oil pressure switch or sender? wtf

[99FiveOh]

Took the car on a LONG road trip this weekend and she did great. I got some driveline vibes to sort out though, but for the most part it was a pretty good ride.

After stopping for gas I pulled back onto the highway and noticed that my oil pressure gauge was dipping pretty low, not in the red zone but pretty low on the gauge. Below the "N". I checked the oil and it's perfect and clean. Not sure what can cause this. It fluctuates a lot and then at times it's rock steady on the "A" in normal.

I hear these are just switches and are either on or off. If that's the case, anywhere on the "NORMAL" gauge means pressure correct? I bought a brand new sensor when I put the motor back together and it said clearly on the screen "Oil Pressure Switch" and the guy told me that it's an on/off switch, not variable.

On a side note, what are the symptoms of very low/zero oil pressure? I was thinking the lifters would start tapping from lack of oil and ultimately bottom end knocking. Oh and the oil pump is brand new as well and the pickup was ultra clean even though I still ran some carb cleaner through it.

 

[BlownFiveLiter]

Mine's done it for years. It looks like I have no pressure at idle sometimes, but the engine hums along no problem. It did it on my old engine and the new one I swapped in after I picked up an Explorer engine and put my TFS heads on it.

 

[99FiveOh]

So probably nothing to worry about? I do want to buy a quality Autometer oil pressure gauge kit though. This way I know for certain what my oil pressure is. Not so much for this stock engine combo, but for the turbocharged windsor I have planned!

 

[BlownFiveLiter]

I wouldn't be overly concerned. If you're really worried, pull a valve cover and look at the top end. If you have oil, you have pressure. A cheapo Pepboys Sunpro gauge would tell you for sure though, and probably for under $20.

 

[Bullitt95]

Just replace the oil pressure gauge sending unit (switch). It's a cheap part and it'll take you five minutes to do.

 

[99FiveOh]

That's the point though, I already did replace it. I replaced the old one because it was acting funny, but not like this. I'm at the point where I don't believe any company is capable of producing a quality sensor anymore!!

 

[VibrantRedGT]

Time to put real gauges on the car. I went with Auto Meter mechanical Fuel Pressure, Water Temp, Oil Pressure and Boost (when I had the blower). Removed the Boost and replaced with Oil on the A-Pillar.

With the Supercharger, car was rarely dirty but it was this day.

 

[99FiveOh]

I've noticed during another trip yesterday that the needle will start to fluctuate after about an hour of driving. Also, I notice water dripping on my left foot, it's coming from the A/C vent on the left side of the dash. Just thinking out loud here, is it possible that the water is dripping down onto some electrical connections and perhaps making the oil pressure gauge go nuts?

To rule this out I'd have to drive around for an hour without the A/C on. I will go on a nice topless cruise at some point to see if it still does it. Doesnt' seem likely to me.

On a side note, why is water leaking out of that vent? Is this normal??

 

[revhead347]

Try and see if your ac condensation line is plugged.

 

[99FiveOh]

It's not plugged because it's dripping out of the firewall as it should. I drove around tonight with no A/C and the gauge still acted up so I know the water isn't doing it. I'm going to buy an aftermarket gauge soon.

 

[99FiveOh]

Just wanted to report that when I was swapping my upper intake I went ahead and checked out the little connector for the oil pressure switch. It was on pretty good, but I went to push it and it slipped on quite a bit further. I have taken 2 nice long cruises and the gauge didn't budge. Keeping my fingers crossed!

 

[Bullitt95]

That's the point though, I already did replace it. I replaced the old one because it was acting funny, but not like this. I'm at the point where I don't believe any company is capable of producing a quality sensor anymore!!

I was going to suggest that maybe the wiring connector to the sending unit is loose but it looks like you've already sussed that out. Hope that was indeed the problem.