Low oil pressure caused by sludge in oil?

Well, I drained the oil containing engine flush - the oil came out blackish, not chocolate colored thank goodness. I installed a new oil filter and poured in 10w-30 conventional oil. The engine is ticking just like before. I used some wooden dowels to pinpoint the ticking of the engine... It is coming from the block, not the headers, and not the valve cover either.

Here's my question now... When I did my head install I placed everything back on the head as it was when I removed it ( rockers in their exact places along with the pushrods) I'm now reading about the whole putting cylinder 1 to TDC and starting from there... Did I mess up by not putting the engine to TDC? I don't remember any of my rockers being loose before I put the valve cover back on.

I feel like I should open the valve cover back up and at least put it at TDC for each cylinder and check the tightness. I'd hate for my ticking to be something simple as that.

 
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Valvetrain isn't adjustable. Possibly you could get better torque measurements by tightening rocker bolts with no strain on the pushrods. My money is on the famous ticking 4.0l lifters. Or leaking exhaust from the reinstall. If its lifters I'd leave it alone. Results of new cam and lifters on these amc motors could range from quiet running to catastrophic engine failure.....replacement part quality is terrible.
 
Rickyd said:
Valvetrain isn't adjustable. Possibly you could get better torque measurements by tightening rocker bolts with no strain on the pushrods. My money is on the famous ticking 4.0l lifters. Or leaking exhaust from the reinstall. If its lifters I'd leave it alone. Results of new cam and lifters on these amc motors could range from quiet running to catastrophic engine failure.....replacement part quality is terrible.
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If it’s lifters, damn these things are loud… This ticking is louder than my engine when I’m driving 55mph… worries me it sounds like the top end is getting half the oil it used to from all the “clickty-clacking”

The sound reminds me of a baseball card hitting the spoke on a bicycle wheel. The faster I go, the faster it gets 🤣😬
 
Update as of Sunday evening… Just running 10w-30 with a new filter. Took it for a ride to the grocery store (10 miles) on the way back I stopped at a red light and the infamous “check gauges” came on with little over 5-6 psi oil pressure. I revved up to 1100 rpms and it went back up to 10-15 psi then to 20 when I was going 55 mph… Seems to sound worse.

I did drive it a little harder hoping that would solve it but no, it’s like a ball and chain. Oil pan is coming off when I get the time after deer season (hunting guide)


 
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UPDATE: The sound is gone - always check your rocker arms... Cylinder 5 was loose, causing the ticking. All is fine now.

I've been running 5 quarts of 10w-30 with a quart of ATF for about a week to clean out the engine. Oil pressure is at 40 psi cold. Once the engine reaches 210F, I notice it varies with the rpm (as it should) and at 2,000 rpm it is at 20 psi. At idle it's right at 10psi. The only issue I have is that if I run in the gas station for something and park while its warm, when I go out to crank it again I get the 0 / check gauges beep until I get the rpm up to 1,000 - 1,500 rpm before the computer seems to realize, oh yeah, it has pressure.

Is this something to do with my computer or is the oil pump just having difficulty getting a reading when I restart the engine and it is warm? Once I get going down the road I'm back at 20-40 psi readings. I figure it might have something to do with the ATF breaking down my 10w-30 oil and when I drain and fill with fresh conventional oil/filter I'll be fine.
 
Update: I’ve been running a Mopar Oil Sending unit for a few months now and I’m getting 20-40psi when driving. However, when I start the engine from warm (195-210F) the oil pressure consistently registers low - enough to trip the CHECK GAUGES momentarily. If I start driving it goes back up to 20 and all is fine.

Is this something to do with my oil pump? I’m running conventional 10W-30 oil.
 
CODE5 said:
Update: I’ve been running a Mopar Oil Sending unit for a few months now and I’m getting 20-40psi when driving. However, when I start the engine from warm (195-210F) the oil pressure consistently registers low - enough to trip the CHECK GAUGES momentarily. If I start driving it goes back up to 20 and all is fine.

Is this something to do with my oil pump? I’m running conventional 10W-30 oil.
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Remind me if you ever put a real gauge on there to verify oil pressure. Not in the cab,just with the hood open while warm
 
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Rickyd said:
Remind me if you ever put a real gauge on there to verify oil pressure. Not in the cab,just with the hood open while warm
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I borrowed one from a friend before I put the Mopar unit on. The lowest it got to was 10 psi with the engine idling warm (210F) so I’m guessing maybe my computer connections need cleaning at the PCM?

I was hoping the Mopar unit picked the signal up faster but it didn’t make a difference. I do know that I have the best soak problem but I have never heard of heat soak causing a check gauge light to come on along with 10-15 seconds of 0 on the dash.
 
It most likely has to do with the coolant wearing the main bearings.

A heavier weight oil such as 10W-40 might help, or a high volume oil pump.
 
