I was wondering if anyone had any good info I could read that would help me learn exactly how the crank vent system works on an 84S. I wouldnt care otherwise but I have a puddle of oil in my lower throttle body housing and intake runners are saturated. Ive noticed im also consuming oil. Approx 1 quart in 100 miles. The oil in the engine is clean. Nothing in coolant and no coolant in oil. Ive heard of people having oil in intake, but this is kinda rediculous. Thanks, Bill.

 

Not very well. LOL

On the 84, there is a hose that goes from the throttle body to the oil fill/catch can. Directly below this can is a giant hole that is directly above the counterweight on the front of the crank. It is theorized that it will throw oil up into the catch can during high rpm or severe turns coupled with high rpm. This oil can then get sucked into your intake via the hose going to the throttle body. Even during normal operation there is oil vapor that is sucked into the intake via this hose and over time it can accumulate as you are seeing.

You mentioned oil consumption. Please give us more details about how much oil you are using and how often. Do you ever see any blueish smoke from the exhaust during acceleration?

 

That is a lot of oil consumption. Ditto, more info?

928 Specialists has a diagram showing before / after vent path using Sharkvent product that might be a start for you.

Our 84 USA auto and manual cars consume little oil. Did something change recently with your car?


Is yours automatic or manual?

 

I havent really been driving this car that often lately, only for test drives. I have been having a problem with a sort of misfire under load for months now. I am now entertaing the thought of a major vacuum leak. removed my intake to do some problem hunting and noticed the runner gaskets soaked in oil, walls of intake ports on heads soaked and a puddle in bottom of throttle body. Each time around 100 miles of test drives are done, Ive noticed the oil about a quart low. The other item I found, at the bottom of the oil fill can, where the pipe that goes to the oil pan connects, there is a ring of sealant which fell off. looks like some type of factory cement gooped around the connection point. I will post a picture later. Right now, I want to go through anything that can cause a vacuum leak, then get back to the original problem if it doesent just go away.

 

Is it manual or auto?
Do you need the vac circuit diagrams?
Manual is different with incorporation of vac limiter module that affects bypass air and richness.

 

The car is an automatic. It wasnt consuming oil at all before it started running rough under load. Here are some pictures of what Im looking at. All these parts were clean a couple months ago when I refreshed my intake to chase problem. Also, before the car ran rough I was getting 19 inches of vacuum at the manifold and now am getting 17. Not sure if that is signifigant.

 

Can you pull the spark plugs and post a photo? You might have a cylinder that has gone bad causing oil consumption, blowby and a misfire under load.

 

Here are the plugs, they have around 150 miles on them, One picture is all the plugs rotated. Compression test was 150 per cylinder. All cylinders were nicely equal. Flow test on injectors, all were equal pressure drop. Fuel pressure and flow rate was according to book. Air flow meter is new. etc.

 

Pictures did not go through. Lets try this again.

 

Fuel reg / dampers hold vac?

Vac advance hooked up?

Do you know the correct routing?

I have a 84 auto here in the driveway for the next 2 or 3 hours, then it leaves on a mission, if you need me to compare something.
BTW that amount of oil in picture is very small.

 

??

 

I have good vac advance, timing was set as book said 20 deg btdc vac removed, checked actuator with vac pump, it holds and does its job, I even tried another distributor. regulators and damper were replaced as a problem chaser/pm. Its funny now that I think about it, when I push on the afm door while running, it starts increasing idle then starts running rough, when I release it, it almost stalls but brings back to a stable idle. This car idles very smooth as it was before removing the intake once again. it is only under a load it acts up. If the oil amount is normal, I will begin checking elsewhere. I was looking for something on the lines of a crack in the intake or some type of item that would create a severe vac leak. I replaced all the runner boots, I replaced the throttle body boot. I do have a two inch loss of vac since the problem. I tried pinching off the brake booster with no change other than having to stand on the pedal to stop. Fuel pump and filter is new. If you could snap a picture showing the passenger side front of the engine bay so I could look at the lines for oil can, ac switch evap system etc. Also, I have a noise that sounds like an air leak which goes away when I pinch off the line coming from the air venturi at the top of the manifold to the left front of the throttle body. If I pinch off the line on the other side of that connection which goes to ac switch/evap system, the noise is still there. So I tried replacing throttle body o ring with no change. I checked the Wot switch and the idle switch and they both read properly, also checked them at the plug to the L jet. I tried a different Ljet and still had the same problem. I think, after I put the manifold back together, I will post a video of the car in action from exhaust note to driving it down the road. I do have a major power loss after the problem started.

 

Just a thought. Seems like crankcase is under pressure forcing oil up into the oil separator. Is this car stock? If so, is the air cleaner box full of oil too?

A simple test for positive pressure would be, while the engine is running and has been idling for a couple of minutes, to slowly untighten the oil separator cap. If you can hear a hissing sound as the you do this, you are releasing pressure from the crankcase.

 

Car is completly stock. I do hear a hissing sound when I open the oil filler cap. I just checked that a few days ago. didnt know if it was normal or not.

 

I have had a mist of oil in the airbox, very slight. I always clean it out so it never had a chance to build up, air cleaner is new and doesent show signs of being wet with oil.