2.5L ('98-'01) OIL GAUGE JUMPING WHEN OIL IS HOT

[redcloud]

HI, I HAVE A WEIRD SITUATION WITH MY TRUCK.
WHEN MY ENGINE GETS TO THE WORK TEMPERATURE AFTER DRIVING A FEW MILES, WHEN I STOP AT A SIGN THE OIL GAUGE STARTS TO MOVES BUT WHEN I PRESS THE ACELERATOR IT RETURNS TO NORMAL POSITION
DOES ANYBODY KNOW WHAT IS HAPPENING?

 

[tw205]

As the oil warms it changes viscosity. It may start as 10w when cold but will change to 30w when hot.
The oil pump runs off the engine rotating assembly so it is effected by engine RPM.
It’s not unusual to see changes in oil pressure from cold to hot and from driving to idling. It’s normal.

 

[redcloud]

But I don't why it starts to happened now, I have 8 years with my truck and never do that thing. I see more noticeable when I used Full Synthetic oil instead of mineral oil. Same viscosit (5w20 as my owners manual said)

 

[tw205]

Wear and tear. Like getting old. Most factory gauges aren’t very accurate To begin with. An after market gauge would be more accurate if you are concerned. Inexpensive and easy to install.

 

[scotts90ranger]

The factory "gauge" is an idiot light that is supposed to sit at the center point at anything above about 5psi, so if it's flopping around then you are right at the break point...

Supposedly the O rings on the newer style ('95-01) oil pumps get cranky and leak, the most convenient part of the new setup is you don't have to pull the engine to change the oil pump...

 

[Uncle Gump]

Did this start happening the same time your ABS and brake light started illuminating?

 

[RonD]

As said 1989 and up Rangers do not have a "real" oil pressure gauge
On the engine is an Oil Pressure Switch, and on/off switch, it either grounds the Oil Gauge(Normal) or doesn't(no pressure shown)

Oil pressure on all engines is lower after oil warms up, that's normal

The on/off is set at 5.5psi, off under 5.5psi, on above 5.5psi

Easiest thing would be to remove the switch and clean it out
Unplug BOTH coil Packs, so NO START
Crank the engine very briefly to make oil come out the now open oil pressure switch hole, just in case some "gunk" was in there
Put back in the clean switch, leave lower threads BARE it needs a good ground to engine
See if that's better

You may need a new oil pressure switch but cleaning sometimes works
It maybe shutting off at 8-10psi now


As said the oil pressure reading system after 1988 is totally ELECTRIC
Longshot would be if your alternator has 1 or 2 failing Fields, i.e. lights DIM at idle
Should cause other issues as well but could also cause the jumping oil pressure gauge at idle, as said looooongshot, lol

 

[redcloud]

Did this start happening the same time your ABS and brake light started illuminating?

No, the abs light turns on a week ago, the problem with oil gauge is since April, btw, I change 3 times the cluster of my truck and I have the same problem... I already change the oil pressure switch but its not the same that comes from factory, I will buy the exact same part number to try fix the problem...

 

[redcloud]

As said 1989 and up Rangers do not have a "real" oil pressure gauge
On the engine is an Oil Pressure Switch, and on/off switch, it either grounds the Oil Gauge(Normal) or doesn't(no pressure shown)

Oil pressure on all engines is lower after oil warms up, that's normal

The on/off is set at 5.5psi, off under 5.5psi, on above 5.5psi

Easiest thing would be to remove the switch and clean it out
Unplug BOTH coil Packs, so NO START
Crank the engine very briefly to make oil come out the now open oil pressure switch hole, just in case some "gunk" was in there
Put back in the clean switch, leave lower threads BARE it needs a good ground to engine
See if that's better

You may need a new oil pressure switch but cleaning sometimes works
It maybe shutting off at 8-10psi now


As said the oil pressure reading system after 1988 is totally ELECTRIC
Longshot would be if your alternator has 1 or 2 failing Fields, i.e. lights DIM at idle
Should cause other issues as well but could also cause the jumping oil pressure gauge at idle, as said looooongshot, lol

I will try a new Oil pressure switch, I install another one motorcraft brand but its not te same, btw it fits without problem.

 

[rusty ol ranger]

My 97 460 was doing this and the sender wire was loose.

It also did it once before when the mains were shot.

Id put a actual gauge on it and go from there.

 

[-Nate]

QUESTION :

WHERE is the 2.5L oil pressure switch located ? .

I looked online and they said it's near the oil filter .

No, it isn't .

My presumably original O.P. switch weeps a tiny bit and doesn't turn the gauge on at all until 5 + minutes of driving, I looked but don't -see- the darn thing .

TIA,

 

[scotts90ranger]

Rear of the cylinder head just behind the intake manifold, roughly here:

Taking that long to come up is a bit much, I would question the switch and if that's working the oil pump seals might be going out, the oil pump is behind the auxiliary pulley on the timing belt on the '96ish and newer Lima's...

 

[-Nate]

THANK YOU ! .