Oil pressure low - V8 5.0L

[SoNic67]

[Solved] Low Oil Pressure - V8 5.0L

I am baffled and out of ideas so... here it is.
My 5.0L engine has low oil pressure after warming up and at idle rpm's. At start is great of course, then it drops slowly. It doesn't drop with the same speed as the warming of the water - the water is done warming in few minutes, the pressure keeps dropping and hits lowest end at 20-30 minutes after start up...
What I have done:
1. Initially I replaced the oil pressure switch. The needle on the dashboard was oscillating fast (good/low). Nothing changed. Added a T and installed in cabin a mechanical pressure reader. Pressure with 5W20 Motorcraft oil was dropping below 5 PSI at warm idle. Starting oil pressure (at cold) was at 40 PSI. Added quickly 1 quart of Lucas oil and that improved some the situation - 7 PSI at warm. Lifters noise is confirming the low pressure.
2. Replaced the oil pump. My mechanic put a OEM one and nothing changed. New 5W20 oil, Castrol Syntec. Added again the Lucas additive (syntetic one this time) to keep it above 7 PSI. Now I wish would installed a high-volume one, but he insisted that OEM is just enough. That was an expensive "try to see if that is bad" kind of thing.
3. He read the water temperature with the scanner and it was in the 212F range. He said that the fan clutch might be bad. But the temperature gauge was showing constant temperature, smack in the middle of the scale.
At home I did replace the thermostat (195F) with a 180F one. Temperature dropped a little on the scale (like 1/4") and the oil pressure at warm was around 10 PSI.
4. Driving it, after some 3000 miles it dropped back to 7 PSI (at warm).
5. Replaced the oil. Kinda of dark for synthetic at not even 3k miles. Smells like gasoline a little (or it is my imagination?)
This time I put Mobile Synthetic 5W40 (for Diesel). No Lucas additive this time. Oil pressure starts at some 50 PSI and in 20-30 minutes is back in the 7-9 PSI range (above 5 and below 10 lines).
When I stop sudden (at stop light) it would fluctuate/pulsate for a little bit like the oil in the pan would balance (was doing that from beginning).
Lifters are just a tad less noisy (new oil)... No other bad noises that I can detect. Fuel mileage is average 16.5 mpg (mixed driving).

What would be next step to do? I was contemplating adding an oil cooler, but I wonder if that would do anything different than the "thicker" oil that I already use.
Drive it like that till dies ?

 

[ragajungle]

Unfortunately it may be a bearing or Cam problem. If you replaced the oil pump, filter and draw tube you really answered your own question. If you have a spun bearing it will allow oil to flow past it - lowering OP. Sad truth, but if you put a "true" mechanical gauge on and have no/low pressure and are ALSO getting valve train noise it's time for an overhaul.

Sorry.

Good on you for checking with a gauge and replacing Oil Pump First!

 

[SoNic67]

Yep, of course the oil pump came with the draw tube and filter. Didn't check any crankshaft bearings when I had it open, my mechanic said it looked "all right". I saw the pan - was fairly clean, no big metal pieces that I can see.
I can do some things for myself but lifting the engine to access that oil pump was more than I can do. Especially that all the exhaust manifold bolts where super-rusted.
If it was a main bearing spun - it won't loose all the pressure from the beginning? My "warm" pressure climbs up with the rpm's, I have some 18-20 PSI at 2000 rpm. I don't want to replace the engine if it is still something else to do. How can I check the cam's?

I did investigate the prices for a remanufactured engine - Ford dealership quoted me 2500$ plus 2400$ labor. That's not gonna happen.
What other options are? I saw prices on line between 1300-1800$ (less core) but I don't know the quality.
There is a shop close of me that gives 5 years unlimited miles warranty on their engines. Is that all right?

 

[ragajungle]

get a towing plan, keep up on maintenance, and drive it til it dies - hell it may never die (5.0L is a mad strong box) but save in the meantime. You can find a bunch of 5.0L's in any given Junk Yard. I saw 3 wrecks all under 100K miles when I went this past weekend. (in my JY one would set you back a whole $300)

 

[ragajungle]

One more thing. If you installed a gauge and it is reading between 5-20 psi - try pulling it outta the T and install a genuine oil pressure tester and see what it reads. maybe your cheapy is wacky. ALSO try a seafoam in the crank case. Maybe one of the oil galleys in one of the heads is clocked and some SF could clear it up?? Couldn't hurt.. Has it over heated recently?

