Oil Pump Question

[cudabob496]

My oil pressure seems to be about 15psi lower than normal.  Pump has 50,000 miles on it.
Do I just replace the black high pressure spring, or the whole pump at this time?

[high perf mopar]

that could be due to alot of things,,,ambieant air temps/heat of oil,would drop the oil pressure.excess clearaces,clogged/choked oil filter.if its the spring,the tension would be less after getting hot,,its pretty easy to drop out the pump and look at it..

i run the milodon adj unit so i can dial my oil pressure.
   

[Chryco Psycho]

the black spring is $3
 if you replace the pump get a Melling HP

[72cudamaan]

My oil pressure seems to be about 15psi lower than normal.  Pump has 50,000 miles on it.
Do I just replace the black high pressure spring, or the whole pump at this time?

I've read that 600 hp motors can't handle synthetic oil. Try a regular 10w30.  lol    . Just kidding. It
seems strange you would lose 15 psi suddenly due to a spring. I would drain the oil and see if it's diluted. ie gas?

[high perf mopar]

if u do get a new pump.whatever the make blueprint it yourself...use a drimel tool and radious all the turns just ever so slightly,,,and remove the casting flash,,,easy and do it yourself,they charge alot for that..

[cudabob496]

Thanks.  Synthetic jokes! hahaha! I am running 0wt-30, but when it gets hot, its supposed to behave like 30wt. I was a quart low. I usually
intentionally run a quart low to minimize windage losses. Got a 7 qt pan. But until this summer, I've used 10wt-30 and 5wt-30. Its not an all of a sudden thing.
Use to run 75 to 80 all the time, now I'm 60 to 65.  I'll try a new spring first.  That adjustable Milodon sounds cool!

(If the synthetic doesn't work out, I'll go back to vasoline, lard, or whatever else Cudamaan uses)

[high perf mopar]

milodon #21550 adj oil pump pressure regulator...

http://www.milodon.com/oil-system/components.asp

it can be your freind,,,,along with google these days...LOL...

[Strawdawg]

that is what I would expect from 0-30 wt oil

sounds exactly what I would expect to obtain from using it.

[cudabob496]

that is what I would expect from 0-30 wt oil

sounds exactly what I would expect to obtain from using it.

So, I wonder if when the oil is hot, 10-30 wt will give a higher oil pressure than 0-30 wt at the
same temp? Should be the same pressure, I would think? I have an oil temp gauge, and it was about
160 degrees.

[Strawdawg]

In theory, it should be the same...in reality, I would not be surprised to see it a bit higher.  Why do you want more oil pressure?

[cudabob496]

In theory, it should be the same...in reality, I would not be surprised to see it a bit higher.  Why do you want more oil pressure?

On a high performance big block, wouldn't it be better to have 75 psi than 55 psi oil pressure?

[Strawdawg]

In your previous post you said you had 65 psi...

The old rule of thumb was always 10 psi per thousand rpm so 65 would be good.

With modern oils and modern engine building, many run less than that due to better film strength and tighter clearances which require less volume to maintain the pressure.

I doubt you know what the clearances are in your engine or how well the passages were relieved/radiused so I would look for the old rule of thumb.

If you want more, then you can try a stiffer spring or merely shim the one you have in there.

If the pressure increases then that should be good.  If it does not, you need a better hv pump or a heavier weight oil.

Pressure is simply the resistance to flow so the pump has to have a sufficient volume of flow before the pressure can increase.

[cudabob496]

In your previous post you said you had 65 psi...

The old rule of thumb was always 10 psi per thousand rpm so 65 would be good.

With modern oils and modern engine building, many run less than that due to better film strength and tighter clearances which require less volume to maintain the pressure.

I doubt you know what the clearances are in your engine or how well the passages were relieved/radiused so I would look for the old rule of thumb.

If you want more, then you can try a stiffer spring or merely shim the one you have in there.

If the pressure increases then that should be good.  If it does not, you need a better hv pump or a heavier weight oil.

Pressure is simply the resistance to flow so the pump has to have a sufficient volume of flow before the pressure can increase.

OK, thanks!

But I am wondering if an engine is better off with say 75psi, than 55psi. The high volume oil pump sales folks
seem to push that it is, but I don't know why?

[Strawdawg]

Other than using up more hp and putting more strain on the pump drive, I cannot see why UNLESS the engine was poorly machined and the extra pressure does more to try to push oil thru the more restrictive passages.

[cudabob496]

Other than using up more hp and putting more strain on the pump drive, I cannot see why UNLESS the engine was poorly machined and the extra pressure does more to try to push oil thru the more restrictive passages.

Makes sense. Maybe there's some benefit if the motor is pounding out 2000 horse power at 8000 rpm, where there is a greater
chance of losing some oil film somewhere.  Also, if you lost your oil pump, the high pressure might give you 2 more seconds to cross
the finish line!