Low oil pressure when hot

[AWSOM50]

So I've been having fun tinkering round with all bits on the car, but I think it's time to look at things in order of priority ....

Car runs with good pressure 50 at idle cold startup until it gets to 180F when it all goes downhill.  It's ok at 180F at first, but after about 10 minutes after reaching 180, oil pressure drops significantly.  Down to about 7 - 9 psi per 1000 RPM.  8 psi @ 900 rpm idle.  If it goes to 200+F problem gets worse, maybe 6psi / 1000 rpm

"Knocking" sounds sometimes at idle, but I can't tell if it's the engine because the car has so many rattles/vibrations.  Knocking also occurs when cold with high pressure.  No knocking at speed.  It has a slight valve cover leak.  Feels like it loses power when hot but not 100% sure.  It has only done a few hundred miles since last oil and filter change (8 months ago).  Haven't checked the oil pickup in the pan.  Engine has never gone above 230F and from what I recall has had this problem ever since fitting it (was a fresh rebuild about 7 or so years ago).

I am judging all of this with an auto meter mechanical gauge - it seems to be connected in the non standard place though? - see red circle on pic

My own thoughts/guesses:

- Dip stick wrong length and too little oil? (dipstick is 22.5" from tip to rubber) - engine also has very deep pan
- Needs thicker oil?  I think it has 15w 30 and some 15w 40 mixed in - thinking of changing to 20w 50 VR1 but is this just potentially hiding a bigger problem?  or could it solve it all?
- could try replacing oil pump with high volume one?  I don't know spec of current one - has no branding/part numbers.
- buy a new gauge and sender, either mechanical or electrical?
- inspect oil pickup in pan while doing the change?


I do have a feeling it is a bigger problem like cam bearings etc, but I'm on a learning curve with all this stuff.  If it's a block rebuild so be it.  But I want to try all logical suggestions first.  Any suggestions would be really appreciated to help me diagnose this.  

[myk]

I would start with a mechanical oil pressure gauge.  Take out what's already there in the block and screw in the mechanical gauge.  You're doing this to verify the readings of your current gauge...

[firefighter3931]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection.  

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves.  

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there.  


Ron

[AWSOM50]

I would start with a mechanical oil pressure gauge.  Take out what's already there in the block and screw in the mechanical gauge.  You're doing this to verify the readings of your current gauge...

I'm pretty sure it is mechanical.  It's auto meter part 2312.  It's just in the block at a "second" place similar to this guy's one in a pic I found when I was googling this stuff (right hand side in the pic).  Would u suggest ordering a new one and / or sender as a double check? Perhaps if the oil upgrade doesn't work..

[AWSOM50]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection.  

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves.  

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there.  


Ron

Thanks, Brad Penn looks hard to get hold of in my country, will VR1 20/50 do the job? (I already ordered it actually)

Your oil pressures seem drastically higher than mine.  I always read the rule of minimum 10psi per 1000 rpm but I also heard these blocks like higher pressure.  Do you think I am likely to have an engine problem here?

Before I changed the block I had the same gauge/sender on another 440, it was ten years ago but I always remember it having at least 20psi at idle (certainly never low enough to concern me).

Idle set at 900 or 1000.  Any less and I have to 2-foot it to prevent stalling.  The top pic is of the gauges when in neutral and hot.

Should I bother changing the fuel pump when I do the oil swap?

Thanks

[birdsandbees]

He's telling you to verify that your mechanical gauge is accurate, but using another mechanical gauge to verify the readings.

[AWSOM50]

He's telling you to verify that your mechanical gauge is accurate, but using another mechanical gauge to verify the readings.

Understood.  Should I buy the same gauge /sender again or can you recommend one?  Also should it go on the left or right sender point in the photo with the blue engine block?

Thanks

[68X426]

will VR1 20/50 do the job?

Yes, that's a great oil and weight.  It's well regarded and widely used in the USA.

[firefighter3931]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection.  

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves.  

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there.  


