oil pressure fluctuating.

[70wayfarer]

ok, just got the car fired last night for first time since changing to efi and roller cam. oil pressure was steady bat idle about 50 psi, but as engine temp raised the oil temp went down fluctuating between 25 - 40 psi and came back up to 60 as i brung rpm up to 2500 and stayed steady. oil temp was just under 140 and engine temp 190.i put bradd penn 10w 40 in her. cam and lifters are hughes hydraulic roller. they say to run 10w 30 with their lifters.
i'm thinking oil is thinning out at engine temp.

 

[4spdragtop]

Dads 273 runs 70 @ road speed. Idle its 40. Mech oil psi sender? Air in the tube that leads to back of gauge?
I use Rotella 15W40 with lucas oil additive. 4 years now and runs strong.

 

[SGBARRACUDA]

'm thinking oil is thinning out at engine temp. You think?
I don't see a problem here? Sounds normal. My 69 360 Dart has 60-65 PSI cold, Idles hot at 25 PSI.

 

[pishta]

sounds good to me. Don't let it bother you.

 

[70wayfarer]

before the change to roller cam i ran flat tappet and 20 50 oil and not noticed the fluctuation.

 

[SGBARRACUDA]

before the change to roller cam i ran flat tappet and 20 50 oil and not noticed the fluctuation.

Your saying the oil pressure was the same cold and when hot?

 

[SGBARRACUDA]

Or are you saying that with the engine running at the same RPM, Like when it is at normal running temp that the oil pressure is fluctuating all the time? I mean now with the roller lifters in it.

 

[brasil]

more than 15 PSI HOT @ Idle is fine... Highwayspeed.... 45-50 PSI is also fine.

The rule of thump is 10 PSI every 1000 RPM so you are in the save range.

Concerning the weight... 10 w40 would be my favorite...10W30...is "on the edge"...if you are running your engine HARD....the "30" could probably lead to a problem... ( surely on a very hot day )

Greetings Juergen

 

[nm9stheham]

Since it is cooler and winter there, just keep an eye on when the summer comes at how low the pressure goes when hot. If the pressure gets low enough at low RPM's to be a problem, then switching to an HV pump will bring it up some. The numbers you report are pretty decent.

Sounds like the 10W40 is a compromise between what the bottom end wants, and what Hughes says to use for their hyd rollers.

 

[fnaramore]

I think the concern here is not the numbers themselves, as if he is thinking they are too low, but why there is 15 psi fluctuation at hot idle, if I read that correctly. If it's steady at cold idle and then gets the big swings at hot, I would be surprised if it was air in the line. It might just be the pump gets random strong pumps going as the engine lopes. Regardless, like the others said, the numbers aren't bad so its nothing to fret over.

 

[Rocket]

2 items come to mind.
- You switched from 20W50 to 10W40.
- You switched to roller lifters from solid lifters.

Each of these may have a small impact on the pressure. The roller lifters may bleed off a little more pressure due to clearances. The oil is a little thinner.

You put on the EFI. Did the hot idle speed drop? If yes then this may be contributing a little to lower pressure. Nothing to worry about.

The numbers you are posting are decent pressures. Have fun driving the car.

 

[71DodgeDemon340]

Same here, running 15w50. Idle when cold is 75psi. When warm at idle is 25 psi seems normal. about 50 psi at cruising speed

 

[SGBARRACUDA]

I forgot to add when I posted. I run 10-40 Lucas Hot Rod oil.

 

[brasil]

I use the same weight ...15W50 Motul synthetic oil...
20 psi hot @ idle and 50-55 psi while driving....
The oil filter is also important... I use only WIX Filters...
or the FL1A ...( I know.. Ford stuff...but a good filter )

if there is some air in the pressure line the needle jumps..
but only while the engine is idling... under load..the needle should show a steady pressue

Greetings Juergen