My 2007 Mahindra 6500 4WD has 340 hours and I was just out bush hogging with it holding the throttle against the governor at 2500 RPM when I looked down to see the oil light on! I immediately lowered the RPM, and the light went off. Slowed down to 2K RPM and the light stayed off. Went directly to my shop and changed oil and filter, altho not due for another 100 hours. Went back out and it was staying off, except for an occasional flicker on acceleration. Checked wiring to the sending unit, all seems fine. I suspect the sending unit. My question is- can anyone tell me if I can get a sending unit at an auto parts locally to fit? All it needs is to be the correct thread, right? Most lights are supposed to turn on at about the same pressure, I'm guessing. So why not use any unit that has the correct threads? All I have seen use just one wire grounding thru the sending unit. Thanks, Doug
Oil & Fuel Oil pressure light coming on
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Gale Hawkins
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The only real way to know what is going on is to connect a physical oil pressure gauge at the point the sending unit goes into the engine.
What RPM equals 540 PTO RPM on your tractor?
What RPM equals 540 PTO RPM on your tractor?
Another, and much easier way to know what's going on is to replace the oil pressure switch with a new one. That's why I'm asking if there is any reason not to use any switch from a local auto parts house with the correct threads that is normally closed. Also cheaper and faster.
DavesTractor
Elite Member
That is about a $15 part at your Mahindra dealer if he has it in stock. Plus some freight if he has to order it special and it can't ride in on a stock order. You can mess with just finding one that matches the threads, but keep in mind that screwing a BPT into a NPT hole, or vice versa will work but not quite right and may damage the threads. And different switches come on at different pressures. If I were working on some odd ball tractor for which parts were not available, I would for sure just match up an automotive switch and give it a go (after checking with a manual gauge). But it isn't like this Mahindra part is hard to get or expensive. Maybe just not as convenient as a local parts store, and that I understand.
Gale Hawkins gave good advice in my opinion as far as knowing for sure what is going on by temporarily installing a manual pressure gauge.
Gale Hawkins gave good advice in my opinion as far as knowing for sure what is going on by temporarily installing a manual pressure gauge.
sd455dan
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i agree with checking the pressure with a mechanical gauge,
The average electrical (dummy) light sending unit , only triggers at low pressure usually around 7 psi. if the Mahindra unit works like this why would it be turning on the light at PTO rpm, at that speed the engine should be producing near maximum oil pressure.
The only time that I have seen that style of warning light trigger at upper RPM, is when an automotive gas engine was using a high volume after market oil pump and was pumping all the oil into the top end and starving the oil pickup, resulting in a severe drop in pressure...
Checking the actual oil pressure at PTO rpm is cheap insurance... It is likely just a defective sending unit , but with the kind of damage and expense that can result do to lack of oil pressure .... my :2cents: and from someone who just had a freak oil pressure problem with their own tractor
The average electrical (dummy) light sending unit , only triggers at low pressure usually around 7 psi. if the Mahindra unit works like this why would it be turning on the light at PTO rpm, at that speed the engine should be producing near maximum oil pressure.
The only time that I have seen that style of warning light trigger at upper RPM, is when an automotive gas engine was using a high volume after market oil pump and was pumping all the oil into the top end and starving the oil pickup, resulting in a severe drop in pressure...
Checking the actual oil pressure at PTO rpm is cheap insurance... It is likely just a defective sending unit , but with the kind of damage and expense that can result do to lack of oil pressure .... my :2cents: and from someone who just had a freak oil pressure problem with their own tractor
I want to chime in here since there have not been any more replies. My oil light just came on just from riding it around. It has only 8 hrs on it. I was however washing the mud off from the ride. Why would the oil light come on from water?
flyerdan
Veteran Member
Most oil pressure switches are normally closed so the light illuminates when there is insufficient pressure to open it. When you wash it down, chances are that the water is a good enough conductor to complete the circuit, just like grounding the wire itself.
Hmmm. I'd like to locate that switch and see where its placed and either add some protection to it or replace the dummy light with a real pressure gauge. This is way too important of an issue to have false alarms. Where would I find it?
flyerdan
Veteran Member
According to another thread here, it should be on the right side near the oil filter. If you have just a light it will be a little bulb shaped item with a wire attached to the top, if there is a gauge of sorts as well it will resemble a little dome shaped can with a wire attached. They've gone away from mechanical type gauges in recent years as the tubing carrying the oil can get damaged resulting in a big mess or pumping out all of the oil, in extreme cases.
