Oil Pressure Sending Unit?

starcrwzr · May 14, 2016

I'm new here having recently acquired a 2001 Ram 1500 with 82K miles on it. It was well taken care of and is almost showroom condition. Anyway, was driving it today when the oil pressure gauge dropped to zero and I got the check engine light and the chime, then it went back to 30, then to zero, then to 30, and so on. Engine is running fine and the oil is up to the top of the safe zone, so I suspect the sending unit. Reading the posts here, I've read that the sending unit is back by the distributor on the 5.2L engines. I looked back there and it seems almost impossible to reach anything back there. Is this a dealer job? Any idea on what it costs to have it replaced? Any help or pictures would be appreciated. Thanks in advance!

Scott B.

dudeman2009 · May 14, 2016

There really is no room, removing the distributor cap may be the only way to get enough reach on your tools, unless you've got some swivels and extensions. As for it jumping around like that, before you go through the trouble of replacing the thing. Try following the wires and look for any place they might short out to each other or another piece of metal. I'd also make sure the connector is secure.

One way to check for an open or shorted wire is to have someone sit in the cab and watch the gauge while you fiddle with the wiring. play with it until you can find the spot that causes it to freak out. It may be that a previous repair has caused the wires to abrade against something, or the wires got yanked and damaged that way.

If playing with the wires doesnt cause anything to come up, then you're probably moving on to the sensor. I haven't found any tricks to getting it out, hopefully someone else has something for you.

dapepper9 · May 14, 2016

Can try swapping it. Any auto parts store will have a special socket for it. Slide that over it then use another socket over the special with a ratchet. Easiest way I've found. 5-10 minute swap depending on how young you are and how uncomfortable you find laying across the engine to reach back.

Passenger side of the block between the heads. Next to the distributor.

Mohpar · May 15, 2016

dapepper9 said:
Easiest way I've found. 5-10 minute swap depending on how young you are and how uncomfortable you find laying across the engine to reach back.

Passenger side of the block between the heads. Next to the distributor.

Best way to get to it - remove the air filter box and plant your feet on the frame by the exhaust manifolds and literally sit on top of the A/C compressor/alternator and lie across the throttle body to get to the back. It's so very uncomfortable but it's what you have to do.

starcrwzr · May 16, 2016

Well, I was able to get my cell phone back in behind all the hoses and wiring to get a picture of the sending unit.

Does the wiring look normal to everyone? To my electrical engineering mind the wires coming from the top of the connector look a little strained.

Also, I see obvious signs of an oil leak, is that from valve cover gaskets or plenum?

I realized I'm too old to be climbing up on the engine and trying to replace this myself, so I've scheduled an appointment with a local Dodge dealership to look at the problem. I know, it's easy, but when you're 64, overweight and not nearly as flexible as I used to be, I need to get it fixed. Reading all the posts on three different Dodge forums, I'm concerned that the problem is the oil pump intake pipe falling off, rather than the sensor. But I guess I'll have to cross my fingers and drive it 30 mile to the dealership (closest place I can take it).

Rustycowl69 · May 17, 2016

starcrwzr said:
Reading all the posts on three different Dodge forums, I'm concerned that the problem is the oil pump intake pipe falling off, rather than the sensor. But I guess I'll have to cross my fingers and drive it 30 mile to the dealership (closest place I can take it).

oil pump intake falling off? Really, that's what you came up with? Not to be a ****, here, but how could that possibly happen? The uptake tube has male pipe threads on the end of it. The other end is the pickup and it's a flattish disk like object 4 or 5 " in dia. that pickup is like 1/4 to 3/8" off the bottom of the pan. So, my point is it can't unscrew, there isn't enough room for that to happen.
More than likely the sender is the first thing to replace, as it's leaking anyway. If that doesn't help, you may have a bunch of debris packed around the pickup. You should drop the pan to clean the pickup. If you're lazy you may be able to remove the filter and blow compressed air backwards thru the adapter and out of the pickup end screen. so it will drain out of the oil pan drain hole.
I wouldn't think of driving it 30 miles to a dealership if there were ANY chance it really might have zero oil pressure.

dudeman2009 · May 17, 2016

The wires coming out of that connector look fine to me. As rusty put it, our pickup tubes really cant come off without dropping the pan. That is however a valid concern on other manufacturers, I know nothing about any of them on this specific topic except chevy.

