[Impala79]

Hello, new member. I have a 3800 series 2 that was giving me a code for misfire on cylinder #3. I ruled out spark and fuel. Also noted that misfire was much worse under load (engine pulling higher vacuum). When I pulled the UIM i found pools of oil in the bolt recesses near #2 and # 3 (see photos). The underside and interior of the UIM runners are also oily and have a baked on oil look to surfaces. Also photos.

Are these normal for a failed intake gasket between the crank case and the intake plenum? Will replacing the gaskets cure my problems, or is the engine terminal. I ran good until the miss, and under light load sounds and feels ok.

Thanks for your responses

 

[dezldave961]

The PCV vent tube runs under there and makes a mess over time, and the EGR pipe coming up near the coolant o-rings doesn't help keep it clean, either. Nothing new.

The LIM gasket swap to the updated aluminum ones is vital to long-term survival, regardless. Coolant usually leaks from the lower gaskets failing due to deforming, and the upper o-rings deforming from heat, too.

 

[Impala79]

The PCV vent tube runs under there and makes a mess over time, and the EGR pipe coming up near the coolant o-rings doesn't help keep it clean, either. Nothing new.

The LIM gasket swap to the updated aluminum ones is vital to long-term survival, regardless. Coolant usually leaks from the lower gaskets failing due to deforming, and the upper o-rings deforming from heat, too.

Thank you. I went ahead and bought the ATP UIM after seeing this. I’ll use my fel-pro gasket sets and button it back up.