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JKP said:
It most likely has to do with the coolant wearing the main bearings.

A heavier weight oil such as 10W-40 might help, or a high volume oil pump.
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Yep. I'd try a high volume oil pump before pulling the motor out for rebuild. It can be done in the jeep.

It should get up to bypass pressure in the pump (40-50ish) without reving the motor too high. If its having a hard time doing that going off the mechanical gauge I'd try 10w-40 and then the hv oil pump.

No rattling,knocking etc at cold startup?
 
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Rickyd said:
Yep. I'd try a high volume oil pump before pulling the motor out for rebuild. It can be done in the jeep.

It should get up to bypass pressure in the pump (40-50ish) without reving the motor too high. If its having a hard time doing that going off the mechanical gauge I'd try 10w-40 and then the hv oil pump.

No rattling,knocking etc at cold startup?
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No knocking or rattles on cold start. It’s surprisingly very quiet and when cold the pressure shoots to 50 then to 40 when I get to highway speeds. Idles 20 psi warm.
 
This is what it sounds like when I start up from a warm engine and then I throttle it up a bit... Stays just a hair under 20 psi of oil pressure. What leads me to electrical is that I had noticed many odd quirks fixed by my cleaning up of the wires on the harness when I was installing the new cylinder head. It is odd even with a blown head gasket it didn't hit the check gauge on crank from warm.

 
I want to say that I'm having almost exactly the same issue as you.

On start up, I'll get a healthy 50 PSI. After a while and warm up, it'll drop to 20 psi

I do feel like there may be something clogged in the oil lines as very randomly, it'll drop to 10 and stay there and then with a little more RPM (under 3K), all of a sudden pressure will shoot up back to normal and stay there
 
@annihil8ted keep in mind that oil pressure is supposed to change up and down in direct step with engine rpms since the oil pump is engine driven. 10 PSI per 1000 engine rpms is a good rule of thumb for good acceptable oil pressure. And cold oil will generate a slightly higher psi since it is slightly harder to pump.
 
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ChasUGC said:
It sounds like something is tapping in your engine to me.
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There is a little bit of a tick on cold start but goes away warm. Nothing seems out of the ordinary minus the fluctuating oil pressure randomly. Start ups are always strong and healthy and random halfway through a drive, it'll drop to 10 regardless of RPM and then all of a sudden after a while go back up to 40+. It's almost as if there's a blockage and one there's sufficient pressure to push it through the bottle neck, pressure returns to normal.

@Jerry Bransford yeah that's what I've been reading online too but it's definitely been underperforming the 10PSI per 1K rpms. When low, it seems to just want to sit at 10 PSI and not move. I can definitely feel the thicker fluid on start too but that goes away after maybe 10 minutes
 
annihil8ted said:
There is a little bit of a tick on cold start but goes away warm. Nothing seems out of the ordinary minus the fluctuating oil pressure randomly. Start ups are always strong and healthy and random halfway through a drive, it'll drop to 10 regardless of RPM and then all of a sudden after a while go back up to 40+. It's almost as if there's a blockage and one there's sufficient pressure to push it through the bottle neck, pressure returns to normal.

@Jerry Bransford yeah that's what I've been reading online too but it's definitely been underperforming the 10PSI per 1K rpms. When low, it seems to just want to sit at 10 PSI and not move. I can definitely feel the thicker fluid on start too but that goes away after maybe 10 minutes
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I'd start by simply replacing the oil pressure sender which is an easy job, they commonly have problems. Avoid store-brand or other cheap sensors, go with the best quality you can find which does NOT include a store brand like Duralast from AutoZone. I'd go with a Mopar if you can find it or at least NAPA's best quality/premium sender.

On a Sunday years ago when my son's Grand Cherokee needed an oil pressure sender I went to AutoZone only because my Chrysler-Jeep dealer's parts department was closed. It took three different senders from AutoZone before I finally got one that worked properly. All three were the same Duralast part number. The first didn't work at all and the second worked backwards... high pressure indication at idle rpms, revving the engine caused it to indicate lower oil pressures.
 
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I think that may be the route I go. I don't want to run the engine any longer than it has to in this case as I'm worried about oil starvation and bigger issues. Hopefully it isn't already too far gone

For clarification, when we say oil pressure sender, we're talking about the mechanical pump? Or just the sensor? I see references to both and it feels they're used interchangeably but I want to check to be sure
 
annihil8ted said:
I think that may be the route I go. I don't want to run the engine any longer than it has to in this case as I'm worried about oil starvation and bigger issues. Hopefully it isn't already too far gone

For clarification, when we say oil pressure sender, we're talking about the mechanical pump? Or just the sensor? I see references to both and it feels they're used interchangeably but I want to check to be sure
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Just the sender, not the oil pump.
 
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