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"Low Oil Pressure" at low RPM, okay other wise???

32K views 7 replies 4 participants last post by  Levi'sford 
#1 ·
I'm loosing oil pressure when at idle or low RPM's. Stopped at a stop light and got a "low oil pressure" on guage cluster. Pulled over and checked oil. It was a bit low (not sure why, no leaks, never has used oil before!). Added about 3 qts (all I had), and re-checked, maybe filled a bit high. Started truck and oil pressure guage came up to normal pressure. After a few seconds guage dropped and "low oil pressure" again. Needed to get home, midnight, storm coming, and wife is due any day now. This was our last date night for a while! Anyway upon accerlerating guage came up to normal range, and everything seemed to be running fine. Turned into sub division and when let up on accelerator pressure drops and I get the trouble messege. Rev it a bit and it comes right up??? I'm just under 64k miles and was going to change my oil tomorrow. I will for sure as I think I over filled it a bit. Two weeks ago today engine light came on which resulted in a new EGR valve and Oil cooler. Or at least I think that's what they did. I have a hard time telling what they did for sure based on the paper work they give you. Any ideas???

On a bright side I think this just convinced my wife I need a new 11'!
 
#3 · (Edited)
Sounds similar to a problem I created with aftermarket oil filters. In the bottom of the oil filter housing there is a drain plug that opens when the filter is removed. If this plug is leaking you wont build engine oil pressure.

You can pull the oil filter and look into the housing with a flashlight. Way in the bottom at about the 2 o'clock position is a little button looking thing about the size of a nickel. Grab this gently with long nose pliers and make sure it operates freely up and down.

The idea is that the filter pushes this valve closed and it opens when the filter is removed.

FYI.. The gauge on the dash is a glorified idiot light. It is controlled by a pressure switch that makes at about 7 psi. The gauge will read either Zero or Normal. I installed a mechanical oil pressure gauge just so I could tell what the pressure really is.

Regarding understanding the repair ticket. Read it over real good and if you don't undersatnd something make them explain it until you are satisfied. Also its a good idea to always ask that all the "Bad" parts be shown to you. There is no excuse for the shop not to show you the bad parts.

I hope you have a backup vehicle cuase sure enough when the time comes the truck wont start or worse it will quit on the way to the hospital. Congrats on the new arrival!!!
 
#4 ·
I will check that valve. Our 04' had that happen because of an aftermarket filter. My truck has only seen Motorcraft filters all the way around. Also, great thread about your truck. Very impressive. I wish I had your ability to trouble shoot, but most of all patience. I love working on my truck, and the maint. is fun, but just not enough hours in the day anymore. Even under Ford's warantee by the time I drive it to the dealer (about 70 miles south), leave it for who knows how long, and then pick it up I'm out a day and a half at least. Oh well, hopefully it's nothing major, and as you say, it's a machine, it can be fixed! I will say the Ford dealer in Pueblo, CO on HWY 50 has a great deisel mech. If you break down around here ask for Pete, great guy.

Do you think it's safe to drive the truck the 70 miles?
 
#5 ·
I would trust the idiot gauge as far as I can push the truck. If your oil pressure is truely low then you run the risk of damaging the engine. If you don't put a real gauge on it to know for sure then I would not drive it.

A $300 tow bill is cheaper than a new engine.

I got a great tow bar I made for my truck. It has come in handy recently.
 
#6 ·
the gauge shows low pressure when you have less them 4 psi. engine needs at least 12 I believe is spec for the lpop gauge. most show 25 at idle and anywhere betweek 55 and 75 psi when running. just a thought but mabye you have a bad leak on the high pressure side, draining the low pressure system? low pressure pumps rarely go out. you have any oil dilution issues with fuel or coolant? mine was getting down to 10 psi when I had injectors leaking fuel. barely ran but that was with 5 qts fuel in the oil pan
 
#7 ·
If you are using 3 quarts of oil in between oil changes, and you do not see any leaks, then I would think you are burning it and something within the engine is wrong IMO. I assume it is not going into the coolant ....
 
#8 ·
Thank you for all the info. All of those ideas crossed my mind. I was lucky... only a sending unit... $180, and three hours later it's fixed, which is good casue I have haul a load of trees tomorrow. I don't think it used any oil. I was having a hard time seeing the dip stick, poor light at 12:30 at night. When I changed the oil today there seemed to be more in the oil pan than normal. Thanks again guys.
 
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