I have a 1965 Plymouth Fury 3 with a poly 318 motor and auto trans. 120k miles,runs great but I'm losing oil pressure, last year went from 49 to 45 at hot hwy speed and 20 to 16 at hot idle. this year hot hwy speed is now 40 lbs and hot idle is 12lbs. looking to see if I can just drop the oil pan with the motor in the car to either check the bearings or install a new oil pump without removing the motor. also is the rear main seal a rope or neoprene seal ? Thanks for any info
Oil Pan/Oil Pump ?
- Thread starter 65GUS
- Start date
Your pressures are still safe. But they have changed, have you used a mechanical hand held gauge to confirm numbers.
What oil are you using? Your original rear main will be rope.
What oil are you using? Your original rear main will be rope.
That’s a lot of miles for a 60’s era engine, unless it’s been rebuilt. Oil that’s too thick or too thin can do what you’re seeing. What viscosity? If an oil change doesn’t cure the problem, remember that worn piston rings and bad carburetor floats let unburned gasoline leak into the oil changing the viscosity. Those issues meant polys had a tendency to just slowly get weaker and weaker, while seemingly running fine. Are the spark plugs clean (gray). IOW you need to look at everything. The newer LA engines (273 and its variants) had tighter tolerances and by the late 60’s Chrysler recommended 5 weight oil for them. If you used 10 weight or higher on new engines you had lubrication issues. Modern engines have even tighter tolerances, and need good oil pressure for the VVT. All that being said…it’s not hard to drop the pan and replace the rod bearings. Be sure to mic them so you know what size to buy. As for main seals, my first guess would be rope. You’ll see which one if you decide to drop the pan. If it’s rope there’s a tool to get it over the crank. Cutting it the right length can be a pain. Too short leaves a gap and an oil leak. Too long means the pan doesn’t seat properly and an oil leak.
"Lots of miles", you say? Tell that to our '66 Newport 383 with past 160K and no bottom end engine noises. Or my '70 Monaco 383 4bbl that ran well and quiet past the same mileage.
In a dyno test that HOT ROD magazine did on a 383 back in 1967, in their additions, they suddenly hit a wall at about 450 horsepower. Nothing they tried made any more power. They attributed this to the fact that Chrysler "set them up tighter so they'd last longer". So they pulled the short block down, "clearanced" the pistons and crankshaft toward the higher end of the spec scale and suddenly MORE power resulted. So, to me, the fact that our 383s and other Chrysler engines easily pass 100K miles is a testament to their machining and engine building orientations. PROVIDED, of course, IF the timing chains were replaced at about 80K miles and decent care was taken of them, with somewhat regular oil changes. In normal "street use".
In the middle 1960s or so, it was somewhat common to get "an overhaul" at about 80K miles or so, provided the owner kept the car and didn't trade it off for something newer. Before the timing chain sprocket came apart and caused MORE issues. A main issue was oil consumption or "burnt valves", not engine sounds. With, from what I saw back then, most of the oil coming in through the valve guides/seals rather than up from the rings, although both were contributors.
If you look at engine clearance specs, the minimum specs for piston skirt-to-cylinder wall clearances and bearing clearances are the same for current engines as they were for the 1960s engines. How can modern engines go longer with less "teardowns"? Oil base stocks are generally better now, plus refinements in cyl wall honing and the use of "MM" piston rings (less drag and wear with the thinner, low-drag rings, first used in some top fuel dragsters in the 1990s). PLUS the use of roller timing chains and "shoes" to guide the chains in their route(s), so "no flopping around".
I did notice that in Chevrolet, the crank bearing factory clearances would vary from model year to model year, although still within the normal clearance range. Some years "normal", other years looser, for the same engine model. Their base 2bbl motors and 6-cyl engines had a softer mix of cast iron than the 350 4bbls did. Knowing what to listen for, you can hear the boring machine labor on the 350 blocks, as it makes less noise on the 2bbl blocks. I've heard that difference many times.
