[Texascadillac42]

04 F350, 114k miles. Truck has a hard start/no start condition. Mechanical oil pressure gauge is installed in the low pressure system, and when the truck finally starts it builds about 25psi at cold idle. Which quickly drops to 15psi as the truck warms up, and will soon be at 0-5 psi when the truck warms up more. Can a leak in the HPO system be large enough to create a low oil pressure condition in the LPO system? Or should I be looking in the LPO system first? Thanks.

 

[Luke_]

yeah, ive seen it happen,

basically you need to verify that you have good oil in the sump, if you now know the oil is good, check oil pressure while cranking, if low try overfilling the crankcase by only a few quarts and re check, if this fixes it you have a cracked or damaged pick up tube, if still no change, remove the oil filter and have a buddy hold down the little button on the top of that black thing, and have someone crank the engine and watch that the filter housing fills up with oil,if it doesnt you need a new oil pump if it does fill up you can count on a hpop leak so big that the lpop cant supply the hpop with enough oil.


that should send you down the right path.

 

[Texascadillac42]

Oil filter housing will fill with oil. With roughly 15 sec. of cranking the truck will start and run. Oil pressure is virtually 0 on the LPO side, but the truck does continue to run. I will have a scanner here this afternoon to read the HPO side and see what the ICP is reading. I am still puzzled at how the LPO pressure can be so low, yet the truck still runs.

 

[Luke_]

are you are basing your readings off of the gage? if so, try to avoid driving the truck till you can get a scanner hooked up and see whats going on

 

[jetski86]

I have never seen a truck that runs and has such a large leak that it looses base oil pressure. I am not saying can't happen but this is all I do and it has never came up yet. Keep us updated.

 

[Texascadillac42]

Oil pressure is being read from a mechanical gauge screwed into the port on the oil cooler where the EOP switch is normally screwed in. Truck has not been driven or run more than a few seconds at a time for diagnosis since the problem occurred. I was using the information from Ford (among other things) as a basis for my diagnosis

19417 2003-2007 F-SUPER DUTY/2003-2005 EXCURSION 6.0L - WATCH FOR OIL FLOW FROM THE BASE ENGINE OIL PUMP
SOME 2003-2007 F-SUPER DUTY AND 2003-2005 EXCURSION VEHICLES EQUIPPED WITH A 6.0L DIESEL MAY EXHIBIT LOW BASE ENGINE OIL PRESSURE CAUSED BY A LEAK IN THE HIGH PRESSURE OIL SYSTEM. IF A HIGH PRESSURE SYSTEM LEAK IS SEVERE, THE HIGH PRESSURE PUMP MAY USE A LARGER VOLUME OF OIL THAN THE BASE ENGINE (GEROTOR) PUMP CAN PRODUCE WHILE CRANKING. IF BASE ENGINE OIL PRESSURE IS LOW, REMOVE OIL FILTER, HOLD DOWN THE OIL DRAIN VALVE (LEFT SIDE OF HOUSING) WITH A SCREWDRIVER AND CRANK THE ENGINE WHILE WATCHING FOR OIL FLOW FROM THE BASE ENGINE OIL PUMP. IF FLOW IS PRESENT, USE THE UPDATED DIAGNOSTICS FOR THE HIGH PRESSURE OIL SYSTEM (ELECTRONIC VERSION OF PC/ED, SECTION 4, STEP 10E). IF THERE IS NO FLOW AT THE OIL FILTER HOUSING DIAGNOSE THE BASE ENGINE OIL SYSTEM FIRST (WORKSHOP MANUAL SECTION 303-01C).
EFFECTIVE DATE: 10/06/2006

 

[alexb]

Basically, if you have low base oil pressure, it can effect your high pressure system.
An issue with the high pressure system will not cause you to have low base oil pressure. The first step in diagnosing high pressure oil concerns should be to verify your base oil pressure.

 

[Texascadillac42]

The oil filter housing does fill with oil rapidly when the filter is out, drain valve is held down and engine is cranked. I can pull the low pressure oil pump out and look at it, its really not very much work.

 

[Texascadillac42]

I pulled the cover off of the HPOP and with a friend cranking it over, and the top pipe capped off there is a large amount of oil being pumped out of the side of the HPOP. Here is a picture with the screwdriver pointing out where the oil leak is.

 

[jetski86]

How did you cap off the top? I would be worried about the rust and moisture in the engine.

 

[Texascadillac42]

I just put a rag over it and pushed it down with my hand. Yea I would be worried too. I am not sure of how that much moisture got in the engine, unless it was head gaskets, but as far as I know they have never been done.

 

[Luke_]

well im glad you solve the issue, i have only seen this problem arise twice, once was a bad hpo stainless line, it gushed pretty bad, and the other well, it leaked at where yours is, if you remove the hpop you will see little casting holes and international or who ever manufactured the pumps pressed small little bb's in there, stupid huh? anyways on one of my trucks the bb came shooting out, and was soon found once the the hpop was removed, sitting their in the galley of the motor.

 

[Texascadillac42]

Yea I need to poke around with a magnet in the galley, and see if I have any luck finding the BB, otherwise it may have made it to the pan and gotten stuck to the drain plug.... I just hope it isnt floating around the motor somewhere.

 

[Luke_]

nah, something like that would get stuck long before if floated to anything critical, is kind of a decent size, so you very well may find it a few oil changes down the road lol.

im glad you solved your issue, now have fun putting it all back together.

 

[Texascadillac42]

Hopefully it will be back together tonight. The pump showed up this afternoon from International so it should be a couple hours and back on the road.

 

[Texascadillac42]

Well to answer my original question, can an HPOP leak be bad enough to cause extremely low LPO pressure? The answer is yes. Got the truck back together with a new HPOP, and my base oil pressure at cold idle is 75. Hot idle is around 30. 1200rpm, at operating temp is 45psi. Running down the road it is a bit over 50psi.

Thanks for all the help and advice on this one guys.