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No oil pressure after new oil pump and timing set

Started by AGrayson84, May 23, 2021, 05:50:02 PM

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AGrayson84

Hey everyone, I'm having a heck of a time chasing down an oil pressure issue after replacing nearly the entire front-end of the engine on my 2016 Taurus SHO with the 3.5L EcoBoost engine. Engine has just under 125k miles and though there hadn't yet been any issues related to the water pump or timing set I decided that before the weather got too hot would be a great time for me to get everything taken care of.

I did a new Melling M390HV (high volume) oil pump with the stock pressure spring that came in the bag, water pump, timing chains (all 3), timing sprockets, chain guides, chain tensioners, VVT actuators, camshaft sprocket/phaser bolts, etc. After getting everything back together I installed a new oil filter and filled it up to the top mark on the dipstick with fresh oil. I removed the fuel pump fuse and cranked it over 3 times, for a combined 25 seconds or so. This is all I've done in the past and have never had any issues, though this time I've learned my lesson to fill the oil filter before installation and/or prime the system via the the port for the oil pressure sending unit.

After thinking I had the oiling system nice and primed I reinstalled the fuel pump fuse and fired it up. Sounded awful, all kinds of noise so I shut it down. I figured maybe the engine needed to run a little longer to get the oil flowing, else I needed to try to at least determine where the sound was coming from. I gave it a few seconds and fired it back up and let it run for about for several seconds before the low oil pressure warning came on, and within just seconds after that the engine stalled out and wouldn't turn over with the ignition button. Figured the motor just seized up right there on me.

I jacked the car up and cracked open the oil filter and it was bone dry. I ran to the store and bought a 1-gallon hand pump sprayer, modified it to accept a fitting from my air compressor (regulated to 30 PSI), and connected the output of the spray pump to a 1/4" NPT hose barb so I could prime the system via the oil pressure sending unit port. I pumped 3 quarts into the system, and now the oil filter was dripping when I cracked it loose. Good stuff. I removed the hose barb from the engine and reinstalled and reconnected the sending unit. This time I held the accelerator to the floor and cranked the engine over for over 20 seconds in one doing. Figured that should have finished off the job. Started it up and a lot less noise, but still a low oil pressure warning. Tried it a couple more times (figured if engine damage was already done from lack of lubrication then I was already going to have to plan on a replacement, so it was whatever for me at that point) and the engine seemed to idle fine for several seconds and was responsive to low revs, but would stall out still.

I removed the oil pressure sending unit and hooked up and oil pressure gauge. I've cranked the engine over for over 1 minute between 3 different cycles with 1 minute rest in between (to let the starter cool), and the oil pressure gauge just reads 0 PSI the entire time.

Totally at a loss at this point. I didn't drop a rag into the oil pan or anything silly like that. I even flushed 2-3 quarts worth of fresh oil out the pan before installing the oil drain plug and topping it off. O-ring was properly installed on the pickup tube, and pickup tube bolts are torqued down to 89 in-lbs.

What gives??? And why would the engine continue to stall on me? I was extra careful to set the timing properly (I did oil pump, timing chain, guides, tensioners, phasers, VVT actuators, etc.) on my 5.4 3V years back.... everything is definitely good with the Taurus too). Not sure what else to do except drop the pan and inspect the pickup tube screen, but I have a feeling that's going to a lost cause. I've read today about other people having similar issues, but they seemed to get their system to prime in much less effort. Any ideas? Any solid help at all would be hugely appreciated everyone, thanks so much!!

-Andrew

Macgyver

What is the possibility that the new High volume oil pump is defective ?

AGrayson84

Thanks for the reply Macgyver! It seems like it's a possibility, just a bit unlikely from everything I've read about rotor style oil pumps. I'm not at the point of ruling it out just yet, it's just that tearing the timing cover back off is the last thing I want to do just yet, only to possibly find that the pump wasn't the problem.

I've read about several people having problems getting their new oil pump primed on their EcoBoost, and have seen people talk about going as far as taking out their spark plugs and cranking the engine over for quite a while..... I've now done that for over 1 minute (took 4 consecutive cranks to safely do it without overheating the starter) and still 0 PSI. So I'm basically just here wondering if there's anything else suggested before I go thru the hassle of replacing the pump and have the same problem again haha.

I didn't get a chance to drop the oil pan over the weekend, so that's on the agenda for today.