Phanton Oil Leak

[Brian1951]

I am leaking oil from my 77 Midget and I can't figure where it's coming from. Took it out for a 50 mile drive, when I got back I noticed oil dripping from the passenger side frame rail and floor pan and dripping from the exhaust pipe. I sprayed the underside of engine and tranny with brake parts cleaner and dried everything off. I ran the engine at idle for forty five minutes and can't find anything leaking. Valve cover, oil pan, dip stick and rear mian show no signs of leaking.

 

[bobhustead]

Are you sure it is engine oil? Location sounds like transmission oil is a possibility.
Bob

 

[Brian1951]

Are you sure it is engine oil? Location sounds like transmission oil is a possibility.
Bob

Nothing leaking from transmission, definitely engine oil

 

[bobhustead]

Is it possible that the emission/crankcase vent system is restricted. I only throw this out because crankcase pressure from blow-by would be higher at speed, which is where the leak appears to be happening. This could lead to a pan gasket leak. Just spit-balling cause its hard to figure this stuff out without hands on.
Bob

 

[JPSmit]

Whatever else it seems to be happening when the car is more than idling. So, could easily be the Crankcase ventilation.

 

[Brian1951]

Nothing leaking from transmission, definitely engine oil

Whatever else it seems to be happening when the car is more than idling. So, could easily be the Crankcase ventilation.

Crankcase pressure makes sense, but I saw no evidence of oil leaking from the pan when I was cleaning up the oil. Is it possible that the pressure was high enough for the oil to shoot straight out onto the passenger side frame rail?
The only venting on the engine is the hose from the valve cover to the Webber carb. The hose is not blocked but no way to tell if something is blocked in the carb. Would a vented filler cap be a solution?

 

[bobhustead]

I was picturing stock emission equipment. You can check crankcase pressure by removing the hose from the valve cover, plugging it, and seeing if the condition recurs. While there, make sure the tube into the valve cover is clear all the way in. What are your compression readings? Low compression is either valves or rings and, if rings, elevates blow-by. To make sure the ventilation hose is not blocked elsewhere, start the car with it removed from the valve cover while your thumb covers the end of the hose. You should find pretty good vacuum.
Bob

 

[Brian1951]

I was picturing stock emission equipment. You can check crankcase pressure by removing the hose from the valve cover, plugging it, and seeing if the condition recurs. While there, make sure the tube into the valve cover is clear all the way in. What are your compression readings? Low compression is either valves or rings and, if rings, elevates blow-by. To make sure the ventilation hose is not blocked elsewhere, start the car with it removed from the valve cover while your thumb covers the end of the hose. You should find pretty good vacuum.
Bob

Compression is good on all cylinders, carb vent is working

 

[bobhustead]

I think I'm out of remote diagnosis thoughts. Drive it as you did when you got the leak, but stop every 2 miles to thoroughly look for the source.
Bob

 

[Brian1951]

I think I'm out of remote diagnosis thoughts. Drive it as you did when you got the leak, but stop every 2 miles to thoroughly look for the source.
Bob

Thanks Bob

 

[JPSmit]

wondering if the source is the dip stick but not sure what is causing the pressure. silly question but the oil is not overfull is it?

 

[Brian1951]

wondering if the source is the dip stick but not sure what is causing the pressure. silly question but the oil is not overfull is it?

Not coming from dip stick - oil level is on the full mark

 

[JPSmit]

Mone leaks a drop or two and I suspect it because the oil pan is not perfectly sealed - but this doesn't seem likely. There are various youtube videos about using talcum powder and other products to identify where the leak is coming from.