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Issues with Oil Temp gauge


rich_e777
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Had an odd issue present its self last night after a run down the freeway. Once I got off at my exit and stopped at a red light my oil gauge in the top left corner started dropping erratically until it set the check gauges light on but once I started moving again it returned to normal until I stopped again. Had to clock in and my superiors are not thrilled like I am when I`m covered in Cutlass Crud and smell like WD-40 and trans fluid( Air Wick needs to get on this scent:lol:) So after a few hours a came out on break and messed around with the car and could not reproduce the problem. So I`m thinking its either the oil temp sensor or the oil pressure switch on its way out. Does this sound like an issue someone has come across before? Sorry for the wall of words, my return key doesn't skip lines on this site for some reason.

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1. More likely oil pressure, not oil temp.

 

2. Pressure is most likely to be too low when engine is fully-warm, at idle, in gear. (thinnest oil, lowest RPM)

 

3. Might as well check the oil level, or even change oil and filter if it's about time.

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being a 94, you have the fake guage/sensor if you haven't changed the sensor for a real one and removed the in-line resistor. those will cause the needle to go from a normal position down to 0 and flip back and forth randomly.

 

IF the engine is acting normally during these events(no sudden lifter clatter or tap or knock), i wouldn't pay too much mind to it. you don't need very much oil pressure at idle to keep an engine happy, or at least not on a 60V6.

 

also, to fix the lack of paragraph issue, you have to change the editor style. i forget which works best though.

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I did just change the oil and filter, and stick with the same kind. Also wasn't aware of the fake gauge and would very much like a functioning one. Its the first time ever hearing about that, is there a thread with more info or even a write up on this?

 

Hey alright, thanks again

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Now I`m thinking its a more widespread electrical problem. On the way home tonight going about 55ish I lost all lights on the dash and headlights went out for 2-3 seconds and I think the engine stumbled a bit. Just before that the ABS light came on and I had just tested to see if the ABS system was working and was treated to a face full of steering wheel(works just fine) about 10 minutes later I got home no other issues until I went to raise the windows, engine idling, gear in park, raising the windows made the engine die and really dimmed the lights bad.

 

After a 12 hour shift the only thing I can think of is that maybe the alternator is going bad or one of the various cables might be bad somehow. I`ve got a multi-meter somewhere and can do some testing tomorrow. Also RobertSaar if your still around would Tuner Pro be able to give some insight into this problem? Just need a 12 pin with usb connector, unless a serial to USB adapter will work.

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not that it's very descriptive, but alldata is showing somewhere between the C100 connector and splice S105. S105 is about 2 inches away from the connectors for the ICM. so, that leaves about 90% of the engine harness to look through.

 

i know Ken has mentioned its location before.

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Ok after some sleep, Battery checks out ok, all connections are tight and I`ve been on a little crusade trying to find every little ground and clean them up a little bit with a wire brush. I did pick this alternator up at a junkyard for cheap a few years ago so I guess I cannot be surprised its going bad, that or the voltage regulator(opinions?) which was mentioned to me.

 

I don't think asking the same question probably 20 other people were about/ wanting to ask is hijacking, mind reading maybe. IIRC the Oil pressure sending unit is right above the starter. But I want to say(not going to though) that the inline resistor is up around the coils. But that could be something else I`ll check on it.

 

I`ve got a surplus of different resistors from my stint at ITT tech, though they are meant for internal electronic applications, would one of these work? If so I have plenty and can send them out.

Edited by rich_e777
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your goal would be to completely bypass the resistor.

 

Once it has been located and done the gauge will read 100% or 0%. This is becuase the oem idiot gauge oil pressure sensor is a switch. You must get a oil pressure sender, which is a long version of the sensor. The correct part can be found by referencing 91/92/93 CS with 3.1mpfi/3.4dohc with oil guage, you must make sure the sensor you buy has the same threads as the old sesnor you can no longer use. Also the functional gauge sensor is longer that the idiot type sensor. just make sure you get the right one.

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  • 3 weeks later...

My issue ended up being the connector on the harness which I had to replace and I guess I forgot to clean the connection at the starter right next to it and that cleared up the electrical issue and the static discharge. I have no idea how I over looked that:think:

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  • 2 weeks later...

Anyone know or remember what is an acceptable oil pressure level at idle for a 3100 V6? Last time I changed my oil the pressure gauge intermittedly (new word?) goes crazy and dips down enough to set the check gauges light off. Engine does change in noise or vibration. I thought I had it fixed after replacing the switch and splicing in a new connector but no joy. Put a gauge on it and it reads about 13 PSI at engine idle. I think want to put an after market gauge in now that gives an actual numbers reading. Cannot for the life of me find that damn resistor. Just got done with a head gasket job and had the harness almost completely out of the car going over it. No resistor but did find several frayed injector wires.

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acceptable is at a fully warmed up idle, around 10PSI. around that area, the lifters will start clattering around and you'll run into film strength issues for the bearings.

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acceptable is at a fully warmed up idle, around 10PSI. around that area, the lifters will start clattering around and you'll run into film strength issues for the bearings.
:think:So around 10 PSI is a good thing, bad thing. I did drive around for about an hour before I did as I had drained and refilled the block of coolant, so everything was warmed up to OP temperature. The gauge was fluctuating when I had the gauge on it as well but it didn't change unless I gave it a little gas. A slight hesitation and then the gauge responded accordingly, never went below at least 12 PSI, From what I could tell it maintained about 13 to 14 at idle. If the gauge was reading correctly and there was a low oil pressure issue randomly announcing itself the engine would give some kind of indication right?
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if i saw below 10PSI on a guage, i would start being worried since that means the engine is getting loose, the pump is worn out, there is some kind of significant internal leak, or the oil is thinning out so much at its current temp....

 

the oil pressure dropping could have been the result of the hesitation, rather than the cause. engine speed drops even momentarily and the guage will show it.

 

however, there is the possibility that oil pressure dropped low enough for bearing contact, which would cause a hesitation, but i would expect it to be more constant, rather than intermittent.

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Ok I gotcha now, sorry for the confusion. Never went below 10PSI at idle for sure and the gauge was 30 something years old as well so im sure it wouldn't read instantly. Im going to install an aftermarket gauge and maybe find a pillar pod or just bolt it to the dash. Its got to have something to do with that resistor like you said, Thanks for the help.:thumbsup:

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