haymaker

I just replaced the cat below the exhaust manifold. we couldnt pull it out from underneath the truck coz not only that screws (holding the exhst manifold and cat) are so tight but their positioning was so difficult reach using our available tools. So what we did was pull it out from under the hood, but in order to do that we also had to take out the exhst manifold. Everything went smoothly. We are able to install the new cat. We even put on a new exhst manifold gasket before putting it back. But when I started the engine, the noise came out as if theres a leak coming from the exhaust manilfold. I didnt notice any crack or something that may cause the leak. Should we have applied a gasket maker or some kind of sealant in addition to the new exhst manifold gasket? Any input will be appreciated. Thanks.

haymaker
Nissan Frontier 01 SE 4 cyl, 2.4 lit 97.5K miles

Two Bills

Might want to try retorquing the exhaust manifod. A pain, but.....

You're sure the manifold's not cracked? Seems like I hear about that problem a lot.

haymaker

I have to double check. when we took the manifold out, i didnt see any visible crack. the studs are ok. thats why it really surprised me. thanks.

BTF/PTM

You probably won't be able to see the crack unless you see exhaust vapor getting thru it. One thing you can do to search for a crack or leak is to run a SMALL amount of liquid water into your intake manifold and watch for the steam to come thru the opening.

*edit* sorry, I had jsut gotten done typin up something on how you might have a broken stud, then I saw that you already checked for that. posted edited

haymaker

Ok ill do that today. I do hope its not cracked coz I just spent over 600 bucks for the new front cat and rear O2 sensor. Thanks for the input.

frontera99

The cracks are easy to see on the 4cyl version.