High compression in one cylinder, smoke in exhaust

The G-Series Tuning Forum is the place to discuss G35/G37 performance modifications and mechanical repair.
jusroln
Posts: 4
Joined: Tue Sep 18, 2018 8:20 pm
Car: 2007 G35x

Post

So, my engine threw a rod and bit the dust. I replaced it with a used engine that sounds good but is blowing smoke. I get a big puff at start up and a lot of smoke when accelerating. I dropped the exhaust and determied it was coming form the drivers side. I think the head gasket is good (no oil/coolant mixing, block test didn't show any exhaust gases,...). Did a compression test. All cylinders are around 160psi on my gauge but cylinder 6 is at 185 psi. Tested each cylinder 3 times. Cylinder 6 builds to 185 and then it leaks down rather quickly. When I pulled the tester out it had oil all over it and around it. So, does this sound like valve seals or valve stuck open or does it sound more like a ring issue. Just need to decide if I'm pulling the motor and returning it or if I could get by with replacing some valve seals.


jusroln
Posts: 4
Joined: Tue Sep 18, 2018 8:20 pm
Car: 2007 G35x

Post

Forget to give vehicle info. 2007 G35X auto.

User avatar
telcoman
Posts: 5763
Joined: Sat Jul 08, 2006 11:30 am
Car: Tesla 2022 Model Y, 2016 Q70 Bye 2012 G37S 6 MT w Nav 94444 mi bye 2006 Infiniti G35 Sedan 6 MT @171796 mi.
Location: Central NJ

Post

Return it

Telcoman

User avatar
audtatious
Moderator
Posts: 37008
Joined: Sun Oct 27, 2002 5:31 pm
Car: 2017 Q60 Red Sport. Gone: 2014 Q50s, 2008 G37s coupe, 2007 G35s Sedan, 2002 Maxima SE, 2000 Villager Estate (Quest), 1998 Quest, 1996 Sentra GXE
Location: Stalking You
Contact:

Post

Honestly it can probably be either. You can try using a scope to inspect the piston and any scoring or issues going on. Otherwise you would have to pull the head for further investigation. If the ring/piston is fine then a head job should fix it up.


Return to “G35 and G37 Engine, Drivetrain & Tuning”