Out of nowhere no oil pressure. My shitbox sport fail with arguably the worst engine ford ever made 4.0 sohc lost oil pressure. I changed a head out and replaced the timing guides and chains, tensioners. Runs like a ford lol. Anyways it completely lost oil pressure when i drove it for a test drive. No oil pressure at the top end first. The driver side tensioner failed or it seemed. Replaced it with motorcraft parts. Ran fine then lost oil pressure again. Ive got zero psi at idle and about 8 psi at 2500 rpm. I absolutely hate working on these ford small truck platforms. Its like they said **** the techs and just cram **** in and make it mediocre as **** and send it. So my question is, is the oil pressure relief valve in the pump.ive torn one apart and didn't see one. Or is it the small passage at the bottom of the housing under the oil pump gear shaft. Can the oil filter cause any problems. The oil cooler can it get clogged. Engine has had constant oil changes with motorcraft oil and is very clean inside. I do not use parts unless its real motorcraft parts from cheaper ford parts. Com or ford parts giant. Com. I doubt its bearings because i would have at least 2 to 6 psi pressure in idle and zero would be guaranteed rod knock. The engine had perfect pressure before. The ******* who sold me the truck didnt tell me all 3 chambers were cracked on the driver side head. It ran lean on my scanner and then cleared up when given gas. So i thought vacuum leak. And he told me the intake gaskets were bad. I love peoples integrity. Anyways i hate this truck and just want to fix it and sell it off like i did my ranger. 4.0s are junk. Any ideas on whats going on
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Well I think 99% of Ranger owners would disagree with you on the 4.0l SOHC engine, but to each his own, its a point of view an opinion not true and not false

There really is not a whole lot to the oil system, did you have the engine out?
And did you pull the oil pan to have a look at the oil pump pick up screen and the over pressure valve in the pump
With coil disabled, for a No Start, pull oil filter and put a pan down under it
Crank engine and see what kind of volume of oil pumps out with say a 30 second crank

Oil pressure reading is the oil the engine can NOT use at that moment, so pressure builds up in the main oil passage because oil can't get out thru bearing gaps and valve train
The volume the pump can produce will decide that pressure

 

Wouldn't my gauge tell me that. If i have no oil pressure then theres something wrong. Im probably going to pull the motor and put a junker one in. Ive not a lot of 4.0 sohc owner who've been happy with these shitboxes. Im not trying to continue to bitch about it. Its junk and the truck is going to get sold. Just wondering if anyone had any experience like i did. Perfect oil pressure then straight zero. Something blew out. But with all that great room under the hood its a lot of fun to work on it. This sucks. Im completely done with their small trucks. Im a ford guy but i call it as it is. Junk!

 

Well there is a oil pump drive that has a gear that can come loose, sheared roll pin, its on the top rear of the block, next to bellhousing, where a distributor or cam synchro would have been

Looks like this: https://www.explorerforum.com/forums.../a-jpg.306093/

And this: https://cdn2.bigcommerce.com/server1...0.1280.JPG?c=2

Here is a picture of the top rear of engine(its on a stand), red arrow is the hold down bolt and plate, green arrow is the top of the oil pump drive: https://www.explorerforum.com/forums...drv-jpg.60182/

I am assuming you are using a mechanical gauge for oil pressure testing, not the stock gauge and switch, which is just an on/off switch set for 5psi

 

Ive seen the input bar that goes from the pump to the distributor plug thing. Didn't know it had a pin. Yes im using a mechanical gauge. Could something like silicone cause the filter to clog up and block a passage. I would think there would still be pressure. Silicone was from the previous owner on the pan gaskets. I will look into that distributor plug here tonight thanks

 

Yes, I have seen pictures of silicone ***** blocking the pickup screen in the pan
It was from over zealous use of silicone on oil pan gaskets, when pan bolts are tighten excess silicone squeezes out inside the pan and eventually falls off and gets pulled in to the screen which blocks flow into the pump if there is enough of it
But you would have seen bits of silicone in drained oil if that had happened

Pulling off the filter and doing a Flow/volume test would tell you if that happened

I can't see how silicone could get into oil passages, maybe on a head gasket replacement, but like you said that would tend to make pressure higher not lower

 

well, there u go....previous owner is the issue here! Sounds like the peckerhead really screwed this thing up...sorry about your luck there! I’m thinking your best bet is probably a new motor from a salvage vehicle might be your best bet? My 2010 has 160k and beside regular maintenance, the thermostat housing needed changing..oh and I did a water pump, the first few yrs had issues with tensioners, but that was addressed.

 

I went out to the junker and got a new engine to drop in it. I will do an autopsy on the old turd lmao. Im betting something blew out on the pump or silicone is stuck in one of tensioner oil passages possibly causing the pressure relief valve to engage ?

 

So the pump on the new engine looks funny inside. Aren't the gears supposed to have the marks face up and aligned? Or does that matter. The outside gear looks like its upside down. The mark was facing towards the block while the shaft gear mark is facing down towards the pan.?? My other pump has both gears aligned with marks facing towards the pan. Anyone have any idea on this.

 

Can't say I have pulled a 4.0l oil pump apart, does it look like this: https://www.aa1car.com/library/2005/...p_assembly.jpg

 

This is a 4.0 sohc pump.note those marks .the outside gear square mark is facing down towards the bottom while the shaft gear is facing up just like the pic

 

And in (4x5) 20 rotations of the oil pump drive it will be lined up like your picture again.

 

Nice but it doesn't tell me about the mark being upside down on my pump. The pic i sent isnt my pump. Im actually not able to send a pic of mine as im deployed at work. 20+ days out of state at the moment.

 

Those aren't timing marks, they are just manufacturing marks they are meaningless.

 

Update. Sorry for the late reply. Its been trash the whole summer. 80+ to 100 all damn summer lol. Not working in that. So it turns out the primary tensioner failed, and in doing so, it unblocked one of the oil galleries on the front of the block. Thats why i lost all "oil pressure".

 

Thanks for the follow up and update

Man that is some good(bad) chunks of debris