Ron

Thanks, Brad Penn looks hard to get hold of in my country, will VR1 20/50 do the job? (I already ordered it actually)

Your oil pressures seem drastically higher than mine.  I always read the rule of minimum 10psi per 1000 rpm but I also heard these blocks like higher pressure.  Do you think I am likely to have an engine problem here?

Before I changed the block I had the same gauge/sender on another 440, it was ten years ago but I always remember it having at least 20psi at idle (certainly never low enough to concern me).

Idle set at 900 or 1000.  Any less and I have to 2-foot it to prevent stalling.  The top pic is of the gauges when in neutral and hot.

Should I bother changing the fuel pump when I do the oil swap?

Thanks

The 10 psi per 1000rpm is a good rule of thumb but I like to see more than that at idle. Going by that standard it would only have 10psi at 900-1000 rpm and that's too low for my liking.  

The VR1 is good oil but I'd add a bottle of ZZDP additive just for good measure.  

You might get it better with thicker oil or you may need to go with a HV oilpump. If the pressure doesn't come up with the oil change....the next step is a high volume pump.

Is this a new problem ? Has the oil pressure allways been this low ? What are you using for oil filters ?

The Wix 1515 is the go to filter or if you have a Napa auto parts local you can use the Napa "Gold" filter which is reboxed  Wix 1515.  



Ron


Ps. Assuming the guage is accurate my guess is that the builder set the bearing clearances a bit on the loose side which isn't uncommon for performance builds. The extra clearance is there to account for thermal expansion as the engine heats up and is pushed hard.

[AWSOM50]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection.  

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves.  

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there.  


Ron

Thanks, Brad Penn looks hard to get hold of in my country, will VR1 20/50 do the job? (I already ordered it actually)

Your oil pressures seem drastically higher than mine.  I always read the rule of minimum 10psi per 1000 rpm but I also heard these blocks like higher pressure.  Do you think I am likely to have an engine problem here?

Before I changed the block I had the same gauge/sender on another 440, it was ten years ago but I always remember it having at least 20psi at idle (certainly never low enough to concern me).

Idle set at 900 or 1000.  Any less and I have to 2-foot it to prevent stalling.  The top pic is of the gauges when in neutral and hot.

Should I bother changing the fuel pump when I do the oil swap?

Thanks

The 10 psi per 1000rpm is a good rule of thumb but I like to see more than that at idle. Going by that standard it would only have 10psi at 900-1000 rpm and that's too low for my liking.  

The VR1 is good oil but I'd add a bottle of ZZDP additive just for good measure.  

You might get it better with thicker oil or you may need to go with a HV oilpump. If the pressure doesn't come up with the oil change....the next step is a high volume pump.

Is this a new problem ? Has the oil pressure allways been this low ? What are you using for oil filters ?

The Wix 1515 is the go to filter or if you have a Napa auto parts local you can use the Napa "Gold" filter which is reboxed  Wix 1515.  



Ron


Ps. Assuming the guage is accurate my guess is that the builder set the bearing clearances a bit on the loose side which isn't uncommon for performance builds. The extra clearance is there to account for thermal expansion as the engine heats up and is pushed hard.

Yeah, it reduces the fun when I have one eye on the oil gauge every 2 minutes.  From memory I always had the issue ever since putting in the block.  I don't recall if it was this bad or if it has got worse over time.  I don't feel comfortable with 8psi at idle at all.

Shouldn't I just do the oil pump swap at the same time as the change anyway?  I know it's better to change one variable at a time but I have to do a full oil change again if I change the pump, right?

The current filter seems unbranded, but Wix or Fram both ring a bell.  The one I have ready for the next change is a K&N HP-3001.  Should I use this or order a Wix 1515?

I wish we had stores here to buy this stuff.  It's summit/jegs etc or nothing usually, with a week delivery.  There are a few places to mail order in the UK but stock/variety is limited.

It gets frustrating when I'm excited about changing something then have to wait forever to get a gasket or whatever part I forgot to order.

[John_Kunkel]

- could try replacing oil pump with high volume one?  I don't know spec of current one - has no branding/part numbers.

