Have to ask, but did you check the level of the oil?, also what type of oil was installed? At this point a mechanical oil pressure test is needed. If it is indeed low then I would start with the low pressure oil relief valve and the LPOP. 6.4's do NOT have a HPOP.

 

I did check the oil level, if anything, it seems to be a bit high (thanks Walmart). I didn't address this issue because I didn't think high oil level would cause low pressure. My plan was to change the oil myself here shortly, but I didn't want to end up draining/discarding "new" oil, if the fix requires me to drain the system.

Where is the low pressure oil relief valve? How would I tell if there is anything wrong with it? What about the LPOP? Either fix expensive? Time to fix?

You also just explained why I haven't seen anything on the HPOP for 6.4's :laugh2:

Thanks for the input.

 

The LPO relief valve is in the bottom of the timing cover. If you crawl under the truck and look up at the crank pulley it will be the 12mm allen head that faces straight down on the 6.4. If you remove it, it has a spring and a metal sleeve that acts as the valve. You can pull it and clean it and see what happens, but a mechanical gauge is the best bet at this point. The LPOP is more intensive to do on a 6.4. The fan, crank pulley and LPOP housing has to be removed.

 

I hate to ask, but is there any chance you can find a picture online showing the area you're talking about? I'm 100% sure your directions are flawless, and I'm certain I'll be losing man points for admitting this, but I don't know what the timing cover/crank pulley looks like. I'm handy around the barn but no flavor of a mechanic/I've been very lucky with vehicles so far. Otherwise could you describe what the crank pulley/timing cover look like/where their relative positions are on the vehicle.

Again thank you for your input, It sounds like the valve could be the problem due to the timing related to the oil change (small particle could plug it open during the change?).

I will update with the results, hopefully this will help someone down the line.

 

Honestly I would just take it to a shop that knows these trucks and have them diagnose it for you. If it is a bone stock 6.4 with emissions in place it may be an oil pressure issue. Also verify the weight of oil they installed. At this point it may be cheaper to just dump the oil and put a fresh fill of 15w40 in it. I have seen many places run out of an oil and substitute with a 5w30 thinking it will be ok for the time being.

 

Can someone please help direct me towards the low pressure relief valve that Toren suggested cleaning? 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 the relief valve by chance?

 

Can you pull this without draining the oil?

 

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.

 

That is the valve. The one you circled in pic. Guess we posted at the same time lol.


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That's the stand pipe spring. It is designed to lock the filter out if you try to use the wrong one. Order the center stand pipe in the oil filter housing to replace it. It will come as an assembly. I doubt that was the issue tho. Unless the filter they used was too short and didn't close off the drain back valve in the bottom.

 

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.

 

So the moral of this story is to NOT let Walmart work on your truck.................

 

I can promise I won't be back...

 

Texas sport u mind sending a pic of the piece u put back my os acting the same and im lost.... Is it inside the filter housing or outside on the base?? Thanks im really worried