My oil pressure is going away.....

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superdart

superdart

Shade Tree Tinker Gnome.....
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Location
DFW, Texas
Very disturbing......

At idle, still warming up, my engine shows 60-70 psi oil pressure.

As I drive it on the highway (20-30 mile run) the oil pressure slowly drops down to about 40psi.

Yesterday was 100 degrees here, and after a 5 mile drive around the block, I got back to the house and at idle I was only showing 25 psi!

I shut it off and left it in the drive because I had other things I needed to get done. What REALLY concerns me is the strange groaning noise I got when I started it to pull it in the garage. I had heard it before when moving, and assumed it was a suspension noise...but the car was still in park. It moaned a bit, I revved it slightly (1500 rpms)and it went away, I let off the gas and it came back. Just a quick moan, then it stops. Then it will do it again.

Low oil pressure, odd noises at low rpms...am I losing my main bearings? The motor only has maybe 4k miles on it, and was built by a local guy with a very good reputation when it came to SB Mopars. He has since passed on, so the specs are the only thing I have on the engine. I played with the rockers/pushrods but otherwise have never been inside the motor.

Pertinent Specs:

.030 over 360
9:1 CR
455/475 Herberts E3N cam
HV oil pump
.010/.010 ground crank (maybe the culprit?)
Amsoil 10W40 Zinc oil

I seek the wisdom of others....
 
25 psi doesn't seem too low to me. Sometimes mine dips below 20 after it's been warmed up. I don't think that would do any damage.
 
Oil pressure sounds ok to me. The groan/moan could be power steering pump, alternator bearings, water pump, or maybe even the front pump in the tranny. My 98 durango moans when I first start it if I leave it in park because the tranny doesn't pump in park. If I start it in neutral no moan.
 
The idle oil pressure is perfectly fine, especially on a extremely hot 100 degree day. I sometimes see 15-20 psi on hot days at idle after running a while.
 
Idle is not a good measure for oil pump output. What pressure is it showing at 2K? Even for a HV oil pump, 25 PSI is fairly high oil pressure at idle. Remember, all an engine really needs is 10 PSI for every one thousand RPM, so oil presure can be in the single digits at idle and all is well. I wouldn't worry unless the pressure has changed from the onset. Has the pressure dropped when the engine is hot as compared to when it was first built? Even a little drop is ok as the bearings are breaking in and getting seated to the cam and crank and the oil pump rotors are wearing together. It's perfectly normal for an engine to have higher PSI when cold and then drop pretty significantly when hot. Also, hot weather can have an effect as well. I don't know about the noise, but I wouldn't jump the gun on the engine yet. Mopars are a pretty easy engine to get right and they rarely ever give problems when assembled correctly. At 4K miles, I'd have to say if something was wrong, it would have happened long ago. If you're really worried, drop the oil out of it and check it for metal shavings.
 
Don't sweat the 25 PSI @ idle. That is normal@ idle @ normal running temps. Mine is 65-70 cold, 25 @ idle warm.
 
Ok, thanks all. I will just keep an eye on it. I do check for shavings whenever I change my oil and haven't seen anything.

I didn't think about the trans, really. Everything else mentioned is new or don't have (no PS on this car).

I will just keep an eye on it.
 
If that has a high volume (HV) pump you should have much higher pressures. If it was me I'd have it checked with a mechanical diagnostic oil pressure gage. The hot psi should be at least 25, and the pressure should immediately rise to beyond 70psi cold, and at least 70psi hot at 2500. If there is a problem, catching it before it eats the expensive hard parts is the best solution.
 
How old is the oil?

Why not run 20w-50, I am up in cold Michigan and run 20w-50 right now.

What oil filter are U using? I stick with $ k&n oil filters and Valvoline nsl racing oil. Amazon has a good price on a 6 pack of oil with free shipping.
 
It was a NIB Mellings pump, supposedly high volume. I will note that it was 106 degrees yesterday.

I have checked it against a mechanical gauge in the past and it was accurate...or they were both wrong.#-o

The car has a set of electronic VDO Vision Series gauges.

Why not 20W-50? I dunno....10W40 is typical in this motor and it's treated with Zinc for my flat tappet cams.
 
What is the water temp most often,,,when its 100 plus outside? No oil temp gauge I take it, the police mopars had engine oil coolers.

You can get high zinc oil @ 20w-50. Back in the 70's people all the time used that or straight 30 weight in the summer in these motors that were going on 10 years strong.

Oil filters can block the flow, some claim Fram filters are the worst for clogging up. k&n race filters and the like don't filter as fine in order to allow a high rate of oil flowing.

I would for sure change the oil filter if its been on a while or is a Fram or the like name.
 
Like others said, 20psi hot at idle is not low. If the weather is that hot, I would go with 20W-50. I run Brad Penn 20W-50 and a Mobil1 filter. Avoid Fram - do a Google search and see for yourself.
 
For a stock pump and decent clearances it's fine. For a HV pump which would have a high pressure relief and a lot more volume I would say it's low, 100+ temp or not. The fact that it changed drastically and the noise tells me there might be something worth looking at in the lower end. Might be nothing but I'd want to know for sure. JMO
 
When I am cruisin, and it's hot out, I have about 65 psi HOT at any rpm above 1800. At idle in gear HOT I have about 40 psi. THat is with a HV pump. Sounds like you have a stock pump??

Get out the stethoscope and find the noise.
 
I played around with the car tonight and never did hear that noise...maybe I am just losing my mind?