Measure the thickness of the pump main body (without the cover), standard volume pumps are 1 3/4"...HV is 2".

[firefighter3931]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection.  

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves.  

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there.  


Ron

Thanks, Brad Penn looks hard to get hold of in my country, will VR1 20/50 do the job? (I already ordered it actually)

Your oil pressures seem drastically higher than mine.  I always read the rule of minimum 10psi per 1000 rpm but I also heard these blocks like higher pressure.  Do you think I am likely to have an engine problem here?

Before I changed the block I had the same gauge/sender on another 440, it was ten years ago but I always remember it having at least 20psi at idle (certainly never low enough to concern me).

Idle set at 900 or 1000.  Any less and I have to 2-foot it to prevent stalling.  The top pic is of the gauges when in neutral and hot.

Should I bother changing the fuel pump when I do the oil swap?

Thanks

The 10 psi per 1000rpm is a good rule of thumb but I like to see more than that at idle. Going by that standard it would only have 10psi at 900-1000 rpm and that's too low for my liking.  

The VR1 is good oil but I'd add a bottle of ZZDP additive just for good measure.  

You might get it better with thicker oil or you may need to go with a HV oilpump. If the pressure doesn't come up with the oil change....the next step is a high volume pump.

Is this a new problem ? Has the oil pressure allways been this low ? What are you using for oil filters ?

The Wix 1515 is the go to filter or if you have a Napa auto parts local you can use the Napa "Gold" filter which is reboxed  Wix 1515.  



Ron


Ps. Assuming the guage is accurate my guess is that the builder set the bearing clearances a bit on the loose side which isn't uncommon for performance builds. The extra clearance is there to account for thermal expansion as the engine heats up and is pushed hard.

Yeah, it reduces the fun when I have one eye on the oil gauge every 2 minutes.  From memory I always had the issue ever since putting in the block.  I don't recall if it was this bad or if it has got worse over time.  I don't feel comfortable with 8psi at idle at all.

Shouldn't I just do the oil pump swap at the same time as the change anyway?  I know it's better to change one variable at a time but I have to do a full oil change again if I change the pump, right?

The current filter seems unbranded, but Wix or Fram both ring a bell.  The one I have ready for the next change is a K&N HP-3001.  Should I use this or order a Wix 1515?

I wish we had stores here to buy this stuff.  It's summit/jegs etc or nothing usually, with a week delivery.  There are a few places to mail order in the UK but stock/variety is limited.

It gets frustrating when I'm excited about changing something then have to wait forever to get a gasket or whatever part I forgot to order.

That K&N filter will be fine 

The oil pump can be swapped out without changing the oil.....no worries there.  I would try the VR1 oil first and see what that does for your hot idle oil pressure. 

What oilpan are you running on this engine ?  What is the capacity ? I don't like to use HV pumps with 4qt oilpans. You need 6-7 qts to safely use the HV pump, inmo 



Ron

[myk]

Won't he need a hardened intermediate shaft for the high volume pump?

[AWSOM50]

I would try some thicker oil.....Brad Penn 20/50 is what I use. Has lots of Zinc/Phos for flat tappet protection. 

The main & rod bearing clearances can affect the hot oil pressures. If the clearances are a bit loose the oil pressure will drop once the engine reaches operating temp. My 572 has 75psi on startup and drops down to 50 psi @ hot idle. My main & rod bearings are at .0025 clearance and I'm using a high volume pump.

Try the thicker oil first and see if it improves. 

What rpm do you have the idle speed set at ? I prefer to keep them at 900rpm or more in gear to keep the pressure up and the rotating assembly well lubricated. The cam is splash lubed off of the rotating assembly so you want as much oil as possible to get flung up there. 


Ron

Thanks, Brad Penn looks hard to get hold of in my country, will VR1 20/50 do the job? (I already ordered it actually)

Your oil pressures seem drastically higher than mine.  I always read the rule of minimum 10psi per 1000 rpm but I also heard these blocks like higher pressure.  Do you think I am likely to have an engine problem here?