Just my observations and experiences,
CBODY67
In a dyno test that HOT ROD magazine did on a 383 back in 1967, in their additions, they suddenly hit a wall at about 450 horsepower. Nothing they tried made any more power. They attributed this to the fact that Chrysler "set them up tighter so they'd last longer". So they pulled the short block down, "clearanced" the pistons and crankshaft toward the higher end of the spec scale and suddenly MORE power resulted. So, to me, the fact that our 383s and other Chrysler engines easily pass 100K miles is a testament to their machining and engine building orientations. PROVIDED, of course, IF the timing chains were replaced at about 80K miles and decent care was taken of them, with somewhat regular oil changes. In normal "street use".
In the middle 1960s or so, it was somewhat common to get "an overhaul" at about 80K miles or so, provided the owner kept the car and didn't trade it off for something newer. Before the timing chain sprocket came apart and caused MORE issues. A main issue was oil consumption or "burnt valves", not engine sounds. With, from what I saw back then, most of the oil coming in through the valve guides/seals rather than up from the rings, although both were contributors.
If you look at engine clearance specs, the minimum specs for piston skirt-to-cylinder wall clearances and bearing clearances are the same for current engines as they were for the 1960s engines. How can modern engines go longer with less "teardowns"? Oil base stocks are generally better now, plus refinements in cyl wall honing and the use of "MM" piston rings (less drag and wear with the thinner, low-drag rings, first used in some top fuel dragsters in the 1990s). PLUS the use of roller timing chains and "shoes" to guide the chains in their route(s), so "no flopping around".
I did notice that in Chevrolet, the crank bearing factory clearances would vary from model year to model year, although still within the normal clearance range. Some years "normal", other years looser, for the same engine model. Their base 2bbl motors and 6-cyl engines had a softer mix of cast iron than the 350 4bbls did. Knowing what to listen for, you can hear the boring machine labor on the 350 blocks, as it makes less noise on the 2bbl blocks. I've heard that difference many times.
Just my observations and experiences,
CBODY67
Check it with a different gauge BEFORE any heroics.
I say this many times and it usually gets ignored. Having actually worked on pressure gauges, I can tell you that the usual automotive gauge is cheaply made and I wouldn't depend on them being accurate especially as they get older.
Hi Guys. Thanks for all the information. this is what I got going. I'm running Valvoline VR1 10/30 in the winter and 20/50 in the summer. Its about 85°-93° mainly in summer. I don't use any extra additives or motor flushes.first thing I did was replace my Stuart Warner mechanical oil pressure gauge with an exact s/w duplicate gauge I have. still had the same readings, so I removed the oil filter and cut it open to examine the filter media and there is specs and small little pieces of sludge trapped in my filter. Oil is changed twice a year on 3000 miles annually. I have now changed the oil again and there was specks of sludge coming out of the pan into my oil drain pan. I filtered the drained oil through a paint strainer filter. part of what I don't understand is last year it dropped 4 lb and now this year it dropped 4 lb all within like one day's driving. I saw no metal Speckles at all when I looked at the oil filter media, or valve guide seal pieces, and it has newer metal timing chain and gears. i just changed oil this am ,so I'm going to run it around today and see what its got and I may need to drop the pan cuz I've got a feeling the oil pickup screen is getting plugged up with chunks of sludge thanks guys
How long have you been using that brand of motor oil? Reason I ask is that IF the change has been of more recent vintage, then you are probably seeing the results of a better detergency additive package.
After watching some Lake Speed, Jr videos, it takes two full oil changes to get all of the old oil out of the system. Residual oil held in block passages, hydraulic lifters, and such. So any oil analysis would not be completely accurate due to your change of viscosities, even in the same brand and orientation of motor oil. YET only an oil analysis, multiple ones over time, can pinpoint bearing or cam lobe wear issues as to which "metals" are in the oil sample. Things you can't see by looking at the filter media in an oil filter.
To me, unless there are oil consumption issues with the 10W-30 oil in warmer weather, no reason to go to the heavier 20W-50 in the warmer months, up there.
I believe the FSM has a procedure to remove the oil pan "in car", but it is not easy to do. In the long run, it would be much easier to do what you might desire with the complete engine removed. Plus not having little drops of residual oil hitting you in the process. Or tax your shoulder muscles by always being under your work. Then taking a chance of messing up the new pan gasket on putting things back together "in car".
From s 1951 Plymouth FSM, it was mentioned that if the motor has ANY oil pressure at idle, that's fine. Of course, the only engine Plymouth used back then was the flathead 6-cyl.
