Low Oil pressure

-
i cant tell you for sure but its not the correct engine for this car
anyway i just made 50 psi at idle cold
so thats alot better

its just got a small summit cam , .050 off the heads & about 9:1 comp now with the later pistons with
the slightly higher ch & edlebrock intake with carter 625 carby & shorty headers.
Just wanted a nice cruiser
 
vghoon said:
I kinda feel like a gynecologist!
Click to expand...
LOL. good quip there. BTW, re-reading your original post, I see you re-used the original oil pump and cam bearings. Both are good places to lose pressure. I would not expect the hole you fixed to lower the pressure all that much with a good pump. So with the extra leakage at older cam bearings and a mildy worn pump, it probably was the 'on the edge'. Cold idle pressure with a new pump, 10W30 oil, and all bearing clearances good should typically be up in the 60 to 70 psi range.

I'd suggest pulling the pump and checking the clearances to spec and looking for excess grooving and gouging on the rotor faces and in the pump body, or just put a new pump in. Starting with a worn pump on a cruiser and putting on a lot of miles is just looking for chronic low oil pressure. I know it is pain to get off the pan but I would not hesitate to do so.
 
nm9stheham said:
LOL. good quip there. BTW, re-reading your original post, I see you re-used the original oil pump and cam bearings. Both are good places to lose pressure. I would not expect the hole you fixed to lower the pressure all that much with a good pump. So with the extra leakage at older cam bearings and a mildy worn pump, it probably was the 'on the edge'. Cold idle pressure with a new pump, 10W30 oil, and all bearing clearances good should typically be up in the 60 to 70 psi range.

I'd suggest pulling the pump and checking the clearances to spec and looking for excess grooving and gouging on the rotor faces and in the pump body, or just put a new pump in. Starting with a worn pump on a cruiser and putting on a lot of miles is just looking for chronic low oil pressure. I know it is pain to get off the pan but I would not hesitate to do so.
Click to expand...

Agreed, When I prime a new engine, I'm expecting 70-75 PSI. If not I start looking for a problem.
 
10W30 oil, and all bearing clearances good should typically be up in the 60 to 70 psi range.[/quote]With a standard oil pump this pressure is not going to happen. 60 to 70 psi is crazy with a stock engine. No way any engine came off the line with that kind of oil pressure. 10 psi per 1000 rpm is ok. Expect to see 50 to 55 psi cold at idle. Again, IMO.
Most stock Mopars run 45-50 psi at 2000 rpm hot and anything from 15-30 psi at hot idle.
Click to expand...
 
Mopar Tim said:
10W30 oil, and all bearing clearances good should typically be up in the 60 to 70 psi range.
Click to expand...
With a standard oil pump this pressure is not going to happen. 60 to 70 psi is crazy with a stock engine. No way any engine came off the line with that kind of oil pressure. 10 psi per 1000 rpm is ok. Expect to see 50 to 55 psi cold at idle. Again, IMO.[/QUOTE] There are 2 pressure relief springs being used: one is 55 psi nominal, which supports what you are saying MT. But there is also a 72 psi nominal relief spring, which is used commonly, and IIRC, Krazykuda reports them being used in the Melling pumps. Either spring can be in the standard or the HV pumps. Our 340's new Melling pump runs in the 70's psi cold at idle with 10W30 and I checked the relief spring before assembly; it is the 72 psi one.

If you are really cold (like 30F or lower), the cold pump pressure will run a few pounds higher than the relief spring rating; I assume due to the higher viscosity. So even the 55 psi spring can run up to 60 psi when very cold, I probably should have just said 55-75 psi cold to cover all of the different cases!

And of course, all our pressure readings are varied because of the different oil pressure gauges tool; they are not exactly lab quality accuracy here!
 
The ones that came in mopar pumps are 55 PSI. IMO with a stock,ish 318, you will lose more HP then the extra 20-30 PSI is worth. I think some guys just like to see High Oil pressure, like a bragging right! The dummy light on these engines came on at....5 PSI! anything above that was acceptable on a high mileage engine. Of course you will not want that kind of pressure on a rebuilt engine. Like stated, Cam bearings is a good place to lose oil pressure.
 
