Oil pressure

[SoNic67]

What is the range of normal oil pressure on a V8 5.0L engine? I have:

Cold - 20PSI at idle, up to 35PSI when I rev up the engine. At 35PSI looks like the pressure limiter in the oil pump kicks in because it doesn't go over.
Warming the engine it takes it to 6-7PSI at idle in D (or 8-9PSI in N). At 2000RPM I have 12-15PSI. At 4000RPM it passes 22PSI.

This is with full synthetic oil. And 2 bottles of Motor Honey, because the gauge was oscillating at warm idle - now it stopped.
Any ideas? The engine makes some noise (lifters, don't know exactly), but still has compression.

 

[ranger7ltr]

That is awfully low oil pressure...

Especially when the engine gets warm...10 psi/1000 rpm is a general rule...Sounds like you have either a dying pump and a rapidly dying engine or a worn out engine with a good pump that can't keep up with the oil flowing past the bearings...

My V8 in the Ranger runs 60-80 psi cold idle, 30 psi hot idle...Pressure maxs out @ 60-70 psi from 2k up...My old V6 ran 65 psi cold idle, 25 psi hot idle, maxed @65 psi from 2k-up as well...

I think it is time to pull the pan and change the pump and see if it is just a pump before wearing out the engine with low oil pressure...

If it turns out to be the engine is too worn you haven't spent too much verifying that...Just a pump, pickup screen, and pan gasket... And some sweat equity in the truck...

 

[SoNic67]

I would have the pan down by now, but I cannot remove the engine. And don't know if I can drop the front end (and put it back on).
Thank you for your measurements, mine doesn't get past 40 PSI cold. Idle hot barley hovers over 5 PSI.
It looks like it is related with some other temperature, not with the water temperature. Water temp gets to normal in one mile, but I still have decent pressure then. Only latter, after some 10 miles, pressure gets that bad.

LE: I arranged with my mechanic to drop the front end and then the pan. Hope to find a lot of sludge there and/or a bad pump, if not... I'm f***t.

 

[SoNic67]

I have dropped my Exploder to my mechanic to replace the oil pump. If I have time to swing by while it is worked at, I will take and post some pictures.

 

[SoNic67]

i did replace the oil pump, strainer and... Pressure good at start-up, but still drops a LOT (7PSI) after the first 20-30 minutes of running at noon with 95F outside. In the morning (80's) drops less. Water temperature is constant. Castrol Syntetic 5W-20 oil.
Could it be that the oil gets too hot? And if so, why?
Is there any engine oil cooler better than original one for this V8 5.0L? Because I am out of ideas...

 

[sportrac2001]

Okey. I have a 01 sport trac 4.0 sohc. Thare will be times that when I turn my car on my oil pressure gauge will say tjat its low and ill turn my car off then turn it back on, is thare any reason behind that?

 

[SoNic67]

It might be an intermmitent contact. The oil pressure sender it is just a stupid switch (good/bad).

Now, related to my problem - I had read the water temp with a code reader and it said 209F (fluctuating). I guess that is part of my problem.
I had read that 185F is "the norm". At the parts store they sell thermostats for 160, 180, 195 degree "open temp" and the 195 it is marked as "OE temperature". I am tempted to get the 160F one. Does enybody have some input here?

LE: I did replace the thermostat and the lower water temperature (180 degree) did make a big change in the oil pressure.