i'd just like to say before i start typing down the symptoms here, i did do a search for this page!!!!
Vehicle: 99 s10 blazer LT 4x4 4 door
Issue: exhaust leak at start up, loudest on passenger side around firewall from outside of vehicle with hood closed. as vehicle warms up the sound goes away completely well at idle anyways. the sound reappears around 2-2500 rpms, with the hood popped and my head on the right side of the engine i can't hear a thing at all. at idle doing a walk around the vehicle (with hood open and then again with hood closed) the worst spot is still the right side of the vehicle near the firewall.
Questions: are there common places for blazers to have exhaust leaks that could relate to this issue? and i'd rather find it myself before paying some $80-$100 an hour mechanic, just to poke around. THANK YOU FOR THE HELP IN ADVANCE!!!

 

At the exhaust manifold where it meets the Y pipe is a pretty common place for them to leak, You could possibly hear it from the location you are describing.
One way to find out, is listen under the car right behind the front tires when you hear that noise.

 

At the exhaust manifold where it meets the Y pipe is a pretty common place for them to leak, You could possibly hear it from the location you are describing.
One way to find out, is listen under the car right behind the front tires when you hear that noise.

 

so would that be just exhaust manifold, or the y pipe that need to be replaced, and how many hours labor do you think this would require? and i strongly hope that the motor wouldnt have to be pulled to fix this...Im a college student for the next four years anyways..gotta make it last 4 more years before i can throw a new motor in it, and make it how i really want it to be!thank you again.

 

Its usually the gasket between the 2. To fix that, the motor does not need to be removed, but a word of advice, SOAK the exhaust bolts in pb blaster or some other penetrating oil, to prevent them, or lower the chance of them breaking.

 

it is a 99 with over 85% original parts..only things that have been replaced were normal wear an tear items, and the motor, 3 times. is the reason for having the leak only on one side of the vehicle just because of the way the pipe is run? or more than likely the weak spot in the gasket? thanks again for the help man.

 

alot of times when the exhaust ticks then shuts up after it warms up a bit its the manifold to block gasket, thats very common. ive had lots of leaky Y pipe gaskets and they never shut up

 

I've never run exhaust manifold gaskets on a chevy engine and only one that leaked had a cracked manifold. Chevy 4, 6, and 6 with iron heads and manifolds just seal off if clean when put together. Now with aluminum heads or headers gaskets are required.

Most likely the donut gasket at the bottom of the manifold to y pipe. 4.3s are bad about motor mounts tearing in 2 and this stresses the donut making it leak.

 

In regards to neo7: You are so correct! But my experience with GM engines goes back to the Cadillac 390,which used exhaust gaskets and burned through them,just like the oil those engines used! My 66 small block uses gaskets and has had the same set in for 16 years. My 1984 "M" 350 did not have gaskets from the factory and developed a tick,gaskets did not solve the problem(bad manifold casting)had to go with headers,which I did not want on that truck! Later series of this same 350 (89/91) did not give me any issues,nor has any 4.3 equipped trucks.