Catch Can

[3 G Bee]

Why is it that if the crankcase oil in your engine is clean, is that same oil in the catch can so dirty ???

 

[quietpeen]

and you are saying that it is the gas vapor that gunks up the throttle body, not the oil?

 

[3 G Bee]

Yes that is true, lets go deeper into the engine and its functions, why do pistons have oil rings ?

 

[quietpeen]

my guess is to keep oil out of the combustion chamber

 

[3 G Bee]

Just the opposite to lubricate cool the cylinder walls. The oil ring bands on the pistons are actually 3 rings a corrugated oil ring in middle between 2 small band rings that spread the oil around the cylinder evenly. and the oil ring is at the top of the pistons which leaves a film of oil on the cylinder wall as it moved up and down in the chamber.
So since oil is left above the piston coating cooling the cylinder walls each and every stoke why is harmful to have oil re enter the cylinder from the air intake ?

 

[quietpeen]

That is why the catch can caught on imo. People feel feeding that oil and gas vapor back through the intake is a bad thing (especially for keeping the throttle body clean)

 

[3 G Bee]

yes, but the piston does not come up to the top of the cylinder walls, and the oil ring is still further down on the piston. The top of the piston and the top of the cylinder walls need to cool as well.
The gas that is allowed into the cylinder along with the unspent fuel / air and oil vapour mixture is what cools it just before it is ignited again. To prevent the piston from blowing a hole in it from the combustion explosions every 3rd revolution.
So to answer your initial question ? Yes.

To take the logic from the line if Chrysler felt it was necessary they would have put one in makes perfect sense since they designed and put in oil squirters to squirt oil on the lower skirt of the pistons and underside of Piston tops, because they felt that the piston needed additional cooling to prevent premature failure.

 

[quietpeen]

There is also an argument that Chrysler doesn't put one in because people are lazy and won't empty it regularly

 

[3 G Bee]

Do the other fluid systems have warning lights: Oil, Trans fluid, glycol overheat, washer fluid, brake fluid, TPM,
Those cars with a catch can if they allow the can to fill and all that fluid ends up in the intake at one time will quickly realize they have a problem because the engine will shut down and they will have quit a problem now with oil and gas pooled in all cylinders.

 

[quietpeen]

That would definitely suck. Hopefully somebody that makes the effort to install one makes the effort to regularly empty it