Oil consumption, high compression cylinder 2.

[MSP2003.5_Nick]

04 Mazda 3 2.3L I got 380,000km on it and have been feeding it oil for a year. Decided to finally dip into it, pulled my plugs and found cylinder 2 was soaked in oil both in the cylinder and around the plug itself where the coil pack boot connects to it. Did a compression test and all cylinders were 180psi with exception to cylinder 2 which had 220. Looking down the spark plug hole I could visibly see the oil pooled on top of the piston.

I started with a valve cover gasket cause I thought it could be leaking on top of the plug but that wasn't it. My question is how do I tell what is bad, valve seals, piston rings or head gasket? Or should I just say **** it and pull the motor for a full rebuild of everything?

Car is my wife's daily so I don't want to have it off the road too long if possible. I already pulled the motor last year to replace rod bearings, should have just done the whole job then but I didn't make the connection that oil consumption was the cause of the rod bearing failure until after. Also I've previously changed the PVC with no changes.

Anyone have this problem?

 

[BRIAN_MP5T]

The only way to get oil on top of a spark plug is the valve cover gasket. (or it leaked downs some other way..)

Personally, I would keep feeding it oil till it blows up.. That engine owes you nothing... LOL

The body of the car is probably just as toasted.

Be vigilant in checking the oil level. Unless its burning more than 1L per 1000 Km I say run it..

Save up for a replacement, you wont get any less for the car weather it's **** busted or not. a 04 Mazda anything is basically scrap to a dealer.

 

[MSP2003.5_Nick]

Yeah you're right the body is rusted all to s*** lol. The wife really likes the car, but I'm at the point where I gotta make the decision to paint the car and fix motor, or just drive it into the ground haha. Maybe best bet is to find another one in good shape and use this one for parts or reshell.

 

[Donutz]

This issue is not unheard of in this car. Most people I've known who had this problem sold their cars before something really serious happened. I don't know the exact problem but I'd guess it was the rings, but that is just a guess. Try running thicker oil to slow down consumption; German Castrol is what my friends have used with a fair amount of success.

 

[flatlander937]

The oil is what is causing your compression to be higher... you can do a dry or a wet compression test.

Typically you do a dry compression test first across all cylinders, you find one is low. So it's either leaking from the piston rings or the valves. You pour a bit of oil in the cylinder to wet the piston rings and do another compression test(now considered a wet test)... if the compression goes up considerably, it's bad piston rings... if it had little to no effect, it's the valves.

Dumb question... but when you did the valve cover gasket, you replaced the individual spark plug hole gaskets on the valve cover right(not just the outer gasket)?


Nothing else useful to add... but thought I'd let you know that the oil is very likely affecting the compression reading. You can try doing a wet compression test on the other 3 cylinders just to see how all 4 compare to each other.


I would double check the work from the valve cover gasket install as there isn't really any other way for THAT much oil to get in. What I find more surprising is that it's not burning off nearly immediately... and you have a pool of it on the piston enough to see.

As others have said you've got plenty of miles on it to retire it having gotten your money's worth.

 

[MSP2003.5_Nick]

I did the valve cover gasket after I seen the oil all over spark plugs. Oil no longer sits on top of the plug but if you pull out a plug it is covered from the oil in cylinder. So im definey leaking oil internally into the cylinder. I've decided to pull the head and look at stuff sometime soon, then based on what I find ill decide if its worth fixing or not.