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OT - 1992 Ford F-150 w/fluctuating oil pressure...

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Tip

01-27-2005 04:55:24

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I have a new to me 92 Ford F-150, 302, 4 WD, 90K miles. The oil was just changed and now the oil pressure is going off the scale to zero at idle, sometimes. It shoots back up if you hit the accelerator a bit. While driving, it sometimes drops off when the RPMs fall below around 2000. I changed the oil pressure sensor and the oil filter and no joy.

Any experience out there? I am probably going to install a temporary real pressure gauge and see where I really am.

Thanks, Tip

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Nate1992Evan

02-12-2006 16:42:48

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

I just ran into the same on my 1992 club wagon (same as E150 I think) that I had just picked up. Just bought it and it sat for 3 weeks, start it up and the pressure dropped low but not zero. Next day started it and it went to zero. I changed the oil / filter / sending unit still zero. Used engine flush, still zero. I thought the oil screen was clogged at that point and walked away and thought about it..... Ran and grabbed a cheapo mechanical gauge and put it in and it shows perfect pressure. Sound like the post I had read earlier about the dash gauge chip failing was right.

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Red Raider

01-28-2005 13:01:03

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Before you do anything, replace the sender. I had the same indications you did on an "87 F-150 inline 300. Fixed it.

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Hermit

01-27-2005 20:02:17

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Although your vehicle is 12 volts, I believe some of the instrument gages work at lower voltage. There should be a voltage reducer, usually an IC chip, that regulates the voltage. If this IC chip is going bad, the output voltage will vary randomly causing some erratic readings. If this IC is bad, usually the whole back board behind the gages is changed.

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thejdman01

01-27-2005 18:32:37

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

very well coudl be electrical and hopefully you find the kproblem as eletrical can be suratic and quirky but even if it is an electrical problem id still run a motor flush next oil change. depending on your driving on my wifes truck as she does stop and go doesnt go real far ie never warms up burns condensation out of the block i run a flush ever other oil change. i wouldnt run a flush i fyou just changed the oil but certainly next time i woudl recommend it

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fred kobs

01-27-2005 17:40:21

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

not that it'll help you any Tip, I just wanted to post a general reminder for oil changes. If at all possible put as much oil in the new filter as location allows b4 you install it. i wholeheartedly agree w/mechanical guage. fred

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HUSKY

01-27-2005 17:12:17

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

UNFORTUNATELY I WENT THROUGH THIS PROBLEM APPOX 2 YEARS AGO SAME THING DID THE SAME THINGS OIL PUMP WAS BAD RUINED THE ENGINE $$$$$$$$ PUT IN A REBUILT ENGINE NO MORE PROBLEMS THIS IS A VERY WELL KNOWN PROBLEM WITH THE 302 ENGINE SORRY GOOD LUCK HUSKY

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Tip

01-27-2005 16:44:55

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Thanks for the helpful comments. I played a little today - started fine and ran with normal oil pressure for about 30 minutes. The engine is strong and sounds good with no ticking etc. Got in to move it and down the pressure dropped. I then fooled around with the connection to the new sending unit and "fixed" the pressure or so it seemed temporarily. I took it for about a three or four mile spin and it worked great until I got home and then the pressure dropped again. So, I went out and bought a mechanical gauge. Its too cold to mess with tonight, but I will put it in tomorrow and report back.

The problem is so random that I am guessing electrical, but I am not going to ruin the engine with low oil pressure. Otherwise, I'll be dropping the pan.....

Thanks again!

Tip

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Old Ford Mechanic

01-27-2005 17:10:27

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 16:44:55

Tip,A couple of guys have already touched on what i beleive is your problem.For some reason Fords have had problems with the screen on the suction tube for the oil pump.The screen tends to clog up with deposits from the engine.this is very common in engines that are not serviced regularly.Go to Autozone and buy a quart of motor flush.It is sold under various names such as "RISLONE" and others.Follow the instructions on the container exactly.Then drain out the oil and replace with new and change the filter.I have had several come in with this problem in the past few years and this almost always solves the problem.The restriction causes the pump to lose its prime and suck air instead of oil.Changes in RPM's and ect. cause this.Clean it out and i'll bet your problem will go away.I have had to clean them a couple of times to get the pressure back up to par.Before spending a lot of money try this,it'll be the cheapest route also.I'm not picking on Fords i've seen this in others brands also.

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Tip

01-27-2005 19:13:52

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Old Ford Mechanic, 01-27-2005 17:10:27

Thanks for the help. My neighbor runs a garage and is betting it is a clogged screen. He wants to drop the pan and manually clean it - I'm all for trying to flush it out first.

I'll get on it tomorrow and report back..... ..though I am sure wishing I had a heated garage - about 0 right now on its way to -8 ..... .

Tip

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MAC,IL

01-27-2005 14:09:57

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Tip: You got some good advice except zach's. I would also start with a mechanical guage. I suppose it is not out of the question to have an electrical problem here. More than likely you are going to have to drop the pan, engine may not have had regular service. Lots of sludge. You can check the bearings, oil pickup screen and all that with one go at it. From what you describe, it sounds like a sticking by pass. If they used excessive RTV cement for the gasket as it seems most do anymore, there may be some that has turned loose and messing with pump screen pickup.

