Vapor coming from the oil filler tube

Vapor coming from the oil filler tube
will13fox

will13fox

Jeeper
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Location
Raeford, NC
Vehicle(s)
79 CJ7 original stock V8 and original stock tranny
I just bought a 79 CJ7 when I was driving it to the house I noticed what looked like smoke from under the hood but i didn't smell anything burning. I got to the house and popped the hood and noticed what looks like steam coming from the oil filler tube. I let the jeep sit a few hours and then started it back up and right away the "steam" came back. Any thoughts?
 
Are you sure it is 'steam'?
I would say the PCV system has a problem. It may not be venting correctly. Check the PC valve.

This is just a guess...
 
Could be just blowby, You will get that with a motor that has a lot of miles.
 
Could be coolant, check the coolant for oil and vice versa. Along with keeping an eye on the coolant level and checking for coolant level for any drop. There has to be a lot of blow by in there also. I'm not really sure if it would retain the coolant "Smell"
 
11:16 - 11:19 and three suggestions! A new record! Thanks for being a part of our forum! ;)
 
CJ said:
11:16 - 11:19 and three suggestions! A new record! Thanks for being a part of our forum! ;)
Click to expand...
Thats why this forum ROCKS
 
Thanks for the help guys I stayed up late last night tinkering with the CJ. I changed the oil and checked the coolant. The oil was clean and no coolant in it and the coolant is clean no oil in it. Still got the steam looking vapor. I did however get a PCV it will be in Tuesday so ill give that a shot and let you guys know how it works.
 
my cj dosent have a pcv valve. is it as simple as drilling a hole in the valve cover and adding a grommet, pcv valve, and hose to the carb? i have a 360 and i see the vapor occasionally too.
 
There is also a baffle on the underside to keep oil away from the PCV.
 
About 8 months ago, I had to pull my intake off my 360, and re-install after some cam work. Made the MISTAKE of re-using the intake metal gasket set. (yeah, save $27 by re-using the intake set)

BAD IDEA-WONT SEAL TWICE.

Anyway, I started it, and about 5 minutes later had steam from the oil fill tube. Not blow-by in my case. Shut it down, said a few prayers and re-started it the next morning to see if a miracle had happened overnight...

NOPE... I had water jackets improperly sealed on the intake set, and water was fouling my oil...It was a nasty mess.

Just a thought.
 
jamie said:
my cj dosent have a pcv valve. is it as simple as drilling a hole in the valve cover and adding a grommet, pcv valve, and hose to the carb? i have a 360 and i see the vapor occasionally too.
Click to expand...

Correct. Then ditch the vented oil fill cap. You want a vacuum in the crank case if possible.

To OP: I agree that this is probably just blow by. Even if there was coolant involved, you'd still need blow by to cause the positive pressure to be blowing out the oil fill tube. If you arent loosing coolant or having other performance problems caused by head gasket issues I wouldnt sweat it. I think you are on the right track with the PCV system--did you have one already and are just replacing it or is this a new install?

The PCV usually won't get rid of excessive blow by but can reduce it a little. Most common symptom of no PCV on an otherwise healthy engine is some white/yellow sludge buildup under the oil fill cap or breather. This is condensation/oil residue.

You can do a leak down test if you really want to confirm the blow by is causing the vapor.
 
So another idea would be to get rid of the vented filler cap? If I can figure out how to upload a video I can show you what's going on
 
Well, not necessarily. You get pressure in the crank case both from blow by and from the crank spinning in the oil. The pcv system pulls that built up pressure out and any condensation. If this pressure cant get out, it'll force its way out and you'll get oil leaks. A pcv equipped vehicle wont have a vented cap. You'll be sucking in a bunch of extra air.

So if you dont have a pcv system, you need the vented cap.

Some pictures would be cool too.
 
Ok well I ordered one but I'm starting to think my CJ doesn't even have one ill do a good inspection when the sun comes up there should be something coming off one of the valve covers right?
 
Yup. You'll have a pcv in one VC; usually towards the back. The other vc will have the oil fill cap. The pcv needs a tube/hose to a large port on the carb that has vacuum. It cannot share the same port as the brake booster.

If you have caps or vents in both, you can get a different grommet, cut one, or sometimes the pcv will fit.
 
Ok well I guess I don't have one the the PO put on after market edelbrock VCs and an edelbrock intake my filler is a tube in the front of the intake with an after market vented cap
 
Ok so there are no holes in either of the VCs?
 
Well you can def. pull one and drill a hole in it.

If the blowby isnt excessive, I wouldn't sweat it.

Does she run good?
 
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