4.6 Engine Failure

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Jul 8, 2003 | 12:05 AM

Mark Parnell

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4.6 Engine Failure

I have a 98 F-150 with what should be a blown motor. Setting at stop light engine died, got it to restart but engine gradually started to make noise. Now oil pressure gauge goes to zero. Now motor is making A LOT of noise. After many cuss words I drive this truck two miles to my house with ZERO oil pressure. Now I have the motor out and there is no metal in the pan, no bearings damaged, both valve covers are off and there is no detectable damage in the motor. The only thing is a few dinged teeth on the crank position sensor and the left bank can chain tensioner is what I would call a little soft and the passage behind it was very stopped up with sludge. I’m sure it probably jumped time on the left side and this would account for the noise it made on the trip home, but the zero oil pressure has me stumped as the motor obviously had oil pressure or it would be burnt to a crisp. Does anyone have any ideas?

Jul 8, 2003 | 07:33 AM

jbabbler

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From: DIXIE

4.6 Engine Failure

There is of course the obvious one that I'm sure you considered, the Oil sensor is bad. I believe that the oil pressure gueage is actually a fake. The oil sender is in fact an on/off pressure switch on most Fords. It doesn't actually tell the pressure.

Jul 8, 2003 | 08:07 AM

Mark Parnell

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4.6 Engine Failure

This truck does have a gauge but not what I would call a good one. I think the oil pressure problem was a fluke but it's strange that it happened exactly at the same time. I have found over the years when problems come in pairs thay are most likely related.

Mark

Jul 8, 2003 | 11:27 AM

LxMan1

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4.6 Engine Failure

The gauge will read the same as long as you have over about 6lbs of pressure. There is a resistor in the line so when the oil light is off, it will read up around 1/2 or a little more on the gauge. So whether you have 10 lbs or 75lbs, the gauge will read the same as long as ther is enough pressure to keep the light off.
Could the passage to the oil pressure switch be clogged too?
Just a thought,
Jimmy

Jul 8, 2003 | 11:31 AM

jbabbler

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From: DIXIE

4.6 Engine Failure

Thats right LX, I just checked the factory manual and it shows a pressure "switch" instead of a sensor. It states that the switch closes when enough oil pressure is produced to trigger it. The needle should be just above the half way mark or all the way down if it has no pressure. The guage isnt real unless you installed a new sensor and cut the resistor.

Jul 8, 2003 | 11:36 AM

LxMan1

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4.6 Engine Failure

Yeah, Ford did that to keep people from bringing them into the shop all of the time due to normal variations in oil pressure. I thought about modifying mine by switching to the older style sending unit and removing the resistor. But not while it is still under warranty.
Jimmy