Strange oil pressure

[WVUexplorer]

So i just finished installing new head gaskets and something odd happened. first the engine temp was slowly moving up and down(possible burping issue + i may have turned the thermostat 90 degrees so the breather hole was not up will fix tomorrow) but the big thing is when i took the car around the block the oil pressure gage rose and fell very slowly. it went from perfect center to above the lettering. this is odd because it has never moved before because i believe it is an idiot gauge.

Has any one else had this happen before?

 

[tweakedlogic]

It is most likely cased buy either the gauge it's self, or the wiring/ oil pressure switch. The oil pressure switch is just that, a switch. It's either seeing oil pressure or not. So if you gauge is sweeping, I'd start by cleaning the connector and the switch to see if that helps. It's likely that oil and coolant gummed up the connector causing a high resistance for the wire.

When the switch sees pressure, it closes a ground. So, to test, I would connect a jumper to ground from the wire connector at the switch to see if the gauge works properly.

 

[R&T Babich]

.... The oil pressure switch is just that, a switch. It's either seeing oil pressure or not. ...

On our 2 1992 Explorer XLTs the oil pressure readout is a gauge, not a light activated by a switch. When there is an ON/OFF oil pressure switch installed in a car the OIL PRESSURE light would indicate low oil pressure. The gauges in ours will indicate higher pressures when the engine is first started cold and when the RPM is high. There are lower pressure readings when at idle. Generally oil pressures are around 15-18 PSI at idle and ramp up to 40-50 at higher RPM or when the oil is cold. A pressure gauge that is fluctuating is usually a bad sensor or electrical ground. Check the the wiring going to the sensor for a loose wire connection or worn insulation causing a short.

 

[WVUexplorer]

i realized mine was a on/off gauge because after six years of owning it it has never moved before now so i was a bit shocked when i saw it sweeping. I'm going to try and clean the connector, i'm almost sure that at one point it either had oil or coolant on it during the repairs.

 

[R&T Babich]

I realized mine was a on/off gauge because after six years of owning it it has never moved before now so i was a bit shocked when i saw it sweeping. ...

If your instrument panel has an oil pressure gauge it is probably a gauge even if the needle hasn't moved in years. Your sensor is probably bad. A gauge sensor will have a diaphragm chamber and a variable resistance to change the current flowing thru the gauge. A low oil pressure warning light uses a pressure switch and looks a lot like a coolant temp sender. Go to Standard Motor Products catalog ( http://www.standardbrand.com/Online Catalogs-eCatalog/Content.aspx ), select the Part No. tab and enter PS240 for a pic of the gauge sensor and PS461 for a pic of the warning light switch.

 

[wood1]

http://www.explorerforum.com/forums/showthread.php?t=214175&highlight=oil+gauge+mod

 

[WVUexplorer]

Thanks for your advice but the problem is more in-depth then i originally thought i did a rewrite on the problem and it can be found here.

http://www.explorerforum.com/forums/showthread.php?t=361096

 

[Maniak]

If your instrument panel has an oil pressure gauge it is probably a gauge even if the needle hasn't moved in years. Your sensor is probably bad. A gauge sensor will have a diaphragm chamber and a variable resistance to change the current flowing thru the gauge. A low oil pressure warning light uses a pressure switch and looks a lot like a coolant temp sender. Go to Standard Motor Products catalog ( http://www.standardbrand.com/Online Catalogs-eCatalog/Content.aspx ), select the Part No. tab and enter PS240 for a pic of the gauge sensor and PS461 for a pic of the warning light switch.

Actually, its an analog idiot light. The pressure switch/sending unit on the side of the motor right by the power steering pump is just a switch. Easy way to prove it is to take the wire off the sending unit/switch and ground it. Your Gauge will read about the middle. That is basically what happens once you get 5 psi or so in the motor.

You can make it work like a real gauge (move with pressure) by changing the factory sending unit/switch with one from an 80's ford.

Here is the "how to" on it.. http://www.explorerforum.com/forums/showthread.php?t=65575&highlight=oil

Of course, its possible someone put on a real sending unit instead of a switch on a vehicle over the years but if they didn't short the 22 ohm resistor it will read low.

btw.. Standard lists the ps240 as the oil pressure "switch" for a 1992 ford Explorer.

There is also an oil level switch on the side of the pan but that is even a different #.

~Mark

 

[R&T Babich]

Actually, its an analog idiot light. The pressure switch/sending unit on the side of the motor right by the power steering pump is just a switch. Easy way to prove it is to take the wire off the sending unit/switch and ground it. Your Gauge will read about the middle. That is basically what happens once you get 5 psi or so in the motor.
...

You are absolutely correct Maniak. My other cars are old, like me, with real gauges. To have a gauge that is basically telling you "we have oil pressure" is just lame. I want to see what the oil pressure is doing.

 

[WVUexplorer]

Thank you all so much for the help but I have fixed the problem. This is a very embarrassing mistake but I'm glad it is fixed.

When I was putting everything back together I would place screws and bolts in there proper place but not tighten them in order to make sure everything was in it's right place. So when it came time to tighten it I missed the nut for the wire connecting the cylinder head to ground. So the wire was making a very loose connection causing all my gauges to go haywire.

Thank you all so much for your suggestions and hard work, hopefully the information you provided will assist others in their time of need as it has helped me.