has not been converted to spin-on, which I plan on doing. The tractor does not knock or have engine noise that I can hear, and does not smoke or use oil. It has good power and does not overheat or show any other problems. Is this normal, should I be concerned about it, and what can I do to remedy it if it's abnormal?

Thanks for reading-

Jerry/MT · Jun 11, 2015

You may have a sticking relief valve in the oil pump. I don"t know what the specs are for a Perkins but 25 psi hot doesn"t sound bad. Find out the oil pressure specs before you get too excited.

Phil Tibbetts · Jun 11, 2015

See what it does at idle when hot. If it drops to less than 10 or 15 I would drop the oil pan an look at the main and rod bearings, especially the mains.

Phil Tibbetts · Jun 11, 2015

Forgot to add, another thing I did on mine until I had time to tear down the motor was to add a can or 2 of STP.

Dean · Jun 12, 2015

Did you notice if the spring and support washer are in the filter canister when you changed the filter?

It is not uncommon for these parts to become missing over the years. Of course, if they are not in place you may as well leave the filter out.

If the engine has been running without an oil filter for (?) decades, premature engine wear will result.

Low oil pressure at operatinig temperture (only) is a symptom of worn bearings/pump, etc.

Try 20W50 oil to see if hot oil pressure improves.

Dean

Massey 135 Diesel Oil Pressure

UAFitter

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Jerry/MT

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Phil Tibbetts

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Phil Tibbetts

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Dean

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