 

[SoNic67]

Thanks for reply.
No, it is not overheating at all. Just sounds like a diesel
The oil reader is a cheap dial from autozone, but I think it reads consistent with the pressure-switch - when it was showing below 5 PSI, the needle on the dummy gauge in the dash was dropping too.
I was thinking to sea foam it, but... why it would show low pressure on the bottom (where the sensor is) if something is clogged up on the top?

 

[ragajungle]

I was getting my motors mixed up. I know on my 2.9L if there is excessive valve train noise and low OP chances are the cam bearings are spun. On that motor the cam produces the entirety of the OP for the valve train. If the cam bearing has a greater clearance (from damage) it will allow oil to leak passed the galley never making its way to the heads and lowering the oil pressure. At least I THINK that's how it goes

Probably pretty similar on your motor too I imagine.

 

[SoNic67]

Appreciate all the ideas, thanks. I am still trying to understand how the oil circuit is in a 5.0L engine and why takes so long for the pressure to drop. Almost seems like it needs the metal to get hot (not the oil), and dilate some gap?

 

[windsors03cobra]

It is normal for oil pressure to drop 20 pounds once the oil gets hot and loses viscosity. Anyway in most cases you start off with 50 or 70 pounds of pressure and drop to 30 or 50.
Some motors can run with low oil pressure and some cannot and the Ford Windsor line cannot, it doesnt have a strong rotating assembly to start with and I suspect your engine has been abused. I've done the abuse and seen the affects and sadly with a stock 5 liter this is normally the result.
Driven nicely the 302 is a tough long lasting motor and of course it can be built tough as nails as well.

The oil pump oils the cam and crank first then the lifters. Does it knock like a diesel upon cold start up ? Thats your main bearings talkin to ya. Windsor disease.

Junkyard motors can be had cheaply

 

[SoNic67]

At start is quiet (when I have 50 PSI). The engine has some 100k miles and I have it for less than a year - problems appeared after first oil change. The seller probably put high viscosity oil in it before it sold it to me.
I am vary to get a junk yard engine with the same miles - who knows if isn't the same and I will waste the labor.
I will just drop some Prolong in it, maybe it will help to delay the end.

Sadly this is my first Ford with the engine problems. I had owned 4 other Fords and usually the transmission was the problem at 100k or more. Now I wonder if that's next on my Explorer

 

[2000StreetRod]

Something to try

Warm the engine up until the oil pressure gets low, shut it off for 10 minutes, restart and check the pressure. If the pressure upon restart is back to normal then you may have oil starvation in the pan. Your oil returns could be clogged with sludge.

Did you replace the oil filter when you changed the oil? The filter could be clogged.

If you have an external engine oil cooler it's flow could be restricted.

 

[SoNic67]

I always replace the oil filter with oil change and I don't have external oil filter (yet).

Now that you said that, I remember that at my first oil change I saw that fenomen occuring - that's why I suspected the pressure sensor and replaced it. I used the Gunk oil flush too after that but it didn't helped too much with the pressure issue.

Now I don't remember doing that thing recently, but maybe I didn't paid attention. Thanks for the suggestion, it makes sense...
I will check again when I get home (now I am driving at work my 1996 Mercury Sable DOHC - most reliable Ford engine I ever owned).
I just added 40$ worth of oil and filter, but if that's the case, I will do it again this weekend. I did read that diesel fuel is also good for flush?

LE: C**p! Now that you said that, I realize that would explain why when I stop sudden, the oil pressure would oscillate for a short time - level of oil probably is low at that time and balance moves it in the pan. When I check the level is OK because it has time to drain... But wouldn't the optical oil level sensor pick that up thou?

 

[budwich]

pull a valve cover and see what's happening there. I suspect even with the your "shot of cleaner", if the wrong oil has been run (non-degerent, etc), that you will likely find your answer that you need a "good cleaning" every where. I had a GM bought used that I was amazed any oil flowed (flew???) at all as the valve cover(s) were both "full" of crap.

