You'll need to remove the exhaust pipe and possibly the air pump check valve or air tubing to replace the exhaust manifold.
- Unbolt the exhaust manifold.
- Bolts holding the exhaust manifold are often rusted and will be difficult to remove and have a tendency to break. Spray penetrating oil on them and use a six-point socket.
A rusted fastener can sometimes be tightened slightly to help penetrating oil get into the threads.Rusted manifold bolts are easier to remove with an impact wrench.Use a six-point socket to remove most engine items, especially exhaust bolts and nuts. A twelve-point socket will be more likely to slip, rounding off the corners of a nut.
Use an impact wrench and impact socket to remove exhaust manifold-to-pipe bolts.
- After the block assembly is painted, install the exhaust manifold(s). Some inline engines use a combined intake and exhaust manifold gasket.
- When installing the exhaust manifold(s), tighten the bolts in the center of the manifold first to prevent cracking it.
- If there are dowel holes in the exhaust manifold that align with dowels in the cylinder head, make sure these holes are larger than the dowels.
- If the dowels do not have enough clearance because of the buildup of foreign material, the manifold will not be able to expand properly, and may crack.
- On engines with shared bolts between the intake and exhaust manifolds, tighten the individual manifold-to-engine bolts first. Then, tighten the bolts where the two parts meet.