Low oil pressure alarm sounded on my 08' cat 420e .a true (mechanical) gage shows 55psi at idle hot/ 75 psi at full throttle hot.can this damage the engine and is it possible a bad oil filter would cause excessive pressure at the sending unit which is at the top of the filter base?
- Thread starter rrman61
- Start date
Texasmark1
Well-known Member
If it is full of crud and has no (internal) by pass valve or it too is clogged with crud. First thing to blow would be the filter since you have a gear drive oil pump and the pressurized oil has to go somewhere if the engine is rotating the pump shaft. Just like your hydraulic system. That's my take on it and I'm not a dozer guy but the mechanics are the same as tractors and all.
used red MN
Well-known Member
- Location
- Coon Rapids, MN
Does not sound like that is a real extreme range of pressure to me. What does Cat say is an acceptable range?
notjustair
Well-known Member
What is it normally supposed to run? That's a fine set of pressures for lots of engines.
Steve@Advance
Well-known Member
So, why did it go into low pressure alarm?
Where is the pressure relief valve? If it is accessible, might be worth taking it apart, make sure it is assembled properly, clean, correct spring, etc.
I don't think the relief valve is stuck shut. It appears to be working or the pressure would probably be even higher, especially when cold. Usually the first thing to happen is the filter will blow, but I have seen the pump drive twist off, depending on the design of the engine.
Don't see the filter being able to cause high pressure. Depending on the engine design, some need to have an anti-drain down valve. I have seen those fail, or had the wrong filter, that would cause low pressure on cold start up until the system could refill and pressure up. Most (if not all) filters have an internal bypass, as do some engines. This allows oil to bypass the filter if it were left beyond it's useful life, or brought to high RPM when cold.
Where is the pressure relief valve? If it is accessible, might be worth taking it apart, make sure it is assembled properly, clean, correct spring, etc.
I don't think the relief valve is stuck shut. It appears to be working or the pressure would probably be even higher, especially when cold. Usually the first thing to happen is the filter will blow, but I have seen the pump drive twist off, depending on the design of the engine.
Don't see the filter being able to cause high pressure. Depending on the engine design, some need to have an anti-drain down valve. I have seen those fail, or had the wrong filter, that would cause low pressure on cold start up until the system could refill and pressure up. Most (if not all) filters have an internal bypass, as do some engines. This allows oil to bypass the filter if it were left beyond it's useful life, or brought to high RPM when cold.
Case Nutty 1660
Well-known Member
a filter that could have come apart may cause high readings with the sender where you say,, easy thing to try is install a good quality filter and see if it changes things
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Morgan Flowers
Member
My vote is the oil pressure sending unit is bad- I've had it happen a few times on systems with automatic alarms/shutdowns.
Janicholson
Well-known Member
Take the wire off the sending unit but leave it close to the point it attaches. With it running the light should be on now. With it running ground the wire to the engine with a jumper. The light should go off. If it does not, the wire to the sending unit is broken and "open" the sending unit should be open when the engine is not running, and closed (probably above 10 psi) when running. The oil pressure could be near 100 psi with no engine damage. Farmalls run with the gauge pegged most of the time when rebuilt, about 80 psi is as high as the gauge goes. Jim
ptfarmer
Well-known Member
- Location
- San Antonio, Tx
I think the oil pressure relief valve in the oil pump is sticking some to where it can't run within its normal range.
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