Smoking from valve cover cap

[74 Charger SE]

I have a 318 in my 74 charger. I have aftermarket valve covers, as shown in the attached pics, with a cap on both the passenger and driver's side. I'm getting fumes/smoke coming from the caps, which work their way into the interior of the car via the AC vents, which causes a toxic idle.
1. What could be causing the smoke/fumes? I've no idea how many miles are on the engine and think it may need a rebuild?
2. Would a traditional valve cover cap work better for the fumes and smoke or would that just mask an issue?
https://mail.google.com/mail/u/0?ui...162500&th=1883e9e4bc1c7204&view=att&disp=safe

 

[toolmanmike]

I have a 318 in my 74 charger. I have aftermarket valve covers, as shown in the attached pics, with a cap on both the passenger and driver's side. I'm getting fumes/smoke coming from the caps, which work their way into the interior of the car via the AC vents, which causes a toxic idle.
1. What could be causing the smoke/fumes? I've no idea how many miles are on the engine and think it may need a rebuild?
2. Would a traditional valve cover cap work better for the fumes and smoke or would that just mask an issue?
Gmail


View attachment 1467946

View attachment 1467947

All I see is caps on both sides. Where's your pcv valve? Air in one breather cap, pcv valve in the other valve cover to a vacuum source on the carburetor.

 

[74 Charger SE]

All I see is caps on both sides. Where's your pcv valve? Air in one breather cap, pcv valve in the other valve cover to a vacuum source on the carburetor.

Please forgive me in advance as I'm not the most mechanically inclined so I may not be able to answer your questions but there is no carburetor. EFI installed.

 

[Lefty71]

but there is no carburetor. EFI installed.

Toolmanmike's info is still valid. Vaccuum source can also come from the manifold itself. There has to be something (PCV valve) on one side, and a breather on the other side to allow fumes to get sucked back into the engine. As the motor wears (more miles) you problem will become even worse.

 

[R413]

You need a PCV valve, every car manufacturer has had them since late 60’s early 70’s. Yes even with EFI.

It is vapor or moisture not smoke Out of the cap. Unless the caps are dripping oil and it is getting on the exhaust then it will be smoke, and this does happen.

How long since an oil change?
if it smells that’s a bad sign.

 

[Lefty71]

I cant tell from your pix, but it really looks like those are breathers, not caps....so all you need to do is remove one, find a way to mount a pcv valve in place of that one, and then run a hose back to manifold vacuum as shown.

Trans-Dapt Performance Products 9355 Trans-Dapt Performance Breather Grommets | Summit Racing

Summit Racing SUM-440308 Summit Racing™ PCV Valves | Summit Racing

 

[74 Charger SE]

You need a PCV valve, every car manufacturer has had them since late 60’s early 70’s. Yes even with EFI.

It is vapor or moisture not smoke Out of the cap. Unless the caps are dripping oil and it is getting on the exhaust then it will be smoke, and this does happen.

How long since an oil change?
if it smells that’s a bad sign.

It is vapor. Not smoke. Oil change was done a couple of months ago but it's been at the mechanic for close to a year getting worked on prior to the oil change.

 

[74 Charger SE]

View attachment 1467962
I cant tell from your pix, but it really looks like those are breathers, not caps....so all you need to do is remove one, find a way to mount a pcv valve in place of that one, and then run a hose back to manifold vacuum as shown.

Thank you! Now if vapor is coming from both breathers, will installing a pcv valve on one theoretically solve the issue? Or should a PCV valve be installed on one and a cap on the other?

 

[Lefty71]

It is vapor. Not smoke. Oil change was done a couple of months ago but it's been at the mechanic for close to a year getting worked on prior to the oil change.

No doubt oil has taken on a bunch of condensation from sitting... It'll burn off, but i'd change the oil again if it were mine. You need the PCV system regardless... I posted links above to get you started.

 

[Lefty71]

Or should a PCV valve be installed on one and a cap on the other?

No... look at the drawing.... one side is PCV, the other is air going in(use breather, no cap), A cap would defeat the action of the PCV. It needs a way for air to enter motor.

 

[74 Charger SE]

No doubt oil has taken on a bunch of condensation from sitting... It'll burn off, but i'd change the oil again if it were mine. You need the PCV system regardless... I posted links above to get you started.

Excellent! This is great. Now if anyone happens to be in the Maryland area and has a few hours on their hands.....(I supply food and drinks!)

 

[74 Charger SE]

No... look at the drawing.... one side is PCV, the other is air going in(use breather, no cap), A cap would defeat the action of the PCV. It needs a way for air to enter motor.

awww...breathing...in and out....I got it. (takes a while to sink in)

 

[slepr1]

A new pcv valve is cheap ($10) and you need one. To change your setup with a pcv valve would take 10 minutes with no tools. If you are unsure how to proceed or not mechanically inclined, get it done the next time you get work done. Not having one won't necessarily hurt your engine but having the crankcase breath/vent properly will stop the vapor smell from coming inside your car.
The toxic idle you mention doesn't have anything to do with your setup.

 

[74 Charger SE]

A new pcv valve is cheap ($10) and you need one. To change your setup with a pcv valve would take 10 minutes with no tools. If you are unsure how to proceed or not mechanically inclined, get it done the next time you get work done. Not having one won't necessarily hurt your engine but having the crankcase breath/vent properly will stop the vapor smell from coming inside your car.
The toxic idle you mention doesn't have anything to do with your setup.

It may be more than one issue then. I think i understand the issue with PCV valve and vapor. I assumed this was the fumes I smell inside of the car but the fumes inside the car really smell more like gas.

 

[Paul_G]

If you have a mechanic who works on your car, he should be more than capable of installing a PCV valve for you. If you dont do your own work on this car that is your best bet.

 

[68 Sport Satellite]

Remove both caps and snap a photo of the underside and post here. I had this happen on my car. I had installed Mopar Performance cast aluminum valve covers with a basic flat oil filler cap and the other side with a PCV breather cap that looked a lot like yours but with the hose coming off the side plumbed to the intake. I was getting vapor or smoke on the PCV breather cap side. The underside of that cap has breather holes with a crimped edge. The crimped edge was not sealing and was dripping oil or condensated vapor onto my headers and then causing smoke. I removed the breather cap and applied some gray sealant (can't recall what kind) around the underside outside edge seam and that did the trick.

 

[74 Charger SE]

Remove both caps and snap a photo of the underside and post here. I had this happen on my car. I had installed Mopar Performance cast aluminum valve covers with a basic flat oil filler cap and the other side with a PCV breather cap that looked a lot like yours but with the hose coming off the side plumbed to the intake. I was getting vapor or smoke on the PCV breather cap side. The underside of that cap has breather holes with a crimped edge. The crimped edge was not sealing and was dripping oil or condensated vapor onto my headers and then causing smoke. I removed the breather cap and applied some gray sealant (can't recall what kind) around the underside outside edge seam and that did the trick.

Much appreciated. I'm making a list of what's been suggested so I can provide to my mechanic. I will definitely post back when completed.

 

[KiwiKid72]

.

 

[74 Charger SE]

Hey. Thank you! I can see the breather on the passenger side and the cap on the drivers side. Much appreciated!

 

[KiwiKid72]

The PCV valve hose is connected to the port at the base of my carburetor. With EFI you'd have it to another vacuum source.