Exhaust Manifold Replacement

*Courtesy of acaprez from his website and the MR2 Forum

Shortly after buying the car, I started hearing an odd sound from the engine compartment. From suggestions I concluded it was the exhaust system and after getting an overall inspection done by a mechanic (Toyota Lexus Care in San Diego) I was told the exhaust manifold was cracked. I took what TLC told me and ordered parts from Jay Marks Toyota in Houston, Texas.

I considered getting a TRD header, but the price was too steap, and after reading this on The AW11 Archive I'm glad I didn't. For now the stock manifold is fine for me.

Here is what you need for this job. You need the exhaust manifold gasket, the O2 sensor gasket, and two 'O' ring gaskets for the downpipe. You might also want to replace all the bolts and studs. That includes: three studs that connect the manifold to the downpipe (blue circle), as well as their nuts, two studs, three bolts that attach the manifold to the engine head (red), and the two studs for the o2 sensor (green). I got by without replacing the two studs and three bolts attaching to the head. An exploided view of what I'm talking about as well as part numbers can be seen below:

and the two exhaust o-rings can be seen here:

Those pictues are off Bill Strong's site and his great parts catalog.

1) I'd recommend spraying all the bolts you need to take out at least a few hours beforehand with a penetrating oil. The three bolts connecting the manifold to the downpipe were the hardest to get off. One went without too much trouble, but the other two stripped. My grandpa ended up helping me from that point on, and we had to cut through the nuts. The rest of the exhaust was easy to get off, as was the manifold sheilding.

2) From there on the only big problem we had was the left most bolt under the distributor. I didn't want to remove the distributor itself, and could only get one screw out of the distributor sheild, but that was enough to move it out of the way. We used lots of extentions on that bolt, and loosened it from under the car. The other bolts went easily.

3) The next major step was getting the studs for the O2 sensor out. We got them with a special tool, but getting them back in was another thing since the threads were really bad. Two dealers in the area didn't have those studs in stock (this was a Sunday, so not much was open) but luckily Autozone had studs of the size I needed. Putting it back together was much easier, although that bolt under the distributor was still tricky.

And one more comment, unless you want your car to look like it's on fire, clean the new manifold before putting it in. I think the smell is gone now, though. Here are my posts on the topic on the MR2 Owners Club Message Board. One and two.