Bad valve seals = Bad O2 Sensor - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

S14mc · 06-23-2010, 11:07 AM

The other day I noticed oil leaking from the exhaust manifold port (cylinder #1). It looks like its coming from a worn out/bad exhaust valve seal. Ran a compression and leakdown test, 147-150 across the board and 4%,7%, 7% and 25% on cylinder #1. Spark plugs confirm no oil being burnt in combustion chamber.

My question is this - Will it be okay to drive with my motor (cylinder #1) in this condition? Is the valve seal leak affecting my O2 Sensor erroneously changing the lean or rich reading? Just a guess, but it feels as though this may be the reason why my motor doesn't pull as hard as it used to. When my car is warmed up and goes closed loop it feels my car loses 50% of it power.

Any input would be great!

Thx
Jon

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

06-23-2010, 11:07 AM	#1
S14mc Leaky Injector Join Date: Dec 2002 Posts: 136 Trader Rating: (0) Feedback Score: 0 reviews	Bad valve seals = Bad O2 Sensor The other day I noticed oil leaking from the exhaust manifold port (cylinder #1). It looks like its coming from a worn out/bad exhaust valve seal. Ran a compression and leakdown test, 147-150 across the board and 4%,7%, 7% and 25% on cylinder #1. Spark plugs confirm no oil being burnt in combustion chamber. My question is this - Will it be okay to drive with my motor (cylinder #1) in this condition? Is the valve seal leak affecting my O2 Sensor erroneously changing the lean or rich reading? Just a guess, but it feels as though this may be the reason why my motor doesn't pull as hard as it used to. When my car is warmed up and goes closed loop it feels my car loses 50% of it power. Any input would be great! Thx Jon