03 5.4L 2V - new oil pump won't prime

[Eric M]

I just completed reassembling the motor after doing the head gaskets. I followed FordTechMakeuloco's procedure for priming the pump (crank motor with crankshaft position sensor unplugged until pressure guage shows pressure).

I did this several times with no change to the pressure guage. There should no issue with debris in the oil pick-up (timing guides weren't chewed up, etc.) and I definitely installed the o-ring between the pump and pick up tube.

I decided to remove the oil filter to see if oil was reaching it. It was full of oil BUT the oil was cloudy. I just added new oil!

So, I guess I have two issues that may be interrelated (??): cloudy oil and no prime.

Thanks in advance for any input you might be able to offer.

 

[Hamfisted]

It does take about 30 seconds of cranking for the oil to pick up and circulate before you get a oil pressure indication. How long are you cranking it ? I think you said you drained and installed new oil and filter, right ? Did the oil pump seem to seat correctly when you bolted it down ? Oil pressure sending unit still plugged in ?





.

 

[Eric M]

It does take about 30 seconds of cranking for the oil to pick up and circulate before you get a oil pressure indication. How long are you cranking it ? I think you said you drained and installed new oil and filter, right ? Did the oil pump seem to seat correctly when you bolted it down ? Oil pressure sending unit still plugged in ?





.

I cranked for 10-15 seconds, but I did so several times. I'll try the 30 second crank and see if it works.

Yes, new oil and filer.

Checked the oil pressure sending unit and it looked fine.

The pump itself seated with no problem and I double checked the torque on those bolts.

I definitely put the o-ring on, but I had a heck of a time getting that last pick-up tube flange bolt in, which makes me wonder if the o-ring was damaged with all the fiddling around.

(Regarding the cloudy oil thing I mentioned, I don't think it is related to this problem. When I pulled the heads a good amount of coolant went all over the place and probably ran down the oil passages into the pan, which made the new oil cloudy (?). They have been sitting together in the pan for a couple of weeks now.)

 

[Eric M]

One follow-up question: I did install the high pressure Melling pump. Might this one be harder to prime by just cranking the motor?

 

[Hamfisted]

One follow-up question: I did install the high pressure Melling pump. Might this one be harder to prime by just cranking the motor?

No. They're about the same as far as that goes.
If you have the Expy up on ramps don't be surprised if your fuel pump inertia cutoff switch got triggered and you have to reset it.



.

 

[Eric M]

I did a few 30-40 second cranks and still no pressure. So, I pulled off the filter for a second time and, again, it was filled with oil and a good amounted of oil came pouring out of the orifice on the oil filter adapter.So, some oil was moving around in there.

I know many of you will disapprove of what I did next, but I started the motor to see if pressure would rise. It only ran for 2-3 seconds before I shut if off. But the pressure gauge didn't budge and the "low oil pressure" light stayed on.

At this point is it even worth hooking up a gauge to the oil pressure sensor orifice, or is that just a waste of time? I'm thinking I should check power to the oil pressure sensor plug too.

 

[Hamfisted]

Did it sound and run normal ? No clattering from the top end ? It'll clatter if those valve lifters don't get oil pressure. Either replace the sender or hook up a manual gauge to confirm what kind of oil pressure you're getting. It's a 1/4" NPTF fitting.


Oil Pressure Test Kit on Amazon

Motorcraft Oil Pressure Sending Unit at Rock Auto



.


.

 

[Eric M]

Yeah, the motor sounded exactly like it should, no unusual sounds at all. Thanks for the recommendations. I'll buy a manual gauge and we'll see what happens.

 

[Hamfisted]

Sounds like the sending unit is bad ? Did you ever have any issue with oil pressure indications before you did the rebuild ?






.

 

[Eric M]

Never any issue with oil pressure lights before rebuild. No codes are being thrown either. I just happened upon a video and it appears that this priming problem is fairly common. I am going to take a pressure reading (when my gauge arrives) and then use the priming method suggested in this video:

Melling m360hv prime after no oil pressure after install- unedited but valuable info if you need it

What I had to do the prime a Melling m360hv oil pump on a 5.4 3v Expedition. Sorry I am not a video producer so this a bit rough but wanted to get this info...

www.youtube.com