1948 dodge coupe oil pressure problem

[48clubdeluxe]

Hi, new here, I'm working on a 48 dodge club coupe that's been sittin In a garage for overt 20 years. I got the car running good with good oil pressure, but I was recommended to run a classic car oil which is a 15w40 with zddp. After I did the oil change and its now idleing at 5-8 psi according to the gauge, the filter seems to be filling with oil, but I can loosen the lid on the canister with out any oil spraying out so there doesn't seem to be my much pressure behind it. I don't really know how they r suppose to be, but it doesn't seem right to me bein as tho my pressure has seemed to drop considerably right from the first start up with the new oil. I don't know if I should put 30w oil back in it to see what happens or what my next step should be. Any help or Oppinions would be greatly appreciated. Oh and the car has the original flat head 6 and obdometer is said to be true meaning its only got 29,000 original miles on it

Edited May 19, 2016 by 48clubdeluxe

[_shel_ny]

Long shot, ............but the spring in the oil pressure relief valve may have broken allowing the oil to flow freely back to the oil pan from the filter canister. Or the valve plunger could be stuck open allowing same. Unusual, when the stick, it is closed, and is more likely to result in high pressure readings.

 

A quick check would be to stop the engine. Remove the top to the oil filter canister. Observe if the oil drains back into the pan, or stays in the canister. If the spring is good, I believe it should push the plunger out to where the oil can not flow rapidly back into the pan.

 

You can also pull the square headed nut that is in the block just below the canister drain line to access the plunger, and spring to check it.

Edited May 19, 2016 by shel_ny

[_shel_ny]

Relief valve operation.

 

 

Plunger.

[48clubdeluxe]

Thanks for replies, how would I go about freeing up the plunger if it is stuck ?

[knuckleharley]

Hi, new here, I'm working on a 48 dodge club coupe that's been sittin In a garage for overt 20 years. I got the car running good with good oil pressure, but I was recommended to run a classic car oil which is a 15w40 with zddp. After I did the oil change and its now idleing at 5-8 psi according to the gauge, the filter seems to be filling with oil, but I can loosen the lid on the canister with out any oil spraying out so there doesn't seem to be my much pressure behind it. I don't really know how they r suppose to be, but it doesn't seem right to me bein as tho my pressure has seemed to drop considerably right from the first start up with the new oil. I don't know if I should put 30w oil back in it to see what happens or what my next step should be. Any help or Oppinions would be greatly appreciated. Oh and the car has the original flat head 6 and obdometer is said to be true meaning its only got 29,000 original miles on it

How much oil pressure did it hold BEFORE the oil change?

 

I strongly suspect the 15-40 HD oil may have loosened a bunch of crud and your oil filter is stopped up. The simple way to check this is to pull the filter and see if it feels like it is so heavy it's full of lead or cement.

 

I had this happen with a 57 Ford tractor I bought from a guy. Evidently he drained the old 30wt non-detergent oil when he bought it and filled it with HD oil,and the oil pressure dropped to near zero because the filter got plugged. When I bought the tractor from him he had put a new filter and new oil in it,and it was holding 40 PSI oil pressure at idle,warmed up. I operated the tractor with a bush hog for maybe 10 hours,and the oil pressure slowly dropped down to 5 psi at idle. I didn't have the time or money at the time to put a crank kit in it,so I figured I would drain all the oil out of it (it was at the Full mark on the dipstick),and try to refill it with 40 wt non-detergent and a couple of cans of STP to get by with for a while. When I unscrewed the filter from the block,the damn thing felt like it was full of lead. Seriously.

 

That was when I figured out what the deal was. I drained the oil,put a new filter on it,and filled it with 30 wt non-detergent oil. Started it up,and it jumped right back up to over 40 psi oil pressure,so I ran it that way until I saw the oil pressure drop down to 20 again,and I drained it and changed filters again,and refilled it with 30 wt non-detergent. Had to change the filter one more time,but I can go out in the yard today and start it up,and it will sit right there and hold almost 50 psi oil pressure at idle after warming up

 

No,I did not drop the base pan and clean it. I didn't have the time or the money right then to do that. I needed to run the bush hog,so I just kept changing the oil and filters and filling it with non-detergent oil until the oil pressure held steady.

 

I got lucky.

[Young Ed]

How much oil pressure did it hold BEFORE the oil change?

