Engine Blow-By
 

Hi all, am new here, looking for some advice assistance with my 2005 Mazda 3, Sp23.
Engine is a 2.3L petrol, it runs and performs fine as far as i can tell.
When the engine is idling and the oil filler cap is removed, it seems to have excessive crankcase pressure as it pushes a fair amount of air out. i'm unsure as to what the problem is. If anyone could be of some help or assistance, it would be very much appreciated. thanks

Hey there,

I thought I would offer some assistance. I only know this because my dad is a mechanic. I went to almost buy a Mazda 3, but brought it in to my dads shop to do a mechanical and apparently it had a lot of engine blow by. It had only 100,000km on it and they said it wasn't good for the engine in general, especially at low km's. The car will lose performance and the blow by is caused by running your engine too hard or not keeping up with oil changes. I ended up not buying the car because it can place wear and tear on the engine. The piston rings would probably need to be replaced but the damage to the engine cannot be.

Anyways I hope this helps you a little.

I don't think that's particularly a problem, I remember pulling my oil cap off to see the camshaft moving and I got sprayed with oil splatter. So there's some pressure or movememt there & I wouldn't worry too much about it.

Pcv valve
 

If you replace the pcv valve (which is likely plugged up) it should allow some pressure to circulate out a bit better.... maybe won’t solve your problem but should help and for sure doesn’t hurt at around $7