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01-27-2005 12:21:40

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

You do have good little engine there, the last 2 I had both had 302 EFI in them and both had over 200K when I traded them. I do remember on my 1992, I had a pan gasket leaking, the man who fixed it suggested I put a new oil pump in, said Ford put aluminum pumps in this engine and it could loose pressure. I think that was the reasoning, I trust him, so I do beleive it to be right. it is bad to get old and cannot remember

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Van in AR

01-27-2005 11:56:14

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Had the almost the same problem on a 1995 F-150. Oil pressure was normal at idle and would drop off at RPM to zero. As directed by advise here, ran 2 qts diesel through it for a hour at idle, drained oil, refilled and used 1 qt of motor flush, idled about 10 minutes (directions said 5) drained out and changed filter, had solids in back of filter that would not pour out, cut open filter and it was full of gunky tar. All this on a engine that gets a oil change ever 4000 miles. Figured that the oil pickup was clogged. Yours may be a bad bypass, but may be sticking.
Van

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Van in AR

01-27-2005 14:38:27

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Van in AR, 01-27-2005 11:56:14

Also noted during my problem is that Ford has not used real gages since about 1989, all you have is a NO PRESSURE/PRESSURE gage, ever notice how it always has the same pressure regardless of rpm or load? Its just a idiot light without the bulb.
Van

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big fred

01-28-2005 12:11:14

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Van in AR, 01-27-2005 14:38:27

That's because Ford discovered that the failure rate for the pressure senders was so much higher than for the oil pumps that they ended up having to do unnecessary warranty engine replacements.

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zachh

01-27-2005 12:26:43

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Van in AR, 01-27-2005 11:56:14

Just goes to show you what worthless peices of junk fords are wearing out a only 90,000 miles. Just my take on it

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big fred

01-28-2005 12:08:56

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to zachh, 01-27-2005 12:26:43

I'll keep that in mind if my F-150 breaks down at 90,000 miles, it only has 197,000 on it now. Fortunately I'd be able to drive my Econoline (193,000 miles) or my Ranger (175,000 miles) until I got it fixed.

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rocker

01-27-2005 13:54:59

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to zachh, 01-27-2005 12:26:43

Nice ignorant comment, Zach

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zachh

01-27-2005 16:27:18

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to rocker, 01-27-2005 13:54:59

Maybe be ignorant but surley true

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dr.sportster

01-27-2005 13:15:23

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to zachh, 01-27-2005 12:26:43

KInd of a not helpful answer zachh.He might know the answer to your next Chevrolet problem.

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thejdman01

01-27-2005 09:20:50

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

i agree first thing to do is check it with a manual guage. screw out the oil pressure sending unit screw in guage if those results concure w/your guage on the dash then somewhere there is an oil bypass valve. not a ford fan so i have no clue. some like early 90"s jimmys had a remote oil filter houseing on the left fender in the oil filter housing there was a bypass/check valve also there was one on the oil pump. now heres the part you got to be super careful about running a motor w/o water is stupid and hard on it running a motor w/o oil pressure is terrible literally parts will weld themselves together so i would be hesitant to run it w/o oil pressure but sometimes the check balls in the oil pump get sludge and crud in them and prevents them from seating which prevents oil pressure from building. rarely does a spring break and rarely does the ball wear out as it is in oil all the time however it is relativly unfiltered oil (only by the screen which is poor filtration) rarely but sometimes the balls can wear but i have found it more to be the balls arent seating. sometimes a good and i mean good (amsoil) engine flush will take care of the problem but for engine flush to work the motor has to be running i would be hesitant to run the motor flush in the mtoor and wont do any good w/o oil pressure no oil pressure the oil and the engine flush arent circulating

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george md

01-27-2005 09:16:16

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

tip,

It's a disease of 302's since the advent of fuel
injection,ford was always short in the bearing dept and with the increased hp and torque from
injection they run out of bearings way before
the upper parts of the engine wear out.It happens
earlier if you work the engine as in pulling trailer or hauling heavy loads often. Put in a set of bearings before you ruin the
crank. Being an automotive machine shop I see this
condition quite often.

george

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RandyB

01-27-2005 06:05:40

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

I would try a mechanical gauge first and if still low oil pressure, look for clogged oil intake screen. Little strange that this happen after oil change or did you have problems before? Did you check for broken gasket etc around oil filter blocking port? Did previous owner have a problem and add a very thin oil to hide the problem?

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Revredneck

01-27-2005 05:59:10

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Tip, 01-27-2005 04:55:24

Tip, Sounds like you"re on the right track with the manual pressure gage. Have you changed brands on the oil or filter? I have seen certain filters cause strange problems. A new high quality filter is much cheaper than a major teardown. If the filter doesn"t help, then you"ll need to take off the oil pan and check out the relief valve in the pump. That"s a pain!
Good Luck and God Bless, Tommy

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T_Bone

01-27-2005 07:16:00

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Re: OT - 1992 Ford F-150 w/fluctuating oil pressur in reply to Revredneck, 01-27-2005 05:59:10

Hi Tip,

Along with what Tommy said, I wonder if a stuck open filter bypass valve would cause the erratic readings.

T_Bone

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