Vehicles Affected 1990-1997 Toyota Celica, 1990-1997 Toyota Corolla (w/ O2 sensor in exhaust pipe),  1990-1997 Geo Prism (w/ O2 sensor in exhaust pipe), 1988 Chevrolet Nova

Replacement Part Dorman 674-164

1.6l and 1.8l engines

General procedure for replacing Dorman exhaust manifold 674-164, on Chevrolet/Geo/Toyota with 1.6L and 1.8L engines.

Before starting any repairs, there are some general procedures to follow for safety precautions. Doing this repair requires some under car work. First you must raise and support the front of the car, using ramps or jack stands. (You should NEVER just rely on a hydraulic jack to hold vehicle up) Second, disconnect the negative battery cable, so not to short anything out while disconnecting and removing parts from vehicle.

Now moving on to the removal of the exhaust manifold. 1. remove all electrical wires and vacuum hoses that interfere with removal of the exhaust manifold. 2. remove upper heat insulator from exhaust manifold. 3. loosen the 2 bolts with compression springs, connecting the exhaust manifold to the exhaust pipe. 4. There may be a exhaust stay bolt (mounting tab) located near the manifold to pipe area, this must also be removed.

5. remove the seven stud nuts holding the manifold to cylinder head (in some cases the stud will remove with nut, this is ok, just remember to reinstall in same locations)

Pre-assembly check Exhaust pipe- the old donut gasket has been removed and the mounting surface is cleaned of all old gasket material. Cylinder head- the old manifold gasket has been removed and surface has been cleaned.

If any of the studs, nuts or bolts look questionable due to rust. We suggest replacing them with factory bolts or grade 8 strength replacments. Install new studs in new exhaust manifold.

Installation of exhaust manifold. 1. Install manifold gasket on studs. (gasket may be labaled front or back for installation)

2. Install exhaust manifold to cylinder head, installing all flange nuts a few turns by hand to ensure proper alignment.

It’s always best to install all mounting hardware a few turns by hand to ensure part and fastener alignment, before tighting.

3. fit exhaust donut gasket in groove, and hand tighten exhaust nuts to keep gasket in place. 4. reinstall exhaust stay bracket bolts 5. Torque exhaust manifold bolts to 25 ft. lbs. 6. Tighten exhaust mounting stay to 25 ft. lbs. 7. Torque exhaust pipe-to-exhaust manifold nuts to 46 ft. lbs. 8. Install exhaust manifold heat insulator 9. Torque heat insulator bolts to 71 inch lbs.

10. Reinstall all electrical wires and vacuum hoses that were disconnected for removal of the exhaust manifold.

Lower the vehicle safely and reconnect the negative battery cable.

•Start the engine and make sure that there are no exhaust leaks.
New exhaust manifold will have a funny smell for the first few miles of opperation, while the anti-corrosion coating burns off.

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