The mystery of the missing oil?

-
jwicker

jwicker

Active Member
Joined
Jul 3, 2023
Messages
32
Reaction score
26
Location
Arizona
Hello all. I've been enjoying my dart all winter until today, when I briefly got an oil warning light while stopping. It came on for maybe a second.

I checked my oil after I got home and found it was gone! Just a smudge on the end, under the low end, black, and smelling of gas. No coolant or milkshake.

I haven't noticed any blue smoke even once since my oil change (less than 1k miles ago).

Any guesses?? I have heard the PCV valve could be a culprit but that would be hard to believe....

PCV is currently hooked to (I believe) the correct port on my holley 1920. I filled the oil and checked about 100 times in the first few days.... I'm baffled
 
First get under it and check for leaks.
 
how do the plugs look? and the exhaust tips?

you don't necessarily have to be laying down the james bond smoke screen to be burning a right fair amount of oil.
 
Show us your valve covers. Maybe there not baffled enough to cover the "pcv" . that would suck!
 
jwicker said:
I should have led with that.... No oil leaks, it's parked over a trap and there's no oil in there.
Click to expand...
Uh huh. What if it leaks going down the road? Lets not be complacent and ignorant here. Get under the car and check it, or you'll likely have a repeat performance.
 
? I will get under but like.... You understand if it was leaky, it would be on the tray?

"what if it only leaks going down the road"

And what if the tooth fairy is stealing it??
 
2 quarts in 1000 miles. That's about what my 273 does.

It blows a bit of smoke till it gets warmed up.

It leaks from the front and rear main and the drain plug, ( I have put new seal on the drain plug I suspect it has a crack in the pan)

I check before ever drive.
 
jwicker said:
? I will get under but like.... You understand if it was leaky, it would be on the tray?

"what if it only leaks going down the road"

And what if the tooth fairy is stealing it??
Click to expand...
Oh ok. Have fun then!
 
jwicker said:
"what if it only leaks going down the road"

And what if the tooth fairy is stealing it??
Click to expand...
Damn tooth fairy!


My daughter has a Taurus.

One day she calls me that the oil light was on.

I had her check the oil. Nothing on the dipstick.

I asked her to check if there was oil under the car where she parks, not a drop.

Come to find out the oil filter had been crimped by jippy lube when they installed it

Through expansion from pressure and shut down it metal fatigued and had a pinhole leak.

the leak sprayed in a direction that did not hit the car and only while the engine was running and up to temp.


so before you say it can't happen get under there and look at everything.
 
jwicker said:
? I will get under but like.... You understand if it was leaky, it would be on the tray?

"what if it only leaks going down the road"

And what if the tooth fairy is stealing it??
Click to expand...

I've had more than one car that would do just that, no tooth fairy involved.
It would spill when turning left/right. No smoke, no drips, but half a quart each way to town (20 miles or so). Only found it when I got under it and saw a wet spot and trail under the car from after it would gush and blow away as I went down the road.

Or, ya know, do all the hard stuff first?
 
jwicker said:
? I will get under but like.... You understand if it was leaky, it would be on the tray?

"what if it only leaks going down the road"

And what if the tooth fairy is stealing it??
Click to expand...
No need to be a smarta** here, you're the one asking for help. Rusty's absolutely right, engines behave differently under load and on the road than they do idling into and out of the garage. Man up and get under there.
And you really need to check your oil more than once every 1,000 miles.
 
Alright alright, I'll check it out. Is there any chance it would slow down my engine during a turn? Especially during tight or continuous turns in the last few months, the engine wants to die at low revs while turning the car
 
jwicker said:
I checked my oil after I got home and found it was gone! Just a smudge on the end, under the low end, black, and smelling of gas. No coolant or milkshake.
Click to expand...

So, the oil smelled like gasoline?

If your oil is being thinned out with gasoline, then it could be
  • evaporating (which would make leaks harder to see)
  • being sucked up much more easily by the PCV
  • diluted to the point you're not seeing it being burned off when it sneaks past the rings or gets sucked up by the PCV

I'm not a slant-6 expert, but on the other engines if the fuel pump has a bad diaphragm it will leak fuel directly into the oil pan. Or the carb could just be pig rich and washing down the cylinders, which would also make the plugs black and disguise the burning of oil. Just an additional theory, not saying anyone else is off the mark.
 
jwicker said:
Alright alright, I'll check it out. Is there any chance it would slow down my engine during a turn? Especially during tight or continuous turns in the last few months, the engine wants to die at low revs while turning the car
Click to expand...
tight continuous turn, like a clover leaf connector or a sweeping on ramp? or like from a stop?

either way, unless you have a low oil pressure cut off swtich, a running issue is generally not attached to an oiling issue. but... if you were, say sucking oil at low speed on partial throttle as you were turning? that could certainly make it run funny. and... you wouldn't notice the little wisps of smoke out of your tail pipe because you're focused on like, not running into anything.
 
leak
burn
brain fart.
The only possibilities for missing oil
 
jwicker said:
Any guesses?? I have heard the PCV valve could be a culprit but that would be hard to believe....
Click to expand...

