tommu wrote: ↑Tue Feb 28, 2017 11:30 am
Questions:
1. Should I remediate this before going any further.
2. Is there a straightforward way to reseat or do I need to remove the entire exhaust?
3. Is Ratwell's writeup a good resource to follow?
http://www.ratwell.com/technical/Exhaust.html
Preamble: Are you CERTAIN it is the manifold-to-head copper gasket junction leaking? If so:
1. I think you should. Leaks AT the heads can be vacuum leaks, as the cam has a tiny bit of overlap of exhaust and intake strokes. The 2.0 exhaust valves and seats will appreciate a pressure-tight junction there.
2. Depends on the exhaust system, any other leaks, condition of the studs/heads, and your bench-pressing ability. For example, if the rest of the system is really rusted together, or it's a later system with 28 fasteners and zero other leaks, sometimes it is most efficient to drop the ENTIRE exhaust system from the heads, and take everything from the F pipes/U pipes/J pipes and the elbow and the crossover pipe straight down. (Muffler removal in that case is optional. I've done both, proceed as deemed necessary.) Does this make sense? On late setups where the hardware has been anti-seized correctly (AHEM!) then removing the manifold pipe is no big deal; four screws for the lower tin and two nuts on each head stud. Whenever removing exhaust hardware from a head, hit it with penetrating oil before, then begin loosening after a good soak. If any fastener becomes harder to turn, snug it back in the opposite direction and try again. Usually this back and forth nutting/bolting/screwing will allow any dirt/rust/gunk in the threads to alleviate itself and cause less harm. Zapping it out in one motion can and does harm the threads. Whenever I encounter rough fastener removal, I always chase the threads with a die and engine oil before coating the new fasteners with anti-seize and installing.
3. I don't think Ratwell does a good job of explaining diagnosis or removal of parts, but you WILL want to make sure the new gasket rings when you drop it on concrete; no ticks. Wolfsburg West sells good ones, but I'm not sure about other retailers. I also like a thin and even smearing of Ultra Copper RTV on the gasket before install; the sealing properties are nice but what I really enjoy is the RTV holding the gasket into the head while I fumble with the manifold pipe (or entire exhaust system.)
Clear as mud?
Robbie