Hi volume oil pump

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Brambles

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How much oil pressure does your engine produce at idle when fully warmed up??

Since my engine was rebuilt I have run a stock volume pump and for the first few months while breaking in the motor it had about 25 psi at idle fully warmed up.
Now with 14,000 kms on it ( about 9000 miles I think) the oil pressure at idle is 10 psi. and cruising on the hwy at 2500 rpm its about 25 psi.

I'm told that its still within acceptable specs but its on the low side. The engine doesn't knock at idle so the bearings are still floating in oil.

I want more oil pressure and am wondering if putting in a hi volume pump will boost the pressure up to desired levels? I don't know about Hi-pressure pumps but have always been told not to use them.

I'm going to tear the motor apart and see if I can tell WHY my pressure is low but for now its just being parked.

Any ideas?
 
Before you tear the motor aprt, have you checked the oil pressure sender beside the distributor? On one of my cars that was the reason for this. Next, is there any leaks on the oilfilter adapter? That might also reduce the pressure.

Then there is the pump. I think you can co with a high volume. They work just fine. It's the heart of the engine It's like put in a peacemaker.

What oil do you use? I usually use 10/30. That works just fine for me

Good luck
 
I don't think the sender which is basically an on-off switch that sets at about 8 psi is going to be the issue. Probably not even there if he's plumbed an aftermarket gauge in where it used to be. Obviously he has an aftermarket gauge of some sort in there. The readings are definitely on the low side and I would not consider them acceptable by any means. The first thing to do is get another gauge and confirm the readings. I'd get a test gauge and connect it directly to the pressure port and go from there.

IIRC, the hi-press/hi-vol pumps are not adviseable for use in street Mopars, but can't remember why. In any case, I wouldn't go there to fix a low pressure issue until you confirm the actual pressure and the real state of the stock pump. BTW, mine runs more than double the numbers you quoted.

I hope you got a warranty on that rebuild. :wack:
 
Hi volume pumps can put 6 qt.s into the top of the engine @ 6000 rpm. You can suck air very easily. I would never use one without a deep pan. Terry.
 
You can purchaed a relief spring from MoPar that will do the same job as the HV pump. Easy job.
 
If he does in fact have a electric pressure gauge it can be the sending unit as Dartcharger said. I had a 74 Monaco that showed low oil pressure on the factory dash oil pressure gauge and it was a bad oil sending unit. It was not the on/off type Ace described that is used in the "idiot" light system. It's the type used for an electric gauge which is a variable resistor. If he has a manual gauge testing it against a known good gauge is the way to go. As Terry says a HV pump with a stock oil pan is a NO-NO. I did that once and watched it suck the pan dry at 6000 rpm and before I got it shut off it spun a bearing. I was bummin to say the least.

Either way about it that's quite a drop in oil pressure and warrants an inspection.
 
The heavier relief spring will give higher pressure, but nowhere the amount of flow the HV pump pushes.

So what type gauge we talking about here anyway? The fact that he saw the pressure drop on the same gauge over a relatively short period suggests a problem other than gauge-related. That just needs to be ruled out first.
 
You didn't say if you had a smallblock or a bigblock, but with a bigblock you can change the pressure spring in about 2 minutes. Or you could shim it up with washers. Milodon even sells an adjustable kit if you so desire. Unfortunately, it sounds like you have other issues, though.
 
I like to use the high psi. springs and have the psi. without the volume.
 
Since I rebuilt my 340 I get between 20 and 25 at idle. But when you bring up the rpm's the pressure comes right up. At 2500 rpm's I have 50 to 55. I have always used a high volume pump with stock pan. I have had it up to 6500 rpm's and have never ran the pan dry. The oil pressure has always been over 50. This is my 2nd 340 which I have had a high volume pump and stock pan. I beat my car and have had 0 problems. I guess I've been lucky. It sounds to me that it's leaking somewhere. Maybe a plug is missing.

