Check my PCV setup please

-
equium

equium

Well-Known Member
Joined
Oct 3, 2014
Messages
221
Reaction score
10
Location
Shingle Springs, CA
70 Plymouth Valiant, 318:
So I've been fighting an oil leak that is coming from the rear of the intake. This is the second time I've reinstalled this intake and I was pretty sure I fixed the leak in the beginning. Since then, I've replaced the valve covers and installed new breathers. The leak came back eventually. I've replaced the oil pressure switch and used teflon tape. I just installed a new skip white distributor with new O ring. My theory is that with the new valve covers and the cheap spectre performance breathers, I may have caused excessive pressure and blown out the silicon on the intake. You'll see in the photo I'm using a single PCV and two breathers.
Let me know if this is proper or if I'm doing it wrong.
thanks.
Danny
 

Attachments

  • engine pic.jpg
    45.2 KB · Views: 707
I recently had a rear intake oil leak that was actually the oil pressure sending unit... but i did have to replace my pcv valve just a month after changing it, due to cheap china junk.
 
Without the hose connecting the breather on the passenger side valve cover to the air cleaner on the carburetor, it is incomplete.
 
The PCV is well over 6 months old. I'll get it replaced.
I will also replace the passenger side breather with the type that has the side tube and run a hose to the air cleaner.
I kind of figured I may have done it wrong. thanks guys
 
It's not "wrong", it's just missin somethin.
 
RustyRatRod said:
Without the hose connecting the breather on the passenger side valve cover to the air cleaner on the carburetor, it is incomplete.
Click to expand...

My question is why?

He has the hose from the PCV valve to the carb (drivers side front), the passenger side breather should allow air to enter the engine. As long as that breather has a filter is should be clean air.

I've seen a lot set up this way. Just curious why the breather is hooked to the air cleaner.
 
I have 2 breathers on the pass side.One is open and the other is run to the breather.On the drivers side i only have pcv valve run to intake
 
straightlinespeed said:
My question is why?

He has the hose from the PCV valve to the carb (drivers side front), the passenger side breather should allow air to enter the engine. As long as that is a filter is should be clean air.

I've seen a lot set up this way.
Click to expand...
At WOT, there is very little vacuum under the manifold, and the PCV thus has little suction and is somewhat restricted anyway to the larger volume of blowby at WOT. The rest of the blowby has to go back out the breather at WOT; if it is connected to the inside of the air cleaner on top of the carb, there is a tiny bit of suction there to help a bit.

The breather connection will add a bit of flow at WOT but not enough to cure a bad blowby situation.

It is as much or more a pollution control measure, to route all crankcase vapors through the engine for burning.

I'd be more concerned in this case to make sure the new breather is open enough to flow all the blowby at WOT.
 
I have always ran a breather on one cover with the pvc running to the carb on the other cover. That should be plenty
 
nm9stheham said:
At WOT, there is very little vacuum under the manifold, and the PCV thus has little suction and is somewhat restricted anyway to the larger volume of blowby at WOT. The rest of the blowby has to go back out the breather at WOT; if it is connected to the inside of the air cleaner on top of the carb, there is a tiny bit of suction there to help a bit.

The breather connection will add a bit of flow at WOT but not enough to cure a bad blowby situation.

It is as much or more a pollution control measure, to route all crankcase vapors through the engine for burning.

I'd be more concerned in this case to make sure the new breather is open enough to flow all the blowby at WOT.
Click to expand...


Mark, Thank you for the explanation of why the breather is connected to the air cleaner. You have satisfied my curiosity. I understand what the PCV is for and does, but never why 2 connections. Like I said I've seen many many cars with it just the way he has it routed, and no issues.
 
straightlinespeed said:
My question is why?

He has the hose from the PCV valve to the carb (drivers side front), the passenger side breather should allow air to enter the engine. As long as that is a filter is should be clean air.

I've seen a lot set up this way. Just curious why the breather is hooked to the air cleaner.
Click to expand...

You've seen a lot of them with a piece missing, then. The hose from the breather to the air cleaner is a necessary part of the PCV system. It completes the system so there can be complete circulation.

I am no expert like nm9stheham is. He is really sharp. All I do know is that whenever I either repaired or added the hose from the breather to the air cleaner in every instance it was missing or damage, it stopped oil residue from being puked out of the engine.

See diagram, it is pretty self explanatory.
 

Attachments

  • PCV SYSTEM.jpg
    25.6 KB · Views: 1,056
RustyRatRod said:
You've seen a lot of them with a piece missing, then. The hose from the breather to the air cleaner is a necessary part of the PCV system. It completes the system so there can be complete circulation.

I am no expert like nm9stheham is. He is really sharp. All I do know is that whenever I either repaired or added the hose from the breather to the air cleaner in every instance it was missing or damage, it stopped oil residue from being puked out of the engine.

See diagram, it is pretty self explanatory.
Click to expand...

Thanks Rob!
 