Before I changed the block I had the same gauge/sender on another 440, it was ten years ago but I always remember it having at least 20psi at idle (certainly never low enough to concern me).

Idle set at 900 or 1000.  Any less and I have to 2-foot it to prevent stalling.  The top pic is of the gauges when in neutral and hot.

Should I bother changing the fuel pump when I do the oil swap?

Thanks

The 10 psi per 1000rpm is a good rule of thumb but I like to see more than that at idle. Going by that standard it would only have 10psi at 900-1000 rpm and that's too low for my liking. 

The VR1 is good oil but I'd add a bottle of ZZDP additive just for good measure. 

You might get it better with thicker oil or you may need to go with a HV oilpump. If the pressure doesn't come up with the oil change....the next step is a high volume pump.

Is this a new problem ? Has the oil pressure allways been this low ? What are you using for oil filters ?

The Wix 1515 is the go to filter or if you have a Napa auto parts local you can use the Napa "Gold" filter which is reboxed  Wix 1515. 



Ron


Ps. Assuming the guage is accurate my guess is that the builder set the bearing clearances a bit on the loose side which isn't uncommon for performance builds. The extra clearance is there to account for thermal expansion as the engine heats up and is pushed hard.

Yeah, it reduces the fun when I have one eye on the oil gauge every 2 minutes.  From memory I always had the issue ever since putting in the block.  I don't recall if it was this bad or if it has got worse over time.  I don't feel comfortable with 8psi at idle at all.

Shouldn't I just do the oil pump swap at the same time as the change anyway?  I know it's better to change one variable at a time but I have to do a full oil change again if I change the pump, right?

The current filter seems unbranded, but Wix or Fram both ring a bell.  The one I have ready for the next change is a K&N HP-3001.  Should I use this or order a Wix 1515?

I wish we had stores here to buy this stuff.  It's summit/jegs etc or nothing usually, with a week delivery.  There are a few places to mail order in the UK but stock/variety is limited.

It gets frustrating when I'm excited about changing something then have to wait forever to get a gasket or whatever part I forgot to order.

That K&N filter will be fine 

The oil pump can be swapped out without changing the oil.....no worries there.  I would try the VR1 oil first and see what that does for your hot idle oil pressure. 

What oilpan are you running on this engine ?  What is the capacity ? I don't like to use HV pumps with 4qt oilpans. You need 6-7 qts to safely use the HV pump, inmo 



Ron

Today I changed to the 20w50 VR1 with the new filter.  It took 7 quarts.  I forgot to measure the pan and oil pump.

I'd say it has improved things about 10%.  A nice 70 psi at cold startup, about 20psi when it first hits 180F at idle 1000rpm, then 10 minutes later down to about 9 - 10psi per 1000 rpm, even though it's still 180F.

10psi exactly at idle in gear at 1000 rpm at last check.

There must be a good reason why there is a huge difference between hot and cold.  Am I likely to have a big problem on my hands?  Do I just accept it and run with it the way it is?

You guys think I should try another gauge?  I can't understand why the current gauge would be seemingly accurate at cold but not hot though...

Thanks to all.

[AWSOM50]

Btw, if it makes any difference the engine has a .590 Mopar cam in it.

[BSB67]

Personally, I would verify the gauge.

If the pressure readings are correct, you have only a few choices

1) If you have a std pump on it now, put a HV pump on it and go, understanding that you don't know why the pressure is so low.
2) If you have a HV pump now, go with what you have, and hope it is okay.
3) Get into the motor and find out why the pressure is low.

I don't know if you have a problem or not.  A little more info might be helpful, like after it is really really hot, what is the oil pressure at 1500, 2000, 2500 and 3000 rpm? and which pump do you have, std, or HV?

To me your pressure seems a little too low even with looser bearing clearances and full groove mains, but possible with a std. volume pump, I suppose.

[c00nhunterjoe]

Verification of the gauge is a good idea, but the audible knocking at idle kind of verifies it for me.... sounds like the pan needs to come down and pop a main and rod cap.

