Hello all, I did a search but couldn't find specific blow by info. 04 outlander awd 2.4liter 52000 miles, purchased new and impeccably maintained with regular oil changes and babied driving. I'm quite disturbed at how much blow by is present. vehicle running hot or cold, I remove the oil filler cap and there seems to be a LOT of air coming out. I pull the hose after the pcv valve and there's air coming out of there too, so pcv valve is at least functional. there is no way the pcv valve has anything to do with just how much air is coming out of this engine crankcase. I have not done a compression test, that is next. Mitsubishi service department doesn't know without me bringing it in (what else is new). the vehicle runs great, it does not burn oil, I don't have any discolored exhaust and engine runs smooth. I was wondering if there is some kind of pump specifically forcing air into the crankcase to create that kind of air pressure for some reason. any input appreciated, I will repost when I do the compression test but I do not expect anything amiss there as it runs great. would anybody be so kind as to check their outlander for blowby as well? thanks.

 

Are you sure it's not just pushing and pulling air back in. Pistons moving displace air and cause a pressure/vacuum cycle as they move. Quite normal. If it's running well, no issues.

 

no, it's all air coming out, not back and forth. I see what you're saying about air going in and out, I've felt that a little bit on other cars, very little I should say almost not noticable. Not this outlander though. this is all out. I think blowby is a very important thing to know about as it is a marker for how worn or how poorly put together an engine is. Unless it is intentional....which I can't for the life of me figure out why. has anyone checked theirs? very simple, with engine running, remove oil cap, no you won't get sprayed with oil, although mine does sputter very small and few drops here and there. would love to hear if you have blowby or not.

 

Just did a compression test 2 days ago. I pulled all the spark plugs out, disconnected the throttle body connector and held the throttle body wide open while a helper cranked the engine, I was happy to note that cylinders 1,2,3 have 210psi and cyl 4 has 212psi. However, after I put everything back together I realized that compression test was done with the oil filler cap installed. I think I'll try it again with the oil filler cap removed and see if there's a difference.

 

You could have an oil analysis done. They can tell if there is fuel in the oil, which would be the same as blown rings? $30 bucks and a few weeks to get the results after your next oil change. How have your change intervals been?

 

The compression test will not change with the oil cap on or off. The numbers look perfect, so you're fine.

Some blow by is normal, and sometimes much greater when you have a bigger engine or one with more cylinders. There's going to be more gasses needing to escape from the same size hole, so it'll be a decent amount. I think you're just being overly cautious, and this is nothing to worry about. As long as you've done your part as a good owner, then I wouldn't worry about it.

You could if you just want peace of mind, get an oil analysis from someone like blackstone. They'll include fuel content, etc.

 

yeah I was happy with the compression results, but afterwards I got to thinking. When I remove the oil filler cap with the engine idling, I kid you not, I get air coming out with the same force as if you held your hand a few inches away from a tail pipe. because of this, I think the compression test may be invalid with a closed oil filler cap. if there is increased pressure in the crankcase from blow by, that would also register on the compression gauge since it's all in a closed system, you could think of the crankcase as one big tank of compressed air. I would expect the compression to drop without the cap in place. It may be a small difference, but I will be sure to test again without the oil filler cap as I need to change the spark plugs anyway. that darn air is coming from someplace.....as far as oil change intervals, I change with synthetic 5w30 every 5k miles or so. never need to add oil thank goodness. That is my biggest peev in any engine.

 

Checking the compression again, for your own peace of mind, is a useful thing to do if you are removing the spark plugs anyway. I strongly suspect you'll get the same results. Things like this can drive you nuts, but by the sound of everything you describe, the engine is running like a top. This may be some inherent characteristic of this engine and you are one of the few that ever experienced it by removing the oil cap while running the engine. Let us know the cap-off compression results.

 

thanks, I will post the compression readings with/without oil cap as soon as I get the plugs, which need to be ordered. I was hoping someone would check their blow by status on a 2004 (if possible) outlander 2.4 liter. If someone would say they do NOT get blowby with this engine, I'll know something is up, but if everyone says they too get blowby, I'll know it's inherent in all of these engines.