Slanters,
I am pretty sure that I need a new oil gauge pressure sender, but want to check with the /6 experts on other possibilities:

I noticed that on my 1987 van, 195K miles, that the oil gauge is at zero with the key off but will rise to the second mark (out of 7) when the key is on but not running. It does this hot or cold. There is also an oil idiot light that is on at this time (different sensor). When the /6 is started and running, then the idiot light goes out and the oil gauge rises to mark 4 cold or mark 3 hot idle.
Must be the sensor. OR could it be wiring, connections, gauge, 5V reg, etc?
I'll try a new sensor at the next oil change, but never hurts to ask some questions before I go to the parts store.
thanks,
Fred

powellf@earthlink.net

You need to do some checking first. Disconnect the wire from the oil sender. Does the gauge now stay at zero with key on and engine not running? Now don't automatically assume the sender is bad. The instrument cluster voltage regulator on the back of the instrument cluster could be bad and be sending full voltage to the gauges. To check this, connect a volt meter between the wire you just disconnected from the sender and connect other lead of the meter to ground. With key on, you should see the voltage pulse from zero to near battery voltage. Your meter may not respond fast enough, but you should be able to tell if you are getting the pulsing voltage. Another way is to use a low wattage light bulb like in some testers, connect it between the oil sender wire and ground, the light should blink on and off with key on. With 195K miles, I would suspect the instrument cluster voltage regulator. I would replace it anyway because when it does fail, it often burns up the gauges, then you have major expense.

To test the sender...... you can use a ohm meter but I don't know what readings you should get. With engine not running you should have higher resistance, I guess 90 ohms or more. With enigne running, it will depend on how much oil pressure you actually have. Perhaps 30-50 ohms?? Boths of these are guesses, but it will be higer resistance with engine not running, and lower reistance with engine running. I believe Chrysler gauge senders (oil and temperature) operate in the 10 to 90 ohm range.

I had a oil sender I got from a salvage yard vehicle a while back. It looked like NEW on the outside. I installed it and it did not work. I peeled it open and the inside was all rusty and looked like it sat at the bottom of a lake for a few years.

Good luck.

Thanks for your help, After going through your checks (see below) it must be the sender. I'll change it out at the next oil change.
thanks
Fred

Yes
:
: Now don't automatically assume the
: sender is bad. The instrument cluster
: voltage regulator on the back of the
: instrument cluster could be bad and be
: sending full voltage to the gauges. To check
: this, connect a volt meter between the wire
: you just disconnected from the sender and
: connect other lead of the meter to ground.
: With key on, you should see the voltage
: pulse from zero to near battery voltage.
: Your meter may not respond fast enough, but
: you should be able to tell if you are
: getting the pulsing voltage.

Definitely pulsing, but between 1.5 and 3 volts on an old multimeter. The manual says any pulsing voltage is OK.
:
: Another way is
: to use a low wattage light bulb like in some
: testers, connect it between the oil sender
: wire and ground, the light should blink on
: and off with key on. With 195K miles, I
: would suspect the instrument cluster voltage
: regulator. I would replace it anyway because
: when it does fail, it often burns up the
: gauges, then you have major expense.

Other gauges aren't acting up, but I'll keep it in mind.
:
: To test the sender...... you can use a ohm
: meter but I don't know what readings you
: should get. With engine not running you
: should have higher resistance, I guess 90
: ohms or more.

35 ohms engine off..
:
: With engine running, it will
: depend on how much oil pressure you actually
: have. Perhaps 30-50 ohms??

29 ohms on cold fast idle.
:
: Boths of these
: are guesses, but it will be higer resistance
: with engine not running, and lower reistance
: with engine running. I believe Chrysler
: gauge senders (oil and temperature) operate
: in the 10 to 90 ohm range.
:
: I had a oil sender I got from a salvage yard
: vehicle a while back. It looked like NEW on
: the outside. I installed it and it did not
: work. I peeled it open and the inside was
: all rusty and looked like it sat at the
: bottom of a lake for a few years.
:
: Good luck.


powellf@earthlink.net

Uh-oh.
After a long search this morning the parts guy sold me a Borg warner S333 oil pressure sender for $22. Unfortunately its resistance uninstalled is 800K ohms. It's either defective or it is one of those oil pressure senders for a gauge that really is an idiot light, i.e., it is either on or off and doesn't indicate the actual varying level of oil pressure.

Any idea if this is the correct part number or a backup on the zero pressure resistance being 90 ohms?
This is a 1987 B150 Ram Wagon, 225 /6 naturally.
Sender has pipe threads on one end for oil and threaded stud on the other for wire.
I hate buying auto electric parts!

thanks again,
Fred


powellf@earthlink.net

That does not sound like you have the correct sender. I just checked the one on my 1987 Dodge D150 truck and get about 60 ohm engine not running. About 25 ohm running with engine still cold and oil thick. The reading was bouncing around on my digital meter but the readings are in the range I expected.



cfield@ll.net