But, after driving it around a bunch on the streets and highway (10 miles?) The car was running about 190-200 degrees sitting at a traffic light (still no fan shroud, working on that) and my oil pressure at 650 rpm is 25-30 psi.

At 2,000 rpms I'm showing about 55-60 psi...I'm thinking I have a standard oil pump, because even cold it has NEVER gotten over 60-65 psi.

It seems fine I guess, but if I ever need to get into the engine for anything, I'm putting an HV pump in it.:read2:
 
Those numbers sound great. Nuthin wrong with the oil system. On the HV pump. I wouldn't even think about it. There's nuthin wrong. But....if you just GOTTA have an HV pump, you better put a higher capacity pan on it too, or you can starve tha bottom end at high RPM. I'd leave it alone if it was mine.
 
superdart said:
I played around with the car tonight and never did hear that noise...maybe I am just losing my mind?

But, after driving it around a bunch on the streets and highway (10 miles?) The car was running about 190-200 degrees sitting at a traffic light (still no fan shroud, working on that) and my oil pressure at 650 rpm is 25-30 psi.

At 2,000 rpms I'm showing about 55-60 psi...I'm thinking I have a standard oil pump, because even cold it has NEVER gotten over 60-65 psi.

It seems fine I guess, but if I ever need to get into the engine for anything, I'm putting an HV pump in it.:read2:
Click to expand...

Of course I don't know what a Texan considers "cold" but 25-30 psi at 650 is fine with 10W-40 at 100F ambient. If it drops below 20 psi when hot at idle in those temps I'd start getting worried.

Keep in mind that if it was built with large tolerances (over .002) on the crank and rods and was NOT fitted with a HV pump, oil pressure will be on the low side. Tolerances less than .002 with a HV pump will give a usual 70 psi cold and 35+ hot on a relatively new engine with 65-70 psi around 2500 rpm (where oil pressure is measured on a stock engine). Chrysler says 40 psi at 2500 rpm is just fine...... for a stock engine and they'll live for 100K+ mi. like that.

Here is the exception to that rule:

If you had the engine rebuilt and you are now 20 psi below what you had previously above 2500 rpm, there is a problem.

Not knowing the builder, the clearances, the pump type, etc. I can't tell you if you are having bearing issues due to cam lobe destruction or whatever. I can say that it's a change in oil pressure that you have to look out for given the same viscosity, brand of oil, oil filter, ambient temp, ect.

I hope this helps. :read2:
 
superdart said:
I played around with the car tonight and never did hear that noise...maybe I am just losing my mind?

But, after driving it around a bunch on the streets and highway (10 miles?) The car was running about 190-200 degrees sitting at a traffic light (still no fan shroud, working on that) and my oil pressure at 650 rpm is 25-30 psi.

At 2,000 rpms I'm showing about 55-60 psi...I'm thinking I have a standard oil pump, because even cold it has NEVER gotten over 60-65 psi.

It seems fine I guess, but if I ever need to get into the engine for anything, I'm putting an HV pump in it.:read2:
Click to expand...

Absolutely no need for an HV pump your pressures are perfect.....only reason I'm going with an HV on the 408 is due to the 8 quart pan 8)

Rickster
 
StrokerScamp said:
Those numbers sound great. Nuthin wrong with the oil system. On the HV pump. I wouldn't even think about it. There's nuthin wrong. But....if you just GOTTA have an HV pump, you better put a higher capacity pan on it too, or you can starve tha bottom end at high RPM. I'd leave it alone if it was mine.
Click to expand...

You don't need a bigger pan. Without increasing the pickup tube size, it won't empty the pan. They proved it in one of the mags a few years ago. The extra volume just increases pressure since it can't deliver MORE volume thru the same size tube.

But, what you have for your setup, superdart, is just fine....don't worry about it.
 
redfastback said:
You don't need a bigger pan. Without increasing the pickup tube size, it won't empty the pan. They proved it in one of the mags a few years ago. The extra volume just increases pressure since it can't deliver MORE volume thru the same size tube.

But, what you have for your setup, superdart, is just fine....don't worry about it.
Click to expand...

Your theory is incorrect and here's why. For your theory to be correct, the stock pump would have to be using the stock pickup to 100% of it's capacity. Sorry, but that's just not the case. Also, I've seen first hand people make the mistake of adding a high volume pump while retaining the stock pan in both dirt track and drag racing. The results weren't pretty. I GARRANTEE you that the stock pump does NOT use the stock pickup to it'a full 100% capacity. So, that means a high volume pump will indeed pump more volume than a stock pump. A high volume pump does not JUSt increase pressure. It increases volume ONLY. the extra pressure is simply there because there is more oil being pumped into the same space. The higher oil pressure reading on your gauge is PROOF of this. Were there not a higher voulme of oil going to your gauge, it would show no pressure increase. Further proof is the fact that there are TWO completely different pumps made. One, a high pressure and one a high volume. Are you ready to back up your assertion with a garrantee? You gonna pony up for dude a new motor when he takes your bad advice? I don't care what car rag did what experiment. You sayin that is like Al Gore sayin "I saw it on 60 Minutes...". That does NOT for blanket proof for ALL engines. Have you measured the volume on the inside of the stock pickup and done the math? No. There's no way for you to know what you stated. No way in hell.
 
Ok, well I guess I will stick with the stock pump for what I am doing (which is NOT racing).

And for the record..I am not a Texan, I just live here.:poke:

..and by cold I meant the ENGINE TEMPS, because it was 105 here yesterday. :blob6:

LOL!
 
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