Bought a use 2010 Expedition with a 5.4, by the time we got it home it started running bad. checked everything and finally found a bad rod bearing, had the motor rebuilt (long block). Installed it and it would not hold oil pressure at hot idle, pulled and rebuilt again. Installed again, now it barely idles and the brakes are acting up like it is losing vacuum. Pulled intake three times looking for leaks, nothing found. Once it get hot it dies and will not crank again. Very little power when running. Any help would be great.

 

easy way to test for vacuum leak, block off the intake tube. I like to use a plastic cup. and then try and crank the engine.

it it sucks the intake tube accordion section down, you dont have leaks.
if you hear it whistle, thats your leak
if it actually cranks up and runs you have a massive vacuum leak



as far as lack of power, KISS (keep it simple stupid)
check for proper air, fuel, and spark

air we covered above, also check for clogged air filter. Compression test if necissary
fuel, simple fuel pressure check
spark, simple spark test



that being said the 5.4 3v is a bit temperamental and can frustrate even an experienced technician.... Its even worse dealing with a 3rd party engine rebuilder.... they can cut corners and end up forgetting something like an oil galley plug in a head which then means no oil pressure

 

Alright, tried the plugging of the intake tube and it will not start and does not whistle. As far as everything else written above I have done all those a couple of times. This one is really got me confused. The truck will start when cold and kind of run but down the road, no back fires or bad noise. Once it get hot it dies and will not run long at all when it does start. I have a bad thought it may be out of time on one side causing this but am not sure, plan to take covers off this weekend. Just thought someone might have had this happen to them before.

 

Any check engine lights? If so, post the EXACT codes.

 

whats your compression test results?

fuel leak down test with gauge hooked up?



[generally speaking] cam/crank sensors are known to have intermittent hot issues. If your issues is very linear and predictable as to when it will die every time, this probably isnt worth playing with

 

There's no test port for fuel pressure on a 2010 - but it's quite possible you have a corroded FPDM, that controls the fuel pressure by controlling the fuel pump.

 

im sure that would have shown up with his fuel pressure test "Several times"

 

It's my impression that the only way to test fuel pressure is with an OBD2 scanner?

 

you can add a tester to any vehicle with a quick disconnect. Vehicles don't have to have a "test port"

its essentially a hose with a T and the ability to add a test port in line with the fuel supply line



its not a cheap tool tho. Ive got 550 + tax just in my master fuel test kit

 

Alright, update---- Removed the valve covers and found the #7 cylinder intake rocker arm laying on it's side hung between the cam lobe and cam bearing housing. Has rubbed part of the lobe off and worn away the side of the rocker arm. Called rebuild shop who said this happens all the time, probably just when they do a motor. Anyway, they supplied a new cam, lifter, and rocker arm. I will install this weekend myself so I can make sure it's done correctly.