Fred
 
I pretty much agree with Ace. It sounds like it could be something wrong inside the engine, but you really should verify your electric gauge readings against mechanical gauge readings before you start ripping parts off the engine looking for a problem.
 
At idle my rebuilt 360 gets about 22psi and at 60mph (2200rpm) I get about 60psi. I have a mechanical autometer guage, stock pan,stock pick up tube, with a hi volume pump, 10w30, and a short Wix filter. I did drill 4 extra holes in the plate under the filter and I pollished the rocker arms.
The only time I have ever had oil pressure as low as your motor was with the old 360 that was in my car. At idle it would be 8psi and at 2200rpm it would be at 17 psi. No knocking or anything, I just pulled it apart this last weekend (after sitting for a year and half) and all the main berrings were shot to hell.
 
A pump is just a device that moves fluid. If you cause a restriction of that fluid or if the pump moves more volume that is being bleed off thru clearances it creates pressure. To keep this pressure in check you need a relief valve. If your clearances (because of wear) start to match the pump output the pressure will start to dropping. Putting a higher pressure spring with the same volume pump will do nothing to add more pressure because the pressure is already below the current pressure relief setting. The only way to raise the pressure with the just a pump is add more volume. More fluid in with the same fluid out will net more pressure up until it hits the pressure relief setting.

As far as high volume pumps running the pan dry is just an urban legend. If you can only move so much fluid thru the motor and you add a high volume pump the oil ends up back into the pan because that is were the pressure relief valve dumps. You are just waisting motion by loading the pump and cam gear moving fluid thru the pressure relief.

If you are loosing oil pressure steadily you have something wearing, could be the engine or could be the pump. On a LA you have to pull the pan to change the pump so I would pull the main and rod bearings to take a look.

I will tell you that 20psi at idle I wouldn't sweat. Remember if it is a positive pressure you are moving more fluid that the clearances are consuming. I would be worried more if it doesn't stabilize because it would mean somethings going away.

Chuck
 
340mopar said:
A pump is just a device that moves fluid. If you cause a restriction of that fluid or if the pump moves more volume that is being bleed off thru clearances it creates pressure. To keep this pressure in check you need a relief valve. If your clearances (because of wear) start to match the pump output the pressure will start to dropping. Putting a higher pressure spring with the same volume pump will do nothing to add more pressure because the pressure is already below the current pressure relief setting. The only way to raise the pressure with the just a pump is add more volume. More fluid in with the same fluid out will net more pressure up until it hits the pressure relief setting.

As far as high volume pumps running the pan dry is just an urban legend. If you can only move so much fluid thru the motor and you add a high volume pump the oil ends up back into the pan because that is were the pressure relief valve dumps. You are just waisting motion by loading the pump and cam gear moving fluid thru the pressure relief.

If you are loosing oil pressure steadily you have something wearing, could be the engine or could be the pump. On a LA you have to pull the pan to change the pump so I would pull the main and rod bearings to take a look.

I will tell you that 20psi at idle I wouldn't sweat. Remember if it is a positive pressure you are moving more fluid that the clearances are consuming. I would be worried more if it doesn't stabilize because it would mean somethings going away.

Chuck
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Some good points Chuck. But I believe he said he's at 10psi at idle, so if something is going away it's going away pretty fast seeing as he only has 9,000 mi. on the rebuild.
 
340mopar said:
I will tell you that 20psi at idle I wouldn't sweat.

Chuck
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He's down to 10 at idle and 25 @ 2500rpm cruise.

Brambles,

Do you top off at 25psi or does your oil pressure increase with rpm? For example, does your pressure increase to 35psi @ 3500rpm? 45psi @ 4500rpm? If not, you have excessive bearing clearance problems, a worn out pump with excessive clearances or a blocked pump pickup (pickup too close to bottom of pan or clogged with silicone, old gasket material, etc.) All this assume that your oil pressure gauge reads true.

