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Hi guys, I need some advice on these 3 future jobs I'm going to do during the weekend:

1. Replacing Intake Manifold gasket: do I need to apply sealant? (Permatex Copper Coat High Temp sealant for example), or just install it dry?

-----> Felpro Gasket:

*Intake to Head Gasket (it comes metallic black)

*Intake to Plenum Gasket (it comes Metallic covered with some rubber material, and BLUE RTV around all ports)

2. How to PROPERLY replace Fuel Injector "o-rings".

------>REASON: #1 has dirt built around it, maybe fuel*dust mixing due to leak.

3. Replacing PRECAT with Header:

* Ports (header-exhaust ports) don't align 100% perfect, but bolts DO. Header Ports are like 1/16 of an inch misaligned from exhaust ports. Exposing the Felpro gasket from where the misalignment is.

*Bought Felpro Exhaust Gasket, the non-metallic one, do I need to apply any sealer? Or install DRY and just torque it?

4. Does the secondary 02 sensor monitor or is "responsible" for air fuel ratios? Or it "ONLY" tells the ECU wether the precat is good or bad? I've heard ONLY the primary 02 sensor is...before the precat...I'm asking since I'm going to install a spacer on the secondary 02 sensor after the header intall job, so I don't get the CEL.

*I bought a new primary 02 sensor from NTK, but I'm planning on using the old secondary one with spacer. Good Idea? A friend did this and the secondary 02 sensor read a steady voltage, not oscillating at all and no CEL.



Premium Member
11,752 Posts
Felpro gaskets, particularly the permadry gaskets, are designed to work without extra sealant. They claim extra sealant may compromise the seal.

The rear 02 is responsible for telling the ecm if the cat is doing its job, that's it. Fuel trim is co trolled by the front 02. Spacing the rear 02 should keep the light off on an 02 model.
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