Help with low oil pressure

[moparmike68]

It is weird to have to tell a seasoned shop "how to build", but they often have younger inexperienced guys doing much of the work now. In my case, I trusted the local builder to assemble my stroker. They did just that, assemble. My bearing clearance must be quite large due to the low oil pressure. The old saying of "trust and verify" applies here. I trusted but did not verify. They built engines for us in the past that were excellent.

Well this was an older guy that had an older shop with machines visible so I thought I was good. I thought”oh this guy is older and wiser and is probably good at rebuilding g engines over decades.Not too sure now🫩. You just never know

 

[Ricks72Chlgr440]

Well this was an older guy that had an older shop with machines visible so I thought I was good. I thought”oh this guy is older and wiser and is probably good at rebuilding g engines over decades.Not too sure now🫩. You just never know

Exactly. The shop I use is always really busy so thinking they just quickly built it and out the door. It takes a little longer to use plastigauge for bearing clearance but I doubt it was done. I know Mopar Joe said one time he sent back bearings in a stroker kit because they did not provide the correct clearance. It can happen, but machine shops should check for that.

 

[moparmike68]

Exactly. The shop I use is always really busy so thinking they just quickly built it and out the door. It takes a little longer to use plastigauge for bearing clearance but I doubt it was done. I know Mopar Joe said one time he sent back bearings in a stroker kit because they did not provide the correct clearance. It can happen, but machine shops should check for that.

No kidding

 

[rickseeman]

You said in your first post that you tried a high volume pump and it made no difference. I'm finding that hard to believe. I'm a B/RB oil pump guy. A HV pump is 1/4" thicker than a stock pump. Is that what you put on there? Last week I finished up a 383 rebuild. When I put it on the test stand it had low hot oil pressure idling. So I put a HV pump on and now it has 30-40. The engines in our classic Mopar muscle cars are over 50 years old. There are problems associated with this. One recurring theme you will hear about on the forums every month is “low hot oil pressure idling”. Yes it’s true, you have low hot oil pressure idling. Don’t panic. Your engine is not going to “blow up”. It will still make plenty of oil pressure when you are driving because the oil pump is turning more rpm’s. But when you are idling the engine might be turning as low as 700 rpm’s. That means your oil pump is turning 350 rpm’s. Engines wear. Even though your engine has been rebuilt, there are 16 lifter bores that are worn and there's a lot of oil passing each lifter. Factory rod and main bearing clearances were very tight. A rebuild today likely has more clearance. Your problem is very common. A M-63HV usually fixes the problem. If not you can go to thicker oil. (By the way, the stock spring is red or pink, usually will bypass around 55 psi. The black spring, sometimes called the hemi spring, bypasses around 75 psi. Use whichever spring you like.)

 

[AUSTA]

What is the idle speed how far does the pressure come up by increasing idle speed

 

[moparmike68]

You said in your first post that you tried a high volume pump and it made no difference. I'm finding that hard to believe. I'm a B/RB oil pump guy. A HV pump is 1/4" thicker than a stock pump. Is that what you put on there? Last week I finished up a 383 rebuild. When I put it on the test stand it had low hot oil pressure idling. So I put a HV pump on and now it has 30-40. The engines in our classic Mopar muscle cars are over 50 years old. There are problems associated with this. One recurring theme you will hear about on the forums every month is “low hot oil pressure idling”. Yes it’s true, you have low hot oil pressure idling. Don’t panic. Your engine is not going to “blow up”. It will still make plenty of oil pressure when you are driving because the oil pump is turning more rpm’s. But when you are idling the engine might be turning as low as 700 rpm’s. That means your oil pump is turning 350 rpm’s. Engines wear. Even though your engine has been rebuilt, there are 16 lifter bores that are worn and there's a lot of oil passing each lifter. Factory rod and main bearing clearances were very tight. A rebuild today likely has more clearance. Your problem is very common. A M-63HV usually fixes the problem. If not you can go to thicker oil. (By the way, the stock spring is red or pink, usually will bypass around 55 psi. The black spring, sometimes called the hemi spring, bypasses around 75 psi. Use whichever spring you like.)

