Oil Pressure

[ahodges]

I have a 96 Explorer with the 4.0 OHV. Does anyone know what the oil pressure should be running at when idleing warmed up?

 

[swetrid]

Ford manual only lists 2000 rpm which is 40-60 psi.

 

[ahodges]

hmm.. ok. I'll have to check that then. At idle its only 12psi so I was thinking its kind of low..

 

[swetrid]

I would say normally 15-25 psi at idle would be ok.

 

[windsors03cobra]

Old school rule and pretty much still applies today is 10 pounds per 1000 revs.
Seems most late model engines have 25-35 at hot idle of course and old Ford big blocks would run for ever with 10 at idle and 25 at speed.

 

[SoNic67]

About today engines: I did ride today in a 2010 Cammaro. Has 30 PSI at idle hot and past 70 PSI at 2500 rpm (has a little console with real indications).

 

[ahodges]

ok, thanks guys. sounds like the next step maybe to put a new oil pump in it

 

[ranger7ltr]

My 1999 Explorer 4.0 OHV runs 25 psi idle/50+ psi 2000 rpm...

My truck runs the same pressures in the new shortblock as the old shortblock with 179k miles on it...You might was to check bearing clearances when you change the oil pump...

You also want to check for sludge clogging the heads' drainback holes and the pan contents...

I really hope your replacement pump fixes the low oil pressure...

 

[jd4242]

Stock spec for the ohv oil pump on a new motor all good spec is 25 at idle and 54 at bypass.the mellings m328 high volume pump is a direct replacement and runs 34 at idle and 63 at bypass.before my build i would get down to about 12psi at idle now after the build i still get down to 23psi at idle warm.the ohv motor is the worst motor for oiling and thats why the rockers and pushrods wear sooo bad!

 

[ahodges]

ranger7ltr: Yeah the block that is in it now is a reman long block with 30k on it. I just had the thing out for a rattleing noise which was though to be the timing chain. I replaced the timing chain, guides, and sprockets. Along with one push rod and rocker which were worn pretty bad. So there is no sludge in it. I change the oil every 3-4k and it looks brand new inside.

Deffininatly sounds like I have low oil pressure but I wouldn't think its due to bearing clearances with this low of mileage on it...

jd242: Would a high volume pump hurt my engine if I put it in with everything being stock?

 

[jd4242]

Nope its a stock replacement.its only 9psi more but 20% increase in flow.its what these motors should have came with stock.it doesnt fix the poor oiling of the valve train but helps alot.most people do not ljke running a high flow pump but this is not a true high flow pump,it just puts you up to a standard pump numbers.if you was allready running 60-80 psi then yea there would be no need for a high flow pump but the ohv motor does not run that high.i have had NO problems with this pump and would tell anyone if the have the pan off to go ahead and put it in!!here is a thread i started awile ago about it.
http://www.explorerforum.com/forums/showthread.php?t=247048

 

[ahodges]

Ok thanks a lot! Chances are if you've been running it for 6 months with no problems, then there won't be any. I take it that your valve train quieted down a lot?

 

[jd4242]

oo yea.i had a cracked head and got water in my oil but i found it very fast so my clearances are close to the max,still in spec but high so my motor does run a little on the low side.the m328 is helping im sure with that also but yea its way quieter now

 

[RADIOACTIVE_TOOL_SHED___]

hmm.. ok. I'll have to check that then. At idle its only 12psi so I was thinking its kind of low..

Was it ticking? What did you end up doing? Mines at 10psi hot idle

 

[C420sailor]

This was posted 14 years ago

 

[410Fortune]

10 psi is a little low
But these old 4.0 have low oil pressure at hot idle for sure. I would consider so treatments for carbon build up. There are two or three ways you lose oil pressure in these old engines, 1 is carbon buildup and the most common, it clogs the drain backs and passages. But carbon can be broken up w solvents and detergents. 2 would be old crank bearings not able to hold oil pressure usually a little lower end knock will show up when you are at warm idle. They can run like this for years and years, 3rd would be a problem with the oil pump or pickup tube. Not very common as the oil pumps are very stout. So I would run some marvel mystery oil or sea foam in my oil changes and Mobil one oil see if you can’t get some oil pressure back in time as you bust up the carbon chunks

 

[RADIOACTIVE_TOOL_SHED___]

10 psi is a little low
But these old 4.0 have low oil pressure at hot idle for sure. I would consider so treatments for carbon build up. There are two or three ways you lose oil pressure in these old engines, 1 is carbon buildup and the most common, it clogs the drain backs and passages. But carbon can be broken up w solvents and detergents. 2 would be old crank bearings not able to hold oil pressure usually a little lower end knock will show up when you are at warm idle. They can run like this for years and years, 3rd would be a problem with the oil pump or pickup tube. Not very common as the oil pumps are very stout. So I would run some marvel mystery oil or sea foam in my oil changes and Mobil one oil see if you can’t get some oil pressure back in time as you bust up the carbon chunks

It's a fresh rebuild It's ticking when it's hot but I've heard others with 10psi or around that number and there's is just fine don't want to tear into it just to find out my oil pressure it to low

 

[C420sailor]

Not sure if you have a SOHC or OHV, but my SOHC was sitting at 55psi idle with about 50k mi on it.

How is it at 2000rpm?

 

[RADIOACTIVE_TOOL_SHED___]

Not sure if you have a SOHC or OHV, but my SOHC was sitting at 55psi idle with about 50k mi on it.

How is it at 2000rpm?

40psi it's the ohv

 

[410Fortune]

Ticking when hot? Like a lifter tick? A new engine should not tick at all
Exhaust gasket? Egr leak? Or lifter/ valve train tick?

New engine needs some time to break in as well 500-1000 miles the rings should be fully seated by then. Did you use break in oil?