Smoke from breathers.

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71valiant

71valiant

Make fast, break, repeat.
Joined
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Location
Columbus, Indiana
I just purchased a 67 Valiant from a guy. Its a 69 block 318 with 360 heads, Edelbrock carb and intake and a cam. (not sure of the size) I really have no insight on the motor as he bought it off someone and I dont think he really asked questions. But anyway. The car revs super fast. But my concern is I get quite a bit of smoke from the breathers in the valve covers (i have one on each side and the port holes are baffled,along with a new pcv ran to the front of the carb. I hooked a vac gauge to the front of the carb where the pcv goes and its pulling 15 lbs of vac. But I constantly have oily valve covers where my breathers are because of the smoke. The motor runs strong, the oil is clean (not milky). I'm just stumped.
Heres a pic just for fun.
http://tinypic.com/r/281xwsn/6
281xwsn.jpg

281xwsn.jpg
 
Very cool Valiant! :D. I think the easiest thing would be to do a compression test first and look for inconsistancies in the individual cylinders. That may rule out a head gasket failure. Low consistant readings would lead to lack of ring seal. It's a little hard to tell what a low reading would be not knowing the piston used, the deck ht, and if the heads were milled. If all those measurements lean toward the stock side, that's a very low compression engine in that configuration. The fact that you pull 15" of vac say the cam is fairly mild. If it is a Eddy cam i would guess it's the regular Performer?
 
Yeah. The cam sounds pretty mild. When I got the car the dude had the idle WAY low, so it was slobbering all over the place. I do know the intake is a Performer, not that that makes any difference, but they may have been matching both cam and intake. I'll try to get to the compression test asap.
 
If it were bad gaskets more than likely I'd have coolant in the oil correct? Which is not the case.
 
71valiant said:
If it were bad gaskets more than likely I'd have coolant in the oil correct? Which is not the case.
Click to expand...

Not always. A small breach on the valley side can pressurize the crankcase even though the coolant passages are still sealed.........Not that it's likely, just another thing to look for in the diagnosing process.
 
Very nice Dart, one thing I would do is pull the oil dip stick and see if you see or feel air coming out of it, a head casket can leak between #4 and #6 (lets just say) and it will push compression back down in the crank case, I had a friend that had this happen and a tec here in town said a head it cracked.... I looked at a picture real close and told him it could be just a blown head casket, sure enough the head gasket was leaking between 4 and 6.
 
how about a pic of your engine. are your valve covers baffled? are you pushing white or blue smoke out of your pipes? blow by is usually a sign of oil getting past the rings or insufficient crankcase pressure evacuation. just because a PCV valve is new doesnt mean it is working properly. does your engine push the dipstick tube up?
 
71valiant said:
I've never done a leak down test. What does that consist of?
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You would need a leak down teater. It tests each cylinder to see the percentage of air lose. It is used a lot by racers to see the health of the motor. My buddy that races does both a compression teat and leak down on his motor on a regular basis.
 
71 Valiant,
I hope you have better luck with that problem than I am having.

My breather was smoking like 2 packs a day...the previous owner hid the blow-by problem.

My Duster ran great, other than keeping the engine bay lubricated, supposedly 5K miles on a complete rebuild.

Engine had great vacuum.

I did a compression test and got 145-150 psi for each cylinder.

Did a leak down test and my cylinders were leaking at a rate of 55-60%...not good. The breather whistled like a tea kettle full of boiling water during the test.

I pulled the engine and have it on a stand waiting for me to pull a piston or 2 out.

Looking at bad rings or ring gap, bad assembly or maybe bad machine work.

My wife said no spending $$$ until after the first of the year...hopefully this won't bust my piggy bank...and wind me up in divorce court.

Good Luck,
Paul
 
As far as the leakdown test, it would take a lot of typing to try and explain all technical stuff. So if you have plenty of time on your hands to read through this, lol, i'll post the link to article in CC.

http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/viewall.html

A comp test or even just pressuizing a cylinder can show a obvious failure. If neither shows a problem, a leakdown would be the next test to evaluate the condition of the engine.
 
OldmanRick said:
As far as the leakdown test, it would take a lot of typing to try and explain all technical stuff. So if you have plenty of time on you hands to read through this, lol, i'll post the link to article in CC.

http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/viewall.html

A comp test or even just pressuizing a cylinder can show a obvious failure. If neither shows a problem, a leakdown would be the next test to evaluate the condition of the engine.
Click to expand...

Thanks man.
 
