excessive 340 crankcase pressure

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skidshoe93

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need some advice on how to vent my 340 have catch can with vents coming from both valve covers system is closed but pressure still sends a nice mist of oil out of dip stick tube making a mess have to put a rag around tube kinda takes away from rest of motor detail
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Do you have a PCV valve? Or is it just a breather? Either add a PCV or it might be time for rings.
 
Is it a fresh rebuild?

If so, the rings may not have seated yet.

You can do a compression test on each cylinder, if the rings have not seated, or if they are worn, or if a cylinder is scored the blow by may be pressurizing your crankcase.
 
sounds like ring/bore issue,hope you get it resolved.BTW Schweeeet lookin ride !!
 
You're only showing the driver's side and there's a PCV in the cap. Is there a breather open to atmosphere on the passenger's side cover?
If the PCV is doing it's job, the pressure would not be forcing stuff out the dipstick tube. That's a symptom of ring sealing issues as noted. IMO - it's not a problem that will get any better.
Time to diagnose the engine's condition. Otherwise you're just trying to address a symptom and not the cause. And the cause may cause more problems for you as time goes on. Get a compression gage and test for cylinder compression. Engine should be hot and all plugs out for the test. If that does not indicate a specific hole with a problem, have someone do a cylinder leakdown on it.
 
I put a Wagner adjustable 2 stage PCV valve in my system with an oil trap filter. Very happy with the results. Crankcase pressure increases with load and RPM. This setup deals with it. Caveat, if you are blowing oil mist out the dipstick tube your issues are larger than this will fix.
 
OK, what's with the photos? Number 1,3 show a pcv valve on the left valve cover but number 4 does not. What is on the other side of the motor? Instead of a photo of the car (which is nice) you should show the right side valve cover. Also does your dip stick have a rubber seal at the top? Is the motor, blow by, lifting up the dip stick any?
 
If that breather the PCV valve is in on the driver's side is open to the atmosphere on the bottom, as most are, You need to eliminate it. Put the PCV valve directly into the valve cover.
 
On the race engine, we ran a PCV valve in both valve covers to eliminate high crankcase pressure at high RPMs. Just put a tee at the back of the intake/carb & plumb the second one in.
 
On the race engine, we ran a PCV valve in both valve covers to eliminate high crankcase pressure at high RPMs. Just put a tee at the back of the intake/carb & plumb the second one in.
1: i'm curious about this as i've never heard of someone doing this before. 2: he's got a street car that's spending most of it's time at part throttle and i don't understand how that's going to do him any good
 
1: i'm curious about this as i've never heard of someone doing this before. 2: he's got a street car that's spending most of it's time at part throttle and i don't understand how that's going to do him any good


10 PCV valves won't do **** at high RPM so just ignore that.

If you want to use the system the way it was designed, you need the valve in one cover and a breather in the other cover. Chrysler used filtered air going into the crankcase and that air was pulled through the crankcase over to the PCV valve and then burned in the intake tract.

The system only works at high vacuum throttle openings. At WOT the system doesn't do a thing.

It's my experience that if the rings aren't seated in the first few minutes they'll never be seated correctly. And you can't do anything to fix it except re-ring it and brush hone the bores.
 
On the race engine, we ran a PCV valve in both valve covers to eliminate high crankcase pressure at high RPMs. Just put a tee at the back of the intake/carb & plumb the second one in.

He may not need that. He needs to get his system RIGHT first, and then he can determine if he needs "number two".
 
10 PCV valves won't do **** at high RPM so just ignore that.

If you want to use the system the way it was designed, you need the valve in one cover and a breather in the other cover. Chrysler used filtered air going into the crankcase and that air was pulled through the crankcase over to the PCV valve and then burned in the intake tract.

The system only works at high vacuum throttle openings. At WOT the system doesn't do a thing.

It's my experience that if the rings aren't seated in the first few minutes they'll never be seated correctly. And you can't do anything to fix it except re-ring it and brush hone the bores.

Exactly, since there's no manifold vacuum. lol
 
RRR, get off of your horse. Many of us also have opinions & suggestions for our fellow members. We all try to help one another & don't need someone like you riding herd on us. All I offered was what worked your us, if your disagree that is your option.
 
I have re-looked at the OP and the photos. I am convinced that the OP does not have a clear understanding of how it all works. We should suggest a proper tech article with diagrams for him to study. I am sure once he understands the concept he will be able to get it correct.
 
I have re-looked at the OP and the photos. I am convinced that the OP does not have a clear understanding of how it all works. We should suggest a proper tech article with diagrams for him to study. I am sure once he understands the concept he will be able to get it correct.


The OP should go to the ME Wagner website and read all he can find.
 
RRR, get off of your horse. Many of us also have opinions & suggestions for our fellow members. We all try to help one another & don't need someone like you riding herd on us. All I offered was what worked your us, if your disagree that is your option.


RRR isn't riding a high horse. If you did as you posted, it didn't work. I could not have, as the PCV valve is vacuum operated. At WOT there is very little vacuum and the valve(s) are closed and do nothing.

That's why both RRR and I said not to do that. It is physically impossible for that configuration to do anything.

So neither of us was being arrogant. We were trying to set the record straight. PCV valves do nothing at WOT. Ever. So 1 or multiple valves won't help WOT.
 
It’s really simple. The aftermarket covers make it harder, read the FSM! The PCV must be connected to manifold vacuum.
 
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RRR, get off of your horse. Many of us also have opinions & suggestions for our fellow members. We all try to help one another & don't need someone like you riding herd on us. All I offered was what worked your us, if your disagree that is your option.

Nobody's on a horse or riding anybody. It was a suggestion like everyone else. You're reading into it something that's not there. Also, I never disagreed with anything. All I suggested was that he get the PCV system correct FIRST and go from there, because right now it's not.
 
It’s really simple. The aftermarket covers make it harder, read the FSM! The PCV must be connected to manifold vacuum.

Right. That's all my suggestions were. For him to get the PCV system correct, as intended FIRST and then diagnose. Just doing "THAT" might fix his problem.
 
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