I drive a 2007 f-150 5.4 3v it runs perfectly down the road. But when I start it the engine knocks like it has low oil pressure. If I stop at a red light after a few seconds it knocks. But the oil pressure hand never falls any. I've replaced everything under the valve covers change the oil regularly and it does not show any signs of sludge. Any ideas?

 

I have read in other posts here that the stock oil pressure gauge is not an actual gauge, but rather a gauge type "idiot light". The sender unit is a pressure switch that operates at 7 psi and not a true sensor. To tell what your oil pressure is really doing you will probably have to install a real oil pressure gauge set-up.

From what you describe it certainly sounds like low oil pressure at start-up and low rpms.

 

Yes I've been told the same thing about the pressure gauge being a fancy idiot light. I'm contemplating changing the oil pump and flushing the engine. By the time I finish I could have bought a re-man long block.

 

Possibly loosing oil pressure due to a blown timing chain tensioner seal. How is the idle, is the CEL on or any VCT related codes?

 

^^^^ @cb 13 is most likely right.

I think it is an actionable misrepresentation for Ford to use a pressure "switch" set at about 7 psi, then represent the switch closure on an analogue gauge on the instrument panel indicating mid-range ( "L.....|.....H" ) on the analogue gauge as "OK". ESPECIALLY if the engine will Knock without the switch opening! See Forums ? » Torque OBD ECU Scanner » Torque Discussion / Ideas » ENGINE OIL PRESSURE is not importantTorque

 

It is showing a code for bank 1 running to something or over retarded. I did not know about tI'm in chain seals. I think I'm going to go ahead and let the shop replaces the pump pick up tubes and everything related to the timing chain and guides. Thanks guys.

 

Get them to check the crankshaft endplay. There was a problem with 2007 thrust washers wearing out causing the crank to walk back and forth. This causes the oil pressure to drop. Have them measure the oil pressure with a gauge, Ford spec is 15psi at hot idle but IMO it needs at least 20. If the crank is good and oil pressure is good then Ford has updated VCT solenoids that should fix the rattle. The part number is in my signature. Its also a good idea to replace the chain tensioners like cb suggested, they are bad for blowing out the seals.

 

X2 ^^ The crank end play check is a must. If the crank is the issue, then you will be chasing your tail replacing other parts. The new 15 PSI spec is not accurate. Around 19 or so, they will begin to knock. My 2007 5.4 3V holds 25 PSI after a long drive at idle, in gear. That is what they are supposed to have.