I have a 2004 late build 02/04 6.0 ~175K miles, and hope to get help diagnosing my problem. I am experiencing low base oil pressure at idle and long crank conditions. I will give as much information as I have, but can possibly get more as questions arise.

The first indication of an issue was a “Check Gauge” light and low oil pressure indication at idle, after driving about 10 miles. After sitting an hour there was a long crank condition. The engine does start, but only after cranking for about 30 seconds. When it does start it runs normally with the exception of a low oil pressure condition at idle. If engine is stopped and restarted within a minute, start is immediate. Longer wait to restart results in long crank condition.
I have a Scan Gauge II and AutoEnginuity program with Ford Enhanced Powertrain.

Conditions during long crank, no start:
ICP = 0, IPR = 85, SYC = 1

Conditions after start at idle:
ICP = 752, IPR = 28.5, SYC = 1, FMP = 49.0, FLP = 13.0, LPO pressure - 700 rpm = 5, 1200 rpm = 18, 1800 = 28

What I have done so far to diagnose:

1. Changed oil and verified level before and after. OK
2. Performed filter out of housing fill test. OK
3. Held filter in position without cap, filled and verified housing check valve. OK
4. Removed and checked LPO regulator valve assembly. OK
5. Pulled ICP sensor on passenger side valve cover to verify oil present. OK
6. Performed cylinder contribution balance test. OK
7. Replaced the oil pressure switch and eventually replaced the switch with a gauge.

History:
Purchased 10/2006 48K miles
2008 – 2011 – replaced 8 injectors with stock OEM, Swamps 48V FICM.
2014 – 152K miles, replaced oil cooler, replaced 2 injectors, blue spring, MBRP 4" Turbo back exhaust, Sinister Coolant filter, PM EGR delete, EGT & Fuel psi gauges, 08 trans pan & filter.

I would really appreciate any suggestions or input.

 

Are your oil filter and oil filter cap OEM?

 

 

Yes the filter is Motorcraft and the cap is original. I changed the oil about 2K miles back and no issues until now. I will get a new filter tomorrow and stick it in there to make sure. Thanks Mark.

Thanks Bjorn. I have watched Ron's videos and will watch them again.

Steve

 

Clearly you now Ford's specs on the LPO since the data you posted is at the same rpm's as the specs. Definitely low.

Did you check for metal (with a magnet) behind the LPO regulator plunger? Was it (the plunger) installed/re-installed in the correct direction?

 

Yes. Nothing in there. I was surprised at how good it all looked. The "plunger" looked like new, except for one very slight wear mark at the spring end.

 

Might be time to pull the LPOP.

Before you do that, you did put in a 40 wt oil (or even a 30 wt oil)?

Also, I can't imagine you would have any fuel dilution of the oil since you just changed it, but you might check on that.

It is somewhat unfortunate you changed the oil - an oil analysis on the old oil (for metals) might have been helpful.

 

Rotella T6 both times. To eliminate fuel dilution question (or oil quality) was why I changed it after this started. No change immediately after.

 

So a question. How is the low pressure connected to the long crank? Doesn't the reservoir in the vee maintain a supply for the HPOP at shutdown? Understanding that it isn't enough for more than a very short time, but should be enough for startup supply to the HPOP.

 

It just doesn't sound like a HPO leak or even an HPOP issue, but who knows - maybe it is. Maybe an IPR valve problem could leak enough oil to drop the LPO pressures. Maybe the pressed in ball bearing on the HPOP came out also. Anything in the HPO system that would drop the LPO pressure should cause a no-start I would think (not just a long crank). What is also odd is that it would restart hot if attempted immediately.

Maybe time for an air test ..... before opening up the LPOP.

If it isn't one of the issues above, then I would guess it to be an issue w/ the LPOP or an internal engine issue.

 

Sometimes a bad leak in the HPO system can cause the HPOP to basically draw down the LPO pressures. I always thought that you would get a no-start from that though.

Several issues can result in the HPO reservoir draining down. I wouldn't think that that would cause low pressure in the LPO system though - especially after getting it started.

 

I ordered the IPR test fitting yesterday, just in case. I figure if I don't need it now .......

When its running the IPR and ICP look to be normal values, i.e. following demands of RPM changes.

 

That is what has me thinking it might be either an LPOP issue or an engine problem.

Edit ..............
One of cheezit's old posts has me wondering if a failed o-ring (between the HPOP and block) might cause this.

 

LPOP I can deal with. Let's stay away from an engine problem, please.

 

I hear you!

I added to my post above. In case you missed it -

"One of cheezit's old posts has me wondering if a failed o-ring (between the HPOP and block) might cause this."