Blow-by Talk and Fix

[Drunkenturtles]

I was under the hood today and saw at the connector tube between the intake and valve cover, it made me wonder how bad blow-by truly was. My mustang is at pretty high of mileage and I'm not sure if there's a point in putting in a catch can at 150k miles. How bad is blow-by on/for the 4.6 engine, especially at a high millage? And what is a reasonable way to fix blow-by?
I've seen some stangs with those small air filters attached to their passenger side valve cover and I've heard that blow-by is worse on the driver side. I was considering putting two cans, one for each side, but I don't know if that's an issue bad enough to spend money.

 

[Midlife Crises]

If you have the stock setup on your 4.6 3V all the air, oil and blow by exiting the block goes out the drivers side valve cover and onto the intake manifold. There is nothing coming out the of passenger side valve cover so there is no need for a catch can on that side. Air actually goes in the passenger side breather tube.
If your engine is mostly stock and you are not experiencing misfiring or fouled plugs I wouldn’t spend money on a catch can just so I could say I had one.

 

[Drunkenturtles]

If you have the stock setup on your 4.6 3V all the air, oil and blow by exiting the block goes out the drivers side valve cover and onto the intake manifold. There is nothing coming out the of passenger side valve cover so there is no need for a catch can on that side. Air actually goes in the passenger side breather tube.
If your engine is mostly stock and you are not experiencing misfiring or fouled plugs I wouldn’t spend money on a catch can just so I could say I had one.

I might not have misfires or fouled plugs, but oil still could blow up into the intake and cause build-up. I feel like misfires and plugs are symptoms of a problem that's already gotten out of hand. The only way to know if I'm having blow by issues before it gets bad is to look inside the engine or installing some sort of catch can to see how much oil it catches.
I'm suspecting my car is having problems with build-up from blow-by is the loss of gas mileage, the engine sometimes running rough, and loss of power not reasonable for its age. I haven't put it on a dyno, but I've driven similar mustangs and I can feel the loss of power, and the gas mileage dropping almost 4 miles per gallon. Though other things can affect the car in those aspects, usually its build-up.
Maybe I could buy a cheap one and run it for a few weeks to see what comes up. If it collects a lot of oil I'll invest in a good can.

At least I don't need to worry about the passenger side, so thanks for that info.

 

[Midlife Crises]

The way to tell if you have a blow-by issue is called a cylinder leakdown test. It will tell you what percentage of air you are loosing in each cylinder and where it’s going. As far as oil traveling through the PCV tube and interring your intake manifold; yes it is and it has been doing it for 150k miles. A catch can won’t fix anything or give you back power. How old are the spark plugs? When was the throttle body cleaned last? How many vacuum leaks exist?

 

[Juice]

With the engine running, remove oil filler cap and see if it is puffing any smoke. If you do, it is too late for a catch can.
Blowby can only really be fixed with new pistons, rings, and boring. Aka rebuild.
Now, you said you lost 4mpg, that is a lot. I would suspect a partially clogged cat converter causing the loss of power/economy. And it will affect amount of blowby.

 

[Drunkenturtles]

The way to tell if you have a blow-by issue is called a cylinder leakdown test. It will tell you what percentage of air you are loosing in each cylinder and where it’s going. As far as oil traveling through the PCV tube and interring your intake manifold; yes it is and it has been doing it for 150k miles. A catch can won’t fix anything or give you back power. How old are the spark plugs? When was the throttle body cleaned last? How many vacuum leaks exist?

I understand what you mean by the damage is already done. I could clean the engine but at this point, I wanna see how far she can go. I can check for leaks and the throttle body has been replaced by the last owner. At this point, the only fix is cleaning the engine, rebuild a few parts, and replacing the cats. That's not something I'll bother to do with this car, sadly. Once I get my low mileage 13 gt I'll put a catch can on it. that will do something at 50k or fewer miles.