2001 4.0 Oil Pressure

[MarshSt]

I just joined the forum looking for info on this issue and have found a lot of good stuff here.
I'm helping a friend with a 2001 Ranger with the 4.0 V-6.
Just finished new head gaskets w/head rebuild for coolant leaks.
Started and ran fine after we were done but the oil pressure gauge spazzed out.
Found out about the idiot light/gauge thing and now have a mechanical hooked up to check oil pressure. I have no idea what the oil pressure was prior to working on this.
Oil pressure now is 25-30 psi at start and drops to 12psi at idle after a few minutes.
We already ran Seafoam at idle for 30 minutes with no real change except a few psi drop at initial start. I'm thinking that is the oil thinning from the seafoam.
What it does now is 25 psi at start and down to 12 psi at idle after a few minutes. Revving the engine to 2000 drops the pressure a couple psi but no knocking or lifter rattle.
We're suspecting a blocked pickup so we dumped the oil and have diesel in the pan trying to soak out the intake screen.
I hope that clears it up but I'm wondering if we are overlooking anything.
It sounds like the cam synchro may be able to cause oil pressure problems and I'm wondering if it could be slipping or if they only fail outright. Any ideas would be appreciated.

Thanks,
Steve

 

[Big Jim M]

What?

I just joined the forum looking for info on this issue and have found a lot of good stuff here.
I'm helping a friend with a 2001 Ranger with the 4.0 V-6.
Just finished new head gaskets w/head rebuild for coolant leaks.
Started and ran fine after we were done but the oil pressure gauge spazzed out.
Found out about the idiot light/gauge thing and now have a mechanical hooked up to check oil pressure. I have no idea what the oil pressure was prior to working on this.
Oil pressure now is 25-30 psi at start and drops to 12psi at idle after a few minutes.
We already ran Seafoam at idle for 30 minutes with no real change except a few psi drop at initial start. I'm thinking that is the oil thinning from the seafoam.
What it does now is 25 psi at start and down to 12 psi at idle after a few minutes. Revving the engine to 2000 drops the pressure a couple psi but no knocking or lifter rattle.
We're suspecting a blocked pickup so we dumped the oil and have diesel in the pan trying to soak out the intake screen.
I hope that clears it up but I'm wondering if we are overlooking anything.
It sounds like the cam synchro may be able to cause oil pressure problems and I'm wondering if it could be slipping or if they only fail outright. Any ideas would be appreciated.

Thanks,
Steve

I really do NOT understand the word you used "spazzed".. Perhaps a better description of that was wrong with the engine when you replaced the oil pressure gauge would be better.

Most times when the gauge does funny things it is either the sendor or the wire to the sendor that has broken.

When driving on the highway what is the pressure reading? Do the lifters clatter? Diesel in the oil pan is about the worst thing I can think of for an engine. Get that crap out of there as soon as you can!

The parts that spin the oil pump either work or DON'T! There is no inbetween.. The reason to use the factory gauge is so you WON"T know what the actual pressure is. Guys tend to think they NEED more pressure than Ford thinks they do.

So what I'd say is to put a new sendor on there and if it runs then just run it.
There is always a chance the aftermarket gauge you have is lieing to you and the pressure is somewhat higher than it says.

Big JIm

 

[MarshSt]

The oil pressure gauge started to jump all over the scale as the truck was being driven and finally bounced itself over the top to the wrong side of the peg. I figured that the pressure was right at the switch cutoff and it was cycling on and off. Voltmeter readings confirmed that with both the old and a new replacement sending units. We've had 2 different mechanical gauges on it and they both give the same readings. Decent pressure at idle for a few minutes then down to about 12psi. The pressure does not go over 12psi even at 2000 or 2500 rpm. We have already removed some gunk from the pan and after we get it cleaned out and preoiled we'll fire it up and see if the oil pressure follows rpm. If not I guess it's time to pull the pan. It has 135K on it and it doesn't knock so hopefully the bearing clearances aren't just bypassing any pressure we get.

Steve

 

[Big Jim M]

filter

The oil pressure gauge started to jump all over the scale as the truck was being driven and finally bounced itself over the top to the wrong side of the peg. I figured that the pressure was right at the switch cutoff and it was cycling on and off. Voltmeter readings confirmed that with both the old and a new replacement sending units. We've had 2 different mechanical gauges on it and they both give the same readings. Decent pressure at idle for a few minutes then down to about 12psi. The pressure does not go over 12psi even at 2000 or 2500 rpm. We have already removed some gunk from the pan and after we get it cleaned out and preoiled we'll fire it up and see if the oil pressure follows rpm. If not I guess it's time to pull the pan. It has 135K on it and it doesn't knock so hopefully the bearing clearances aren't just bypassing any pressure we get.

Steve

The oil flters have a bypass valve in them that sometimes goes astray.. Have you installed a new filter of a different brand to see if that is the problem?

Also the oil pump itself has a bypass valve in it, that has been seen to go away in a few engines.

What oil is in there? Where are you?

The 135K on that engine is just about getting it broke in real good. Nothing in that engine should be considered worn out!

