I have some small leaks(few mm) in my manifold and down pipe. As mine is a rare US manufactured car(civic vti 99) and I'm in uk, mechanic said it will be quite difficult to find the part.

I aksed him if anything else could be done and he said not really you need the part and I believe he said gum gum would just come off.

Is welding the holes a way to repair leaks? Why might he not have suggested that?

  • The actual leak is usually just the tip of an iceberg of corrosion inside the exhaust. You can't weld rust.
    – alephzero
    Commented Dec 14, 2018 at 20:22
  • Is the manifold cast iron or steel? Commented Dec 17, 2018 at 16:52
  • Would an epoxy putty (e.g. JB Weld ) work in this case, as long as none of the product got into the pipe?
    – B540Glenn
    Commented Dec 17, 2018 at 19:51
  • @B540Glenn the header will get way too hot for an epoxy. Have you looked on ebay for the part? Here in the us was have "craigslist", might be able to find something similar there and try your luck
    – DatsunZ1
    Commented Dec 20, 2018 at 20:07

3 Answers 3


As other answers have said it is possible to weld manifolds but it's not easy nor guaranteed to be successful. A lot will depend upon where the hole is and how good the guy is doing the welding. Some just can't be salvaged.

Nine times out of ten you're going to be much better off just replacing the affected part - unfortunately as you've already discovered getting a replacement for yours might not be quite that simple. The manifolds for both the 1.6 Vti (B16A2 engine - manifold part# 18100P30000) and the 1.8 Vti (B18C4 engine - Part# 18100P9KG01) are now discontinued by Honda and as such are hard to get hold of and expensive when you can.

The silver lining is that aftermarket parts exist! Still not back-of-the-sofa change in terms of cost (£200-300) and since many of the ones out there aren't direct pattern parts but rather upgraded units you'll have to declare it to the insurance but it might be your best way of sorting it.

PS: You'll also need to be careful when ordering as I believe some won't fit if the car has A/C.


Yes, you can repair by welding, but you have to be good - "bird crap" won't cut it...

I have made exhausts and welded them, custom made an exhaust for a v8 into a landrover...


Cast iron can be welded using gas but it is not easy to weld. If the iron is thin attempting to weld it will enlarge the hole and may prove impractical.

Manifolds can also be fabricated from scratch (from plate and tube steel) this is popular with customisers and performance enthusiasts. steel is much easier to weld.

Or perhaps you can get one from USA, I have purchased parts from the other side of the world in the past, but I dread the shipping cost for such a heavy part.

  • 1
    You can MIG/stick weld cast iron if you clean the heck out of it and ensure it's warmed up prior to welding, welded in short spurts, and kept warm to allow to cool slowly after welding. Commented Dec 14, 2018 at 20:34

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