Could a blown head gasket causes engine blowby?

[perucho]

...You may simply need to drive it more, especially at freeway speed, to break the rings in.

Yes, he may need to seat the rings still but he needs to get rid of that venting setup asap. By the way, my b3 had a warped head (previous owner overheated the engine) were the head gasket didn't seal anymore and had oil in the water. Re-torqued the head bolts but couldn't correct the damage. However, the car idled/run just fine.

[lancerevo]

Thanks for the input. I love to learn. Can someone draw a diagram how can I connect the catch can correctly. What I tried was to eliminate the pcv, because some say that the blowby from the engine when entered in the intake it reduces performance.

[blkfordsedan]

I'm sorry, but I don't see anything wrong with the way you have it set up right now. All you're doing is running 2 hoses to the catch can, which is vented to atmosphere. This is no different than the way engines were design from the 50's to the '70s. All they had was a filtered breather on one valve cover. In fact, the early FE blocks only had a draft tube that ran from the back of the intake manifold down to underneath the car. A lot of engines only had a filtered breather located on the side of the block above the oil pan.
All you need is a way to relieve the crankcase pressure. I see no way that you are pressurizing anything the way you have it now. There are advantages to a functioning PCV system, but it's not required. You can put the catch can between the PCV valve and the intake vacuum port, but you'll have to remove the "fresh air" vent so you don't have a vacuum leak. Also, If you put vacuum to the catch can, I would install a ball valve in the drain line that goes to the oil pan. There's a lot of windage & oil vapor in the crankcase and you don't need to be sucking a vacuum on it.

If you have blow-by issues, it's from mechanical issues and not your catch can set up. If you have bubbles in the radiator, you have a bad head gasket, cracked or warped head, etc.. I think its possible that a bad head gasket that leaks compression into a water jacket would also leak compression into an oil return passage and cause blow-by. If you run a compression test you can test dry and then squirt oil in the cylinders. If the compression goes up after you add the oil then the rings are leaking.

[lancerevo]

I'm sorry, but I don't see anything wrong with the way you have it set up right now. All you're doing is running 2 hoses to the catch can, which is vented to atmosphere. This is no different than the way engines were design from the 50's to the '70s. All they had was a filtered breather on one valve cover. In fact, the early FE blocks only had a draft tube that ran from the back of the intake manifold down to underneath the car. A lot of engines only had a filtered breather located on the side of the block above the oil pan.
All you need is a way to relieve the crankcase pressure. I see no way that you are pressurizing anything the way you have it now. There are advantages to a functioning PCV system, but it's not required. You can put the catch can between the PCV valve and the intake vacuum port, but you'll have to remove the "fresh air" vent so you don't have a vacuum leak. Also, If you put vacuum to the catch can, I would install a ball valve in the drain line that goes to the oil pan. There's a lot of windage & oil vapor in the crankcase and you don't need to be sucking a vacuum on it.

If you have blow-by issues, it's from mechanical issues and not your catch can set up. If you have bubbles in the radiator, you have a bad head gasket, cracked or warped head, etc.. I think its possible that a bad head gasket that leaks compression into a water jacket would also leak compression into an oil return passage and cause blow-by. If you run a compression test you can test dry and then squirt oil in the cylinders. If the compression goes up after you add the oil then the rings are leaking.

I agree with you because, I never seen anything wrong with this setup. The only reason that I wish to improve is to have 2 oil catch cans to separate the fresh air intake and outlet fumes from mixing together.

[perucho]

That setup is not vented to the atmosphere. It's trapping gases in the engine and the pressure build up is apparent at your valve cover gasket.
You could also have head gasket issues but you mentioned that your vacuum gauge tells you otherwise. In any case, you shouldn't have these problems with a freshly rebuilt engine.
At the end of the day it's your car so if you want to keep adding oil catch cans, go at it.

[lancerevo]

That setup is not vented to the atmosphere. It's trapping gases in the engine and the pressure build up is apparent at your valve cover gasket.
You could also have head gasket issues but you mentioned that your vacuum gauge tells you otherwise. In any case, you shouldn't have these problems with a freshly rebuilt engine.
At the end of the day it's your car so if you want to keep adding oil catch cans, go at it.

Right now it's not blowing blowby or bubbles from the radiator. The only thing is the oil cap seems a little bit chocolate color. Could it be condensation from a bad pcv system? Why are you saying it is pressurizing in the valve cover where it is clearly vented to atmosphere?

[perucho]

I guess i should have looks closely at the drawing I didn't notice that the catch can is vented. That would prevent pressure build up. However, your system does not scavenge gases out of the engine.

[lancerevo]

Here is the best setup I can think of.

[blkfordsedan]

Dude, you're over-thinking it. You don't need anything that complicated. I just re-read your first post and realized you rebuilt the motor 5 months ago. If the rings and head gasket are doing their job, you shouldn't have any blow-by issues if N/A. If you do, something's wrong. Just a couple things;

First, the rings need to be broke in and develop a seal. the Time/miles required depends on the ring material (cast, chrome, etc), the cylinder wall finish (hone job), clearance and on the way you are driving it. It's not uncommon for a fresh rebuild to burn some oil. But if it was a good rebuild with quality maching & assembly and you broke it in properly, the rings should seat fairly quickly.
Second, unless you used a head gasket that specifically states it will not require re-torquing, you will need to retorque it. Even then, I've had to retorque after a few thousand miles.
Third, the main purpose of the catch can is to catch the oil vapor and keep it out of the engine intake. The way you have it installed, it will collect and condense moisture from the air as the engine cools. There is also moisture created during the combustion process. That would account for the milky color you see on the oil cap and in the catch can. Personally, I would not return the contaminated oil back into the oil pan. There's no reason to, unless you lose so much oil you're afraid of running it out of oil. I would re-install the PCV system, take the breather off the can, and install the "closed" can between the PCV valve and the intake manifold port. As you drive, it will allow the PCV system to do it's job but at the same time will seperate the oil from the other gasses and collect it in the can. When the can fills up, you drain it.
Fourth, if you have issues, a compression/leakdown test will tell you where the problem is.
I have my catch can installed the same way as you currently do, but its because I have such excessive blow-by that it will blow a quart of oil into the air intake tube and fill the VAF meter up with oil in about 150 miles. When I get my B6 installed, I will install the can as intended.

[lancerevo]

Here is my setup which is like the stock system but I think it's better because, the intake for the pcv is not from the intake hose. It's breathing from a catch can.

[lancerevo]

The engine is working perfectly now with the pcv valve connected correctly. The pcv valve works with engine vacuum. At cruising speed it works the best by sucking engine blowby to the intake so, it will let the engine breathe fresh air in and remove bad gases out. No more Chocolate color oil caps.