Oil pressure jumps

irishrednek

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Mar 31, 2016
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Hey everyone it's been awhile since I've been on here, I transferred from California to Virginia. So as the tithe says my oil pressure jumps around. A bit of history first.

I started to drive it cross country with a uhaul coming into Arizona I had a some issues with it not wanting to pull up the hills. Considering I had some bigger hills to go through in Kentucky and the Virginias I decided to pull it on a trailer. I get to the new house unload everything and check the fluids top off what's needs topped off and drove it for a week an hour or so a day no issues. I filled up the tank Sunday night went out the next morning to leave for work and it wouldn't start. Found out that it was some watered down gas so I put some seafoam in and things worked great until the other day u noticed the oil pressure needle went from the middle to right on the N. Then the needle starts jumping around b,UT it never hit the low. It would hit the line and bounce back up to the N. When the needle would even out it would edge closer to the low line.

I was messing with it tonight and when I held the rpms at 2 everything was fine when it dropped down the needle would jump around then steady out. And randomly it would jump the steady out.

You guys are the pros here and yall have helped me in the past I'm hoping yall are able to point me in the right direction this time as well.

 

Seabronc

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With an old engine, Sea Foam sometimes reveals wear problems.  You could try a quart of Lucas in the oil and see if that smooths things out.  I ran for years on 10W50 and a quart of Lucas due to oil pressure problems.  Oil pressure is just that, the more wear you have the easier it is to push oil and the lower the pressure.  Also, you might want to put a new sender in place of the old one.  I also added a wet oil pressure gauge which is more accurate than the Ford one.  For hot climate running I would go with heavier oil and Lucas.

:)>-

 
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miesk5

96 Bronco 5.0
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Yo irishrednek,

As the Man advised.

Test & Installation Tips in a 90...same as 89; "...My oil pressure gauge was reading on the "N" of the NORMAL range. After doing some research it seemed like it could be the oil pressure switch, also known as a sensor or sending unit. Disconnect the wire from the switch, ground it to the truck and turn the key on. If your gauge quickly moves to the left, the problem is most likely the switch. The switch on my 5.8 is located near the oil filter. It is in a difficult spot to work on so I advise that you go to NAPA and get an Oil Pressure Switch socket to do the job. The cost is about $7-$8, this will save you time and will help you reinstall the new switch. Wrap some teflon tape around the threads and install. Make sure that it is in tight, I don't know about torque specs, I just put mine in quite snug. Hook the wire back on and start your engine. For me it was the cure. My oil pressure now reads over near the "M" on NORMAL..." miesk5 Note; The stock gauge & Sender will drop off after pressure reaches a certain level. You might actually have 6 psi, but the gauge will read 0 PSI"...by 420nitro

Installation, Sunpro,w/T for stock gauge in an 86

Source: by Sixlitre (Malcolm H, Eddie Bauer) at

http://www.superford.org/registry/vehicles/detail.php?id=4970&s=22156

Sender Failure; "Corrosion or faulty electrical connections; If the oil pressure gauge is pegged low after the engine is running, or is pegged high after the engine is running, or if there is intermittent illumination of an oil pressure indicator light, the sender could be faulty. Related Components to Check; All appropriate electrical connections to and from the sender The oil pressure gauge or indicator light; Appropriate fuses (see Shop or Owner’s Manual for fuse layout)..." miesk5 Note; enter applicable info for year, etc.

Source: by MOTORCRAFT®

 

irishrednek

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Mar 31, 2016
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Before I disconnected the oil pressure sensing switch I took note off what the needle did when the key was placed on and when I started the truck. Turnin the key on with the wire connected the needled pegged all the way to the left. When I started the truck the needle was on the N.when I disconnected the wire and turned the key on the needle pegged to the left I grounded out the wire and nothing happened. When I started the truck with the wire off the needle pegged to the left and the engine light came on. I figured that this would happen but I wanted to make sure that I covered all bases.

I'm going to take a guess and say that I probably have another wiring issue since the needle pegged while attached and stayed pegged when grounded. If the needle would peg when I grounded it then my thoughts are that the wire is possibly grounded out somewhere.

 

Seabronc

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Depending on the year of the truck, and I don't remember at what year it changed, the sender is a grounded variable resistor or simply a grounded switch.  Older ones had the restrictive sender and more recent Broncos have the switch type.  Also, just having thought of it, the sender must have good contact between the engine block and the sender threads.  Try removing the sender, cleaning the threads and re inserting the sender.  DO NOT use any Teflon paste or tape on the threads, they are designed to seal without that and using Teflon will mess up the connection.  A poor connection could make the reading erratic.

:)>-

 

irishrednek

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Mar 31, 2016
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It's been a awhile but I have finally been able to swap out the oil pressure switch with a mechanical one and as of right now the pressure stays steady at 50. But my engine light stays on how do I get this to stay off since the switch is not installed?

 

miesk5

96 Bronco 5.0
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Yo,

Is it the Malfunction Indicator Lamp (MIL) or Check Engine Lamp (CEL)?

If so, Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/?pid=74587&mode=threaded

Some basics;

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Then turn off engine, all accessories/lights (close driver's door) , etc.

Do KOEO test First

Post Code(s) here according to:

KOEO

&

KOER

If not, will need help, because this wiring diagram does not show an oil pressure warning Lamp.

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21140

 

irishrednek

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Mar 31, 2016
Messages
16
OK ill look into that when I get to the house. I took it for a spin and besides the light everything seems in order at higher rpms the oil pressure sits between 45 and 50 psi. And at lower rpms it drops and settles between 15 and 20 psi.

 

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