New to me Barracuda with Mopar Crate 390hp low oil pressure

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Overlook68

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Prior owner installed a 390hp Mopar crate 360. According to him he change to a bigger roller cam and roller rockers. I assume this was done years ago when the engine was installed. I can see orange or bronze looking rocker arms from the oil fill cap. She sounds like a big cam. He spent money and time on the car but he clearly wasn't a engine or car guy. So I question if these were changed out correctly.

With fresh 5w40 synthetic oil on a cold engine 65 degree day. I get 75psi at idle. As it warmed up on a drive it held 50psi and increased with rpm. Once warmed up at idle near 20psi. In gear and loping around 850rpm the gauge would read near zero. Slight bump in throttle and PSI jumps back up to 20-25. Put it in Neutral rpm are up and PSI is back to 20-25

These are some off brand gauges and the Optima battery is now 11 years old so when its gear at low rpm the volt meter is bouncing and the lights flicker as the electric fan is pulling power. I know that volts can cause irregular meter readings on some gauges. Could the cheap gauges and/or low battery volts be throwing out the very low oil pressure reading? This is my best hope.

The PCV is stopped up or something because she is pushing oil out the filler plug and PCV on the passenger side and crankcase filter on the drivers side. I plan on getting the adjustable PCV valve.

Zero smoke on start up. Zero smoke when driving. I pulled a oil sample at this oil change to see whats the oil like.

What is my best case and worse case scenario?
 
Overlook68 said:
The PCV is stopped up or something because she is pushing oil out the filler plug and PCV on the passenger side and crankcase filter on the drivers side. I plan on getting the adjustable PCV valve.
Click to expand...

Yeech. Sounds like excessive blowby. Time for a compression test or a leakdown test.
 
Demonic said:
Yeech. Sounds like excessive blowby. Time for a compression test or a leakdown test.
Click to expand...

Zero smoke. But a compression check is easy. I've got a mechanical oil pressure tester on order. I think the parts store has loaner tools for compression check.
 
Explain the PCV system. It has a PCV on one side but what's on the other side?
 
First, get some valve covers on that thing that have baffles in them. If you can A) See the rockers through the fill hole, B) pushing oil out the crankcase filter, and C) plugging up your PCV valve; there obviously aren't any baffles in the ones you have now.
Second, get some thicker oil in there- 10w30 or 10w40. Then see how your oil pressure behaves.
 
Because your located in the warm South, I'd run 20 w 50 or straight 30 wt HD.
 
RustyRatRod said:
Explain the PCV system. It has a PCV on one side but what's on the other side?
Click to expand...
Passenger side has what i assume is PCV screwed into the valve cover. Hose runs to intake Manifold. Front passenger side is rubber plug.

driver side rear has a baffled vent. Front driver side is oil fill cap not baffled.

Valve covers are Mopar that I assume came on the crate engine.
 
Try a mechanical gauge as suggested to get around any electrical effects.

I've run synthetic for at least 1M miles in all sorts of uses, including racing. Low pressure does not worry me.... I have raced 4 miles with zero oil pressure with Mobil 1 (blew an oil fitting) with no damage found at teardown. (I have a witness.) IMHO it is step backwards to move to non-synthetic.

There is a 15W50 Mobil 1 that should help the pressure if it is not a gauge issue. And probably other synthetics that are heavier; I just don't know them all.
 
Passenger side has what i assume is PCV screwed into the valve cover. Hose runs to intake Manifold. Front passenger side is rubber plug.
Click to expand...

If there isn’t some sort of breather in one of the valve covers...... there needs to be.
It should be on the opposite side of the motor as the PCV valve.
 
I changed the 11 year old Optima Red Top battery. When at low idle, hot engine and the electric fan on the volts are near 12 and slightly bounce up to 12.5. Oil PSI reads 2-5psi. But once the electric fan stops. Volt meter is back up to above 13 and oil psi is around 10-15. Gauge is not marked below 25. So I have to guess.

mechanical gauge is in the mail.

Looks like the prior owner wired the electric fan to the Painless wiring brand fuse box. I’ll change this to a relay and pull power directly from the battery.
 
Drain the synthetic. Stick in 10w-something or 15W something and see if the pressures change.
If the PCV cannot handle the blow by, somethings wrong and it's probably not the PCV. From what you are describing, and understanding it's a Mopar produced crate engine originally, I would look at the oil pressure with dinosaur oil in it, and if it's still low, I'd pull the engine for inspection.
 
Overlook68 said:
I changed the 11 year old Optima Red Top battery. When at low idle, hot engine and the electric fan on the volts are near 12 and slightly bounce up to 12.5. Oil PSI reads 2-5psi. But once the electric fan stops. Volt meter is back up to above 13 and oil psi is around 10-15. Gauge is not marked below 25. So I have to guess.

mechanical gauge is in the mail.

Looks like the prior owner wired the electric fan to the Painless wiring brand fuse box. I’ll change this to a relay and pull power directly from the battery.
Click to expand...
Sure sounds like your problem is in the electrical gauge. And one other contributor to that situation would be that the alternator output voltage will drop as RPM drops low, and will also drop as the alternator gets hot. If the alternator is on the small side and not up to the job of supporting the current draw of the fan, then that will make it even worse.