Chuck is right on regarding volume vs. pressure. Excellent explanation! :thumbup:
 
It's been a while since I have driven it, I took it off the road and haven't put insurance back on it.

If I recall the PSI did climb with engine RPM, usually staying with the 10 psi/1000rpm rule.

The pressure on a cold motor is way up there If I recall it was 60-70 psi when the engine is cold.

Thanks a lot guys for all the info, its a weird problem for sure.

Brambles
 
Brambles,

I have come across your other post that mentions that the "rebuilder" who built this engine stripped threads out of the crank snout. I'm sorry bud, but I'd tear this thing down and find out what the heck is going on if you plan on keeping it. Something (see my post above) is not right if you're dropping oil pressure this fast.
 
I dont like electric oil pressure guages. I used one once years ago - an autometer guage (read: not junk). Oil pressure readings varied depending on the load on the charging system. Maybe theres a fix for this - I suppose a capacitor in line might help. Anyway, I'd check it with a quality mechanical guage before doing anything to the engine.

If that checks bad, then there are a number of causes:

Stuck by pass valve in the pump

Faulty pump, excessive internal clearances (worn out)

Excessive rod and or main journal clearances

Improperly installed oil gallery plug - the one above the pump inside the block.

Plugged oil pickup. I've seen first time engine builders use too much silicone sealer on gaskets and have the silicone excess come loose and find its way into the pickup. Had a friend of mine do this - his pressure was fine until a few hundred miles then the silicone came loose, we found his pickup full of silicone "worms". Lots of fun pulling the pan in the car to fix this.

I've not had issues using a high volume pump, so maybe you want to look into one when you reassemble the motor.

Good luck with it, and dont drive it until you figure it out.
 
I run a hi-volume pump with a stock pan and 6qts of oil and I have seen 6400RPM and never once sucked my pan dry....that sucking the pan dry is total BS.....hell half of the guys I know that run a deep pan only run 6 qts in it and they have hi-volume pumps and never suck it dry....you only need to run enough oil to cover all the parts and keep the sump covered....extra oil is just extra weight and windage in the crankcase. I don't think a hi-volume pump is gonna fix the problem...first check the sender just because it's easy to do and rule it out....if that's okay then you have other problems. It's either a bad pump relieve or you have bearing clearence problems. How good is this rebuilder? Were new cam bearing installed? Were the rod and main bearing clearences checked when it was assembled.
 
He he he, run 3 quarts and see what happens. Ha hah a.

Seriously, the guys are right. Run a deep pan and HI-PO pump with 6 quarts and never worry, never starve.
 
rumblefish360 said:
He he he, run 3 quarts and see what happens. Ha hah a.

Seriously, the guys are right. Run a deep pan and HI-PO pump with 6 quarts and never worry, never starve.
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ha ha...yeah you'll need new bearings and stuff real quick like that......but ya might be surprised if it's street driven with a standard oil pump......
 
i have a hv pump in my 360 and i have about 75 psi cold and about 35/40 warm with 10w-40 oil never sucked the pan dry
 
Dusterb318 said:
I run a hi-volume pump with a stock pan and 6qts of oil and I have seen 6400RPM and never once sucked my pan dry....that sucking the pan dry is total BS......
Click to expand...

If your running a stock pan with 6 qts. in it aren't you over filling it by a quart (or 2)? Maybe the reason you aren't running it dry. I know a racer that told me he was having problems running his dry and he over fills it a qt. and has no problems now. I know for a fact my 360 was full to the full mark on dipstick (4 qts. in the pan and 3/4-1 for the filter) and sucked the pan dry at a little over 6000 rpm. I watched it do this on the gauge or I couldn't say this. Another thing to remember is 360 main bearing surface is larger than 318 and 340's so requires a little more oil. This combined with possiblity more bearing clearance and running a windage tray and the block wasn't de-burred. Well you guys can say it's bs but...
 
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