Low idle oil pressure, after high volume pump install.

[domsaleo]

Have you put a mechanical gauge on this motor to verify the oil pressure?

Do you have the original, stock oil pressure sending unit installed in this motor?

With the Melling High Volume oil pumps I normally see 32-34psi as my hot idle pressure and I am always using a mechanical gauge on my customers builds.

On the last 5.7 I finished a few days ago with Hellcat pump my hot idle was 39psi on the mechanical gauge and the instrument cluster showed 46psi on the stock oil pressure sending unit. I tested it against an O'Reilly special and it showed 45psi in the instrument cluster.

I still need to purchase the mechanical gauge. Been very busy lately. I recently replaced the oil pressure sensor. At cold start I'm showing like 80+ PSI on the cluster. The only time it goes down to the low 20's is right when it's at full op temp. If I give it just the tiniest bit of throttle it goes up to 30+. So I need to get the mechanical gauge on it to double check. I'll try and do it as soon as I can, and report back.

 

[Fast69Mopar]

I still need to purchase the mechanical gauge. Been very busy lately. I recently replaced the oil pressure sensor. At cold start I'm showing like 80+ PSI on the cluster. The only time it goes down to the low 20's is right when it's at full op temp. If I give it just the tiniest bit of throttle it goes up to 30+. So I need to get the mechanical gauge on it to double check. I'll try and do it as soon as I can, and report back.View attachment 562923

Everybody is different and that's what makes this world and this forum a great place. I really only like to spend my money once when performing repairs or when trying to squeeze every last ounce of power out of a motor.

That being said I would have never even started that engine without a mechanical gauge installed especially after installing a new oil pump. I don't trust parts, period, even if they are new. I have to see that part work before I believe it. The parts game is a racket and so many times it's a race to the bottom to see who can provide the cheapest part and when that occurs quality control goes south too.

 

[mrack]

I’m obviously not at all knowledgeable on non mds swaps, don’t you need a tune to do the swap anyways?

 

[Fast69Mopar]

I’m obviously not at all knowledgeable on non mds swaps, don’t you need a tune to do the swap anyways?

Yes you need a tuner or a custom tune to disable the MDS in the PCM.

 

[domsaleo]

I’m obviously not at all knowledgeable on non mds swaps, don’t you need a tune to do the swap anyways?

I have a super chips from many years ago I bought. I have had MDS disabled for years. Problem is, I wish I would have gotten the diablo to set the idle rpm just a tad higher, then I wouldn't worry about the low psi. Nonetheless, I still need to root out the actual issue if there is one.

 

[Fast69Mopar]

I have a super chips from many years ago I bought. I have had MDS disabled for years. Problem is, I wish I would have gotten the diablo to set the idle rpm just a tad higher, then I wouldn't worry about the low psi. Nonetheless, I still need to root out the actual issue if there is one.

What was your oil pressure at hot idle before the oil pump and engine repairs?

 

[domsaleo]

What was your oil pressure at hot idle before the oil pump and engine repairs?

it would drop down to the teens Sometimes. I won't lie, I didn't much look at the digital output. Mostly just checked the analog gauge on the dash. I know it was pretty low though.I had a oil leak that I thought was the rear main. Appears to be the same leak im having now where the crank position sensor is. So I was adding oil as needed. So here and there ran low oil thus the lifter failure. Pulled the engine and the rear main is perfect. Also redid the oil pan and gasket. Idk the mystery on why my pump seems to be perfectly fine except at hot idle. Again, could be my sensor. I'm on a mini vacation with the family right now but in a couple days I'm going to hook up the gauge and find out the true pressure. God willing it'll show 30+..

 

[Xsen]

Did you replace the spring in the Melling pump with the optional blue spring from the kit, that is supposed to keep max pressure @ about stock levels?

Given the 5-30 oil, even hot (or normal operational temp) idle should give you more than 20 psi. Either the sender is faulty, or you have a weird oil leak somewhere in the lubrication system... Have you checked all bearings for wear and their clearances when you were rebuilding the engine?

 

[domsaleo]

Did you replace the spring in the Melling pump with the optional blue spring from the kit, that is supposed to keep max pressure @ about stock levels?

Given the 5-30 oil, even hot (or normal operational temp) idle should give you more than 20 psi. Either the sender is faulty, or you have a weird oil leak somewhere in the lubrication system... Have you checked all bearings for wear and their clearances when you were rebuilding the engine?

I left the higher pressure spring in the oil pump since I was doing the MDS delete. I didn't do a total rebuild, the engine was a reman that had maybe 40k miles on it. Everything moved smoothly and appeared to be fine. Im not a skilled builder or anything

It eventually had the lifter failure I assume from the same oil leak that I am now dealing with. I even spread rtv all over the oil pan gasket to make sure it sealed. I'm still getting fresh oil on the block after driving. I never removed that camshaft sensor. I'm assuming it has contact with oil and maybe the o ring needs to be replaced?

(Didn't say this is the original post because I wasn't aware of it yet.)

