mystery oil loss

[normanpitkin]

my 1941 chrysler was hard to start ,it started eventually coughing and spluttering ,i drove about 90 seconds and then parked up.When i looked outside i saw all the oil on the ground! Engine didnt seize and is now empty of oil ,there is plenty of oil in the engine bay ,all round the distributor.Ive checked all the oil lines and can see no leaks and the sump is all ok too.Its not the head gasket either ,what can it be?

[Doug&Deb]

Had you just changed oil? I’ve mis seated the gasket on the filter and made a real mess more than once. How about the drain plug?  I used a plastic washer on the plug instead of copper and it caused the plug to constantly loosen. 

[normanpitkin]

nope ,no change of oil or filter for a year!

[1949 Wraith]

Clean up the mess, fill with oil and have someone momentarily start the car while you observe for leaks.

[Sniper]

Here's my thinking.  If it didn't leak out before the engine was running and then it only took 90 seconds to empty the pan then it's a pressurized oil leak.

 

I think the idea of refilling and having someone else start the engine while you look is a good one.  Don't forget the pressure relief valve is in that area and it's seal could be leaking.  You may have a crack in one of the lines feeding the oil filter or gauge or they could be loose.

 

 

[normanpitkin]

Thank you all ,i think i will get someone to crank it and see what we can see! Will keep you posted!

 

[Young Ed]

2 hours ago, normanpitkin said:

Thank you all ,i think i will get someone to crank it and see what we can see! Will keep you posted!

 

That brings up a good thought- pull the coil wire and just watch for the leak while it's cranking. I would think you'd still build enough oil pressure to find it with a little less mess and risk of running out of oil

[desoto1939]

Check the rubber oil line that feeds the oil pressure guage. The rubber will crack with age and it might be on the back or on the under side of the rubber hose. Do you have rubber hoses running to your oil filter and yes retighten the cap to the oil filter also check the bolt that holds the lid down on the oil filter canister

 

Rich Hartung

[normanpitkin]

First thing i checked was the oil pressure gauge line <i had that go on my New Yorker years ago so i hoped it was that ! A quick and easy fix but nope

[normanpitkin]

Progress update .filled up with oil and car started with good oil pressure ,the only odd thing is the dipstick is covered with oil and i cannot get a reading from it! Seems like the oil loss was from the downdraft tube as the exhaust is coated with oil?

[Sniper]

That doesn't sound good.  Only thing I can think of that would blow that kind of oil out the road draft  and dipstick tube is a lot of blowby, as in hole in the piston type blowby.  Can you do a compression test?

 

 

[greg g]

I would do a compression test. Also a couple of us have found fatigue cracks in the oil filter lines. But the cracks were in the flairs and covered by the flange nut.

 

But most oil was lost at a rate of 1qt per hundred miles. But these wouldn't leak till oil pressure was up so no visible evidence at idle.

Edited November 15, 2020 by greg g

[P15-D24]

6 hours ago, greg g said:

I would do a compression test. Also a couple of us have found fatigue cracks in the oil filter lines. But the cracks were in the flairs and covered by the flange nut.

 

But most oil was lost at a rate of 1qt per hundred miles. But these wouldn't leak till oil pressure was up so no visible evidence at idle.

Agree, check the oil lines. I had one crack and it was leaking a quart every 30 seconds.

[normanpitkin]

the mystery is solved! The carbs were somehow leaking into the engine causing a massive build up of crankcase pressure ,All the oil was then burped out through the downdraft tube.There was about 4 times as much petrol as oil in the engine ,its because Im running triple carbs i guess.If I had smelled the dipstick i would have realised the engine was full of petrol NOT oil.

[Dodgeb4ya]

Strange...

[desoto1939]

since you had a massive amount of gas in the oil pan the first thing that I would suspect to be bad is the fuel pump since the pump goes into the crank case and the cam. Make sure this is not the problem.  If your car was leaking gas directly from your carb you would have smelt the gas fumes and I would assume that you plugs would all be black becasue of the extra fuel being dropped into the intake and there would have been alot of black smoke out the tailpipe.

 

Seems to be a very strange situation.

 

Rich Hartung

[greg g]

What do your plugs look like?? Normally assumption would be they were fuel fouled if excess gas was coming through the carbs.  As mentioned fuel pump could be the problem.  Other source might be inoperative step up valves especially if all three are involved. The default is to be full open when there is a problem.  Like a stuck on cold enrichment jet in a fuel injection set up.  Is your car the straight 8??

[Plymouthy Adams]

what pump are you running that could possibly override the fuel flow stop capability of the carb's needle and seat...perhaps a fuel regulator is in your future.....if and when buying an electric fuel pump you need to buy them per pressure rating...Facet is one of the more common that supplies the same style pump in different pressures....(often marketed as Purolator and or Carter)

[normanpitkin]

Good points ,Ive checked the pump ,the flange is in and its pretty new.seems to be fine.plugs were black AND there was soot from the pipe.I wonder if maybe an idiot(me) left the electric priming pump on whilst I talked to the builders??? Electric pump is a low volume 6 volt one ,its been on the car for 4 years. Im running triple carbs  and this has only just happened ,Im pretty sure its my own stoopid fault  No leakage from the carbs at all ,i have checked the floats on all three as well.