Oil Pressure Issues?

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Savatreatabvr

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Sitting at a stop light my oil pressure gauge on my 2002 4.7l RAM suddenly dropped to zero, I reved the RPMs and the gauge shot back up to normal. It was fine until the next stop light then it did it again. While it's doing this the engine sounds and runs perfectly normal. Got home, checked the oil and there was none on the dip stick. Normally I check it once a month or so but this time its been a few months so I filled it with oil and everything was fine for a few days then sitting at a stop light it did it again, dropped to zero.

I had a old Pontiac Gran Prix back in the day that did the same thing, come to find out the oil pump was weak. Replaced the oil pump and it was fine for another 80k miles. Do the 3rd gen RAMs have issues with weak oil pumps or is this a completely different issue?
 

crazykid1994

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Sitting at a stop light my oil pressure gauge on my 2002 4.7l RAM suddenly dropped to zero, I reved the RPMs and the gauge shot back up to normal. It was fine until the next stop light then it did it again. While it's doing this the engine sounds and runs perfectly normal. Got home, checked the oil and there was none on the dip stick. Normally I check it once a month or so but this time its been a few months so I filled it with oil and everything was fine for a few days then sitting at a stop light it did it again, dropped to zero.

I had a old Pontiac Gran Prix back in the day that did the same thing, come to find out the oil pump was weak. Replaced the oil pump and it was fine for another 80k miles. Do the 3rd gen RAMs have issues with weak oil pumps or is this a completely different issue?
You could have a leak that is bleeding down oil pressure. How many miles are on the truck? Could be a faulty sensor as well.
 
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Savatreatabvr

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If it was a faulty sensor would the gauge still move when given RPMs?
 

EdGs

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I have an '02 1500 with the 4.7 going through this, I need an OE Sensor, aftermarket ones this truck does not like.

Oil pressure goes to 0, but no difference in running, no tapping or knocking.

Mechanical gauge shows good oil psi.

Also if I check oil right after shutoff, it will read low. So let yours sit a bit before checking.

If you were burning it, I would think you would see it.

Are you using coolant?
 
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Savatreatabvr

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I have an '02 1500 with the 4.7 going through this, I need an OE Sensor, aftermarket ones this truck does not like.

Oil pressure goes to 0, but no difference in running, no tapping or knocking.

Mechanical gauge shows good oil psi.

Also if I check oil right after shutoff, it will read low. So let yours sit a bit before checking.

If you were burning it, I would think you would see it.

Are you using coolant?
Not using coolant. When the gauge first started dropping to zero it was after 10 miles of driving, it's now dropping to zero after just a few miles. I read that a spun rod bearing would cause low oild pressure but I would think it would be a constant low pressure, not bounce from normal to zero to normal?
 

EdGs

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I believe the OE sensor is a standard 1/8 npt pipe thread, if you can tee it and have the OE sensor and a mechanical gauge you could at least see if there still is physical pressure when your OE reading wigs out.

Like I said, when mine acts up, there is no knock or tap, and I have verified that there is oil pressure. The original sensor started leaking oil, and I have since put in 3 different aftermarket sensors, and all are/were varying degrees of junk.

Money is a bit tight, and I dont drive it much, so trying to wait a bit to buy a new OE one.
 
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Savatreatabvr

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You could rig a mechanical gauge. Not sure. I’ve never dealt with that
It's got to be a bad sending unit or gauge because now right after starting it the oil pressure drops to zero but there's no knocking or ticking and the truck runs fine, well it's running a bit rough but I don't think it's anything to be concerned about. I say that now but who knows, lol.
 

IdahoRed

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I've been chasing this issue for years in my 02. The first one from AutoZone lasted about 2 years. Replaced engine once due to cracked heads. The rebuilt engine was no different. but the sensors lasted shorter and shorter times. I tried different brands and the last time I went for an OE pressure switch. It lasted about 15 min. If I hold the idle at about 800 there is no issue but the default idle is around 600 in gear. I'm about ready to install a mechanical gauge if I knew how to bypass the stock gauge so I don't get check instruments message
 

rodnocker1

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My 2002 4.7 has been doing this for a while now. Usually no issue but occasionally the Pressure Gauge goes to zero and then USUALLY back up to normal. Once or twice, it would go to zero, start back up, back to zero, back up (you get the Idea). Engine runs just fine, no oil leaks, doesn't burn oil, and has never been low when I checked it (FWIW, I'm 66 years old and one of those "Old School" guys that grew up changing my oil about every 3,000 miles or so and my Truck has 298,500 miles on it so I've gone through alot of Oil and Filters, LOL). It really seems that what's happening is that the Sensor is losing electrical power.
 
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