 

[Fast69Mopar]

I left the higher pressure spring in the oil pump since I was doing the MDS delete. I didn't do a total rebuild, the engine was a reman that had maybe 40k miles on it. Everything moved smoothly and appeared to be fine. Im not a skilled builder or anything

It eventually had the lifter failure I assume from the same oil leak that I am now dealing with. I even spread rtv all over the oil pan gasket to make sure it sealed. I'm still getting fresh oil on the block after driving. I never removed that camshaft sensor. I'm assuming it has contact with oil and maybe the o ring needs to be replaced?

(Didn't say this is the original post because I wasn't aware of it yet.)

Since this is a reman motor I'm going to bet dollars to doughnuts that once you install a mechanical gauge and verify the oil pressure that it does not match the EVIC pressure reading but it is probably only a few numbers off and the low oil pressure at hot idle is going to be caused by excessive clearance in the rod and main bearings. If you pulled the oil pan and removed a couple of rod bearings and took some measurements you would probably find an extra
0.003" clearance.

If I had known it was a reman I would have recommended you remove the oil pan from the beginning and toss in a set of rod and main bearings and go on about your business.

 

[domsaleo]

Since this is a reman motor I'm going to bet dollars to doughnuts that once you install a mechanical gauge and verify the oil pressure that it does not match the EVIC pressure reading but it is probably only a few numbers off and the low oil pressure at hot idle is going to be caused by excessive clearance in the rod and main bearings. If you pulled the oil pan and removed a couple of rod bearings and took some measurements you would probably find an extra
0.003" clearance.

If I had known it was a reman I would have recommended you remove the oil pan from the beginning and toss in a set of rod and main bearings and go on about your business.

Damn, well I appreciate the heads up. I just glanced over it without doing any of that. Kind of assumed they would be fine since it had such low mileage on it and it turned over nice and smooth. I know they have super tight tolerance though, probably should have done a bit more research on what to look for first. Once I get back I'll do the pressure test and keep my fingers crossed.

 

[Wild one]

I left the higher pressure spring in the oil pump since I was doing the MDS delete. I didn't do a total rebuild, the engine was a reman that had maybe 40k miles on it. Everything moved smoothly and appeared to be fine. Im not a skilled builder or anything

It eventually had the lifter failure I assume from the same oil leak that I am now dealing with. I even spread rtv all over the oil pan gasket to make sure it sealed. I'm still getting fresh oil on the block after driving. I never removed that camshaft sensor. I'm assuming it has contact with oil and maybe the o ring needs to be replaced?

(Didn't say this is the original post because I wasn't aware of it yet.)

Just because you deleted the MDS doesn't mean you need the high pressure spring.If you have to tear it down to where you have access to the oil pump,swap in your original bypass spring if you still have it,or at the very least swap in the low pressure Melling spring. Even non-mds 6.4's don't use a high pressure bypass spring,and they have a built in internal oil leak with the piston squirters

 

[domsaleo]

Just because you deleted the MDS doesn't mean you need the high pressure spring.If you have to tear it down to where you have access to the oil pump,swap in your original bypass spring if you still have it,or at the very least swap in the low pressure Melling spring. Even non-mds 6.4's don't use a high pressure bypass spring,and they have a built in internal oil leak with the piston squirters

I followed most of what I did off reigniteds channel on YouTube. He was explaining that it's not an issue using the higher psi spring in it, while it's not necessary I'm sure. Hope to God I don't need to go back into it lol, but if I do so be it..

 

[Wild one]

I followed most of what I did off reigniteds channel on YouTube. He was explaining that it's not an issue using the higher psi spring in it, while it's not necessary I'm sure. Hope to God I don't need to go back into it lol, but if I do so be it..

And if you go looking he also has a video up using a couple resistors to fix the oil pressure code.
Somebody finally clued him into using the stock bypass spring awhile ago,but he hasn't made a new video about it yet.
The mans good,but he's human and has made mistakes at times,and one of them is using the high pressure spring in the Hellcat and Melling pumps,the high pressure spring it not needed in a 5.7 or 6.4,all it does is rob horsepower and create more oil heat

 

[domsaleo]

And if you go looking he also has a video up using a couple resistors to fix the oil pressure code.
Somebody finally clued him into using the stock bypass spring awhile ago,but he hasn't made a new video about it yet.
The mans good,but he's human and has made mistakes at times,and one of them is using the high pressure spring in the Hellcat and Melling pumps,the high pressure spring it not needed in a 5.7 or 6.4,all it does is rob horsepower and create more oil heat

****, well looks like I'll have to try and do that swap at some point.. just got the damn thing running after months of waiting.
Thanks for the input. At least I can do that leaving the engine in, just a little less fun.

 

[SD2020]

2011 ram 1500 5.7

So I recently replaced my MDS lifters with non-MDS, replaced the oil pump with melling high volume oil pump, and installed an MMX NSR NTR camshaft. I also switched to a slighty thicker M1 5w-30 oil.

