breather on the valve cover

[escobar]

A p.o. put an after market breather on the valve cover, here's my dilemma.

Some moron hooked the pcv hose to the same vacuum line as the power brake. Probably because the air intake filter housing is after market with no port for a pcv. So I unhooked it, and ran it down the block by the front differential- old school style.

On the other end of the valve cover there is an after market breather. Said p.o. just kinda cut out the rubber a little and stuffed the breather in there.

The engine has a lot of blow by but the pcv hose should handle it. I'm getting some oil out of the breather now and its getting all over my newly cleaned valve cover with new gasket.

What would you guys do here?

Btw, after replacing the valve cover gasket (this could just be coincidental) it seems as though the oil pan oil rear main is leaking more, I'm even getting a little oil out of the dipstick. I've got the pan gasket to replace tomorrow.

 

[Rescue Diver]

A p.o. put an after market breather on the valve cover, here's my dilemma.

Some moron hooked the pcv hose to the same vacuum line as the power brake. Probably because the air intake filter housing is after market with no port for a pcv. So I unhooked it, and ran it down the block by the front differential- old school style.

On the other end of the valve cover there is an after market breather. Said p.o. just kinda cut out the rubber a little and stuffed the breather in there.

The engine has a lot of blow by but the pcv hose should handle it. I'm getting some oil out of the breather now and its getting all over my newly cleaned valve cover with new gasket.

What would you guys do here?

Btw, after replacing the valve cover gasket (this could just be coincidental) it seems as though the oil pan oil rear main is leaking more, I'm even getting a little oil out of the dipstick. I've got the pan gasket to replace tomorrow.

What's wrong with running the PCV off the same line as the power brakes? It's all shared vaccum from the intake.

If your crank case isn't vented good enough and you have a lot of blow by from worn out rings, I can easily see extra pressure causing and already leaking rear main to leak even more if you fix a leaking valve cover that was also acting as an additional pressure release.

 

[escobar]

What's wrong with running the pcv off the brake vacuum?

It was robbing my brake of its effectiveness. As soon as I unhooked the pcv line off of it and capped the vacuum my brakes worked A LOT better. The valve cover was robbing my system of all vacuum and making my engine run badly. You can't just run a non-sealed system into a dedicated vacuum system without changing your mixture either. Now my engine- despite wear has more power, better idle, and I leaned the settings to run better and save more fuel.

 

[Rescue Diver]

What's wrong with running the pcv off the brake vacuum?

It was robbing my brake of its effectiveness. As soon as I unhooked the pcv line off of it and capped the vacuum my brakes worked A LOT better. The valve cover was robbing my system of all vacuum and making my engine run badly. You can't just run a non-sealed system into a dedicated vacuum system without changing your mixture either. Now my engine- despite wear has more power, better idle, and I leaned the settings to run better and save more fuel.

The brake booster and PCV both get vaccum from the same source whether it be through the same hose or separate ones so as long as the hose is big enough diameter, it shouldn't make a difference. If your PCV valve was bad and acting as a big vaccum leak on the same hose as the booster, I could see this making a difference. I only have one large vaccum port on my intake, so I have both run off the same line with a T. My power brakes work just fine.

On a side note, I had a noticable improvement in my power brakes when I installed a new PCV valve a while back without changing the way I had them plummed.

 

[escobar]

I don't know man. Could be an amc thing- but every pcv I remember runs into an air filter housing port. You still get a slight "pull" but not off the vacuum system. Ill try a new pcv and set it back up.

What about the breather? Is the OEM breather free flowing or checked? I just can't stand oil leaks.

 

[CJ]

My PCV runs to the main vacuum port along with the brake booster also.

 

[escobar]

Well . That seals it. Gonna get a new pcv and go back to vacuum. See what happens. The old one feels fine but- here we go again. I'm new to amc stuff.

 

[Rescue Diver]

I don't know man. Could be an amc thing- but every pcv I remember runs into an air filter housing port. You still get a slight "pull" but not off the vacuum system. Ill try a new pcv and set it back up.

What about the breather? Is the OEM breather free flowing or checked? I just can't stand oil leaks.

Every old school car I've ever owned and built(and that's a lot) had the PCV run to main vaccum. The PCV valve flutters open and closed so it lets the system build vaccum. They aren't just an open hole into the valve cover.

 

[Rescue Diver]

Well . That seals it. Gonna get a new pcv and go back to vacuum. See what happens. The old one feels fine but- here we go again. I'm new to amc stuff.

Yeah, a PCV valve might move freely and even look clean and still be bad and rob you of vaccum. That's why they're regular maintenance like changing your oil and filters. I only paid like $4 for my new one at Advance.

 

[CJ]

Hold on though - my 72 CJ is a V8 and the workshop manual show that for the AMC 258 i6 / 4.2l it goes to the air cleaner. For the V8 it goes to the manifold.

The closest diagram I can find for your PCV system is 1977, and it shows the PCV going to the manifold also.

