Hey guys, thanks for taking the time to read my post.

I have a 2008 6.4L F350; It has 108K on it. Following a famous Walmart oil change, my oil pressure light came on. It comes on when RPM's are low, (under 900-1K). I have no loss of power, and the truck starts up normally.

I have replaced the oil filter, the oil filter cap, and the oil pressure sensor.

Does anyone have any idea on what might be causing the problem? Batteries on the truck likely need to be replaced, but the light only came on immediately after an oil change.

I read that the HPOP has a plug that commonly blows out on the 6.0's, but I cannot find anything about it on the 6.4's. Is there anything else that could cause this problem? How hard would it be to check to see if it's missing the plug, how hard would it be to fix it?

If anyone can find another related post, or pictures/videos, that would seriously help me out.

Again, thanks guys. Any help would be sincerely appreciated.

 

Does it still do it?

What oil did they use?

What oil filter?

Mine does it after it's warmed up, every time. 190,000 miles on it though. I most likely need to replace the front cover. The front covers come with new oil pumps.

 

Sticker says Conventional 15W40. I don't know if they had an OEM oil filter in, but I know that it has a motor craft in it right now. When I compared the two, they did look the same to me. The oil filter was free of debris, just had oil.

After I replaced the oil filter/cap/sensor I still have the problem.

Engine temperature doesn't effect it, light comes on at low RPMs, hot or cold.

 

Just at start-up?

 

Is their "Conventional 15w-40" rated for the 6.4?

 

No, any time the RPM's are under 1000, the light comes on. If the RPM's are above 1K, the light goes off. How warm the engine is/how far it's been driven has no effect on the issue. It's RPM driven as far as I can tell.

Off the oil's description online:
"Designed for heavy duty diesel and mixed fleets in all types of over-the-road service"

 

one of the problems with "retail" oil service centers is that they do not prime the filters....so the pump runs dry for the time it takes for the filters and such to fill with oil.

thicker oil will increase oil pressure....find out what the put in it and bump up the weight....im suspecting they put 5W40 instead of 15W40.

truth be told...when engines wear the tolerences change and blow by and oil pressure are two indcations....you cant put 5W40 in a 100K engine....it will just drink it up.

my truck has 87K on it...but the 84K prior to when I got it were hard miles...everything is worn out....if I don't use 20W50 motorcycle oil, she smoke like a misquito truck. if I put 5W40 in it...the engine sounds like someone is shaking a toolbox full of tools.

 

Can someone please help direct me towards the low pressure oil relief valve? Someone on another forum suggested cleaning it and I cannot for the life of me find it online or otherwise. Looking around the crank pulley, I couldn't find anything that looked like an allen head bolt.

I saw another thread a while back where this remedied the problem, and I'm going crazy trying to find it. I would sincerely appreciate the help. I will change the oil myself this weekend with OEM parts etc, but if the valve is clogged this won't solve the problem.

If the cleaning the valve+oil change doesn't fix the problem, I will bring the truck in. I understand I'm assuming liability by working on my own vehicle but I'm trying to learn my way around it.

Again, Thank you all for your help. I'm starting to go a little crazy trying to chase down this problem.

 

Is this it by chance?

 

Not sure this will be any help to you but I seen this awhile back and thought its worth putting up here. Hopefully it will shed some light for you. Good luck

 

I pulled the relief valve and cleaned it, (it is the circled item in the picture) this did not solve my problem.

Then, I opened up the oil filter housing, grasping at straws, and coincidentally and found 3 pieces floating around freely in the bottom. Can anyone tell me how to fix it? Will it cause damage driving in the meantime? I'm assuming it's a valve that can no longer close that causes a drop in pressure.

 

PROBLEM SOLVED!!

It is a drain valve that sits in the base of the filter housing. I found a picture online, saw that mine wasn't broken in any way so I just pushed it back into place. It clicked right in. Oil pressure is normal at idle now.

I hope this helps someone else!! I tried replacing the sensor, cleaning the relief valve, installing a new OEM filter/cap; which did nothing. Checked inside the housing, found loose parts.

My problem was the drain back/check valve in the bottom of the oil filter housing. Thanks to everyone who took the time to help out.