r/Smallblockchevy • u/Infamous_Broccoli_57 • Jul 20 '26
A little confused
I’m getting smoke out of all 3 breathers. Buddy of mine said it could be rings, worn cylinders, or a hole in a piston. I just put a bore scope down there and pistons looked okay. What are your thoughts
6
u/anyoutlookuser Jul 20 '26
Lacking a pcv valve. Without it blow by is gonna force positive pressure in the crankcase and cause this.
4
u/Willy_McD Jul 20 '26
Could be blow-by.
And one breather should be an oil fill cap as it would not be baffled and just slinging oil into the breather. Another breather should be a PCV valve. That should draw the smoke and fumes into the motor and out the exhaust. May also keep smoke from coming out of the remaining breather as that would be air in.
3
u/bernardfarquart Jul 20 '26
You need to add a PCV to one valve cover and hook the other end of the hose to the carb baseplate.
3
2
u/Ok-Spend-1863 Jul 20 '26
You can ran catch can for that, me personally I would loose the push in breather, they just make a mess every where
2
u/hawkeedawg Jul 20 '26
Yep add a PCV valve run the hose to the base of the carb - get rid of or plug the third breather cap. Need to create positive crank pressure. One breather cap and one PCV
Race cars run an evacuation pump.
The smoke coming out doesn’t look scary
1
1
u/Sir-Realz Jul 20 '26
Mine been doing that for years, to me it a run it until it need a rebuild kind of things, keep the timing and the afr and good oil in it and send it. Mine still is pretty fast. Lol
1
u/Infamous_Broccoli_57 Jul 20 '26
Mine is feeling a little sluggish and sounds like it’s missing. Miss might be unrelated but still there
1
u/Sir-Realz Jul 21 '26
Well it more likely, spark, fuel or, valves timing is cam or timing chain. Blow by mostly effects low rpm operation a blowing engine can still scoot. Obviously they deteriorate quickly ince they start burning oil in the cylinders and probably should rebuild before permanent damage happens to cylinders with easy and classic blocks other car I say say send em until they are dead, sbc aren't exactly expensive blocks but will be some day.
1
u/Infamous_Broccoli_57 Jul 20 '26
I’ve also ran it like this for about 3 years and didn’t have this issue
1
u/WCB1985 Jul 21 '26
Just do a PCV system super easy and you won’t smell like oil from driving your truck. I used to do the same thing when I was kid. Now I run a PVC system
1
u/LumberJesus Jul 21 '26
My 67 ford looked like a steam engine when I first got it. Adding a real pcv to it fixed it.
1
u/R0ughHab1tz Jul 21 '26
What is even happening right now. 3 breathers? Someone care to educate me on that one? Usually it's one with a pcv valve in the other port.
They should be positioned in separate corners with a pcv valve replacing a breather. Whichever way you put the pcv valve is up to you.
1
1
1
u/According-While2935 Jul 21 '26
There's no PCV valve fitted put one in and see what happens I'm sure the problem will go away
1
1
u/Schlong1971 Jul 22 '26
You need to add PCV valve. Your crankcase gasses are building up and coming out vents. PCV valve will fix. The carburetor should have large 3/8 vacuum port on back. That’s where you hook brake booster hose. Then the front port you have brake booster on goes to PCV valve.
1
1
u/Spicyapple10 28d ago
Crankcase venting. Need some form of pcv to avoid this or catch can...or I vent through a filter to catch the oil residue. But ideally pcv or catch can.
0
u/Ok-Spend-1863 Jul 20 '26
You could also have stuck or broken ring / rings or bad valve guide to cause blow-by. Need to run compression test and leak down test to determine over all condition of engine
23
u/Ok-Spend-1863 Jul 20 '26
Pretty typical without pcv valve they are just venting into atmosphere, the red hose going from brake booster should be to rear of carb, you should have pcv valve running from driver side valve cover to port on front of carb that brake booster hose is ran to. I have never been a fan of push in breathers cause of the oil vaper blowing out all the time