Sudden oil pressure (reading) drop

[mjmcg]

I already posted this question as a result to an older thread but I don't think it got positioned for anyone to even see, so I'm using as a stand alone post.

I've had my 2011 1500 5.7 for about 4 years. Got it with 32K mi on it now at just under 80K.
I religiously monitor all my gauges constantly to the point of obsession. Oil pressure at full temp & highway speed (55-70mph) is always 50+/- 1 or 2.
this week I've noticed it's only at 40 or below. This didn't come on gradually, this was a one night it was "normal" and the next it was 40. All else seems to be running as normal. With a 190 T'stat I run around 188-194 coolant temp, 170-180 oil temp; 100-114 trans temp.
I run a superchips tune with the MDS disabled; clutch fan delete / electric fan replacement and full alum rad. Noting leaks, no codes, no light.
Any input what I might want to keep a look out for?

 

[crash68]

How many miles on the oil change? Have you verified the reading with another gauge?

 

[Jwithing]

What's your idle pressure? Whats your idle hours vs. Total run time? My initial thought is you need to have your idle bumped up with a tune to help avoid, or delay, the infamous lifter failure. Not sure if that's doable with superchips.

 

[mjmcg]

The only other gauge I have available at the moment is the mechanical sweep dial in the cluster but there are no numbers on it just the hash marks... But if memory serves me I think that still reads the same but I can't say for certain. It holds just above the mid point but I don't know what the scale is on that one.

I've got a little over 7500 on this oil, full synth with royal purple filter and always topped off.
I've been doing this since I got it without issue... Yet

I've had the mds shut off for the last year or better, I don't immediately suspect valve train, though I realize anything is possible.

 

[Bigskyroadglide]

I'd suspect the easy things first. Low oil. Clogged filter where it in bypass full time, bad oil sending unit, etc before I suspect engine issues.

Unless the engine is clicking or knocking it probably something simple.

Always start with the easy stuff. An oil change is cheap compared to a sending unit change and it's routine maintenance. If you need to replace the sending unit, get OEM not aftermarket

 

[burner71]

clogged filter

 

[Jwithing]

Agree check the smaller stuff first. Sorry, I'm going through my own engine issues rigjt now so my mind immediately went doom and gloom lol

 

[crash68]

The only other gauge I have available at the moment is the mechanical sweep dial in the cluster but there are no numbers on it just the hash marks... But if memory serves me I think that still reads the same but I can't say for certain.

All the information in the cluster like oil pressure come from the same sending unit.
As others have mentioned changing the oil/filter is the cheapest thing to try. After that putting an actual gauge on the oil system would accurately rule out a bad sending unit. The OEM sending unit is under $50(part# appears to be 5149062AB) if you just want to throw a part at it.

 

[mjmcg]

Just did an El cheapo (not El Chapo) oil and filter change for diagnostics... At speed pressure back to 51, warm idle back to 30. I have always changed the oil in June with full synthetic and a royal purple filter. I had under 8k on that oil/filter. WTF? Piece of crap.
I had my suspicions, you guys confirmed it. We can all rest a little better tonight.
LOL thanks guys.

 

[Jwithing]

Just did an El cheapo (not El Chapo) oil and filter change for diagnostics... At speed pressure back to 51, warm idle back to 30. I have always changed the oil in June with full synthetic and a royal purple filter. I had under 8k on that oil/filter. WTF? Piece of crap.
I had my suspicions, you guys confirmed it. We can all rest a little better tonight.
LOL thanks guys.

Glad to see your issue cleared up. However, that idle pressure is still a bit low overall if its normal. One current, leading theory around the infamous hemi lifter failure is high idle hours and idle pressure in the 30's. Tuners can bump up idle RPMs to increase idle pressure into the 40s

 

[Bigskyroadglide]

I've bumped my idle rpm by 100 on all my rams. Now at 650 vs 550. Idle oil psi is 48 for each engine across 3 vehicles at 190 oil temp.

Oil pressure at speed is 55

 

[Treburkulosis]

I never go over 5k with my oil change. 143k on mine and its 50-60 psi.

