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Intermittent Oil Light - Oil Pressure Sensor?

96K views 43 replies 18 participants last post by  Jeepman 
#1 ·
Wifey called today and said that the oil idiot light was coming on when she was on the brakes and/or turning. Went to a mechanic who said that the top end was sludgy and I had him do a flush. He got that done and it seemed to help for a while, but the light came back on later in the day. Took it back to him and he says that the oil pressure sensor/sending unit was leaking and that was likely the problem. Possibly shorting out the sensor.

Anyone else believe that this could be the problem? What else could it be? Anyone seen this issue before? I did a search but all I could find was a discussion on synthetic v. non-synthetic oils.

I would attempt a diagnosis myself but it's dern cold up here this week and I would rather pay a couple of bucks than work outside in sub-zero temps. Just want to make sure I'm not getting fleeced...
 
#2 ·
Chrysler/Dodge oil sensors are notorious for leaking ......
It's cheap insurance to replace it.

If you want, you can change your cluster (gauges) and have the one with the oil pressure gauge (different sensor). OR install an auxiliary pressure gauge somewhere, even if it's under the hood. :cool:
 
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#4 ·
At idle and turning, sounds more like "low oil level". Have you checked the dipstick for OIL, lately?

Replace the sensor, and check the dipstick for oil ?
Sounds like you're 4 quarts low .......
:lol:
 
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#8 · (Edited)
Regardless of what the mechanic said, the sender is a common and cheap part to change in this situation. It's the cheapest part in the system. That said, the only way to know if you have an indication problem vs an oil starvation problem is to remove the sensor and connect a direct reading oil pressure gauge in it's place. This will tell you the true pressure in the system. If it then reads the correct pressure you start with a new sender. If it reads low then you have a bad pump or an oil channel or galley is blocked internal to the engine. It's a simple system with few options to repair.

BTW - Why did the mechanic do a flush? Did he pull the valve covers and see the sludge or just surmise there was sludge. Flushes are a risky proposition.
 
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#9 ·
Regardless of what the mechanic said, the sender is a common and cheap part to change in this situation. It's the cheapest part in the system. That said, the only way to know if you have an indication problem vs an oil starvation problem is to remove the sensor and connect a direct reading oil pressure gauge in it's place. This will tell you the true pressure in the system. If it then reads the correct pressure you start with a new sender. If it reads low then you have a bad pump or an oil channel or galley is blocked internal to the engine. It's not rocket science.

BTW - Why did the mechanic do a flush? Did he pull the valve covers and see the sludge or just surmise there was sludge. Flushes are a risky proposition.
Thanks RIP,may wish to expound on the "risky part" :eekkkk:
 
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#10 ·
Okay... I'm going to brave the temps (have to snow blow anyway) and swap out the switch tonight. Looks easy enough, and like you all have said, it's cheap insurance.

I'll report back.
 
#11 ·
Man, don't know about your Mechanic. I see no justification for a flush. Furthermore they can stir up a lot of dirt to block otherwise open passages.

Most likely the sensor or a poor connection to the sensor. The cold weather may be a factor in the leak appearing. Cold contracts and leaks occur which may not occur during warmer temperatures or when the engine is warm.

Internally a pressure regulating valve could be acting up (staying open) and maybe only when it is cold.

Does your oil filter have an anti drain back valve? Not an issue in your case, I don't believe, as the problem is during operation, not start-up.
 
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#12 ·
Checked the oil... it was full.

Swapped the sensor and it seems to have fixed the problem (so far). Drove it around a while and no light. Woo Hoo! That would have been a much easier job if I removed the filter, but the oil was fresh and I'm a cheapskate.

Thanks for the help!

I am questioning the mechanic now... read up on flushes. Hopefully it didn't do any more harm than the ding to my wallet.
 
#14 ·
Congratulations. :thumb: How's the frost bite? :cool:
I should have mentioned to use a trouble light to see and to also use as a hand warmer. I don't envy you working in the cold like that. Did the front disk brakes and rotars on a 93 Dodge Shadow one cold Winter evening (-10 C) and used the trouble light to keep my hands warm. That job required extreme focus to "get it done right" the fastest. I made 0 mistakes. :thumb:

As to your Mechanic, I would question him as well. What filter did he put on?
 
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#13 ·
Good advice from RIP. I would hook up a gauge and get actual oil pressure values at idle and other various RPM levels. If low, it could be a bad pump, blockage or (fingers crossed), loose bearings (typically main or rod).

Engine flushes are usually to be avoided because they can disturb years of sludge accumulation and allow chunks of debris to get stuck in oil passages, thereby causing more engine damage than if left alone.
 
#15 ·
Believe it or not, I really didn't get that cold except for my feet (didn't put on the second pair of socks). Must be all the ice fishing training! :blink: I used a trouble light, but unfortunately it's a florescent so no warmpth to speak of.

The filter was turned so I didn't get a brand name off of it, but I can tell you it's white for what it's worth :nut:
 
#16 ·
Believe it or not, I really didn't get that cold except for my feet (didn't put on the second pair of socks). I used a trouble light, but unfortunately it's a florescent so no warmpth to speak of.