 

[SoNic67]

One of covers was pulled off when some work was done at the head block (spark plug broke and remover broke in there too). It wasn't too dirty... It's a pain to get those covers off, maybe I'll do it this week end if is not raining.

 

[slo5oh]

Sonic67,
You would not have been better off with a high volume oil pump. On a stock 5.0 they only cause other problems.
If you're not able to do any of the work yourself, this could get expensive. If you have the time and money, as others have said, you should pull a new engine (and heads) from the junkyard. Be sure you're not getting one out of a cash for clunkers aka CARS vehicle. These ones had the oil drained, liquid glass poured into them, then they were run until they seized.
Take the heads to a decent machine shop, pay the couple hundred $ the shop wants to clean them. I recommend you do a 3 angle valve job also.
Now the fun part... IMHO never, never, never run what you find at the junkyard. With the engine already out, you could have a mechanic do a complete poor mans rebuild, new rings, bearings, oil pump, timing chain. I can't say how much all this will cost you, as mechanic prices will be the biggest expense.
Something else to think about... if your mechanic already replaced the oil pump, you could have had him drop all the mains and replace the bearings just as easily. I've seen it done with a 5.0 in a mustang... it's bound to be easier on an explorer. At this point though I'd be worried that you hurt your valves by running them with low oil pressure.

 

[SoNic67]

I cannot win! This Exp is a never-ending saga...
Today wife took the Exp and forgot the lights on for some 5 hours. Started the Exp, and about right away, the CEL came on, some big vibrations and a huge thump... She called me to the rescue.
I get there - code P0340. Drove the Exp home slowly (at more than 50mph was shaking). Searched this forum - code is for Camshaft Position Sensor, but a lot of people reported that a bad alternator give that false code.
Measured my alternator - puts out 13.3V. The battery has datecode 8/2009.
So... I have bought a remanufactured alternator and is waiting to be swaped. 150$ at Advance Auto Parts with a 40$ off (a code for internet order). Hope that's all...

 

[ragajungle]

Sonic,
Sorry you are going through it with the truck. if the cam position sensor is throwing a code after a thunk there's a strong possibility that with all the starving of oil pressure you have officially spun a cam bearing. Stop putting money into this truck and start looking for a replacement motor and I wouldn't drive it anymore.

 

[windsors03cobra]

Yea that is a real shame to have be dealing with problems like that especially on a good engine like the 5 litre.
I know so many of us are daily driving reliable and good running 5.0 Exploders with 200k+ miles.

And with 13.3 volts on a year old battery I'm putting my money on those components are completely fine and your whole truck shake over 50 mph is your 302 saying goodbye. :thumbdwn:

 

[SoNic67]

OK, I have replaced the alternator. Voltage is now 14.5V at idle, the P0340 code cleared itself, truck doesn't "shake" anymore. Looks like the Camshaft Position Sensor Circuit is very sensitive to correct voltage.
Now I still have the problem with the oil pressure. Looks lik ethe Turbo Diesel oil 5W40 is doing a better job at keeping the pressure high - I did a few short trips and the pressure was always over 10 PSI. I am thinking to use some Sea Foam in it to try to clean the eventual clogged passages. Or use something milder like Auto-RX...
I did read about ATF and it doesn't look that good of an idea.

Could you see any other options?

 

[SoNic67]

Ok... updates.
Seafoamed. Drain the oil and replaced the oil with fresh 5W30 Motorcraft. Pressure changed back in worse.
I am still trying to clean the eventual blockages/ stuck lifters - now with Auto-RX. It needs to stay in the engine a while to work.
Another ideea - rading about the Camshaft Position Sensor and the Syncroniser, looks like the syncroniser gear trives too the oil pump. I wonder if the gear is all right in my engine?
I am posting a video of my oil pressure. Initiallly I was thinking that the oil level gets too low because it cannot return freely in the oil pan. But... maybe is that looking like the gear is not engaging corectly at low RMP? Anyone has a take on this?
PS: That is with the transmission in park. At the end of the video, I am putting it in drive and the pressure drops below 5 PSI. The dashboard dummy indicator starts to oscillate too (the OEM pressure switch sensor is opening/closing with that pressure).

Video of oil pressure oscillating at idle.

PS: The Motorcraft gear looks like it has some kind of phosphating treatment on it - can anybody thell if that is true? The other cheap syncronisers don't have that color.