ferdf-150

I've always had an issue with an exhaust leak on my 4.9L/300 96 F150 and was considering putting on headers as a way to fix this problem. Wondering if anyone else has had any luck repairing this exhaust leak and if anyone knows of any headers that would fit the truck fairly easily?
Thanks

justintendo

you need to determine where the leak is coming from. headers are more prone to leaks than the stock exhaust.

265258

I just bought an 86 F150 with cracked exhaust manifold. The PO had a replacement manifold in there so I swapped it. Before I installed the manifold I used a burring bit to smooth out the edges on the manifold, especially where the heat exchange is under the carb. It's a good practice with casted parts because any sharp edges in the exhaust flow path will collect more heat than the rest of the manifold and increase risk of cracking it. The extra heat will also create hot spots in the gaskets and seals possibly burning them out. I also used Permatex spray on sealant designed for hot applications on all the gaskets. Another thing worth noting, is if you replace the intake exhast manifold. It pays to take a few extra minutes to lay the gasket on the exhaust and intake and make sure the head ports are lined up well and there are no over laps. Also uuse the burring bit around the manifold ports to smooth them out as well. You don't want any rough casting edges around the ports where the gasket surface is. all those little rough spots collect heat. When I installed the gasket, I discovered a 5/16" hole throught the intake and block that can be used for the purpose of making sure the gasket is lined up perfectly. It's at the top just to the left of the #1 intake port. I just stuck a bolt in there to hold the gasket and intake in place while I installed all the bolts and exhaust manifold. I also noticed on the exhaust manifold that the first bolt hole for the exhaust on number 1 is huge, obviously meant to have a spacer in there for some dumb reason. I had to find something to install on the bolt shaft to take up the slop, otherwise there is no way of knowing if the exhaust manifold gets lined up correctly on the head. When I torqued everything, I made sure the heat exchange bolts were snugged before torquing the exhaust and intake bolts. Over all, installing the manifolds and making sure the ports were lined up with the head ports correctly was a P.I.T.A, but it's worth it to take the extra time to do it. If you replace the gaskets and take these precautions, you should be able to take care of that leak.

raski

You should be able to see black carbon streaking where the leak is. For me, I would repair the leak and the header approach would be my last option.