 

[Zinger1]

Yeh, good call on the filter. I will add one thing re oil pressure, and I do some towing probably beyond the limits & works well with 3.92 cogs but had the cam/lifter issue. I did a cam/lifter job on mine in Dec and used cheap stock parts off ebay because I'm already at over 170k and it won't be forever before a complete do over. I wrestled with doing the 6.4 cam, etc, and found out a lot about the design issues and idling/oil pressure, etc.

Now, Melling is coming out with a new pump early this year for this 5.7 motor that has a higher volume at idle but wasn't ready yet. However, I got a good idea from a tech there that suggested a 6.4 pump which looks exactly the same but is a different part no and has a slightly different oil delivery scale. Mine idles at 45 and goes up to abt 60 otherwise. The reason I did that was that looking at my parts that failed on #7 (cam was way dished out and lifter was beaten down a bit and had actually turned sideways so didn't totally disintegrate) The point to me was, at 167k I'm past due for cam/lifter issue anyway and seeing the oil flow is front to rear on the cam and I do a lot of idling, I wanted to cover the idle lubrication of the cam/lifters better. (ps I go from 8-10k between changes and use Penz 5-20 and the synth Fram - I've done the science so anyone who wants to discuss why, msg me. I use Blackstone oil analysis) Melling should begin putting this new pump out about now... ..told me Feb/Mar 2022 and it will be the foregone conclusion for anyone doing anything on the MDS motor. (Note - I found a sneaky way to change the pump without removing the pan!)

The result on my cam/lifter job? It has brand new power which was always very good and I'm getting between 18-20 mpg at 5280 to 9k feet elevation, ie going up and down the hill! (a little less in the winter, a lot less towing) I'm a happy camper with this truck much more than my monster 7.3L diesel F350 and will redo the motor in another 100k, probably the tranny sooner but happy with the work I did. (x-drag racer who built the motors)

 

[Dusty]

I already posted this question as a result to an older thread but I don't think it got positioned for anyone to even see, so I'm using as a stand alone post.

I've had my 2011 1500 5.7 for about 4 years. Got it with 32K mi on it now at just under 80K.
I religiously monitor all my gauges constantly to the point of obsession. Oil pressure at full temp & highway speed (55-70mph) is always 50+/- 1 or 2.
this week I've noticed it's only at 40 or below. This didn't come on gradually, this was a one night it was "normal" and the next it was 40. All else seems to be running as normal. With a 190 T'stat I run around 188-194 coolant temp, 170-180 oil temp; 100-114 trans temp.
I run a superchips tune with the MDS disabled; clutch fan delete / electric fan replacement and full alum rad. Noting leaks, no codes, no light.
Any input what I might want to keep a look out for?

I've seen this exact scenario before. Twice. In both cases the oil pump inlet screen was partially clogged. However, in both cases the engine oil maintenance was suspect.

Someone my son knows installed a new oil filter and within days noticed the oil pressure never exceeded 28 pounds, hot, cold, or any RPM. Ended up being a defective oil filter.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 064446 miles.

 

[Dusty]

Yeh, good call on the filter. I will add one thing re oil pressure, and I do some towing probably beyond the limits & works well with 3.92 cogs but had the cam/lifter issue. I did a cam/lifter job on mine in Dec and used cheap stock parts off ebay because I'm already at over 170k and it won't be forever before a complete do over. I wrestled with doing the 6.4 cam, etc, and found out a lot about the design issues and idling/oil pressure, etc.

Now, Melling is coming out with a new pump early this year for this 5.7 motor that has a higher volume at idle but wasn't ready yet. However, I got a good idea from a tech there that suggested a 6.4 pump which looks exactly the same but is a different part no and has a slightly different oil delivery scale. Mine idles at 45 and goes up to abt 60 otherwise. The reason I did that was that looking at my parts that failed on #7 (cam was way dished out and lifter was beaten down a bit and had actually turned sideways so didn't totally disintegrate) The point to me was, at 167k I'm past due for cam/lifter issue anyway and seeing the oil flow is front to rear on the cam and I do a lot of idling, I wanted to cover the idle lubrication of the cam/lifters better. (ps I go from 8-10k between changes and use Penz 5-20 and the synth Fram - I've done the science so anyone who wants to discuss why, msg me. I use Blackstone oil analysis) Melling should begin putting this new pump out about now... ..told me Feb/Mar 2022 and it will be the foregone conclusion for anyone doing anything on the MDS motor. (Note - I found a sneaky way to change the pump without removing the pan!)

