2010 Ford Ranger 4.0 Oil Pressure

[batchley13]

Thanks to everyone on this forum. I have read a lot to get through several issues and am stuck now and need some help. I replaced the 4.0 motor in my sons truck. It is a refabbed motor from a local machine shop. I got it in and it started first try. No leaks and gauges looked good. I took it out for a drive and the oil light comes on at idle. I know this is a big issue with these motors and I have watched several videos on people having to fix it.
At idle the oil pressure is 6 PSI, at 2k RPM's it is 31 PSI, and at 3k RPM's it is 42 PSI. The machine shop is telling me this is enough oil pressure for this motor. I don't think it is and really want to get it resolved. I did put new o rings on the oil filter housing when I put it on the new motor, I have a motocraft oil filter and am now running STP 5W-30 full synthetic. The motor has 475 miles on it. I just did the first oil change. The oil had air bubbles in it when I changed it. It looked kind of foamy. I attached a picture of it. I think the pump is sucking air somewhere. In my research it seems that the connection of the pick up tube to the pump usually is the place its happening due to poor design. I have done everything the shop suggested I do and the oil pressure is still too low.
I guess my next step is to drop the pan and look at the pump and pick up tube. My question is can I do that without pulling the motor. It is a 2 wheel drive ranger. I really think its the pump and just want to fix it as efficiently as possible. If anyone has any suggestions I would really appreciate it.

 

[tinman_72]

Typically 10psi per thousand RPM is all you need. At idle 6 is acceptable but it seems low for a freshly rebuilt engine.

 

[alwaysFlOoReD]

The oil looks foamy to me too. I'd be concerned. I've never rebuilt a 4.0 but did a 460 not long ago. I had to do some filing to the shoulders of the oil pump flanges so the bolts would fit properly. This was on a new aftermarket brandname pump. Quality control is not what it used to be...
I also made sure the pickup tube was attached securely and sealed.
Hopefully someone will chime in on whether the pump is easily accessible.

 

[batchley13]

Typically 10psi per thousand RPM is all you need. At idle 6 is acceptable but it seems low for a freshly rebuilt engine.

We are driving it. It seems to be fine and I hope that the oil pressure at idle is enough. The motor is still quiet and there isn't any rattling or anything.

 

[Uncle Gump]

The 4.0L SOHC has a lower pan that isn't bad to get off. Once off you should have access to the pick up and the oil pump.

 

[bobbywalter]

you are using a quality aftermarket gauge i am assuming?

 

[batchley13]

you are using a quality aftermarket gauge i am assuming?

harbor freight gauge set. Its new though.

 

[batchley13]

The 4.0L SOHC has a lower pan that isn't bad to get off. Once off you should have access to the pick up and the oil pump.

you cannot get to the pump from the lower pan. I ended up buying a new HV pump and a new 2 piece metal pickup tube to go with it. It has to be a 2 piece tube to get it installed on this model.
I was able to use an engine hoist and and lift up the front of the motor as high as it would go. I had to remove the intake manifold to get it high enough to remove the oil pan. I removed the oil pump the machine shop had on there and did notice that there was not a gasket between the pump and engine block. That and the pickup tube connection to the pump was over tightened and had cracked the plastic. I don't think that is what caused the issue because the o ring seal was not damaged on that. I think I was losing the oil pressure at the pump connection to the block. I guess its common practice not to put a gasket there on new builds but it did not appear to be perfectly flat looking at the wear on the pump flange.
I got the new HV pump in with gaskets and put new gaskets on the oil pans. I started the truck with the oil pressure gauge hooked up. It was at 60 psi on cold start which is way over what I was getting before. And after it warmed up it held at 14 psi. From the shop it would never go above 6 PSI and the shop would not help me resolve it. I was on my own so I just went ahead and did what I could. The ford dealership tech told me that 6 PSI was way too low and that it had to be at least 12 psi at minimum. The machine shop kept telling me that 6 PSI was fine and they were not going to do anything unless the motor got noisy. I really couldn't believe that a machine shop would say that.
The issue is resolved and I feel good about it. It was a pain to replace but having the oil light coming on on a brand new motor is just not something I could let go. I am grateful that it is resolved and the truck should last my son many more years now. The motor runs much much smoother.
I think the problem was no gasket between the pump and motor block. I included a picture of that connection on the pump and the wear line on it.
So long story short, you don't have to pull the entire motor to drop the oil pan but it does take a lot of work to get it done.
Thanks for everyone's help.

 

[RobbieD]

Thank you for a very useful post, and great job on resolving the issue.

 

[Uncle Gump]

@batchley13

Is the truck 2wd or 4wd? There was just someone else that did an oil pump and had no problem.

I'm glad you got it resolved.

 

[batchley13]

@batchley13

Is the truck 2wd or 4wd? There was just someone else that did an oil pump and had no problem.

I'm glad you got it resolved.

2 wheel drive.