Check out Morris online shop manuals. -->>Jeep Informational Center at Morris 4x4 Center

 

[Rescue Diver]

I don't know man. Could be an amc thing- but every pcv I remember runs into an air filter housing port. You still get a slight "pull" but not off the vacuum system. Ill try a new pcv and set it back up.

What about the breather? Is the OEM breather free flowing or checked? I just can't stand oil leaks.

If you're getting oil dripping from your oil breather, it's pretty saturated. A lot of blow by can cause this. New rings would be the best way to make it better by getting rid of most of your blow by. For now you could just get an oil breather that has a vent hose that you can run to your air breather. That might help a little with the drip.

 

[CJ]

A p.o. put an after market breather on the valve cover~~~

The FSM for 77 (closest I could find) shows a non vented cap - not a breather for a AMC 258 i6 / 4.2l .

 

[Rescue Diver]

The FSM for 77 (closest I could find) shows a non vented cap - not a breather for a AMC 258 i6 / 4.2l .

With the blow by he's describing, it might do some good to run a vented breather with a hose to the air filter. It can't hurt?

 

[Rescue Diver]

Hold on though - my 72 CJ is a V8 and the workshop manual show that for the AMC 258 i6 / 4.2l it goes to the air cleaner. For the V8 it goes to the manifold.

The closest diagram I can find for your PCV system is 1977, and it shows the PCV going to the manifold also.

Check out Morris online shop manuals. -->>Jeep Informational Center at Morris 4x4 Center

Maybe they did it differently back in the early 70's? That doesn't neccessarily make it better, or wrong to do it the way they did it later. My AMC 258 i6 / 4.2l was built in 1978 according to the casting. I bought it complete and from the looks of it, it had never been rebuilt or played with. I believe it had all the original hard, dried up hoses on it and the PCV ran to the intake. Of course I imediately did a rebuild and replaced all the hoses while I was at it.

 

[CJ]

Maybe, but the FSM also shows the vent that is supposed to be used is ported to the air cleaner. Is the air cleaner stock and is there a vent to the valve cover? If not then yes, he needs to run a aftermarket breather.

 

[CJ]

~~~ the PCV ran to the intake. ~~~

Yep - that is what I said in this post... -->> http://www.jeep-cj.com/forums/f2/breather-valve-cover-8139/#post69540

 

[Rescue Diver]

Maybe, but the FSM also shows the vent that is supposed to be used is ported to the air cleaner. Is the air cleaner stock and is there a vent to the valve cover? If not then yes, he needs to run a aftermarket breather.

On my 1969 Corvette with the monster cam and huge intake runners in the heads I bought, it didn't have enough vaccum to make a PCV valve function correctly so I just ran two oil breathers. There's a million different ways to do things correctly.

 

[CJ]

Apples and oranges. My CJ couldn't pull enough vacuum either when I raced it, I also just ran breathers. This is not a race car and really should have a functioning PCV system (for his hardware).

We talking about a stock CJ AMC 258 i6 / 4.2l with an aftermarket valve cover and hooking up the PCV system correctly for his application.

escobar, Sorry to get this tread off track - a picture of your current cover, PCV routing and air cleaner would really help us give you the best advice for you current setup.

 

[Rescue Diver]

Apples and oranges. My CJ couldn't pull enough vacuum either when I raced it, I also just ran breathers. This is not a race car and really should have a functioning PCV system (for his hardware).

We talking about a stock CJ AMC 258 i6 / 4.2l with an aftermarket valve cover and hooking up the PCV system correctly for his application.

escobar, Sorry to get this tread off track - a picture of your current cover, PCV routing and air cleaner would really help us give you the best advice for you current setup.

Absolutely agreed. A stock torquey AMC 258 i6 / 4.2l with its little cam and small intake runners builds ton's of vaccum. He might as well make use by way of a good PCV valve of it to get some of the blow by pressure out of his motor while at the same time running a vented breather cap with a hose to the air cleaner to help even further with less likelyhood that oil will drip on his valve cover from a regular vented breather.

I was just explaining that just because something came from the factory a certain way, it doesn't mean it's done wrong if it's done a different way.

Right now I'm just running a stock PVC and a regular vented breather cap. When I swap to the 4.0 head and aluminum valve cover this weekend, I plan to run a vented oil breather cap with a hose to my new Edelbrock 10" air breather, while still running the stock PVC to the intake.

 

[Saddle Tramp]

PCV valves originated as part of the smog controls implemented in the late 1960s early 1970s. The PCV valve has always put the gases from inside the crank case back into the intake system at some point to be mixed with the fuel/air mixture to be burned during cylinder combustion. If your engine has a lot of blow by oil will be forced out of the PCV or breather. The I6 is particular noted for this problem. The YJ setup has the PCV hose connecting to the air intake pipe just after the air plenum box. The intake pipe at that point slopes towards the plenum box causing the excess oil to drip into the box wiping out the air filter and generally making a mess on the driveway. You can drive them a long time this way before rebuilding the motor but some guys will use a drink bottle to put the PCV hose into to catch the oil rather than blow it all over everywhere.