 

I strongly suspect the 15-40 HD oil may have loosened a bunch of crud and your oil filter is stopped up. The simple way to check this is to pull the filter and see if it feels like it is so heavy it's full of lead or cement.

 

I had this happen with a 57 Ford tractor I bought from a guy. Evidently he drained the old 30wt non-detergent oil when he bought it and filled it with HD oil,and the oil pressure dropped to near zero because the filter got plugged. When I bought the tractor from him he had put a new filter and new oil in it,and it was holding 40 PSI oil pressure at idle,warmed up. I operated the tractor with a bush hog for maybe 10 hours,and the oil pressure slowly dropped down to 5 psi at idle. I didn't have the time or money at the time to put a crank kit in it,so I figured I would drain all the oil out of it (it was at the Full mark on the dipstick),and try to refill it with 40 wt non-detergent and a couple of cans of STP to get by with for a while. When I unscrewed the filter from the block,the damn thing felt like it was full of lead. Seriously.

 

That was when I figured out what the deal was. I drained the oil,put a new filter on it,and filled it with 30 wt non-detergent oil. Started it up,and it jumped right back up to over 40 psi oil pressure,so I ran it that way until I saw the oil pressure drop down to 20 again,and I drained it and changed filters again,and refilled it with 30 wt non-detergent. Had to change the filter one more time,but I can go out in the yard today and start it up,and it will sit right there and hold almost 50 psi oil pressure at idle after warming up

 

No,I did not drop the base pan and clean it. I didn't have the time or the money right then to do that. I needed to run the bush hog,so I just kept changing the oil and filters and filling it with non-detergent oil until the oil pressure held steady.

 

I got lucky.

Wonder what would have happened if you'd have kept filling it with detergent oil. You'd have eventually gotten the same result but I wonder how many filters it would have taken???

[mopar_earl]

The byoass oil filter only gets oil when the pressure is 40 or above. So at hot idle it won't get flow.

Polish the plunger with fine sandpaper or scotch brite pad.

Earl

[knuckleharley]

Wonder what would have happened if you'd have kept filling it with detergent oil. You'd have eventually gotten the same result but I wonder how many filters it would have taken???

I dunno. Would I have gotten it cleaned out before the finer grit stuff wiped out the bearings?

 

That's always a question,but I didn't want to take a chance on it. The original oil system on these old engines were set up so any debril or dirt would settle to the bottom of the oil pan,and flush out when you changed the oil. It was a system that worked just fine as long as you kept changing the oil,but things went all to hell when you stopped changing oil in engines that never really ran long enough to reach and maintain normal operating temperatures for any amount of time,and got REALLY bad if you used crap oil like Quaker State that had that waxy residue due to the oil they were refining. I suspect Pennzoil was the same,but you couldn't buy it in the area I grew up,so I don't know that for sure. What I do know is you could buy Quaker State every place you could buy gas,including rural grocery stores.

 

The old non-detergent oil works just fine as long as you run the car long enough to get everything up to normal temps most of the times you start it up,and you only drain the oil to change it immediately after shutting the hot engine down so that all the crud is still in liquid suspension,and flows out the drain hole. Most people seemed to prefer to wait until the engine had cooled down before draining the oil,and the end result was gunked up engines.

 

BTW,the only place I have found 40wt non-detergent recently was at amazon. I prefer 40 wt for summer driving,and switch back to 30 wt for winter use.

 

BTW-2. If I ever do a total rebuilt on any of these engines,all they will see after that will be 5w-30 or 5w-40 HD synthetic oil. Until that happens,I will keep using the non-detergent.

Edited May 19, 2016 by knuckleharley

[Don Coatney]

I dont understand how a plugged by-pass filter can effect oil pressure. The oil filter is supplied from the oil galley same as the oil gauge. 

[knuckleharley]

I dont understand how a plugged by-pass filter can effect oil pressure. The oil filter is supplied from the oil galley same as the oil gauge. 

If you are talking about my old tractor,I'm guessing it isn't a bypass system.

 

What I do KNOW is that the problem went away after changing the oil once and the filter 3 times and adding oil after the filter changes.

[_shel_ny]

MoPar 6cyl

 

Yes, no flow, but by the diagram, the bypass oil filter canister gets oil all the time.

 

 

Oil drains from the filter when the oil pressure is sufficient to move the plunger.