The filter was turned so I didn't get a brand name off of it, but I can tell you it's white for what it's worth :nut:
The filter had frost bite. :lol:
 
#20 ·
I just got back from Barstow, CA before this oil problem hit. Talk about a shock to the system. Barstow: 68°. Michigan: Move the decimal place left... and put a - in front of it.
 
#21 ·
By the way, HOW did the mechanic determine the engine was Sludgy ? :ask_wsign If he just removed the "710" cap and looked in, that's not much to see. He would have had to remove the valve cover to get an accurate analysis of the overall status. :nut:
 
#22 ·
Wimps, and that's no Cornish Saint. :lol::lol:
 
#23 ·
Great help for new member

I have that intermittent oil pressure light on a 1998 Plymouth Grand Voyager Expresso with the 3.8 liter engine.

My mechanic told me that if the valves weren't clicking it was probably the sensor. I didn't know the location, but the folks at auto zone said start by looking in the oil filter area or just check online. So here I am.

I have three old minivans with the 3.8 engine and one with the 3.3. Don't ask why I have so many.

If I remember correctly, the old Slant-6's had the oil pressure sensor near the filter and that was on the external oil pump.

The 273 on my Barracuda has the oil pressure port at the back of the engine near the distributor. Very hard to get to, but not as hard as stuff on these new cars.
 
#25 ·
I'm having the same issue with as the original poster. The oil pressure light is coming on when the engine slows to an idle and when turning corners. We have a 1999 T&C with the 3.8L engine. It sounds like the pressure sensor is bad. I know the oil level is fine since I changed the oil myself and checked the level.

I'm glad the forum exists. I was suspecting the sensor, but this thread make me more confident the sensor is the problem.
 
#26 ·
More complete cluster ??

Very good post, I had the same problem on my '97 Caravan, the oil idiot light was only working at warm start, at cold starts it was always off. The oil pressure switch was leaking and I bought a new one at Ebay for US$ 10.00, just 10 minutes to replace at a jackstand.

But I became very curious about the more complete cluster with oil pressure gauge. Was it available for some Chrysler minivans? And for which model/year? If it was available, I suppose that a voltmeter was included in the package also...I consider the voltmeter very usefull to check the charge conditions. Does anyone can clarify ?
 
#27 ·
I have had the low oil problem on my 3.3 90 GC. Sending unit solved it. On the "sludgey" thing, I would recommend using a high detergent oil (Pennzoil is food for this) and change the oil a few times for every 1000 miles. Put a drop of the oil on a piece of White heavy paper, like matte photo paper, and compare them until they start looking the same after 1k. Then just change as normal.
 
#29 ·
On the 3.3/3.8 the sender is located by the oil filter area. It screws into the side of the engine. The autozone replacement will be fine.
 
#30 ·
If you switched oils recently, using a lighter oil, it could cause this. You might try a heavier weight oil, from 5W to 10W, 20 to 30, based on your cars recommendations. But it is likely the sending unit.
 
#31 ·
I bought the replacement sensor but it seems to be the wrong size or I removed the wrong sensor from the car. I have a 2000 town and country with a 3.8 engine. I went under the car and to the left of the oil filter (by left I mean towards the passenger side) was what I think is the sensor. I unscrewed it, after breaking the clips holding the harness on, and the one I pulled off has about a pencil size thread, whereas the replacement part has a thread about the size of your thumb. So either I got the wrong part or I removed the wrong part.

Can anyone confirm which is wrong?
 
#37 ·
Hi. I'm new in this forum. Recently bought a 2001 Cravan Sport. Ironically, once begin to put it up to date, I ended up doing a lot of stuff. This forum has been very useful no matter my recently registration since one of the issues was the oil light appearing intermittently. I have a Mazda RX-8 and a Protege and have registered in the corresponding similar forums which my experience have been great. Tonight, after finally been able to do the oil replacement the Caravan (the crank bolt was practically stock and rounded), also changed the oil pressure sensor, which I bought from a typical auto part. Tested for a short drive, no oil light so far. Have to test during a long drive but I pretty sure the oil light issue was the sensor.

My thanks to everyone that post its experience for the benefit of others. By the way, I recall reading that a long 27 mm socket was needed but also a 1 1/16" will do the work.
 
#38 ·
Just went through an oil pressure sensor replacement here as well.
2006 T&C Touring w/ 3.8
First noticed that "aladdin lamp" pulling up to a stop light with AC running on a hot day.
Had a recent oil change, so knew oil level should have been correct.
If I would put in neutral & rev the motor just up to 1K rpm, the light would go out.
Problem became more frequent over the next couple days.
What should be a simple replacement was frustrating due to the routing of the AC Compressor lines.
I was unable to fit a deep 1-1/16 impact socket that I own past the AC Lines.
I had a MAC shallow 3/4 drive 12 point that fit, but would just spin. (worn 12 point)
So I bit the bullet & bought the proper socket for about 16 bucks.
Supposed to work for 1" as well as 1-1/16" sensor/switches.
Anyway, upon removing the connector, oil ran out of the plug holes, so I used first carb cleaner to hose it off, then some contact cleaner to finish up.
When removing the sensor, a little oil will run out, so have a drain pan handy.
Put it back together with the new sensor, and so far so good.
 
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