There is no shame in taking it in to someone to get it fixed, I refuse to do anything bodywork except put paint in a spray gun and go to town, I also won't touch anything exhaust related i'll pay someone else to deal with that crap.

starcrwzr · May 18, 2016

Just spent $350 to have my local Dodge dealership replace the sensor. Drove about 50 miles and just before arriving home, the oil gauge dropped to zero again, came back, dropped again came back and then dropped for the remaining mile to home. So obviously, the sensor wasn't the issue. I will take it back next week after they've had time to think about the problem. I informed the service adviser by email of the lack of repair.

dudeman2009 · May 20, 2016

My original guess still stands, wiring issue. At this point, all dodge is going to do is guess and throw parts at is, unless they have a good tech working for them. But in my experience, parts throwing is the most common. In all the places i've worked, i've only seen one other tech than myself really diagnose problems.

starcrwzr · Jun 11, 2016

I was able to get Dodge to refund me half the cost of putting in the sensor, since that wasn't the problem. They said for two hours of labor they could wire around the harness. I said BS, I can do that myself and in a lot less time. But I don't think that's the issue. The last time I drove it the oil pressure dropped to zero and stayed there. I thought it was a wiring issue so I ignored it. after a couple of miles I started hearing the tappets. I immediately pulled over and shut off the engine. Waited 30 seconds and started it back up. The oil pressure came up to it's normal 35 and stayed there and the tappets quieted down. I drove the remaining 20 miles to home without any problems. So now I'm thinking it's oil starvation and that something is blocking the oil intake screen. When I shut it off, the junk falls off and I get normal oil pressure again. I'm taking it to a well seasoned highly recommended mechanic and explained the problem to him. He and I agree the first step is to drain the oil and put a bore scope into the pan and inspect the pan and intake screen. If it's full of crap, then we'll pull the pan and clean everything up, probably replace the pump as well. Let you know what we find next week.

dudeman2009 · Jun 11, 2016

A bore scope will find a lot of things that could cause it, but its not as good as a look yourself. Unless you have 4 wheel drive (in which case I don't have a great idea) dropping the pan is pretty easy. I did mine about a year ago because it was leaking oil near the back of the pan gasket.

Rustycowl69 · Jun 11, 2016

If it is plugged with debris, it could be valve stem seal pieces, but my money is on nylon teeth pieces from the cam timing gear.

dapepper9 · Jun 12, 2016

Rustycowl69 said:
If it is plugged with debris, it could be valve stem seal pieces, but my money is on nylon teeth pieces from the cam timing gear.

I would put money there as well as simple sludge buildup

starcrwzr · Jun 26, 2016

Here's an update. Found a reliable mechanic not too far from my home, a one man shop, and we discussed the problem. He says he's replaced a bunch of the Oil Pressure Sending Units in his life, but since I'm hearing tappet noises when the gauge drops to zero, then he suspects that it's something in the pan. So he drained the oil and tried to get a bore scope in to look around, but unfortunately, there's a baffle in the way and he couldn't see anything. So I said pull the pan. He called to tell me that he had the pan off and the bottom was full of a hard sludge in clumpy pieces. The oil intake screen was also half plugged so my guess that the screen was becoming plugged was correct. He has cleaned out the pan, replaced the oil pump and pickup tube for good measure and will finish the job on Monday. He suggests changing the oil in 1000 miles and bringing him the filter so he can cut it in half and look inside. He asked if the truck sat a lot without being driven, and I said that I think it was a daily driver, but only short hauls so that the engine never really got up to temperature. So it looks like my problem has been solved.

Rustycowl69 · Jun 26, 2016

I'd pull the valve covers off, too. If there is sludge in there, there is probably sludge in the lifter valley. If you can scope the valley, do it, you may have to pull the intake, too. If there was enough sludge in the pan, to plug the pickup, there's got to be more elsewhere, and it will continue to wash into the sump, hence the advice to change the oil in short intervals. You probably don't want to hear the story, how I know about this. Hopefully you caught it soon enough.

Oil Pressure Sending Unit?

starcrwzr

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dudeman2009

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dapepper9

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Mohpar

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starcrwzr

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Rustycowl69

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dudeman2009

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starcrwzr

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dudeman2009

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starcrwzr

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dudeman2009

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Rustycowl69

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dapepper9

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starcrwzr

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Rustycowl69

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