Thanks for your info! To be honest , my memory may be a little fuzzy as it was about 10years ago that I had the rebuild done. I thought that I had tried both a high pressure, and a high volume pump, but looking at the two pumps I have, they look identical size(only difference is the springs. One is pink, the other possibly black or no color). One has the small tag “m63 hp” on the bolt. The other has no tag. I’m now thinking that I have a stock pump and and a high pressure pump. So I guess I did not try a high volume pump. . What is your opinion on the fears stated by people on the forums, that a HV pump could suck the stock pan dry? I have a stock pan with windage tray. I don’t race the car and will occasionally take it out on the road/highway for a blast or two to “blow the carbon out”. My next plan was to try my current pump and change from Brad Penn 10w30 to valvoline 10w40 racing oil and see if that helps the pressure. If not, then I may try the hv pump.
Thanks!

 

[moparmike68]

What is the idle speed how far does the pressure come up by increasing idle speed

I don”t remember, since it was last spring/summer when I last drove it. I believe it was around 700-800rpm and the pressure did increase with acceleration/increased rpm’s but I often wasn’t paying too much attention to the upper pressure , but instead the extremely low end pressure.

 

[Challenger RTA]

700-800rpm

Not that this is the problem but it's misunderstood. For one thing you not driving a Diesel. Diesel are built in a manner to idle for hours if need be. A car engine is built to start at high idle to warm up and run. Not to sit an idle. That is one of the hardest things on them. 700-800 rpms that just bothers me but it might be ok. The pump isn't spinning that fast. When I prime an engine I use a 3600 - 1600 rpm drill on the lower speed for toque. check out below. You can see how long it takes to get the oil there. You can her the Milwaukee drill zinging away. Made in the USA.
By the way and it still runs since 85.

 

[moparmike68]

Not that this is the problem but it's misunderstood. For one thing you not driving a Diesel. Diesel are built in a manner to idle for hours if need be. A car engine is built to start at high idle to warm up and run. Not to sit an idle. That is one of the hardest things on them. 700-800 rpms that just bothers me but it might be ok. The pump isn't spinning that fast. When I prime an engine I use a 3600 - 1600 rpm drill on the lower speed for toque. check out below. You can see how long it takes to get the oil there. You can her the Milwaukee drill zinging away. Made in the USA.
By the way and it still runs since 85.

Thanks

 

[rickseeman]

Thanks for your info! To be honest , my memory may be a little fuzzy as it was about 10years ago that I had the rebuild done. I thought that I had tried both a high pressure, and a high volume pump, but looking at the two pumps I have, they look identical size(only difference is the springs. One is pink, the other possibly black or no color). One has the small tag “m63 hp” on the bolt. The other has no tag. I’m now thinking that I have a stock pump and and a high pressure pump. So I guess I did not try a high volume pump. . What is your opinion on the fears stated by people on the forums, that a HV pump could suck the stock pan dry? I have a stock pan with windage tray. I don’t race the car and will occasionally take it out on the road/highway for a blast or two to “blow the carbon out”. My next plan was to try my current pump and change from Brad Penn 10w30 to valvoline 10w40 racing oil and see if that helps the pressure. If not, then I may try the hv pump.
Thanks!

I wouldn't worry about "sucking the pan dry". Get a M-63HV pump and put your pink spring in it. This should bypass around 55 psi and give you better hot oil pressure idling. If the 10-40 oil doesn't work you can try 20-50. We know your engine has a lot of clearance.

 

[moparmike68]

I wouldn't worry about "sucking the pan dry". Get a M-63HV pump and put your pink spring in it. This should bypass around 55 psi and give you better hot oil pressure idling. If the 10-40 oil doesn't work you can try 20-50. We know your engine has a lot of clearance.

Thanks

 

[moparmike68]

I wouldn't worry about "sucking the pan dry". Get a M-63HV pump and put your pink spring in it. This should bypass around 55 psi and give you better hot oil pressure idling. If the 10-40 oil doesn't work you can try 20-50. We know your engine has a lot of clearance.

20w50 is pretty thick for cooler weather and cold starts. Wouldn’t a lower number such as 5w50 or 10w50 be thinner at start up to get the oil to where it needs to be quicker?

 

[Ohiowoodchuck]

sorry if I missed it earlier but what brand of oil are you using? I switched a couple years back to Brad penn racing oil in just about everything but my newer truck which takes synthetic.

 

[moparmike68]

sorry if I missed it earlier but what brand of oil are you using? I switched a couple years back to Brad penn racing oil in just about everything but my newer truck which takes synthetic.

I used Brad Penn 10w30 since the break in oil was changed. I had the Brad penn in it until now and it probably only had another 500 miles. So the engine has less that 1000 miles on it. I’m changing it (with valvoline racing 10w-40) because I think the 30 wt oil was getting too thin when at operating temp and was giving me low oil pressure. Thought I’d see if a heavier weight oil would get me some more oil pressure when hot, before I change to a hv pump.