1972DusterPaul said:
71 Valiant,
I hope you have better luck with that problem than I am having.

My breather was smoking like 2 packs a day...the previous owner hid the blow-by problem.

My Duster ran great, other than keeping the engine bay lubricated, supposedly 5K miles on a complete rebuild.

Engine had great vacuum.

I did a compression test and got 145-150 psi for each cylinder.

Did a leak down test and my cylinders were leaking at a rate of 55-60%...not good. The breather whistled like a tea kettle full of boiling water during the test.

I pulled the engine and have it on a stand waiting for me to pull a piston or 2 out.

Looking at bad rings or ring gap, bad assembly or maybe bad machine work.

My wife said no spending $$$ until after the first of the year...hopefully this won't bust my piggy bank...and wind me up in divorce court.

Good Luck,
Paul
Click to expand...

Hopefully this isnt the same problem.
 
You have more than likely pushed a head gasket into the lifter valley. They always go egg shaped with the point towards the lifter valley. If not that then you have a cylinder head that is not sealing on the deck surface somewhere. J.Rob
 
I am having the same problem with my motor. A leak down test is what I would do. I recently compression tested my motor and had about 224 psi each cylinder (according to my guage), give or take 1 or 2 psi. So everything "seemed" good. But a leak down showed every cylinder was about 4-8% except my #8 which was 14%. I was having some detonation problems and didn't know it at the time, but it caused the motor to start smoking out of the valve cover breather and right side exhaust when revved up. The air seemed to all leak past the rings on #8 through the crankcase so it may be a cracked ring or something. Who knows until I get it apart. Get the leak down tester, hook it up to your air compressor, set your #1 cylinder at TDC on the compression stroke so the valves are closed, make sure you have a wrench on your crank so it doesn't rotate, test at 100psi, rotate the crank 90 degrees, and go to the next cylinder in the firing order, repeat. 1-8-4-3-6-5-7-2
 
What you need is a breather with a nipple on it that has a hose that runs to the air cleaner, installed on the valve cover opposite the valve cover with the pcv valve in it. Take off and plug the breather on the cover with the pcv valve in that one.
The idea here is at high vacuum driving conditions, the pcv valve will pull out the oily smoke and burn it. At low vacuum driving the pcv valve shuts off and the carb will draw through the hose to the nipple breather and burn it that way.
It will keep the outside of your engine clean and the inside too. Plus it adds a little bit of oil to the top of the piston rings to make them last longer too.
Hopefully it's something simple like this and not internal problems.
Your car is really cool!
 
bobscuda67 said:
What you need is a breather with a nipple on it that has a hose that runs to the air cleaner, installed on the valve cover opposite the valve cover with the pcv valve in it.
Click to expand...

This is the way mine is set up. The breather vents into the bottom of the air cleaner by a piece of heater hose and the blow by is sucked into the carb. I thought that it was actually supposed to work the other way where filtered air is pulled into the breather through the hose. But my engine is so worn out it pulls blow by through the PCV and the breather. You can see the hose on my right (left in pic) valve cover.

IMG_6708.jpg


I KNEW my engine was worn out when I bought it. I hope that this isn't the problem with your engine.
 
To some extent this is the purpose of having breathers - to vent these crank case fumes and gases. a bit of smoke coming fromt hem is not uncommon. If you are also running a PCV as it sounds with dual breathers and still wetting down your engine compartment it does sound like too much blow by. If your leak down numbers look reasonable you could go to a vacuum system to pull vacuum on the crank case or try a simple header evacuation set up.
 
I have beat on my 340 for 18+ years and its getting retired for a 408. only because it smokes a little in the shut down area.(probably valve guide)
But, my point is, that the only time i get smoke to come out of my breather is when i disconnect my pcv from the valve cover.

Are you Positive that its working properly? Does the hose from the carb have vacuum? could it be plugged/restricted?
Pcv not fitting tight in its grommet?
leaking around the carb to hose/ hose to pcv fitting?

Your finger and some carb spray is all you need to do these tests..............
 
As mentioned, the factory setup was a hose from the oil cap/breather to the air cleaner. I think the purpose is to flow either way - suck clean air from after the air filter to the crankcase (by PCV sucking) or to vent blow-by that overwhelms the PCV under hard throttle into the carb. My 69 Dart had that setup (federal) and I think CA cars much earlier (recall my 65 Dart was). After-market chrome air cleaners usually have a knockout hole in the bottom to connect a hose to the bottom.
 
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