If you perceive the main bearings to be wearing, as evidenced by the hot base idle oil pressure, consider that any oil being lost from between the bearings is being slung around the inside of the motor, including onto the cylinder walls. If the oil rings are worn a bit, they will not scrape the additional excess oil from the cylinder walls before the oil can migrate upward to the combustion chamber. Which means, basically, MORE oil consumption. That might be hard to document with 3K mile oil changes.
The OTHER thing is that unless you are getting a main bearing knock upon first start-up after the engine sits for a good while, no real need to worry about it.
To me, an engine oil analysis needs to have an oil sample that has more than 5K miles on it, up to about 6K miles, or when the oil hits "1 quart down" the first time, so the original oil is not diluted by fresh oil. Some oil labs will provide an extractor/retention device to remove the oil into a vial and then send the vial to them. No need to get it out of the drain plug stream when it's changed, that way. OR to have to wait for an oil change.
In the mean time, enjoy the car!
CBODY67
After watching some Lake Speed, Jr videos, it takes two full oil changes to get all of the old oil out of the system. Residual oil held in block passages, hydraulic lifters, and such. So any oil analysis would not be completely accurate due to your change of viscosities, even in the same brand and orientation of motor oil. YET only an oil analysis, multiple ones over time, can pinpoint bearing or cam lobe wear issues as to which "metals" are in the oil sample. Things you can't see by looking at the filter media in an oil filter.
To me, unless there are oil consumption issues with the 10W-30 oil in warmer weather, no reason to go to the heavier 20W-50 in the warmer months, up there.
I believe the FSM has a procedure to remove the oil pan "in car", but it is not easy to do. In the long run, it would be much easier to do what you might desire with the complete engine removed. Plus not having little drops of residual oil hitting you in the process. Or tax your shoulder muscles by always being under your work. Then taking a chance of messing up the new pan gasket on putting things back together "in car".
From s 1951 Plymouth FSM, it was mentioned that if the motor has ANY oil pressure at idle, that's fine. Of course, the only engine Plymouth used back then was the flathead 6-cyl.
If you perceive the main bearings to be wearing, as evidenced by the hot base idle oil pressure, consider that any oil being lost from between the bearings is being slung around the inside of the motor, including onto the cylinder walls. If the oil rings are worn a bit, they will not scrape the additional excess oil from the cylinder walls before the oil can migrate upward to the combustion chamber. Which means, basically, MORE oil consumption. That might be hard to document with 3K mile oil changes.
The OTHER thing is that unless you are getting a main bearing knock upon first start-up after the engine sits for a good while, no real need to worry about it.
To me, an engine oil analysis needs to have an oil sample that has more than 5K miles on it, up to about 6K miles, or when the oil hits "1 quart down" the first time, so the original oil is not diluted by fresh oil. Some oil labs will provide an extractor/retention device to remove the oil into a vial and then send the vial to them. No need to get it out of the drain plug stream when it's changed, that way. OR to have to wait for an oil change.
In the mean time, enjoy the car!
CBODY67
Took the car out and ran it today in the afternoon at about mid-80s degrees, fresh oil filter fresh oil change pressure still reading about the same maybe even dropping a little lower at 38 to 40 psi at highway speed and 8- 10 at idle. In 2022 it ran 49 hwy and 20 idle. There is no unusual or new noises at startup or driving and ive ran VR-1 since ive had the car. I have now resigned myself to get some help dropping the oil pan and look to see what's going on there.
volksworld
Well-Known Member
have you ever had the valve covers off it? way back when detergent oil wasn't readily used poly motors used to build up so much hard sludge the oil drainback holes in the heads would plug up ...
Yes, I had the valve covers off last year. took them off to paint them satin black with new poly 318 decals. the top of the heads were all nice and clean a little dirty oil color but no sludge at all or didn't see any pieces of valve guide seals there either. I was pretty impressed with how clean they were. I came up with another idea that maybe a small piece of sludge has partially plugged up my tiny copper line running to my mechanical oil pressure gauge, so before I get too excited about dropping the pan I'll get a new copper line and fittings and install them and see if maybe it was just plugging up there. trying to do the easy things that I can do myself before jumping in head first into dropping the pan or pu lling the motor.
live4theking
Old Man with a Hat
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Blow some air through the line back into the engine.
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