The result on my cam/lifter job? It has brand new power which was always very good and I'm getting between 18-20 mpg at 5280 to 9k feet elevation, ie going up and down the hill! (a little less in the winter, a lot less towing) I'm a happy camper with this truck much more than my monster 7.3L diesel F350 and will redo the motor in another 100k, probably the tranny sooner but happy with the work I did. (x-drag racer who built the motors)

Or try the Hellcat pump. 2017 and up they enlarged the oil pump outlet and increased the rotor thickness (12.4mm to 14.0mm) and number of lobes for increased output. The Hellcat pump has an even thicker rotor. Not sure about the specs for the 6.4 pump.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 064446 miles.

 

[Wild one]

Yeh, good call on the filter. I will add one thing re oil pressure, and I do some towing probably beyond the limits & works well with 3.92 cogs but had the cam/lifter issue. I did a cam/lifter job on mine in Dec and used cheap stock parts off ebay because I'm already at over 170k and it won't be forever before a complete do over. I wrestled with doing the 6.4 cam, etc, and found out a lot about the design issues and idling/oil pressure, etc.

Now, Melling is coming out with a new pump early this year for this 5.7 motor that has a higher volume at idle but wasn't ready yet. However, I got a good idea from a tech there that suggested a 6.4 pump which looks exactly the same but is a different part no and has a slightly different oil delivery scale. Mine idles at 45 and goes up to abt 60 otherwise. The reason I did that was that looking at my parts that failed on #7 (cam was way dished out and lifter was beaten down a bit and had actually turned sideways so didn't totally disintegrate) The point to me was, at 167k I'm past due for cam/lifter issue anyway and seeing the oil flow is front to rear on the cam and I do a lot of idling, I wanted to cover the idle lubrication of the cam/lifters better. (ps I go from 8-10k between changes and use Penz 5-20 and the synth Fram - I've done the science so anyone who wants to discuss why, msg me. I use Blackstone oil analysis) Melling should begin putting this new pump out about now... ..told me Feb/Mar 2022 and it will be the foregone conclusion for anyone doing anything on the MDS motor. (Note - I found a sneaky way to change the pump without removing the pan!)

The result on my cam/lifter job? It has brand new power which was always very good and I'm getting between 18-20 mpg at 5280 to 9k feet elevation, ie going up and down the hill! (a little less in the winter, a lot less towing) I'm a happy camper with this truck much more than my monster 7.3L diesel F350 and will redo the motor in another 100k, probably the tranny sooner but happy with the work I did. (x-drag racer who built the motors)

The 6.4's use piston squirters while the 5.7's don't,so they need slightly more volumne to compensate for the squirters.If your sneaky way of doing the bolt in the pick-up tube is using fishing line or dental floss wrapped around the bolt to thread it into place,it's not really sneaky,that trick has been around for awhile,lol

 

[Joseph Godvin]

Never trust an electric gauge sender, pull sender and check with a good mechanical gauge !!!

 

[Zinger1]

The 6.4's use piston squirters while the 5.7's don't,so they need slightly more volumne to compensate for the squirters.If your sneaky way of doing the bolt in the pick-up tube is using fishing line or dental floss wrapped around the bolt to thread it into place,it's not really sneaky,that trick has been around for awhile,lol

Thanks for your note on the squirters. Ok, maybe there's a better word than sneaky but I sure liked the way it worked! I also shortened the fastening bolt because it is about 1 1/2 in and only uses abt an inch of the thread. Makes the job a lot easier and needed less fish line, lol. I had a couple of magnet tools down in there in case my large clumsy fingers dropped it! Sure was a lot easier than doing what I saw guys doing by dropping the pan.

Incidentally, I have about 10k on it since the job and running well. I'm just planning a few things when I get to the complete overhaul, like a little heftier cam to support those great heads and maybe the 6.4 intake, etc. I'd like to hear your thoughts. One reason I didn't use the 6.4 cam was the little oil trough that is different from the 5.7 cam or that was what I read was one difference in the structure. Maybe that has something to do with the 6.4 squirters? I could not find out and didn't want to cowboy my job.

 

[jws123]

All 3 of my rams hot idle 23-30 psi when driving 55 or so never a issue.