How to Replace an Exhaust Manifold

An exhaust manifold is normally made up of cast iron, and has small areas of unequaled lengths that will move your exhausts from the ports to your header. If you are noticing a gray smoke, it may be time to check your exhaust manifold.

To get to the manifold, you will have to remove your exhaust pipe. On some cars, you have to take the air pump check valve also known as the air tubing off to get to the exhaust manifold. First, you will need to unbolt the manifold, which normally has 10 bolts. More often than not, they are rusty and this makes them even harder to get off, and sometimes they will break. If you see that there is a buildup of rust, it may be beneficial to spray on a little penetrating oil and then use a 6 point socket. You can also try to tighten the bolt a little with the oil on it, to help get the oil into the threads. You may need to use an impact to get the pipe-to-manifold bolts off, as they are normally torqued down well.

You will need to paint the block assembly, and then install the manifold. Most engines that are called inline, will use a intake and exhaust manifold gasket combo. To install the manifold, just tighten the bolts down in the center first. This helps to keep the manifold from cracking, or causing open areas of the gasket. Some cars also have dowel holes in the manifold that are supposed to line up with the cylinder head. So if yours has these, make sure they are larger than the dowels you have on hand. If you don't have enough room because of grease or buildup of other materials, your manifold won't be able to expand the way it was made to, and it can possibly crack. So make sure that you scrape away any foreign materials before trying to insert the dowel rods.

Some engines have shared bolts between the exhaust manifold and the intake. If yours does, then you will want to tighten each individual manifold-to-engine bolt first. Once these are done, then you can tighten bolts where both parts come together.

Congratulations, you have just removed the old and replaced with a new exhaust manifold. You not only saved money, but you did the job yourself in just a little spare time.