And FWIW, when the oils get really hot, the synthetics will maintain as good a viscosity as a dino oil, and when reeeealy hot, like under hard endurance racing conditions, will maintain viscosity better. So a hot temp pressure issue is not gonna see change much if at all with an oil type change, just a hot viscosity change. At lower temps, then the dino oils will thicken up more as temp drops to what we typically consider low oil temps (like 100F), and so would show higher pressures then.
 
Last edited:
Overlook68 said:
Prior owner installed a 390hp Mopar crate 360. According to him he change to a bigger roller cam and roller rockers. I assume this was done years ago when the engine was installed. I can see orange or bronze looking rocker arms from the oil fill cap. She sounds like a big cam. He spent money and time on the car but he clearly wasn't a engine or car guy. So I question if these were changed out correctly.

With fresh 5w40 synthetic oil on a cold engine 65 degree day. I get 75psi at idle. As it warmed up on a drive it held 50psi and increased with rpm. Once warmed up at idle near 20psi. In gear and loping around 850rpm the gauge would read near zero. Slight bump in throttle and PSI jumps back up to 20-25. Put it in Neutral rpm are up and PSI is back to 20-25

These are some off brand gauges and the Optima battery is now 11 years old so when its gear at low rpm the volt meter is bouncing and the lights flicker as the electric fan is pulling power. I know that volts can cause irregular meter readings on some gauges. Could the cheap gauges and/or low battery volts be throwing out the very low oil pressure reading? This is my best hope.

The PCV is stopped up or something because she is pushing oil out the filler plug and PCV on the passenger side and crankcase filter on the drivers side. I plan on getting the adjustable PCV valve.

Zero smoke on start up. Zero smoke when driving. I pulled a oil sample at this oil change to see whats the oil like.

What is my best case and worse case scenario?
Click to expand...
I have always disliked electric gauges for this vary reason, they can be problematic with large power draws like fans and fuel pumps.
What oil filter are you using?
Where is your oil pressure sender located?
 
nm9stheham said:
Sure sounds like your problem is in the electrical gauge. And one other contributor to that situation would be that the alternator output voltage will drop as RPM drops low, and will also drop as the alternator gets hot. If the alternator is on the small side and not up to the job of supporting the current draw of the fan, then that will make it even worse.

And FWIW, when the oils get really hot, the synthetics will maintain as good a viscosity as a dino oil, and when reeeealy hot, like under hard endurance racing conditions, will maintain viscosity better. So a hot temp pressure issue is not gonna see change much if at all with an oil type change, just a hot viscosity change. At lower temps, then the dino oils will thicken up more as temp drops to what we typically consider low oil temps (like 100F), and so would show higher pressures then.
Click to expand...

Shop tested the alternator and it showed low amps at idle. With the electric fuel pump and electric fan is pulling more than the little alternator puts out at 900rpm.
Most likely will get a 160amp one wire conversion.
 
Demonic said:
Yeech. Sounds like excessive blowby. Time for a compression test or a leakdown test.
Click to expand...
On a 80 degree engine I got 140psi on every cylinder plus or minus 4psi. Thats is pretty good, correct? It's been years since I've done a leak down test. I think i need a different tool.
 
If you are getting an adjustable PCV from Wagner, get on their Web site and they will show you how they want the baffles. Locktite the screws.
Are you running a carb ? My pcv hose goes to the back of my carb, so is your carb plugged, or what's your set up? HTH
 
Overlook68 said:
Looks like the to the rear of the intake manifold.
Click to expand...
With the sensor in that position it may read a bit toward the low side. As it is at the end of the oil galley.
If your filter adapter has a plug in it try applying a mechanical gauge there it may be more of a true reading.
Filters can make a difference, try a different filter, I use WIX non racing filters - no issues
Good luck
 
Overlook68 said:
Shop tested the alternator and it showed low amps at idle. With the electric fuel pump and electric fan is pulling more than the little alternator puts out at 900rpm.
Most likely will get a 160amp one wire conversion.
Click to expand...
Roger. One thing I have become aware of is that 1 wire alternators can fail to self-excite and won't put out current if they sit for many months. It is not all of them; just the few that lose adequate residual magnetism in the rotor core when sitting for a long time.
 
70 DUSTER CRATE said:
If you are getting an adjustable PCV from Wagner, get on their Web site and they will show you how they want the baffles. Locktite the screws.
Are you running a carb ? My pcv hose goes to the back of my carb, so is your carb plugged, or what's your set up? HTH
Click to expand...

Running Mopar fuel injection kit. PCV hose goes the backside of the intake manifold under the throttle body.
 
512Stroker said:
With the sensor in that position it may read a bit toward the low side. As it is at the end of the oil galley.
If your filter adapter has a plug in it try applying a mechanical gauge there it may be more of a true reading.
Filters can make a difference, try a different filter, I use WIX non racing filters - no issues
Good luck
Click to expand...

Im not using a filter adaptor. Later on I want to do an oil filter relocation.

It had a short Fram filter in the stock location. I used a short Purolator premium filter.
 
The 5w or 10w number for oil only has to do with how the oil flows cold. 40 oil is the same at operating temp regardless of the w number. My diesel has the same hot oil pressure with 5w40 as it does with 15w40.
 
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