[AWSOM50]

Thanks guys, will measure the pump asap and feedback.

I can't get it above 180F at the moment as it's so cold here.  Oil pressure is nearly exactly 10psi per 1000rpm when hot.  20psi @ 2000 rpm, 30psi @ 3000 rpm etc

I also want try another sender but I am still confused if I am using the correct or wrong sender point.  There are 2 on my car.  In the pic below I am using the RED sender to my mechanical gauge.  The BLUE electrical one is not in use.  Is this wrong?  Should I get a sender for the BLUE point instead like this? http://www.ebay.com/itm/1968-1974-Dodge-Chrysler-Plymouth-V8-Oil-Pressure-GAUGE-Sending-Unit-/361250182944?hash=item541c305720

Then a mechanical line will just pop right on?

Thanks so much again

[igozumn]

Use either port.  When the Indy cylinder heads came out, you had to plumb oil lines to each of those ports up to the cylinder heads for an oil bar to supply oil to the rocker arms.

[Challenger340]

I think the reason you are seeing diminishing Oil Pressure once warm is it is a high clearance Engine(Bearings), either from wear... or just plain was built that way.
And I think the reason Oil pressure is dropping the longer it is up AT temp... is because the longer the water temp stays at 180*... the hotter/thinner the Engine Oil gets.
Remember, just because the water temp initially comes up to 180*... the Oil could still be down at 120*(thicker), then the longer you run it, eventually the Oil temp comes up as well(thinner) and pressure drops.  You will know once the warmer weather arrives, and the longer you drive it(Oil warms), the pressure drops again.

[AWSOM50]

I think the reason you are seeing diminishing Oil Pressure once warm is it is a high clearance Engine(Bearings), either from wear... or just plain was built that way.
And I think the reason Oil pressure is dropping the longer it is up AT temp... is because the longer the water temp stays at 180*... the hotter/thinner the Engine Oil gets.
Remember, just because the water temp initially comes up to 180*... the Oil could still be down at 120*(thicker), then the longer you run it, eventually the Oil temp comes up as well(thinner) and pressure drops.  You will know once the warmer weather arrives, and the longer you drive it(Oil warms), the pressure drops again.

Thanks, that makes sense.

I measured the pump, it's 1 3/4" excluding the cover (I didn't realise it was so easily accessible).  So standard volume I think.

So I'm going to get a Melling M63HV pump, priming shaft and new sender just in case and go from there unless someone tells me to get the Mopar P4286590 pump instead...

I realise this doesn't identify the real issue other than the assumption of a loose motor but if it gets the idle PSI up a bit I think I'll be happy to run with it.

Still not sure on the knocking, I think it is possibly the headers fouling on the engine bay.  One side is completely touching at rest.

Thanks guys, I'm learning so much from this.

Btw, reading about priming a new pump, I have very strong doubts that the guys who fitted the block would have primed it....  no way they would have had the mopar shaft anyway

[dual fours]

Hey firefighter3931 concerning your Reply #8 above, Isn't the WIX Filter a number 51515? I think the NAPA Gold number is 1515.

[AWSOM50]

Won't he need a hardened intermediate shaft for the high volume pump?

Is there an easy way to tell if my current one is hardened or not?  Or should I just assume it isn't since I don't have a HV pump?

Looks like a tricky job to replace...

[firefighter3931]

Hey firefighter3931 concerning your Reply #8 above, Isn't the WIX Filter a number 51515? I think the NAPA Gold number is 1515.

You are correct D4's on the part numbers 

Thanks for the correction 


Ron

[firefighter3931]

Won't he need a hardened intermediate shaft for the high volume pump?

Is there an easy way to tell if my current one is hardened or not?  Or should I just assume it isn't since I don't have a HV pump?

Looks like a tricky job to replace...

The oil pump drive is easy to replace ; once the distributor is out insert a flat screwdriver in the slot and turn it the opposite direction of rotation....the gear will back right out.

I prefer the harden shaft OP drives for 2 reasons ; the tapered shaft is stronger and the gear is also pinned onto the shaft for additional strength. 


Ron