My old 383 runs about 30 psi on the gauge.....a bit low and I have not really heated the engine for long runs yet. Normally, in the old days, cold pressure was much higher and I am thinking of shimming valve a bit to see if I can raise it a taste. Thoughts?
Engine oil pressure relief valve shimming
- Thread starter 66furys
- Start date
What is the oil pressure after driving for 10 miles or so? It can take that long for the oil temp to approximate coolant temperature. What is the oil pressure at 2500prm hot?
Orientations on oil pressure have changed over the years. Used to be that 10psi/1000rpm was the general guide for max hot oil pressure. With better oils and such, many OEMs have lowered their oil pressure specs a bit, which means more power to the flywheel than in earlier times. But even using the prior guide, that would mean 50psi at 5000rpm, fwiw.
Enjoy!
CBODY67
Orientations on oil pressure have changed over the years. Used to be that 10psi/1000rpm was the general guide for max hot oil pressure. With better oils and such, many OEMs have lowered their oil pressure specs a bit, which means more power to the flywheel than in earlier times. But even using the prior guide, that would mean 50psi at 5000rpm, fwiw.
Enjoy!
CBODY67
bigmoparjeff
Senior Member
I had to do that on a 1948 Packard that I did some restoration work on some years ago. New pumps were not available for that particular engine and the internals of the pump were in good shape. The spring had just lost some of it's tension over many decades.
Jeff
Jeff
'66 Fury I
Active Member
Proper oil pressure depends on the capicity of the pump, the clearances in the engine and the operation of rhe relief valve. These three need to work together to build pressure. Shimming can raise the pressure, but only if the spring is weak. If the pump is worn (reduced capicity) or the engine is "tired", shimming will do nothing.
If the engine were mine, I would remove the pump, inspect and replace if necessary. If this fixes the problem, great, but my best guess is that worn bearings are your problem.
I've "been there, got the t-shirt". Lindsay
If the engine were mine, I would remove the pump, inspect and replace if necessary. If this fixes the problem, great, but my best guess is that worn bearings are your problem.
I've "been there, got the t-shirt". Lindsay
Great job on the Packard engine. I have only driven this car for a few miles on my back road as I have tried to ressurect her. So, warm, but maybe not hot. Did get the brakes too hot.....looked like a fire under the hood....trying to wring in the new shoes. But, the OP just stays at about 30 no matter, so far. Changed to 40 w oil, but same. Yes, might run on this low pressure, but am wanting to tweek it a bit, aaarrgh. A bit strange that it does not really go up with RPM....just hangs out.
Thanks Lindsay....that is why I went up in oil viscosity to see about bearings, but no change. And yes, maybe pump, but want to check the easy relief first....if it could help. But, you are right.....flow vs restrictions means pressure.....and I aint happy.
bigmoparjeff
Senior Member
If this is a car that was sitting for a long time, it would be a good idea to pull the oil pan to make sure the pickup isn't clogged up with junk. It's not all that hard to do on a big block C body. You just need to drop down the center link for room to get the pan out.
Jeff
Jeff
Gerald Morris
Senior Member
Try the shim. It's an easy, no-brainer test. If it works, rejoice. If not, you might want to start unbolting stuff. A new oil pump might do you good. I did well with that about 5 yrs or so ago. Still have the original pump, which isn't all THAT bad, but sure enough, a new one did a little better. I also flushed out the crank case well with kerosene, drained it well, blew that out w a little compressed air and a shop vac on the oil pan drain hole, and have kept good oil pressure since, for the past 5 years.
All great points. I am more concerned about the pickup strainer....since all the fluids in this beast were awful when I got it.....no driving for a long time. So, I first added one washer no. 10 at 0.038 in....not much change. Added a second one, and pressure is up about ten pounds.....still does not come up much with RPM. Idles now about 30 or a bit higher on the new gauge, and will rise to about 45. So, for now I am happy....will see wha hoppens over time. One thing I think i noted, is that the spring may not be tight against the plug....I cannot feel it contact when installing the plug. So, there may be a bit of room to get oil flowing before it comes into action...not sure.
Gerald Morris
Senior Member
Hmm, might be time to replace that spring, or oil pump.
DO check that strainer. I found that flushing the engine out with one of those diesel+kerosene+Other flammable Solvents helped a fair bit. I got my air compressor, blew from the pump into the pickup tube just after draining the thinned oil, then used my shop vac to suck the crap out of the oil pan. THAT worked. I used a small bright flashlight for a looksee in through the drain, saw a shiny interior, and filled the crankcase properly. Those pickup screens can be cleaned without opening the crankcase.
Thanks Gerald.....one of the first things on my beastie was fluids. Oil so bad that I did fill with couple gallons of diesel and let soak. Did not go thru your points of agitation or other. So do not know whether gummed up. I keep finding goodies from a machine this old, and am wondering if it will settle....not yet. Road trip today, and more small vibes. Want to at least re-check those rear axle bearings.....not sure whether it is road or car yet. Not stopping yet.....more to go.