What is the difference from the air breather evacuating pressure to the atmosphere and the crankcase filter pulling from the atmosphere as compared to a closed system
 
"Stops oil residue from being puked out of the engine"
 
I agree with 73AbodEE.
PCV on the DS valve cover to manifold vacuum, breather on the PS valve cover to the air cleaner housing. All other valve cover holes need to be plugged.
With the breather on the same valve cover as the PCV valve, it is doing nothing for the entire motor, only the one valve cover.
 
ChrisPerry said:
I agree with 73AbodEE.
PCV on the DS valve cover to manifold vacuum, breather on the PS valve cover to the air cleaner housing. All other valve cover holes need to be plugged.
With the breather on the same valve cover as the PCV valve, it is doing nothing for the entire motor, only the one valve cover.
Click to expand...

That's correct. The circulation is drastically reduced. I missed that he had a breather on the same side as the PCV valve. It should not be there.
 
The only time I ran a hose back to the air cleaner was when I was running a factory air cleaner. On my 340 and 408 I ran a PVC valve on the drivers side and a vented breather on the passengers side. Never made a mess, but I always ran baffled valve covers. The last summer I ran the 408 on occasion it would push the dip stick up a little when it was ran really hard, but never puked anything. The rings were shot.
 
RustyRatRod said:
That's correct. The circulation is drastically reduced. I missed that he had a breather on the same side as the PCV valve. It should not be there.
Click to expand...

He could swap valve covers and put the PCV at the passenger side rear and both caps on the drivers side, but that wouldn't solve the problem of the air going in not being filtered.

Maybe best to put the PCV on the passenger side rear and only have one cap with a filtered air inlet on the drivers side front.
That way the PCV valve would be in the back and a little cleaner looking.
I stress those "filtered" air comments because I don't like the thought of dust and crap getting sucked into the engine and I don't trust the filters in the caps to catch all of it.

Always hated those Chevy motors that had the hose going right into the side of the air cleaner housing with those stupid little square mesh things you could throw a cat through.
(you know, those little oil and dirt caked squares in the little pocket inside the air cleaner)
I like that inlet air to have gone through the actual air filter the intake uses, and that's why I plumbed my fresh air intake on the bottom of the air cleaner between the element and carb intake.
 
TrailBeast said:
He could swap valve covers and put the PCV at the passenger side rear and both caps on the drivers side, but that wouldn't solve the problem of the air going in not being filtered.

Maybe best to put the PCV on the passenger side rear and only have one cap with a filtered air inlet on the drivers side front.
That way the PCV valve would be in the back and a little cleaner looking.
I stress those "filtered" air comments because I don't like the thought of dust and crap getting sucked into the engine and I don't trust the filters in the caps to catch all of it.

Always hated those Chevy motors that had the hose going right into the side of the air cleaner housing with those stupid little square mesh things you could throw a cat through.
(you know, those little oil and dirt caked squares in the little pocket inside the air cleaner)
I like that inlet air to have gone through the actual air filter the intake uses, and that's why I plumbed my fresh air intake on the bottom of the air cleaner between the element and carb intake.
Click to expand...

I am still unclear as how this is all plumbed on an aftermarket breather. Pics would help.

:color:
 
As long as the air getting sucked into the crankcase through that RH valve cover breather is filtered, there is really no reason to run a hose to the inside of the air cleaner. The factory did it that way just so it would get filtered air going into it. You can just install a K&N breather (the ones that look like a mini air filter). It will do the samething.

There must be baffles under the breather and under the PCV valve, otherwise you'll be sucking an excessive amount of oil thru the system.

As someone else noted, you also must plug up the breather hole on the LH valve cover.

Sounds like you might have leaking valve cover gaskets. Check for interference between the gasket retention "lips" on the covers and the intake manifold. This is a very common problem. The lip(s) can be easily ground off in the areas they are hitting the intake.
 
72Valiant4Door said:
I am still unclear as how this is all plumbed on an aftermarket breather. Pics would help.

:color:
Click to expand...

Very simple. In fact, a LOT of aftermarket air filters have a knockout plug on the base plate and come with a nipple that screws to the bottom and routes a hose to the valve cover breather. The hose end at the air filter does not have to go through the filter. All that's important is that it routes to the carburetor intake. You can add a simple filter inside the air filter similar to what Chevy did that TrailBeast was talking about. Although crude, they do work well.
 
69_340_GTS said:
As long as the air getting sucked into the crankcase through that RH valve cover breather is filtered, there is really no reason to run a hose to the inside of the air cleaner. The factory did it that way just so it would get filtered air going into it. You can just install a K&N breather (the ones that look like a mini air filter). It will do the samething.

There must be baffles under the breather and under the PCV valve, otherwise you'll be sucking an excessive amount of oil thru the system.

As someone else noted, you also must plug up the breather hole on the LH valve cover.

Sounds like you might have leaking valve cover gaskets. Check for interference between the gasket retention "lips" on the covers and the intake manifold. This is a very common problem. The lip(s) can be easily ground off in the areas they are hitting the intake.
Click to expand...

The air being filtered has nothing to do with it. Look at the diagram I posted. The air going into the breather hose even flows backwards from the air being filtered. The only purpose for running the hose on the outside of the filter was to keep oil residue from being sucked into the carburetor in WOT operation.
 
You must log in or register to reply here.
-

Back
Top