If you got missing oil with NO visible external leaks, then it has to be going out the exhaust.
If it's going out the exhaust there will be evidence in the talipipe, and in the combustion chambers, and therefore, on the plugs.
The why of it is a different story.
The PCV valve is just doing it's job.
On a 1920, I doubt you can plumb the PCV incorrectly.

However, the PCV system may not be working due to blockage, or it may be overwhelmed by the preponderance of the fumes. In this case, the crankcase pressure will try to back up into the air supply line which ends in the air-filter housing. GO LOOK. If you drive a car in this condition, it will have running issues, and the pressure will tend to blow out of the engine at the weakest links ............ such as the valve cover gasket, the valve seals, and any other seals or gaskets, including the rear main seal, which will leak out the transmission bellhousing.
Of course, it will only do this while running, and usually the oil only comes out at speed.

Since you mention the oil smelling like gas;
1) drain that stinky oil, ASAP. If your oil is that polluted, then it is a lousy lubricant.
2) fix the carb, or the fuel pump.
Since you also mention an engine running issue, the float level is most likely too high and/or unstable
But things do not end here.
Additionally;
> your engine may be down on power, or the brakes are dragging, or you got extra weight in the trunk, or your driving uphill all the time, whatever; requiring more throttle than necessary or usual. Or perhaps the vacuum advance system may have failed.
In any of these cases, if the engine is down on power, this will require more throttle than necessary, especially during PT acceleration, which will create more blow-by gasses, which may overwhelm the PCV system;
>of course the excessive CC-pressure may blow past the intake valve seals into the combustion chambers,
>and overwhelm the oil rings ...................
> and blow out the weakest link;
>and more than likely will manifest as excessive consumption ....... or the disappearance of it, as time progresses.
Good luck
 
Mine had sat for years before the previous owners got it running again. First couple years it probably used a quart every 500 miles. It's better now, but suspect the valve stem seals have crumbled away. Probably only put 1500 miles on a year so I haven't done anything yet.
 
So typically the dipstick is not at he bottom of the oil pan. That may not mean you're out of oil it may just mean your below the bottom of the dipstick. You could drain the oil out see how much is left or go ahead and add oil until it shows up on the dipstick again. If this is the case then it's not unusual to burn one or two quarts in an older motor over a period of several months depending on run time.

You didn't mention how much oil you had to add!
 
1920 carbs have an issue of the PCV port in the base of the carb getting plugged up. Check and see if you have vacuum at the valve. If not, then check the port on the carb. If no vacuum, remove the carb and clean the port from the outside, and from the carb base (1/4 inch drill bit by hand). Also make sure the PCV hole in the intake manifold is clear, and the base gasket is installed the correct way.
 
jwicker said:
Alright alright, I'll check it out. Is there any chance it would slow down my engine during a turn? Especially during tight or continuous turns in the last few months, the engine wants to die at low revs while turning the car
Click to expand...
Slanty fuel pumps are "upside down", they will leak fuel into the crankcase before it comes out the diaphragm breather hole, diluted oil will burn away while driving quickly...and may not be as visible as You might think. Check it out..
 
also to note: an exhaust system will hold an absolutely astonishing amount of oil before it manifests on the tips of the tail pipes.

(and gas too, but that's a story for another time)
 
The engine in my 65 dart didn’t have a ton of blow by but drank a quart of oil every couple hundred miles. The rings had almost not tension left and the cylinders were shot. Modern synthetic oil doesn’t burn blue smoke like the good ‘ole days.
 
Okay, investigation largely complete.

Photos of plugs, valve cover, and restrictor attached.

Here's a series of events I belive contributed. (all like six months ago)
  • I installed a new mechanical fuel pump as I suspected the old one was leaking into the crank case
  • Oil changed
  • After I put in the new fuel pump, I noticed the car flooding and causing the car to die. This made me think the new fuel pump had too much pressure, so I installed a fuel restrictor thing to take it down to 6psi on the dial.
  • I then discovered my float issue in the carb (sticking float), fixed that and bench tested/adjusted the carb, and put it back on. No more flooding. I left the restrictor in place, I guess because why not.
Cut to today.

I removed the fuel pump and bench tested it, and as suspected, it tested fine. No leaks into the crankcase side. Upon re-smelling the oil, I firmly believe that it smells like burnt oil, NOT GAS.

I removed the fuel restrictor because, when I removed the fuel like from the output of the pump, it sprayed like hell. I think it was causing a ton of back pressure on the pump which is not good. Some is normal but this was aggressive.

I also added about a quart of oil and it leveled out nicely on the dipstick.

I'm going to keep an eye on the oil far more often and see how it goes.... I'm sure the rings are tired and it's just an old burny engine.

Oh yes - undercarriage inspection revealed no leaks around junctions or connections, however, the space behind the main crank pulley was dirty and oily, though not quite "wet". Could be a front main seal?

As far as the low power while turning, I suspect that having my fuel filter turned sideways (to fit the restrictor) was causing gas to rush in the carb and flood, or away from it and starve.

These are just theories and I'll need to re-test.

Anyone have more thoughts?

IMG20240303182053.jpg


IMG20240303171716.jpg


IMG20240303171657.jpg


IMG20240303171706.jpg


IMG20240303171650.jpg


IMG20240303171640.jpg
 
You must log in or register to reply here.
-

Back
Top