I called Mellings when the subject came up in my oil pump pressure relief spring how to. The Mellings guy stated that all Mellings pumps come with the 72 psi spring, both standard and high volume. Mellings does not use the lower pressure spring...

Mopar Performance told me that all of their pumps are 55 psi springs (give or take), whether you get the standard or high volume MP pump. They offer a spring kit to convert their pumps to 75 psi if you desire. The MP guy couldn't tell me if they bought oil pumps from Mellings or not... I'm sure that they are not Mellings if they come with a 55 psi spring...
 
FWIW.... I bought the Mopar Performance HV pump last fall that we used and it had the Melling PN on it.... and the heavier 72 psi spring. So MP can vary , I guess.... .or the MP guy you spoke with had old or erroneous data.
 
nm9stheham said:
FWIW.... I bought the Mopar Performance HV pump last fall that we used and it had the Melling PN on it.... and the heavier 72 psi spring. So MP can vary , I guess.... .or the MP guy you spoke with had old or erroneous data.
Click to expand...

I didn't want to say it, but he e didn't sound like a real "go-getter" that likes to do/know as much as he can about the product (if you know what I mean...)... Just putting in his manditory 9-5 and out.... :color:

They could buy some from Mellings... Or even change once in a while...
 
Mopar Tim said:
The dummy light on these engines came on at....5 PSI!
Click to expand...

And just for the record, I've beat on a lot of 318's that had blinking oil lights at a low idle when warm. Never, ever, ever lost 318, and I've owned lots of 'em.
 
318willrun said:
And just for the record, I've beat on a lot of 318's that had blinking oil lights at a low idle when warm. Never, ever, ever lost 318, and I've owned lots of 'em.
Click to expand...

Right! What most people don't realize is, there is NOT an oil pressure spec for idle, I don't believe. The only spec I have ever seen is at 2K RPM.
 
RustyRatRod said:
Right! What most people don't realize is, there is NOT an oil pressure spec for idle, I don't believe. The only spec I have ever seen is at 2K RPM.
Click to expand...
It seems to me we get caught up in the "whats the oil pressure SUPPOSED to be" It kind of is what it is. I have found no credible info on Oil pressure at idle. They only, like RRR said, at 2k RPM.
 
krazykuda said:
I didn't want to say it, but he didn't sound like a real "go-getter" that likes to do/know as much as he can about the product (if you know what I mean...)... Just putting in his manditory 9-5 and out.... :color:

They could buy some from Mellings... Or even change once in a while...
Click to expand...
I got a similar impression from my brush with Edelbrock tech support... not someone with any real experience .... it is the current model for customer and tech support that seems to have infected all large businesses: fill the role but minimize the cost. Often the managers have no real experience either, and are there to just manage the model to a cost spreadsheet. The main technical products company we buy from went through this cycle and fortunately have recovered some technical expertise.
 
Mopar Tim said:
It seems to me we get caught up in the "whats the oil pressure SUPPOSED to be" It kind of is what it is. I have found no credible info on Oil pressure at idle. They only, like RRR said, at 2k RPM.
Click to expand...
True only to a point IMHO; there is enough corporate experience here to give a reliable range of what one should expect with certain conditions: oil weight, pump relief spring, new bearings and so forth should give a reasonably accurate picture of pressure range. No one who has repeatedly built a number of engines X, Y or Z will fail to figure out what a normal oil pressure range is for that particular engine. There have been plenty of statements in this thread alone about the OP's original pressure being abnormally low and something must be amiss.
 
nm9stheham said:
True only to a point IMHO; there is enough corporate experience here to give a reliable range of what one should expect with certain conditions: oil weight, pump relief spring, new bearings and so forth should give a reasonably accurate picture of pressure range. No one who has repeatedly built a number of engines X, Y or Z will fail to figure out what a normal oil pressure range is for that particular engine. There have been plenty of statements in this thread alone about the OP's original pressure being abnormally low and something must be amiss.
Click to expand...
Yes seems something else is wrong with the OP engine. Thanks!:cheers:
 
You must log in or register to reply here.
-

Back
Top