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383 low oil pressure

ZDECKICH

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Hey guys,

I just got a "new" to me 1968 Charger with a "rebuilt" 383. Come to find out the guy I got it from had 0 idea on how to build the car and did a lot of things very half assed.

The oil pressure gauge in the car doesn't work so hooked a mechanical gauge to it. I think the car sat for a few years. Cold start up its at 25psi and drops to 8-12 at a warm idle. Its making a noise from the back of the motor towards the back of the oil pan. When driving it will get up to 30psi when driving 40-65mph. Any idea where I need to start looking at to figure out this noise and low oil pressure? Also, no idea what weight oil is in it but took a little oil out to see if there was any metal in it and looked clean. The car does seem to drive pretty good and smooth.

charger383.jpg
 
Did he check bearing clearances during assembly?
 
What oil filter? Start at the oil pump relief valve and spring. Maybe it's an old worn out pump. Maybe the bearing clearances are loose. Put a flat washer in the cap of the relief valve to increase pressure is a quick fix/bandaid.

Does it run good, hitting on all 8 cylinders? If a pushrod bends and a lifter comes out of the bore it can cause low pressure and noise.

Do you know what rear end gear ratio? Is it 1800 or 3000 RPM going down the highway?
 
Shimming the relief valve spring only increases the bypass pressure. It has to reach or exceed the rated psi first, which, going by the op's specs is nowhere near that.
 
What oil filter? Start at the oil pump relief valve and spring. Maybe it's an old worn out pump. Maybe the bearing clearances are loose. Put a flat washer in the cap of the relief valve to increase pressure is a quick fix/bandaid.

Does it run good, hitting on all 8 cylinders? If a pushrod bends and a lifter comes out of the bore it can cause low pressure and noise.

Do you know what rear end gear ratio? Is it 1800 or 3000 RPM going down the highway?

if has highway gears for sure. going 50 its about 1800-2k. Tach isn't working but that's my best guess.

It does seem to run pretty good actually, despite the low oil pressure. Ill see if I can take a video of it later today to see if you guys can hear the sound its making.
 
What oil are you using?
 
1st things 1st, drain oil, send sample in for analysis. Replace filter with quality filter and oil with 20w50. At this point you will at least know that it has good filter and oil. After that, it could be many things. Easiest w engine still in is oil pump in my opinion.
 
From my experience, use a Wix filter, not Fram. From an earlier post, if a pushrod bends and a lifter pops out of its bore (highly unlikely), you would have NO oil pressure, not just low.
 
but took a little oil out to see if there was any metal in it and looked clean.
Open up the oil filter to see what's in it.

If it's a knocking noise, check for a loose torque converter bolt if auto.
 
Why not straight 50 weight if we are trying to raise pressure with the fluid.
 
Change the filter to a Wix and fill it up with VR1 20w-50 (or equivalent) and get it warm and see what the oil pressure is. 10 LBS per 1000 RPM is the minimum standard. You want at least 50 lbs at 5000 rpm.
 
Open up the oil filter to see what's in it.

If it's a knocking noise, check for a loose torque converter bolt if auto.
One of the first things I checked as it almost sounds like a lose bolt on the converter. They were all there and tight.
 
Change the filter to a Wix and fill it up with VR1 20w-50 (or equivalent) and get it warm and see what the oil pressure is. 10 LBS per 1000 RPM is the minimum standard. You want at least 50 lbs at 5000 rpm.
Yea this is what im doing today, Ill put on a WIX and do either straight 50w or 20w50.
 
1st things 1st, drain oil, send sample in for analysis. Replace filter with quality filter and oil with 20w50. At this point you will at least know that it has good filter and oil. After that, it could be many things. Easiest w engine still in is oil pump in my opinion.
Yea I took a sample that im sending to Blackstone this week to see if there is a high about of cooper to see if I spun a bearing or not. Ill also cut open the stock filter to see if I see anything in the filter element.
 
I'll take a wild guess and say his "rebuild" may not have been extensive. I'll say possibly the crank was worn, he put standard bearings in it and now you have a lot of clearance. Not really a problem. The stock M63 pump may not have enough capacity. It's summertime, fill it with Valvoline VR1 50w and see what it's got. If you still aren't happy, put a M63HV pump on it and I've never seen that not fix the problem. Everything is going to be ok.
 
After the oil change it is really easy to remove the relief valve and spring, inspect for wear, install a washer and see the increase in pressure.

Cost? $0 and 30 minutes.
 
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