Oil Pressure Gauge "Dances" Low When Stopped

[Dabblingman]

Hey! A week into our 1999 3.0 V6 Ford Ranger. Much to learn. Many quirks.

Today, noticed that the oil pressure gauge is normal (in the middle) when....
1) Driving (moving)
2) In Neutral
3) In Park

BUT, when in DRIVE, but stopped, the needle on the gauge drops to the low side and bounces up and down on it. A special "Check Gage" (they, that's how it's spelled) light comes on. Once I drive away (from the stop light, etc), everything is OK.

Anyone ever see this? Any ideas? Thanks in advance!

 

[franklin2]

I would assume Ford was consistent with this, my 1989 f250 has a fake gauge. Instead of a sensor out on the engine to send back oil pressure readings, they just installed a switch and put a resistor on the cluster circuit board. If you have over 5 pounds of pressure, the switch opens and the resistor is hooked in so the guage reads straight up in the middle.

If you get less than 5 pounds oil pressure, the switch will close, grounding out the gauge wire and making the gauge go to zero.

Your best next move is to go to the store and buy a real pressure gauge, one of the cheaper ones with the tubing will work. Hook it up and see what pressure you are really running. if it really is going up and down on either side of 5 pounds, if you went to a little thicker oil it may make the problem go away. Needless to say if this works you have some wear in the engine, but you might be able to work with it. A new pressure switch may help it also. But see what pressure you really have with a real gauge.

 

[pjtoledo]

my 2000 has been doing that on and off for at least 15 years.
I usually put 10-30 or 15-40 oil in for the summer, 5-30 in winter.
that helps, but does not totally eliminate the issue.

 

[tinman_72]

When you have the factory "fake" gauge, the sending unit has a single wire connection. It is a male prong sticking out and the wire is a female piece that goes on. This can get dirty and cause a weak connection resulting in the gauge intermittently or permanently showing low. This is a very common scenario. The first thing I would do is clean that connection and see if the issue goes away. This is a free procedure.
You can convert the "fake" gauge to a real one by replacing the sending unit (do a Google search for the correct unit) and placing a jumper wire to bypass the resistor on the gauge cluster. If you want to see an actual number for oil pressure, pick up an aftermarket gauge like Franklin recommended.

 

[fastpakr]

If you do end up pursuing an aftermarket gauge, this pod blends in almost completely on the A pillar:

Amazon.com: AUTO METER 15309 Gauge Works Single Gauge Pod : Automotive

Buy AUTO METER 15309 Gauge Works Single Gauge Pod: Housing Pods - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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You'll just need to find a matching trim paint color and give it a quick spray before installing.

 

[Stage.it.rev40]

Hey! A week into our 1999 3.0 V6 Ford Ranger. Much to learn. Many quirks.

Today, noticed that the oil pressure gauge is normal (in the middle) when....
1) Driving (moving)
2) In Neutral
3) In Park

BUT, when in DRIVE, but stopped, the needle on the gauge drops to the low side and bounces up and down on it. A special "Check Gage" (they, that's how it's spelled) light comes on. Once I drive away (from the stop light, etc), everything is OK.

Anyone ever see this? Any ideas? Thanks in advance!

had the same issue. Dancing around, 203k. & Drops at stop. I didn’t know but the previous owner didn’t put the synchro bolt in When replacing the heads says couldnt get it started and it was a timing issue. Synchro Jumped out and locked up. Not saying yours is., long story short today it’s back after a new crank, flexplate, oil pump and gaskets and fluids to match. @ start up top end noise started up. Didn’t know if heads were broken in yet. But good luck!

 

[Bill Williams]

I have a '91 with the 2.3 ltr powerhouse(41k legit mles)...recent past history was a dancing oil pressure gauge,, changed the oil and the sending unit.. Now the symptom is, when I start it up the needle goes from normal to pegging on the left to zero, and then after about 15 second it moves back up to normal....AND when I start it and until it get up to normal(after 15 seconds) the engine sounds louder until it reaches normal then quiets down.. It may be time to sell it as I am not a car guy

 

[franklin2]

I have a '91 with the 2.3 ltr powerhouse(41k legit mles)...recent past history was a dancing oil pressure gauge,, changed the oil and the sending unit.. Now the symptom is, when I start it up the needle goes from normal to pegging on the left to zero, and then after about 15 second it moves back up to normal....AND when I start it and until it get up to normal(after 15 seconds) the engine sounds louder until it reaches normal then quiets down.. It may be time to sell it as I am not a car guy

Like I recommended in my first post, go buy and install a aftermarket gauge and just hang it under the dash. You can waste a lot of time and money relying on the stock gauges for troubleshooting. The general minimum for oil pressure is 10lbs per 1000 rpm. So if you are idling at 600 rpm, and have 6 psi oil pressure, that is considered minimum oil pressure.

 

[Brain75]

It would take a number dummy to find the parts I am sure (if they exist), but one thing we did on the farm in the 80's and 90's (all trucks were mid 80's F150's and F250's) was to replace the idiot gauge in the dash cluster with an OEM 70's gauge (in the 70's they were real gauges and not idiot gauges) and run a new sending unit wire/new sending unit, among those years the design was identical all they swapped fine and looked factory. 88-92 (2nd gen) look very much the same, still an analog looking dash and I bet there might be a good OEM real gauge out there. I forget the year they switched from real gauges to idiot gauges but I think we tried to stay under 1978 ish for that reason.

In my 1948, the forum guys at FTE suggest you buy 70's gauges + sending units, and then reskin them with a beauty kit from one of the antique parts places like MACS Antique Auto, etc to get a factory look when you swap from 6volt to 12volt.
The '48 dash has a lot of spare room all over the place you could put hide an army back there between gauges.

 

[franklin2]

Be careful, all Ford gauges are NOT the same. Yes they are the same basically when they started going to 12v systems in the very late 50's all the way to 1986 for the big trucks. Not sure on the rangers, but in 1987 on the f150/250/350 they went to a different gauge system that will require a different sending unit. They have different ohm values and actually read backwards from the older Ford units. Ford went to a system that works more like the GM system.

But with all that said, you go to all that trouble swapping to a newer gauge and what do you end up with? A Ford guage that has "L" , "NORMAL" and "H". That only gives you general information. You are much better off using aftermarket gauges will real numbers on them.