oil in air cleaner housing

BarryK · 05-03-06, 03:00 PM

my '65 L76 has always had a bit of an issue with blowing oil up the ventilation tube into the air cleaner housing.
I know it's not the oil from the oiled foam air cleaner element itself as over the winter I swapped that out to a standard paper filter.
It's not a LOT of oil but definitely some blowing up into there.

In addition, I go thru approx a quart of oil every 500-800 miles. Hard to say the milage more closely as my odometer doesn't work. The amount of oil in the air cleaner housing is nowhere as much as the motor seems to be go thru though.

I do NOT see puffs or clouds of smoke (of any color) when starting the car or when she is running.

would these two issues be related or more of two seperate issues to deal with?
Could these issues be cause by the rings, the valves, the valve seals, or what, and how do I go about diagnosing the problem to see where the problem is?

4WDVETTE · 05-03-06, 03:53 PM

First, I would check for leaks. Sometimes the rear main seal can be the culprit - leaking when driving. If no leaks, it must be something with combustion. I had heard somewhere if your engine burns 1 drop of oil each revolution, you would be out of oil within 1,000 miles. Don't know if that is true or not but it kind of makes sense when you think about the kinds of RPM's the engine spins.

Steve

BarryK · 05-03-06, 04:08 PM

Steve

not a leak anywhere and that's pretty easy for me to check since I went through that whole engine clean-up in the winter including repainting the block. Any leaks anywhere would be very easy to see.
There is no evidence of leaks, drips, or anything anywhere on the block, bellhousing or tranny so even if it was from somewhere on the block and blowing back as I was driving I would expect to see SOME residue on the bellhousing or tranny but all three are clean and spotless plus not so much as a SINGLE drip under the car.

I figure it has to be burning the oil somehow but I would have expected to see some evidence of that thru the exhaust from smoke or something wouldn't I?

motorman · 05-03-06, 04:40 PM

Quote:

Originally Posted by BarryK

my '65 L76 has always had a bit of an issue with blowing oil up the ventilation tube into the air cleaner housing.
I know it's not the oil from the oiled foam air cleaner element itself as over the winter I swapped that out to a standard paper filter.
It's not a LOT of oil but definitely some blowing up into there.

In addition, I go thru approx a quart of oil every 500-800 miles. Hard to say the milage more closely as my odometer doesn't work. The amount of oil in the air cleaner housing is nowhere as much as the motor seems to be go thru though.

I do NOT see puffs or clouds of smoke (of any color) when starting the car or when she is running.

would these two issues be related or more of two seperate issues to deal with?
Could these issues be cause by the rings, the valves, the valve seals, or what, and how do I go about diagnosing the problem to see where the problem is?

check to see if the PCV system is creating a vacuum in the crank case. if not check to find out why. the seal on the dip stick going bad is one source of the problem of no vacuum in the crankcase.

I'mAVettehead · 05-03-06, 04:43 PM

Leave it alone and stop worrying.

BarryK · 05-03-06, 04:46 PM

Quote:

Originally Posted by motorman

check to see if the PCV system is creating a vacuum in the crank case. if not check to find out why. the seal on the dip stick going bad is one source of the problem of no vacuum in the crankcase.

motorman
how would I check for a vacuum thru the ventilation system?

on my '65 there is a rubber hose from the oil fill tube to a 90* fitting on the carb. that fitting is the closest there was to a PCV valve in '65. Than there is the vent tube at the back of the block to the air cleaner housing.
What's the best way to check vacuum on that system?

paul67 · 05-03-06, 08:06 PM

Barry,
A little story related to my former 1979. Great car for many years but started to suck oil about three years ago. About one quart per 500 miles. Went through the usually compression diagnosis and the like. All was well. We pulled the valve covers off and the valve stem seals were toast, I mean they were literally burnt. They came off in chipped pieces. We installed Crane seals. That car does not use oil now.

BarryK · 05-03-06, 08:34 PM

gee Paul
was that meant to make me feel BETTER than perhaps my valve stem seals are toast?

Mike McKown · 05-03-06, 08:59 PM

Quote:

Originally Posted by BarryK

motorman
how would I check for a vacuum thru the ventilation system?

on my '65 there is a rubber hose from the oil fill tube to a 90* fitting on the carb. that fitting is the closest there was to a PCV valve in '65. Than there is the vent tube at the back of the block to the air cleaner housing.
What's the best way to check vacuum on that system?

I don't know the best way to check your car or even the RIGHT WAY. I think there is a written procedure in the shop manual but I don't have one handy. One way to check it though is to take your oil fill cap off and lay a sheet of soft paper on the fill pipe opening. With the engine idling, it should try to suck the paper in the fill tube and the longer you wait, the harder it should pull, to a point. If you rev the engine a little and you see a large discharge of pressure coming out of the fill pipe, you have a blowby problem(rings). If you see a discharge of pressure coming out at idle that tries to blow the paper off the fill pipe, you either have a blowby problem or no vacuum on your crankcase. The vacuum source is the hose you mentioned running from the fill pipe to the carb. If you have no pcv on your fill pipe like a '66 then the fitting on the carb the hose attaches to should have a very small restrictor or bleed in it. It could be stopped up. Run a small wire in it to check.

Your engine is set up to draw fumes and blowby out of the crankcase and into the carb. The fresh air to replace it comes from the air cleaner. So, if the vacuum of the carb drawing on the crankcase is overcome by blowby, the result will be the pressure blowing oil condensation the wrong way, through the oil separator in the lifter valley and up into the air cleaner.

Hope you're not confused.

gmjunkie · 05-03-06, 09:05 PM

Quote:

Originally Posted by BarryK

gee Paul
was that meant to make me feel BETTER than perhaps my valve stem seals are toast?

Aw Barry,Valve seals aren't bad!! Another $30. in tool's and you'll be set!! 2 1/2 or 3 hr. that one is purdy easy!! I've got confidence in you, You'll get it!! As far as the oil in the tube,Check pcv and pcv hose and all vacuum fittings!! Make sure the inside of pcv hose is not decaying coming apart!! Some times under a load the inside can collapse and cut vacuum to pcv, Thus cutting down crankcase ventilation!!!!

BarryK · 05-03-06, 09:15 PM

Mike
thanks, that (mostly) makes sense. I'll try that test tomorrow.

Junk
sure, easy for you to say....... but $30 in tools here, $50 there, $75 another time, etc and it all adds up
Well, it's still cheaper to buy the tools and learn it myself than to pay a mechanic especially based on past experience when i'd pay a mechanic and I'd STILL have the same problem or even worse, a larger problem when I'd get the car back.

paul67 · 05-07-06, 08:44 PM

Barry,
A valve seal job can be done in a $30 parts/$20 pizza afternoon. You may have to add some beers. Get some friends together. We did this on my 1979 years ago and the oil consumption went from a quart per 200 miles to a quart per 2,000 miles.