 

 

If the top is loosened on a running engine I would expect to see oil going on the ground rather quickly no matter what the pressure.

[mopar_earl]

The oil relief blocks off the bypass filter with low oil pressure, like at idle. Should be in your manual. There is an old Chrysler tech flim strip on YouTube that explains all this.

Earl

[VFFFrank]

Don's correct .....a plugged bypass filter element will have no effect on oil pressure because.....it's a bypass filter. A plugged filter would have the same effect as having no filter at all, i.e., ports blocked off with pipe plugs.

Frank

.

[knuckleharley]

Don's correct .....a plugged bypass filter element will have no effect on oil pressure because.....it's a bypass filter. A plugged filter would have the same effect as having no filter at all, i.e., ports blocked off with pipe plugs.

Frank

.

Guys,what can I say? All I can do is report on what was happening,what I did about it,and what I observed happening.

[_shel_ny]

MoPar.  Not replying to Ford tractor posts.

 

The oil relief valve blocks the oil return to the pan from the canister until enough oil pressure is achieved to overcome to force of the spring allowing the valve to move.

 

It does not block oil from getting to the canister.

[knuckleharley]

MoPar.  Not replying to Ford tractor posts.

 

The oil relief valve blocks the oil return to the pan from the canister until enough oil pressure is achieved to overcome to force of the spring allowing the valve to move.

 

It does not block oil from getting to the canister.

Well,I hope you weren't offended. Mechanical is mechanical,and most of the things we are working on are not unique to mopars.

[_shel_ny]

Well,I hope you weren't offended. Mechanical is mechanical,and most of the things we are working on are not unique to mopars.

Not offended, just wanted you to know I was not replying to, or disputing what you were saying

[48clubdeluxe]

I just ran out to look at the car, it has not been started in over 24hrs and the canister is still full of oil, so from reading the comments(greatly appreciated) this could be the oil relief valve not letting the oil back to the pan ?

[_shel_ny]

I just ran out to look at the car, it has not been started in over 24hrs and the canister is still full of oil, so from reading the comments(greatly appreciated) this could be the oil relief valve not letting the oil back to the pan ?

The oil does not drain back into the pan with the engine off.  The spring keeps the plunger pushed toward the engine blocking the return.

[_shel_ny]

Diagram of oil flow with engine running.

 

Oil pressure pushing(unseating) the plunger uncovering the return path as explained in the diagram shown in post # 3.

[Sharps40]

In all of this clutter....did you ever get a known good oil pressure gauge, hook it up and check to see what the oil pressure reads?  Could be your dash gauge.  Or it could be your oil pump or main bearings or rod bearings or ..... 

 

Start simple and work the problem from a to z. 

 

You say it had a 20 year sit.  Might well be worn/loose parts that held pressure for a bit due to dried on gunk and mess but are now clean and spraying oil all over the crankcase. 

 

But, 8 to 10 lbs of pressure at idle speed is in spec.  We were always told 10 lbs per 1000 rpm to float the crank and cam in its bearings and keep on driving.

 

Luck to ya.

[Merle Coggins]

I just ran out to look at the car, it has not been started in over 24hrs and the canister is still full of oil, so from reading the comments(greatly appreciated) this could be the oil relief valve not letting the oil back to the pan ?

 

That would be correct if the return line of your filter is connected to the bottom of the canister. Some are connected at the top. And some that are connected at the bottom are actually ported up through the center tube so that the oil returns from higher up on the filter canister.

[mopar_earl]

Doesn't matter if the relief valve blocks the supply or return on the bypass filter. The flow is stopped at low pressures to the filter. No oil will move if the supply or return is block by the relief valve. Can't flow oil in or out unless both passages are open.

Earl

[_shel_ny]

This will be my last post on this subject.

 

I am apparently hard headed, or the diagram in my shop manual is generic, and is not correct for a Dodge 230 6 cyl engine.

 

If the cover is removed from the the canister, I would like someone to explain to me what would stop oil from flowing to the canister.

[Don Coatney]

This will be my last post on this subject.

 

I am apparently hard headed, or the diagram in my shop manual is generic, and is not correct for a Dodge 230 6 cyl engine.

 

If the cover is removed from the the canister, I would like someone to explain to me what would stop oil from flowing to the canister.

If the cover is removed on a by-pass filter all bets are off and oil pressure would drop. Path of least resistance....