I have 53k on 2021 mazda Cx5. Getting blowby. What could be causing this. I let dealer do all my oil changes. I guess this wouldnt be covered under 60k warranty. Also wondering what might cause this car runs fine and idles fine. Not smoking. Checked pcv valve like some video said seems to be ok , Any idea no codes or engine light. Does it possibly need walnut blasting. just heard about this 10k miles ago. I put put in 5w 20 oil would that cause it. hardly think so. I am thinking carboned up intake valve unless anyone can think of something else

 

Are you saying when you remove the oil cap on the valve cover.

 

You really are not giving complete information….

 

Often claimed on many platforms but we will stay specific to Mazda Skyactiv engine is the false impression of blowby when the engine is running and owner remove the oil cap on the valve cover. The pressure creating what in some engines from Say pre 1990s would be concerning. But on newer engines specifically Mazda Skyactiv engines that pressure is actually a good sign . This is also how the complete Positive crankcase ventilation system (PCV) works on thease engines.
So normal to the responding to the 1st post.

As for carbon at those low miles on the engine with no other indicators like reading spark plugs (properly) unexplainable oil consumption, engine check light , exhaust smells like rotten eggs, and several others the newer Mazda Skyactiv DI engine don’t have the major issues as earlier DI engines for carbon in the combustion chambers.

Those really concerned can get the intake and combustion chamber scoped. But unless there are signs it’s unlikely to have enough if any to be concerned before acquiring over 150k miles or more.

 

thanks i was freaking out here. Just changed plugs here recently they looked great. No smoke from exhaust. Starts fine just a little hesitant sometimes when cranking. Replaced plugs with autolite instead of NGK. I am now 72. taken care of my cars my whole life. Only go to garage during warrant period. About 6 months ago i found out about these direct inject engines and how they carbon up. Was planning on doing the walnut blasting. Hoopefully i dont have to do that now..

 

Ypu should only read info on the internet first about what a service concern is and then how or if it could be related or encoded with your Mazda Skyactiv engine or Skyactiv engines manufacture date 2016 to present .

Besides more DIY and even individuals that are trained tend to do a poor job at that mess producing walnut blasting . 😂

 

i have read and watched videos about walnut blasting, Also i have confidence in my ability. i have changed out motors transmissions and rear ends thru the years. i also troubleshoot the electronics. I have owned over 30 cars. I have never taken car to dealer for repairs once out of warranty. I have a garage full of tools only used once. Although i have to admit the newer cars are more challenging. Biggest problem i have faced is dealers forcing you to buy parts from them that and my age. However of all the cars i have owed this is first Mazda. Thanks for your for your help . Really appreciated.

 

You may want to test your battery. Assuming you are still on the original? If so, at 4yrs you could need a new one. I changed the battery on my '21 earlier this year.

 

wow …^^

This is a good catch at reading the first post and GREAT advise recommendation.

It’s called a load test. Your battery is likely to fail and even if you are not having starting issues batteries in a state of not passing a load test will just one morning or when you stop to run in a store to buy groceries, when you go to start the engine ….it won’t.

 

Yep definitely worth looking into. One of our 2021s with 70k miles needed a new battery after failing a test with only 211 CCAs. I'm sure spending 2 years in new england and 2 years in Florida didn't help that battery lmao. I'm keeping a close eye on my 2021 CX-5 now since the battery works fine, but can be hitting the point of needing replacement soon.