Gerald Morris
Senior Member
I had to do axle bearings w our '66. Still have that 2:76 rear end today, and might yet use it, while rebuilding the 3:23 we got w Gertrude. Sure would like to get a Sure Grip.... alas! Glad to see you used diesel right away. Do you hear any moaning or whining from the rear axle? Listen especially while going around curves. You might get by with adjusting the bearings a little too....
Don't really need to go around curves, just gently sway the car side to side in your lane at about 45 mph or so. You can hear the bearing noise as it varies with the addition and subtraction of side loads on it. If you hear it while driving in a straight line, gently apply the brakes to re-center the axle shaft in the bearing to decrease any noise or feelings of a grinding bearing on the axle shaft.
One thing I figured out way back in the middle 1970s, was that when doing an oil change, there was still a residual amount of "old oil" near the drain plug and in the bottom of the sump. An inexpensive way to get it out? After the oil drain was a thin stringy oil string, I'd then pour an extra quart of oil (Castrol GTX was less than a dollar back then) into the valve cover and wait for that to drain, as the oil drain became clear again. I figured that was easy to do and inexpensive, to ensure that more of the oil in the engine was fresh. Gave me a bit more time to lay under the car (securely on jack stands) and enjoy the view.
Enjoy!
CBODY67
One thing I figured out way back in the middle 1970s, was that when doing an oil change, there was still a residual amount of "old oil" near the drain plug and in the bottom of the sump. An inexpensive way to get it out? After the oil drain was a thin stringy oil string, I'd then pour an extra quart of oil (Castrol GTX was less than a dollar back then) into the valve cover and wait for that to drain, as the oil drain became clear again. I figured that was easy to do and inexpensive, to ensure that more of the oil in the engine was fresh. Gave me a bit more time to lay under the car (securely on jack stands) and enjoy the view.
Enjoy!
CBODY67
Gerald Morris
Senior Member
Wise Words! Yes, a residuum remains of the old oil in the bottom of the oil pan, and I too have poured a little (~ 1/2 pint) of clean oil into the crankcase while the pan is unplugged when that stuff looked bad. I doubtless will this coming month, to get all the summer oil OUT. Havoline mineral oil runs fairly cheap, and is decent oil also, w a shot of Lucas ZDDP it does very nicely. I also want to get rid of any solvent left in my crankcase, and this method does for that too.
Thanks guys for pointers. I have not tried to listen or move the car on the road. Just having a bit of vibration that seems associated with the tires and road. New tires all around now, so it is something else.....and today, I began to worry. I have only just pushed and pulled on the driveshaft joints...not really well yet, on the gravel. I used to have a nice garage and two post lift, but not now. Just minor worries for now, but something. So will follow your advice and do some more running. thanks
Axle bearings are one of those things that as long as they aren't too noisy, they aren't going to self destruct, so I suggest driving the car for a bit and see if it gets better, worse or stays the same.
A mechanic friend (really good mechanic too) told me once that he's seen cars that have been sitting that the ring gear sits up out of the oil and gets a little rust on it. Some miles will usually clean it up.
Regarding the oil pressure, again, I'll suggest testing with another gauge. Aftermarket gauges are very cheaply made and I would never rely on one. Believe me, I worked over 20 years in the gauge calibration business and saw a lot. Drop a gauge with a Bourdon tube once (like when it was shipped) and the fragile mechanism that links to the pointer can go wonky real fast.
Anyway.... If you want to shim the spring, why not just go with one of these and just adjust to what you want. Milodon 21550 Milodon Externally Adjustable Oil Pressure Regulators | Summit Racing
Now that I'm thinking on it, there's one around here somewhere... I'll have to dig it out.
A mechanic friend (really good mechanic too) told me once that he's seen cars that have been sitting that the ring gear sits up out of the oil and gets a little rust on it. Some miles will usually clean it up.
Regarding the oil pressure, again, I'll suggest testing with another gauge. Aftermarket gauges are very cheaply made and I would never rely on one. Believe me, I worked over 20 years in the gauge calibration business and saw a lot. Drop a gauge with a Bourdon tube once (like when it was shipped) and the fragile mechanism that links to the pointer can go wonky real fast.
Anyway.... If you want to shim the spring, why not just go with one of these and just adjust to what you want. Milodon 21550 Milodon Externally Adjustable Oil Pressure Regulators | Summit Racing
Now that I'm thinking on it, there's one around here somewhere... I'll have to dig it out.
Learned something again today, thanks, did not know they made adjustable units.....would be a good idea. But, you are also right that I should hook up a good gauge. I lament that when I added the new pressure sender, it was large and rubbed against the mainifold....a pain. But, it went in, and it could come out. I think if I pull it, I will add an extension to keep it off the hardware. Just thinking......
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