SBC blowby problem

so my biscayne was sitting for about two weeks took it out to town the other day no issues then friday i drove it to work and noticed what i thought was smoke coming out of the p***enger side i get to work pop the hood and notice its coming from the valve cover breather on that side...now then my 350 has a pcv system and wasnt doing any of this before sitiing... i messed with the timing alittl today and it did help some...any suggestions???

 

is this certain death of this engine?

 

Check that there is va*** on the pcv valve. Also check that the breather is clean and letting fresh air in.

 

i do have va***...and the breather is clean
i plan on running a compression test tomm.

 

any other suggestions

 

Blow by is what it is cant put a good picture on it.time to face it

 

What exactly will happen if you keep driving it with the blowby ? I,m guessing more smoke and loss of power ?

 

Make sure you also have vacuum on the "engine" side of the PCV valve. Having vacuum on the "vacuum" side of the valve doesn't eliminate a plugged PCV valve.

 

Valve seals perhaps? Not to difficult to take a look. I only say this because I've had bad luck with the stock style O ring seals. I now use umbrella seals. I also had an old pickup with a 350 that was so gummed up that the oil would pool in the lifter valley and top off the heads. This caused other symptoms like low oil pressure.

 

valve seals dont cause blowby. Blowby is from compression gases leaking into the crankcase. Bad rings pistons worn cyls ect , can cause it. you state something about timing. bad incorrect timing can burn a hole in a piston very quickly. Do a compression check. many engines without a PCV dont have blowby. OldWolf

 

Take the PVC valve out and check that it isn't plugged. Now shake it and make sure that the little rattly doodad in there is loose and not stuck.

Are you sure that it is blow by and not oil leaking around the bottom of the breater and running down on the exhaust?

 

sounds like the pcv system isnt pulling the g***es through....check the PCV valve and make sure the hose to the PCV valve hasnt either collapsed on itself or become disconnected

 

Those umbrella seals are so outdated.... Nowdays we use perfect circle oil seals... Those work a hell of allot better...

 

well i talked to a guy at work about it and he recommended checking the oil journals in the heads to see if maybe one was clogged..ofcourse its raining today and im sick as a dog so no progress

 

As state dabove, blowby is unburned fuel vapor that has found its way past the rings and into the crankcase. Nearly every engine, especially street engines with some miles on them, will have some amount of blowby and for the most part it's pretty harmless. At least as long as the crankcase is properly vented. (road draft tube or preferably a PCV system) Excess smoke from the tailpipe isn't going to be the result of blowby.

The harm comes when there is insufficient c/case venting. Fuel (as well as water) vapor is trapped in the crankcase and as the engine cools they condense, get mixed in with, and dilute the engine oil. Not good for anything that runs in oil, especially bearings.

Keep clean oil in it and keep the crankcase vented properly and you'll likely still have a lot of miles left ahead of you. That's ***uming that the rings and bearing aren't already shot.

 

Ok gentlemen i ran a compression test today and go figure the second cylinder from the front on the drivers side only has 30psi...so needless to say am i screwed????

 

Well it sounds like maybe you've got a bit of work ahead of you. Check the compression in the weak hole again after adding a few squirts of oil thru the spark plug hole. If the compression reading comes up noticeably higher then you've probably got a ring problem. If the compression doesn't come up then then you may have a valve that's not seating properly.

Has this engine got a ****load of miles on it or had a hard life that you're aware of?

 

i dont know a whole lot about the engine when i bought the car the guy said it was a recent rebuild...it runs strong and hasnt givin me any issues before this..so far everything looks clean the oil isnt chocolot milky...the rockers look pretty new...what should the other compressions be because they were reading between 110-115

 

One source says that the compression should be between 130 and 170.

If the compression comes up noticeably after squirting a few shots of oil in the cylinder the rings are either stuck or worn more than the rings in the other cylinders.
A recent rebuild could mean many things. it might mean that it was done a few years ago or it might be that has only a few thousand miles on it. And some peoples concept of recent is a lot different than others. Also what cons***utes a rebuilt engine differs between people. There are those who don't consider an engine rebuilt unless it has been bored and has new pistons and there are others who feel that a quick and nasty rereing job and touching up the valves is rebuilding the engine. I did the news rings and bearings and valve job on the sbc in my daily and it has run like a bandit for the past five years and about 70K but it has a bit of blowby just like your engine has and puffs smoke when it first fires up due to the seals and valve guides being worn.

 

keep in mind im checking the comp with a loaner gauge from autozone...so it may be off some but the one cylinder is for sure wacky ill try the oil trick tomm and if no love i guess ill be pulling the head to see whats up

 

I have a PCV valve on one rocker cover and a vented push in breater in the other. I've found that the vacuum source can have a dramatic effect. I had two sources - at the carb base plate and on the manifold. When hooked up to the manifold, I have smoke coming out the push in breather with oil forming inside the breather and leaking out and onto the exhaust. BUT when I hook the PCV hose up to the carb base plate source, I have almost none of this effect. I figure it's because of the venturi effect caused by the carb - I think there is probably more velocity/flow at the carb base than the intake manifold.

.02

Troy

 

I dont know if its a coincidense but all sbc i have rebuilt
was most worn in that cylinder

 

well i did the oil in the cylinder and it increased the psi 10 so now i have 40 but its still not what it should be so i suppose now im pulling a head

 

so if i am reading what yall said already the rings could be fine and this could be a valve issue????

 

so like i said i did the wet compression test and it only increased the psi maybe 10 so i broke out the tools and pulled the intake and head and here is what i got... a bent pushrod on a none ***ociated valve..can i buy just one of these???? and other than that nothing unusual the piston isnt destroyed..from what i can see the rings look like the others...now as far as the head goes im clueless how would i tell if one is burnt up???? the pics are of the trouble piston and valves...

 

To bad you didn't do a leakdown test first, oh well , set the head so the gskt surface is horiz., then pour a light liquid [ mineral spirits?] in the comb. chamber & see if it runs out the ex. port or int. port, should tell you which valve is bad .

dave

 

Yea they sell pushrods individually. Since the intakes off look through the front oil drain holes and see if the timing gear is a steel double roller or aluminum/nylon that has gone bad. Also, look in the valve spring for a possible broken dampner.

 

ok well i did some numbers searching and the head is a 305 head if that makes a diff

 

oyeah and its a steel double roller

 

so anyone have any other suggestions before i start tearing down a head???