I have a 00 with the 4.6L and manual trans, when the outside temp is below 30 the dummy oil guage will read 0 at start up. If I raise the rpm's a little the guage goes up to normal!?! Let the rpm's drop and the guage drops. After the motor warms up the guage is fine.

Ford replaced the sending unit 2 months ago. Any thoughts????????



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2000 F150 XLT 4x4 Extended Cab

• Deep Wedgewood Blue
• 4.6L Manual Trans
• Ford Tonneau Cover
• Magnum Bug Deflector
• Panther 16x8 wheels with 285/75 R16 BFG All Terrain T/A
• 'Superchips' Performance Chip
• K&N FIPK (With custom mod)
• Westin Side Bars (Black)
• 3" Jardine Cat-Back Exhaust with Crome Tip
• Clear Corners
• Tinted Font Side Windows

 

I had a worry about a similar problem when the oil light came on in a Volkswagon Rabbit I had in college. The mechanic said to unscrew the oil fill cap and wait a few minutes after cold start up for oil to start squirting out of the opening (just throws a small stream). Sure enough it did and I just needed a new sending unit.

Otherwise is it idling fast enough? Could be effecting the oil pressure or the alternator/bad battery is not putting out the voltage so the guage fluctuates. If you have changed the oil regularly I would be very surprised if the oil pump or passages are clogged, even with high mileage. (My Rabbit had 160K on it and was fine).

 

Thanks for the advice, but the truck only has 5300 miles, the oil is full and is Mobile 1. I may not be idling fast enough, because when I give it a little gas the guage will go back up. Does anyone know what the rpm's should be on cold start up?

 

Does anyone think it could be the superchip or the mobil1??? Or could I just have another bad oil preasure sending unit?

Sean

 

Sigalph
Check your oil, is it still fresh, not thick, could it be bad oil ?.

Could also be a bad filter !., if you can chage your filer (Motrocraft at Walmart $2.97) and top oil level.

My engine starts at about 1500 RMPs, then it goes down to about 1200, then about 800 to 900 RPM for a few minutes, then will drop to about 750 RPM in Park.


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2001, F150 SuperCrew, 5.4, Limited 3.55, Trailer Tow, 255-70-16, Captain Chairs.
Assembly Date 10/4/2000.
*************** AUSTIN, TEXAS ***************

 

The "gauge" is supposed to drop when the pressure goes below 4 psi and I would think that if it dropped that low you'd hear it in the valve train (I could be wrong about that).

You might try cleaning the connection at the sending unit and making sure it's tight. If that doesn't do it remove the sending unit and attach a real gauge at that location to find out what you're real pressure is.

 

Sigalph,
I use the Mobil 1 with the motorcraft filter
and have no problems what so ever.
As far as the sending unit, I doubt that
you have that bad of luck that you received
three bad sending units. I know you might
not want to hear this but, next time you start the truck. let the pressure drop and see if it starts to knock, then you'll know that oil pressure is really dropping.
How many miles do you have on the truck?
Remember one thing also, Your boarding on the
lemon law. you paid too much to be putting up with this...
Good Luck!

 

sigalf- Mobil1 and Superchip here, no change on the gauge at all.

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2000 F-150 XL, RC, LB, 5.4L, 4R70W, 3.55LS,
Class III tow, Payload #3, & Convenience pkgs.,
4-wheel disc/ABS, Chestnut/Parchment 40/60,
Ford bedliner w/Paintsaver & gas/wheel/spare locks,
K&N F.I.P.K. w/Outwears pre-filter, Superchip,
Dynomax ultra-flow welded 3" cat-back w/ 3" Y-pipe,
Hellwig front & rear anti-sway bars, Rancho RS 9000s,
Mobil 1, K&N oil filter.

 

I have the same exact problem with my 5.4 on cold mornings. I am suspecting a loose oil pickup tube. On a cold morning when the oil is thick and gets pumped up into the top of the engine thus lowering the oil level in the pan below the point of the loose tube it then sucks air until oil fall back into the pan bringing the level above the loose area where the air leak is. When the engine heats up the oil thins out and returns faster to the pan thus keeping the level higher than when cold.

I would sure like to confirm this.

 

OOPS!

 

I am having same problem with oil pressure gauge. Just started with cold weather, today I filled up with gas and the gauge did not move up to full. Drove about 5 miles and shut engine off and then restarted and fuel gauge worked properly. Both gauges are on the same side of pod. Maybe electrical problem with dash? Any ideas?

 

Sigalph, I'm thinking it is the gage that is giving you problems. Oil pressure goes up when cold. You can test the gages easily.

Hold the trip reset button in when you start the truck. After it starts the odometer will say test. You now have it in test mode. YOu can do the same thing with out starting the truck just by holding the Trip reset button down.

Once in test mode you can let go of the button. Each time you press the button it will display a different test. The first or second test is for the gages. All gages will go come up, pause, then drop back down again. Try it cold and see if the oil gages moves normally.

You can cylce through and test it again, but it is a long way around the horn. Here is a link with more information:

HEC Diagnostic Mode

 

This is not the problem.

 

I have a 2000 f150 with the 5.4 and have the exact same problem. The first time it gets started after setting overnight
and its cold say maybe 35 or below the oil pressure gauge
will go up to normal. As soon as the idle comes down the
gauge will fall all the way down as if the key had been turned
off.If you rev it up the pressure will come back up but as soon as the idle comes back down the gauge falls back off.I have let it sit
with the gauge all the way down for a good while and no engine noise.I changed the oil and filter but it made no difference.After it warms up it doesn't do it and ive never had it do it after it sits at
work during the even if the temp doesnt get above 30. I really hope someone can help.

 

Could be...

Sending unit (oh no, not another one).

Clogged oil screen (In oil pan).

Oil pump.

Bad bearings.

How many miles on your truck?

Does your oil look dirty?

What viscosity oil do you use? (5w30)?

Is your oil level ok?