Big JIm

 

[MarshSt]

The oil and filter were changed during the initial pressure gauge issue at a Ford dealer so it had a brand new Motorcraft filter and oil before he limped it back to my house.
My buddy has a new Fram (not my first choice but at least we prefilled it) filter and Castrol 5w-30 to go back in before we start it again.

I was thinking it may be the pump relief valve but we haven't pulled the pan yet to look. We hooked my Accusump to it to pre-oil it before we restarted it last time and had about 30psi before he hit the starter. If the relief was bad I don't think we would have built that much pressure. We had the pre-oiler attached to the sending unit hole so maybe we didn't get an actual 30 psi down to the top of the pump.

Steve,
Black Diamond,WA

 

[Big Jim M]

Steve

The oil and filter were changed during the initial pressure gauge issue at a Ford dealer so it had a brand new Motorcraft filter and oil before he limped it back to my house.
My buddy has a new Fram (not my first choice but at least we prefilled it) filter and Castrol 5w-30 to go back in before we start it again.

I was thinking it may be the pump relief valve but we haven't pulled the pan yet to look. We hooked my Accusump to it to pre-oil it before we restarted it last time and had about 30psi before he hit the starter. If the relief was bad I don't think we would have built that much pressure. We had the pre-oiler attached to the sending unit hole so maybe we didn't get an actual 30 psi down to the top of the pump.

Steve,
Black Diamond,WA

Before I'd be pulling the pan I think I would invest in a few quarts of straight 40W and see what that would do to the pressure. If the pressure increases your problem prolly is other than the pump.
Big Jim

 

[Sasquatch_Ryda]

Minimum oil pressure at 2000 rpm (engine at operating temperature) is 15 psi so you are a bit low.

 

[MarshSt]

The 40 weight sounds like a good plan. Even 15 psi sounds too low at that rpm but at least it's a spec to referrence. We are going to work on it more this weekend and may be able to borrow a bore scope. Do you know which direction the relief valve sits in the oil pump?
Thanks,
Steve

 

[MarshSt]

It's better but why??

We flushed the diesel and Seafoam out of the oil pan and got quite a lot of small particles out. We reoiled it and ran it with the existing Motocraft filter. 30 psi at start and then it settled in around 22psi. Still no rise in pressure with revs although we didn't go over 3K driving it around to check it out under load. So we gained 10 psi.
My buddy changed the oil and filter after the test drive with a Fram filter and Castrol 5w30. He started it up and the pressure was 50psi at idle at start and then down to about 45 as it warmed up. It was pretty steady there and actually climbed a little with some revs but we didn't have time to drive it with the gauge on.
We were wondering what was going on so we cut the Motocraft filter open to see what was wrong and it looked only slightly dirty but otherwise good. There were a few of the small particles that we saw from the oil pan but nothing even close to plugged up.
He's driving it with just the original idiot gauge and we will put the mechanical on it again soon to check the actual pressure.
We didn't find anything obviously wrong but it appears to be acting right again. All I can think is something caught in the pump relief.

Thanks again for all of the input on trying to solve this.
Steve

 

[Big Jim M]

This post

We flushed the diesel and Seafoam out of the oil pan and got quite a lot of small particles out. We reoiled it and ran it with the existing Motocraft filter. 30 psi at start and then it settled in around 22psi. Still no rise in pressure with revs although we didn't go over 3K driving it around to check it out under load. So we gained 10 psi.
My buddy changed the oil and filter after the test drive with a Fram filter and Castrol 5w30. He started it up and the pressure was 50psi at idle at start and then down to about 45 as it warmed up. It was pretty steady there and actually climbed a little with some revs but we didn't have time to drive it with the gauge on.
We were wondering what was going on so we cut the Motocraft filter open to see what was wrong and it looked only slightly dirty but otherwise good. There were a few of the small particles that we saw from the oil pan but nothing even close to plugged up.
He's driving it with just the original idiot gauge and we will put the mechanical on it again soon to check the actual pressure.
We didn't find anything obviously wrong but it appears to be acting right again. All I can think is something caught in the pump relief.

Thanks again for all of the input on trying to solve this.
Steve

Tells me the bypass in the motorcraft filter went south on ya! Filters do have them ya know. Good news to hear.
Big JIm

 

[cowboykilroy]

The way my engine builder explained the oilfilter bypass valve was it allowed the oil to bypass the filtering element. No effect on the oil pressure just running unfiltered oil thru a race engine at 7000 rpms not good.Thats why we used HP1 motorcraft filters ,no bypass. If you think about how the filter is plumbed into the engine for it to cause a huge oil pressure drop it would have to divert oil back into the pan and there is no passage at that point in the system,that would allow that to happen. Sooo what you probably had was a piece of crud causing the oil PUMP bypass valve to stick open. I would ,and I did put a oil pressure gauge on my truck to monitor pressure and not trust the idiot light.

 

[baker2506]

What?

I really do NOT understand the term Big Jim used "funny things".. Perhaps a better description of you are trying to say would benefit all reading.

 

[adsm08]

What?

I really do NOT understand the term Big Jim used "funny things".. Perhaps a better description of you are trying to say would benefit all reading.

Until you posted this thread had not been active in a little over 9 years.