ford 5.4 3v low oil pressure

[gary]

Hello Everyone. i have a problem like many other people and would like to find the solution.
its a long story so here goes.
firstly i am a UK based american limousine service provider. i run six 2008 expedition/navigators with the 5.4 3v engine.

The first 5.4 i had issues with was a 08 navigator with 50k miles. the problem was Cam phaser issues, naively i changed the phaser and solanoids on both banks and sent the vehicle back out to work, weeks later the engine seized, it had picked up on the big end connecting rod bearings and crank.
I replaced the engine with a reman, problem solved.

Now i have another vehicle showing the same symptoms.
after a little research i decide to check the oil pressure on all the vehicles

vehicle – cold start psi — hot idle — hot idle at 2000 rpm (manufacture spec is 75 psi)

reman engine — 90 psi 40 psi 80psi

limo 2 60k 80psi 35psi 70psi

limo 3, 4 and 5 same as 2

now problem limo 68psi 25psi 60psi

so i have started tear down the engine
firstly i replaced the timing gear, cam phaser, solenoid, oil pump and chain tensioners.
i rebuilt the engine and the oil pressure was the same
68 psi at cold start 25 psi hot idle 60 psi hot fast idle

so i then decided to go ahead and change the 5 main crank bearing and 8 big end connecting rod bearings,
after a rebuilding and starting the engine i now have the following oil pressures.

70 psi at cold start 20 psi hot idle 58 psi hot fast idle 2000rpm

so the next step i replace both cylinder heads for reman heads, rebuild and test, the results are the same

70 psi at cold start 20 psi hot idle 58 psi hot fast idle 2000rpm

so i have today spoke to ford america who say replace the Oil pump with 5.4 mustang high output oil pump

can anyone shed some light on this oil pressure issue, as i have another four vehicle with similar mileage and don’t want to have to replace all the engines.

thanks for reading.

Topic

[Lorrin Barth]

My opinion is that that is enough oil pressure.

[Ryan Wofford]

Honestly as long as you are getting oil pressure and it’s fairly steady (not fluctuating much at a steady speed), I’d say you’re fine

[gary]

ok thanks for the reply,
i was hoping for some experienced technicians to throw some solutions in here.

if 25psi is causing me problems how can you think that 20psi will be fine ??

[Ryan Wofford]

You haven’t listed any problems, so how can I diagnose anything so far you’ve only told me that compared to other limos thisone has lower oil pressure, like I said low oil pressure isn’t a huge problem uless it fluctuates alot while maintaining a certain speed, no oil pressure is a problem however. Unless you can list more issues with the vehicle (CEL, knocking, performance issues, etc…) we can’t really help you

[gary]

my apologies, the 5.4 3v has inherent phaser issues, which i believe is caused by low oil pressure (i may be wrong)
this causes advance and retard issues, The vehicle in question will try to stall on deceleration and also developed a slight knock prior to changing the shells. The shells by the way were not damaged nor was the crank marked.
The VVT solanoid needs 25psi to function correctly, Given we had achieved 25psi in workshop conditions but still having problems when “on road duty cycle” i am trying to find the cause of the low oil pressure.

[Ryan Wofford]

I’m Actually kinda of agreeing with the dealer or the “ford America” I’m guessing that the added strain of the extra weight of the limo might emphasize the oiling issues, I would replace with a high output pump if possible on it and see if that helps, it would also solve the performance issues with the phaser. But Oil pressure is caused by the clearances between all the moving parts in an engine, the closer the clearances the higher the pressure, low oil pressure is caused by the excessive wear and expansion of these clearances due to a lack of lubrication, that is why your new engine has great oil pressure, I would install the high output pumps on all of the engines at some point as a preventative measure to keep this from happening to them and greatly extending the life of the engines, it sounds like the other engines are fairly healthy at the moment so you don’t have to do them immediately but if there is ever a chance where they’re not rented out for a couple of days I would put one in them.

[Author]

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