Slick 60's

Well...my old 390 sat for 2 years while we was working on the floor pans and had the cab off..well when we tagged it again we started experiencing some pretty bad blow by from the oil cap and the pcv valve..it passed compression test with almost flying colors with 2 cylinders that were barley lower than the rest. And granted it was put together by dad in his back yard from the best parts he had..the block had been bored .30 over and someone let it sit and the block has a crack..but im getting off topic a little. Any ideas? Weve replaced the pcv valve and hoses, put a like new aftermarket oil breather cap...and got desperate enough..to run an oil addictive..and took it for an 80 mile drive at about 55mph...didnt do a thing for it..
Ill get some pics of the blow by tomarrow..its nit super bad but its a steady steam or 2 on each valve cover hole..
Any helps apreciated..I WANT THE BLOW BY GO AWAY! Well...my old 390 sat for 2 years while we was working on the floor pans and had the cab off..well when we tagged it again we started experiencing some pretty bad blow by from the oil cap and the pcv valve..it passed compression test with almost flying colors with 2 cylinders that were barley lower than the rest. And granted it was put together by dad in his back yard from the best parts he had..the block had been bored .30 over and someone let it sit and the block has a crack..but im getting off topic a little. Any ideas? Weve replaced the pcv valve and hoses, put a like new aftermarket oil breather cap...and got desperate enough..to run an oil addictive..and took it for an 80 mile drive at about 55mph...didnt do a thing for it..
Ill get some pics of the blow by tomarrow..its nit super bad but its a steady steam or 2 on each valve cover hole..
Any helps apreciated..I WANT THE BLOW BY TO GO AWAY! Well...my old 390 sat for 2 years while we was working on the floor pans and had the cab off..well when we tagged it again we started experiencing some pretty bad blow by from the oil cap and the pcv valve..it passed compression test with almost flying colors with 2 cylinders that were barley lower than the rest. And granted it was put together by dad in his back yard from the best parts he had..the block had been bored .30 over and someone let it sit and the block has a crack..but im getting off topic a little. Any ideas? Weve replaced the pcv valve and hoses, put a like new aftermarket oil breather cap...and got desperate enough..to run an oil addictive..and took it for an 80 mile drive at about 55mph...didnt do a thing for it..
Ill get some pics of the blow by tomarrow..its nit super bad but its a steady steam or 2 on each valve cover hole..
Any helps apreciated..I WANT THE BLOW BY GO AWAY

Is the steam pressurized or just calmly exiting the valve covers? A pressurized stream would indicate either valve stem or ring problems. A calmer presence would indicate you are not evacuating the crankcase effectively.

bruceandersson wrote:Is the steam pressurized or just calmly exiting the valve covers? A pressurized stream would indicate either valve stem or ring problems. A calmer presence would indicate you are not evacuating the crankcase effectively.

I think ive only seen smoke onece when the oil cap was on, when the cap is off its just a steady stream
And dad assumed the rings had stuck from sitting..but good compression, driving it getting it good and warm..if theyre stuck i guess they are not coming unstuck anytime soon...?

Without seeing, its hard to picture. You need two things to scavenge the normal vapor out of a crankcase. You need a source of vacuum to pull the vapors and you need a source for air. Your drivers side cap looks like it may be for the vacuum side. Blow-by would have some decent pressure behind it. The y-blocks and early sixties engines did not use a positive crankcase ventilation (PCV) system. They used road draft tubes. The vacuum cased by air rushing by the open end of the tube pulled the crankcase vapors out through a mesh filter. These would always release some vapor when not moving. Not steam like from a kettle, but a gentle small cloud. If that's all you are seeing - verify your PCV system is complete and functional.

bruceandersson wrote:Without seeing, its hard to picture. You need two things to scavenge the normal vapor out of a crankcase. You need a source of vacuum to pull the vapors and you need a source for air. Your drivers side cap looks like it may be for the vacuum side. Blow-by would have some decent pressure behind it. The y-blocks and early sixties engines did not use a positive crankcase ventilation (PCV) system. They used road draft tubes. The vacuum cased by air rushing by the open end of the tube pulled the crankcase vapors out through a mesh filter. These would always release some vapor when not moving. Not steam like from a kettle, but a gentle small cloud. If that's all you are seeing - verify your PCV system is complete and functional.

Just added the air cleaner to oil cap portion of the pcv system , heres what i saw yesterday after adding that i pulled out my 3 month old pcv and it seems like its working, has suctiin and clicks, but...my engine didnt die when i pulled it iut and when i leaned on the gas white smaoke appears to be coming from theback of rhe air cleaner or ive blown a gaskit, but it runs great...my be time ro run another compresstion test

Installing new valve seals is a easy way to eliminate them being bad. Time consuming but cheap . Tom

tomrooster wrote:Installing new valve seals is a easy way to eliminate them being bad. Time consuming but cheap . Tom

well its not burning the oil...uet anyway it may after i put rhe breather kit on, but its coming from the valve cover holes right now...

tomrooster wrote:Installing new valve seals is a easy way to eliminate them being bad. Time consuming but cheap . Tom

well its not burning the oil...yet anyway it may after i put rhe breather kit on, but its coming from the valve cover holes right now...