exhaust from oil filler pipe...WTF?! help plz

[teasdam]

My car has been stumbling a bit lately, but nothing serious...one of the plugs tends to foul up and just needs replacing. The other day I swapped in a new plug, but I managed to crossthread the new plug and mess up the threads. I bought one of those helicoil type kits and installed a thread insert...no problems. So I go to start up the car and try out my new setup today and it wouldn't start for a long time. For some reason, it was acting like it was flooded and disconnecting the injector would clear things up and the engine would run momentarily. It took a while for that to go away, but it did...don't know if this has anything to do with the problem.

 

Now, the car will start and run pretty well..about as well as when I first started this ordeal. The problem now is that the oil filler tube puffs smoke like it's an exhaust pipe or something. The "smoke" goes away at higher rpm, but it puffs like a coal train at idle (with white smoke). I also noticed that pressing the palm of my hand against the filler tube opening (to block the exhaust) causes the engine rpm to drop. I'm also getting several codes...off the top of my head I think they were 12, 31, 32, 33, 51, and 61....to name a few.

 

The "smoke" coming from the filler tube is not blue like burning oil, or sweet like burning coolant, also no signs of coolant in the oil...so I assume, for whatever reason, I'm suddenly getting an extraordinary amount of exhaust blow-by on one of the cylinders.

 

Anyone have any idea what the hell happened? I just rebuilt the engine a few months ago and the only problem so far has been a minor oil-burning in one cylinder which the machinist warned me might develop..but he never hinted something like this might happen. Is this a head gasket problem or bad rings or what? Compression test the next step? I can't imagine this much smoke is from a plugged PCV or something simple.

[Turbone]

Was the PCV a OEM part? Aftermarket ones have been known to be junk quickly. It does sound like its blowby tho. Was it a complete rebuild? Maybe things are still trying to seat in the engine.

[Roundeye]

I wish I could give you some good news, but.........

 

Broken ring(s), incorrect ring(s), improperly installed ring(s) or a head gasket blown in the right spot, or worst of all...a cracked head and or block (least likely) would be suspect . If it were an older engine, I would even suspect broken/cracked piston or hole burned in piston. A ton of blowby is NOT normal on a low-time engine. If it was rebuilt months ago, the rings should have long-since been seated. (given normal usage since then).

 

A simple compression test will give you an idea, but I would do a differential compression test. This applies air to the cyliders and you can then see how much of it is being held. You can then listen through your oil fill as each cylinder is tested to see which one(s) is defective. The one that keeps fouling the plug is where to start looking.

[subiemech85]

change the oil to John Deere Break in oil.

 

if you use too good of oil, it does not have the correct friction properties to allow the componets to set

 

and change the drain plug gasket and oil filter

[teasdam]

it was a complete rebuild last March. What the deal was, one of the cylinders was scored kinda bad. The machinist recommended boring it out and getting oversize pistons but I didn't want to drop that kind of money. He said I could expect to burn a little oil but that was OK with me.

 

As far as I can tell, this problem developed after tapping out the plug hole for the thread insert. Could some shavings have dropped into the cylinder and thrashed the rings? I tried to minimize this possibility and sucked everything up with a vacuum hose..but still, just weird how this started right after doing this.

 

I ran some of that John Deere break-in oil when I first started driving and things have been fine up till now, so things should be well set.

 

For this compressions test, are you saying get a fitting so that I can apply air pressure through the plug hole and listen for air escaping through the filler tube? Is there a way to tell if it's a head gasket vs. rings?

[Roundeye]

For this compressions test, are you saying get a fitting so that I can apply air pressure through the plug hole and listen for air escaping through the filler tube? Is there a way to tell if it's a head gasket vs. rings?

First part of your question: Yes. Second part: No (unfortunately) not without disassembly.

 

 

If doing a differential compression test, a special manifold is used to apply pressure to a cylinder and another gage is used to see how much is actually held by the cylinder. On aircraft piston engines, we usually use 80 psi. That means 80 psi is avail. to the cylinder, but it may only hold, say, 70 (a good number). mid 60's and lower = time to start looking for trouble.

 

On a car,this test must be done with the cylinder locked on top dead center. On a plane, one can turn the prop to achieve best reading, we don't have that luxury on a car engine.

 

If you are simply looking for the source of a leak, you can use a simple single gage regulator: Turn the engine over by hand until the cylinder is at top dead center on compression stroke. Apply a small amount of pressure to the cylinder and listen to the oil fill tube for hissing (bad rings, piston, warpage or crack in head and or block or bad head gasket), look for bubbles in radiator (bad head gasket, warpage or crack in head and or block), also listen through the intake for hissing (defective intake valve or seat) then listen through exhaust pipe (defective exhaust valve or seat) I just did this to one of my '85 XTs using 25psi to find the cause of low compression in one of my cylinders.

 

NOTE: the engine MUST be at exactly top dead center on the compression stroke to do this test. Otherwise the engine will rotate when pressure is applied. The engine could rotate at any time during this test if it is not locked down somehow. Remain clear of any belts and pulleys during this test!