 

[Chryco Psycho]

I beg to differ , sucked an oil pan dry at high RPM tore up the crank brgs

 

[540HemiCuda]

The HV pump can drain your pan.......when pushed hard. Like hard acceleration which pushes the oil to the back of the pan and away from the pick up, or with hard cornering, or with sustained full throttle runs. You can run the smaller pan with the HV pump as long as you are careful. The 6 qt pan is a couple of hundred bucks from 440 Source and would be necessary if you are going to 'push' the engine.

May I suggest one step at a time; start with the heavier weight oil since it's the easiest and cheapest. See what that does. Then, if that doesn't work, go to the next, more expensive step of HV pump and possibly the pan. Both can be changed in the car. It is tight. You may need to loosen the engine mounts to raise the engine and knock the drag link loose for working room, but it can be done.

.

 

[moparmike68]

The HV pump can drain your pan.......when pushed hard. Like hard acceleration which pushes the oil to the back of the pan and away from the pick up, or with hard cornering, or with sustained full throttle runs. You can run the smaller pan with the HV pump as long as you are careful. The 6 qt pan is a couple of hundred bucks from 440 Source and would be necessary if you are going to 'push' the engine.

May I suggest one step at a time; start with the heavier weight oil since it's the easiest and cheapest. See what that does. Then, if that doesn't work, go to the next, more expensive step of HV pump and possibly the pan. Both can be changed in the car. It is tight. You may need to loosen the engine mounts to raise the engine and knock the drag link loose for working room, but it can be done.

.

Thanks, I have been a little apprehensive about changing to the hv pump for that reason. I initially bought a larger pan from 440 source but it didn’t work. It was taller along the shallow part of the pan (also the thickness of the 2 gaskets and windage tray may have pushed the pan even farther down close to the drag link bar), and my drag link rubbed on the panso I think returned it or sold it. Went back with the stock size pan.

 

[rickseeman]

20w50 is pretty thick for cooler weather and cold starts. Wouldn’t a lower number such as 5w50 or 10w50 be thinner at start up to get the oil to where it needs to be quicker?

20w50 is supposed to act like 20 weight when cold. You have to decide if you want to try the thicker oil first or the HV pump. That's a decision for you. Personally, I think our engines are 55 years old and even if they have been rebuilt, they have much larger clearances than they did in 1969 and the only real fix is the HV pump. In the 70's if my worn out engine didn't have enough oil pressure and if I didn't have $30 for the HV pump, I would just change to 50 weight Valvoline racing oil.

Now it's 2026 and I'm a BBM oil pump/system guru. I can solve any BBM oiling problem blindfolded. It's easy for me. I have 15 of the most popular BBM oil pumps, all the Melling models, all the Milodons, Chrysler and Keith Black. And I test them on my test stand engine. I wouldn't run a wedge oil pan on a wedge for any amount of money. I'd put on a Hemi pan. Period. (Like Mopar tells you to do.) And if it hit the drag link I would put on the 440 Source drooped drag link. If my engine had low hot oil pressure idling I would put on the HV pump. You see? BBM oiling problems are an easy fix for me. You will work your way through this and everything will be fine. We like working on and improving our cars.

On my test stand now I have a billet Keith Black oil pump. Instead of dual feed lines it has 1 -20 line to the pump and an internal cavity in the pump to feed the top and the bottom of the pump like a dual line Milodon would have except with less hoses and fitting issues.

 

[moparmike68]

Thanks, I have been a little apprehensive about changing to the hv pump for that reason. I initially bought a larger pan from 440 source but it didn’t work. It was taller along the shallow part of the pan (also the thickness of the 2 gaskets and windage tray may have pushed the pan even farther down close to the drag link bar), and my drag link rubbed on the panso I think returned it or sold it. Went back with the stock size pan.

 

[Ohiowoodchuck]

I ran straight 50w cenpeco and schaffers in my dodge ram pulling truck with a 5.9 Cummins. All bearing tolerances were set to max tolerance. It carried 70lbs at startup and 40lbs at idle, when warm. That was brand new oil. I would start loosing pressure after a couple runs cause the diesel fuel would start diluting the oil. It might be worth a shot like the gentleman have mentioned above. 5-6 quarts of 50w oil isn’t going to cost you that much vs. a tear down.