so i started the car today just to let it run for a little while and check all the fluids

first thing i did was check the oil, when i pulled the dipstick out it started sucking air in, the sound it made was like opening a bottle of coke or something, when i pulled out the dipstick, there was no oil on the end, so i ran and shut the key off thinking i leaked all my oil out

after shutting off the engine i checked the oil again, this time it read full, but had a bunch of air bubbles in the oil, probably from the air sucking in

also the engine started fine, was running great until i pulled the dipstick out, then it started to bog a little

anybody know what might be happening? im guessing its something to do with vacuum, obviously, but i know nothing about vacuum really, im expecting the worst, because ive never heard of air being sucked in through the dipstick, and whatever might be wrong probably isnt something i want to hear

thanks in advance

 

Sounds like you have a PCV valve hooked up to one valve cover like it belongs, but the other side where the tube is that's supposed to let in filtered "makeup" air to replace what the PCV sucks out, is blocked off. Also sounds like the PCV valve itself is broken, such that uncorking the crankcase by removing the dipstick, created a giant vacuum leak.

Plumb it right and put in a new PCV valve, and it'll be fine.

 

awesome thanks, thats a relief, i did notice as soon as i put the dipstick back in the idle picked back up

but after looking at it, it seems i may have had this problem for a while and just didnt notice it

this is my pcv valve right? isnt it supposed to have a hose running from it to the carb?


im just wondering, because this is how it was setup by the PO

one valve cover has a plastic tube running into it with a hose attached from it to the carb, air travels both ways through it

the other valve cover has the pcv valve in it, with nothing attached, air only travels one way

im just trying to make sure it isnt backwards, but to me it seems like it is

excuse me for my ignorance, lol

 

PCV on the driver's side? Air bubbles in the oil can be from several things such as the pick up tube blowing off in the oil pan, broken oil pump shaft, oil level low enough to suck air and cause cavitation.

 

well the oil level is fine, and yes the PCV is on the drivers side valve cover

i did some reading on what pcv actually does, and the pcv configuration seems to be set up right, i took the hose that runs from the carb to the passenger valve cover off of the carb and blew air through it into the valve cover, and air came out of the pcv on the drivers side cover, so it doesnt seem to be clogged, at least not at the top end of the engine, and its not clogged at the carb either

everyone i ask has never heard of such a thing, and i cant find any information on the internet except for a few posts that dont really help much

 

with the motor running, if you remove both hoses from the valve covers, the hose PCV valve is connected to should have vacuum on it.
the hose on the other side should not have any vacuum. it is a vent hose and should be connected to the air filter housing.
it lets filtered air into the crankcase at idle and low throttle conditions. if its hooked up to the carburetor, then its mis-routed.
when there is little to no intake vacuum, the vent hose then acts as a bypass and allows excess blowby to flow into the air filter housing.

with both hoses unhooked from the valve covers and the holes in the valve covers plugged, there should no crankcase vacuum with the motor running.
if there is, then you probably have a leaking intake gasket.

 

thanks for the help and putting up with my ignorance

i did what you said, but as soon as i pull the hose off of the passenger side valve cover the engine bogs out and dies, according to the "emission hose routing" sticker, its suppose to let air in, if all its supposed to do is let in fresh air why is it dying? i dont know whats going on there, this sort of thing makes me think its hooked up backwards or something

and the pcv feels like its sucking air in, i thought it let air out... i dont know

heres a pic of where it hooks into the carb, it looks like its supposed to be this way, but yall probably know better



and where it goes into the base of the carb

 

That looks like the PCV valve in the passenger side. What's in the driver side?

 

the hose on the passenger side valve cover is straight through, i can blow through it both ways, the drivers side has the pcv, but i can feel air sucking in through it, not a lot of air, but it is sucking air

when i took the pcv out i could blow through the bottom of it, but not through the top where a hose is supposed to connect to, so it must be pulling air extremely hard into the passenger valve cover

the engine still runs perfect, doesnt run hot or anything, stays at about 190 once warm, so i can still drive, its just one of those things that bothers me

 

PCV valves operate on vacuum, it should have vacuum on the top side of it provided to it by a vacuum hose that routes to the intake system somewhere(I do not know where for your specific engine, the engine should not be sucking air into the crankcase through the pcv valve, the pcv valve is for venting crankcase pressure caused by blowby, when combustion gases slip by the piston rings, which happens to some extent even if everything is in good order, so basically, when you're looking at the PCV valve as it is installed, the airflow should be coming out of it, not going into it, imo change the valve, its like $3 and quite possibly part of your problem, also, make sure the top of it is connected to intake vacuum. The other valve cover is going to have something a little different, generally its a hose that connects it to the intake system directly, and prevacuum, as it feeds air into the intake, basically its there because there is no vacuum at wot making the pcv valve ineffective at full throttle, so its a secondary thing to do the same thing more or less, but it also has an effect on idle and such....hope all that helps...

 

Also it shouldn't matter which goes on which side, so long as they are hooked up to the right stuff.

 

Your pic shows clearly what's wrong.

As I explained above, the PCV is supposed to draw vapors into the intake, to keep the oil clean. The fitting on the base of the carb that you have hooked up to the pass side VC, should go to the PCV valve which is in the driver's side VC.

THe fitting in the pass side VC should go to an air filter of some sort, usually that extra little one in the side of your main air cleaner assembly, to allow filtered "make-up" air into the crankcase, to replace the METERED amount that the PCV valve takes out.

With yours hooked up like it is, you're putting hard manifold vaccum on the crankcase, without the metering efect of the PCV valve. That's why it has suction in it.

Get you the little filter, put it in your breather, hook it up right, it will behave much better.

 

ah ok, i get what youre saying, ill try that tomorrow and post back, its too cold and dark out right now

thanks!

 

ok, so this is how i set it up, pcv to the carb, so the vapers go into the intake. and the hole in the other valve cover just needs a filter over it. right?

im just making sure

 

That sounds like a better idea. You can go pick up a new PCV though so you don't have the hose sticking up vertically out of the cover.

 

That and its a $3 part that probably hasn't been replaced since the 80s...

 

alright! yeah that fixed it, the car sounds sooo much healthier now too, and i thought it sounded good before

yeah im gonna go ahead and pick up a pcv so the hose isnt hitting the hood, that and a little filter for the passenger cover

thanks to all of you for helpin me out, and for putting up with my ignorance

 

There you go- now you're cookin' with gas!

If you have trouble finding a breather to put in the other valve cover I thought I'd pass along some info you might find helpful....

Stock centerbolt valve covers like you're using take a 1" OD grommet to press into the hole in the valve cover . Most aftermarket valve covers take a 1.25" grommet which means most of the stuff you see at the speed shop won't work at all with those valve covers. So you can't use any old breather or grommet on that valve cover- most of the stuff you will find is too big to fit into those valve covers. The cheap solution is to use a PCV grommet made for those valve covers (almost exactly like the one your PCV valve is currently pressed into but without the "angle" built into it) and then use a K&N breather designed to fit in a 3/4" hole.

Just something to keep in mind for the future in case you need to find a solution.