I have a 2000 mazda proto. when I take the oil filler cap off a lot of air come out. sounds like an air compressor help!!!!!

 

That's blow by!
1) faulty PCV valve, change it (Mazda never does)
2) if that doesn't work, get a compression test for your worn piston rings, leak down test

 

Hmmmm, don't be so quick to condemn the engine. Air pressure coming out of the oil cap is not uncommon. If it has some symptoms of blowby then possibly, but if you have no symptoms like cronic oil leaks/consumption/plug fouling/etc then i doubt you have a problem. If you replace the PCV then get one from a dealer. They are not by any stretch of the imagination all created equal. If i overhauled every engine that had what you describe i would be in jail.

 

thanks to all for answers to my problem with my mazda. replaced my pvc valve ,air filter and hoses it doesn't use oil or leak , no fouling spark plugs so I guest everything is good also no lost of performance thanks again for the help p.s I almost forgot compression is at 174 lbs and according to manual 185 is the specs

 

Its natural for air to escape thru the oil filler cap hole if the engine isrunning . The pumping of the pistons will push air around inside your engine.

 

so is174 lbs compression good ? the engine is a 1.6 L

 

Compression sounds fine. A good decarbon never hurts. Techron is the best for that. Add it to the gas and drive while it cleans the carbon from your valves.

 

Very Good!