Checked my oil today, saw it needed a little bit added but when I removed the filler cap, I saw this. Is this the infamous lung butter? Should I be worried? I haven't seen this in my car before, and I just changed the oil about 100 miles ago. Running a 13b with Holley carb.

 

Yep, that's the stuff. Caused by water vapor trapped in the crankcase - - not necessarily coolant, even atmospheric water can cause it.

You need better crankcase venting.

 

On normal motors, I always found that it was a sign of short running as well... can that be the case with these too? Definitely needs ventilation, but the oil should be allowed to get hot enough to burn off the moisture/condensation too...

 

yep that is also true

 

I get that too. As long as I'm changing the oil on a regular basis I don't consider it to be a major concern.



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Kentetsu, how often changing oil is a regular basis? The oil filler cap and oil filled has the lung butter. VERY SCARY!!

 

This was covered in a recent thread, scrolling down not too far will get it. You need to vent the oil filler neck in some fashion. I use a pcv valve, others don't, some drill a hole in the cap and install a 90 degree fitting.

 

So I should reinstall the old original cracked oil filler cap??

And how often should I change my oil and filter?

On my '68 vw beetle, I changed it according to chilton's manual, I think every 6 months or 2000 miles. There was metal in the oil SURPRISE! After rebuilding the engine, the oil got changed every other month. And vw bugs were supposed to be bullet proof.

 

You can run a tube from the oil neck to the port on the intake manifold just below the idle mix screw. In the tube insert a pcv valve. The vacuum will pull the vapor from the neck. As stated above, running the engine sufficiently to heat the oil and release the vapor is key.
I change oil seasonally, as my car is driven only 5 or 6 thousand miles/year.

 

i had lung butter, capped off the small pipe on the side of the filler neck and drilled a hole in my filler cap. that's all. It's gone, no messes, no complaints. The only reason I capped off the port on the filler neck (not center iron) was to keep oil from coming out of it when filling engine.

 

+1

Except if you're running a Holley carb, where youll have to either tap the manifold for a "PCV" port or tee into your brake booster line for a vac source, as there are no other ports on the aftermarket 4150 intake manifolds.

 

I've recently developed this problem myself. I did notice a huge crack in my oil cap. I wonder if that's the problem because I never had it before?

 

My theory is that the crack develops due to the problem. Every 12a or 13b Ive ever seen with a cracked filler cap had lung better problems. My solution was to use a breather on the filler neck port, and run fuel line from the intermediate iron to the RB intake filter canister. You may periodically need to blow through the hose to clear some funk out. No butter in the neck though.

I have a hunch the vapor is from either the coolant seals leaking, or premix/gas diluting the oil in some cases.

 

The sum of all the advice is that the the oil filler tube needs to be vented either to the vacuum, or openned to the atmosphere?

But it there already is a 1/4" id tube going to the rat's nest.

Am I missing something?

 

I don't understand all the workings of the rats nest, but if it's not venting, something's blocked.

 

I had an FC with the stock everything installed that was making lung butter. We replaced the purge valve just recently and it didnt fix the problem... stripping the emissions and going to the PCV valve eliminated it, so Id question just how good the stock ventilation works after about 25 years..

You should have a set-up that allows the nipple on the center iron below the filler tube vent to fresh air, (or the factory charcoal canister) and the one on the filler tube needs to be connected to a source of vacuum, preferably with a PCV valve inline to minimize vac loss. My engine (12A) tends to use the lower nipple almost as intake to the crankcase, and the tube on the filler neck as exhaust... if that makes sense.

If the "exhaust" gets stuck in the filler neck, it makes that gross snot that I always find in RX-8 filler tubes, known as "lung butter".

 

LUNG BUTTER DISSAPPEARED !!! Changed my oil last night.

So what happened? I haven't changed anything. Usually when something like this fixes itself, it is a precursor that something awful is about to happen.