Exhaust Leak at #1 Cylinder Oil Drain Hole

[Shawn W.]

I have a 69 with a 427/390 HP engine. After a short drive the other day I noticed a exhaust leak/smoke coming from the engine area. I then found exhaust coming out of the oil cap breather on the drivers side valve cover. I took the valve cover off and noted that all of the rods and springs were operating but there was exhaust coming out of the oil drain next to #1 cylinder. I am stumped. Any ideas?

[Joe C.]

Re: Exhaust Leak at #1 Cylinder Oil Drain Hole

I have a 69 with a 427/390 HP engine. After a short drive the other day I noticed a exhaust leak/smoke coming from the engine area. I then found exhaust coming out of the oil cap breather on the drivers side valve cover. I took the valve cover off and noted that all of the rods and springs were operating but there was exhaust coming out of the oil drain next to #1 cylinder. I am stumped. Any ideas?

Are you sure it's not blow-by? What is the condition of the PCV valve? If it's working correctly, then the engine should drop about 50 or so RPM if you put your finger over the end of the valve.

[Joe L.]

Re: Exhaust Leak at #1 Cylinder Oil Drain Hole

I have a 69 with a 427/390 HP engine. After a short drive the other day I noticed a exhaust leak/smoke coming from the engine area. I then found exhaust coming out of the oil cap breather on the drivers side valve cover. I took the valve cover off and noted that all of the rods and springs were operating but there was exhaust coming out of the oil drain next to #1 cylinder. I am stumped. Any ideas?

Shawn-----


Like Joe, my first suspect would be blow-by rather than exhaust gas (actually, blow by is largely exhaust gas but at some level it's normal). However, if it is actually non-blow-by exhaust gas the only reason I can think of at the location you described is a cracked cylinder head, where the crack extends from the exhaust port to the oil drain-back area.

[Shawn W.]

Re: Exhaust Leak at #1 Cylinder Oil Drain Hole

I will check out the PCV valve for proper operation and am going to replace the valve cover seals. The car has not been driven much in the past 10 years and when I pulled of the valve cover the gasket fell apart.

Thanks for the help.

[Joe L.]

Re: Exhaust Leak at #1 Cylinder Oil Drain Hole

I will check out the PCV valve for proper operation and am going to replace the valve cover seals. The car has not been driven much in the past 10 years and when I pulled of the valve cover the gasket fell apart.

Thanks for the help.

Shawn-----


Original and original-type valve cover gaskets were cork. After long service and many years they will often fall apart when removed.

[Dick W.]

Re: Exhaust Leak at #1 Cylinder Oil Drain Hole

Coming out of one drain back hole would lead me to think broken or stuck compression rings on adjacent cylinder