(MDS delete purchased through moes performance.)

Cold start: 80+ psi

Driving operating temp: 65+ psi

Idle operating temp: ~24 psi


I feel like the idle pressure is way low considering the pump. I know the truck idles pretty damn low as it is, but without being able to adjust the idle at all I am worried that I could run into the same lifter issue down the road. Any ideas? Thanks

I just saw this thread.
My 2011 has the MDS delete, same cam, same oil pump ( high pressure spring in ) After the engine rebuild my idle pressure at stock rpm was, I think, 27. I upped the idle to 750 and its 37psi. Cold start psi is also 80. I also run 5-30 oil. I have not verified the psi with a mechanical gauge. My motor runs good, ( HF 87 tune ) but I have been fighting with trying to find a "pump" whine sound since it was rebuilt. I feel like it could be the oil pump or trans pump. It sounds like a power steering pump, but the noise persists with the belt off. Also the noise is louder cold and quieter but still present at operating temp. 4000 kms on the rebuilt motor, engine oil samples return normal.

Fast69, do you see those hot idle pressures at the factory rpm?

 

[Wild one]

I just saw this thread.
My 2011 has the MDS delete, same cam, same oil pump ( high pressure spring in ) After the engine rebuild my idle pressure at stock rpm was, I think, 27. I upped the idle to 750 and its 37psi. Cold start psi is also 80. I also run 5-30 oil. I have not verified the psi with a mechanical gauge. My motor runs good, ( HF 87 tune ) but I have been fighting with trying to find a "pump" whine sound since it was rebuilt. I feel like it could be the oil pump or trans pump. It sounds like a power steering pump, but the noise persists with the belt off. Also the noise is louder cold and quieter but still present at operating temp. 4000 kms on the rebuilt motor, engine oil samples return normal.

Fast69, do you see those hot idle pressures at the factory rpm?

My cammed 5.7 idles at 50/51 psi hot with the idle rpm bumped up to 750,and sees 75psi hot at it's 6600 rpm shift points,and generally its at 60/62 psi cruising down the road at 60/65 mph.
All with a stock/original oil pump.
Matt Fikac who's probably got more modded Rams on the road then anybody else,doesn't reconmend the high volumn pumps,and i'd be more inclined to think he has more experience with the hemi trucks as anybody ,and if he doesn't reconmend them,that says more to me,then re-ignited does.

 

[Fast69Mopar]

I just saw this thread.
My 2011 has the MDS delete, same cam, same oil pump ( high pressure spring in ) After the engine rebuild my idle pressure at stock rpm was, I think, 27. I upped the idle to 750 and its 37psi. Cold start psi is also 80. I also run 5-30 oil. I have not verified the psi with a mechanical gauge. My motor runs good, ( HF 87 tune ) but I have been fighting with trying to find a "pump" whine sound since it was rebuilt. I feel like it could be the oil pump or trans pump. It sounds like a power steering pump, but the noise persists with the belt off. Also the noise is louder cold and quieter but still present at operating temp. 4000 kms on the rebuilt motor, engine oil samples return normal.

Fast69, do you see those hot idle pressures at the factory rpm?

I see a lot of 5.7 HEMI's on a weekly basis and I am always looking at what the EVIC says for oil pressure. 27psi is a touch low for your hot idle compared to what I see in other motors coming through the shop. I see 30-32psi oil pressure at hot idle with the stock idle RPM on most. Yours is not far off. I have found in my own inspections and diagnostics on 5 or 6 5.7 Eagle motors that had hot idle oil pressure below 30psi there was some excessive clearance on the rod bearings and the largest discrepancy I found on these motors was about 0.0031" and the other journals were within 0.0017".

Just a quick guess on your pump whine sound would be the trans pump. I have been around the RFE since it's inception in the 1999 WJ and that pump can easily be mistaken for a whining power steering pump.

 

[SD2020]

Dang, well this motor has new pistons and bearings in it already. The clearances should have been done right. Also to note, is the transmission did not whine before the engine was pulled, but the engine was apart for many months before getting repaired. The only thing I can think of is they could have bolted up the TQ to flywheel wrong or something and caused pump damage. I recently dropped the transmission oil pan and put new filters on it, and cleaned the pan and magnet off. Everything looked ok.
I have a video of the sound from in the cab somewhere

 

[Fast69Mopar]

Dang, well this motor has new pistons and bearings in it already. The clearances should have been done right. Also to note, is the transmission did not whine before the engine was pulled, but the engine was apart for many months before getting repaired. The only thing I can think of is they could have bolted up the TQ to flywheel wrong or something and caused pump damage. I recently dropped the transmission oil pan and put new filters on it, and cleaned the pan and magnet off. Everything looked ok.
I have a video of the sound from in the cab somewhere

When the motor was assembled do you know if the bearing clearances were checked with Plastigage or were the journals mike'd with a proper digital/manual caliper?

The reason I ask is because Plastigage is not always the most accurate measuring tool.