Smog oil-filler cap

[ncbugeye]

I read somewhere that the oil-filler cap in smog-equipped 1275cc engined cars is important. It is supposed to regulate the crankcase pressure (or is it actually vacuum?) and let in a prescribed amount of air.

Where is this all leading, you may ask.

When I bought this car last year, the PO told me he had had a small engine fire in the car several years previously and not to worry, he had replaced everything that had been damaged.

Well it actually turns out to be NOT EVERYTHING. I was looking at the oil filler cap today and saw that it was partially melted on top.

Question is, what could the results/symptoms/behaviour be if the filler's pressure regulation function had ceased to work correctly, i.e. it was perhaps either open too wide or partly or completely blocked? I know this is a leading question, because I am going to compare the replies I get with my actual symptoms.

This is not a test. All opinions will be welcomed.

 

[bugimike]

I suppose it depends on how melted, or how it melted as to what it may or may not be doing! I had a melted cap that I ran for quite some time, but did not really notice any difference when I replaced it (which I did for cosmetic reasons!). /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Billm]

Remember that the reason that the cap lets in air is to purge the flammable gases in the crankcase and keep them below an explosive mixture. If no air is comming in it is possible (but highly unlikely) to get a crankcase explosion. Or at least that was what the official explanation was.
Too much air in and you get oil leaks(not enough vacuum), not enough air and you could get an explosion.
Bill

 

[jhorton3]

Do the caps on the aftermarket valve covers allow enough air in? I've been thinking about getting an allow cover for my engine.