Alright, i have two small exhaust leaks one from each donut, or the donut gasket. Are these expensive parts and how hard are they to change? Also is there a good patch or something of somesort that i can use for the mean time? I have a 98 f150 4.6L

 

What is a donut/donut gasket?

 

It's that joint right after the headers before the cats.... i'm pretty sure those are called donuts

 

no, there are no donut gaskets in our exhaust systems. They are just bolted together, not gasket. How do you know its leaking from that area?

 

Well i'm unsure if there is a gasket there or not, its possible, but I dont believe there is one, it should be just pipe on pipe. That area is better revered to as the downpipe/manifold outlet.

 

oh, alright, i didn't know if there was a gasket or not, i'm new to exhaust... but i know it's leaking because i can feel the air blowing out from it, and i bought cheap sealent from auto zone and tried to put that on, and it went away and i wouldn't feel it anymore or hear it anymore from inside the cab, but a peice just fell off and it's back. I'm not sure if it got wet and fell off, or i just didn't put enough sealer on. and sorry for my crappy spelling.

 

Dont know why that area would leak unless you just removed the system and bent the piping where it couples to the manifold.

They have a sealant that hardens you can put on there. YOu warm the engine up, smother this puddy on there, let it dry over night and it should be good. It is temporary though

 

Well its possible that it would rust away. Just need to get new downpipes and maybe shorty headers.

 

can i just replace the donuts? or do i have to replace everything. and i'm not too sure why it's leaking, and it's leaking from the same spot on both donuts. My guess is like darren said, it just rusted, because it's a 98 and there is some rust on it.

 

Hey Jbracket....I just had them replaced on my 97 150. That is correct that there is not a donut gasket in there it is a machined fit. The leak begins when one or both of the studs holding the flange rust in half.

The hard part is the passenger side...there just isn't any room to work. I just had my drivers side fixed to the tune of $170. What they did was busted the remainder of the bolts off then used a torch to blow them through. Then in comes the stainless nuts and bolts and buttoned it all back up. It was 2 1/2 hours on their part and I was glad to see THEM do it!

It would have been another $100 to have them do the other side.

Hope this helps!

Ken