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2002 civic exhaust manifold

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Dec 23, 2016, 5:29 AM

Post #1 of 4 (1543 views)
2002 civic exhaust manifold Sign In

Working on the ol' 1.7 honda civic and noticed a small crack in the exhaust manifold above the oxygen sensor about an inch long . I don't hear any noticeable noise from it and wondered if it can be "patched" or welded or if it can do any harm . Also how would something like this occur , did king kong work on this car at one time ? Thanks .

Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 23, 2016, 5:34 AM

Post #2 of 4 (1541 views)
Re: 2002 civic exhaust manifold Sign In

That is a common issue. If you know how to braze cast iron, you might be able to patch it. It is probably better to replace the manifold. Also make sure all the manifold support braces aren't missing or broken. The only affect that crack will have besides leaking exhaust gasses is that it can suck air into the manifold messing up the reading from the O2 sensor.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Dec 23, 2016, 5:45 AM)


Dec 23, 2016, 5:59 AM

Post #3 of 4 (1528 views)
Re: 2002 civic exhaust manifold Sign In

O.K. thanks , I have the small tank MAPP and oxygen torches and brazing rods , steel is easy but cast might be different , I'll research it , try a test piece first .

Veteran / Moderator
nickwarner profile image

Jan 4, 2017, 8:19 AM

Post #4 of 4 (1485 views)
Re: 2002 civic exhaust manifold Sign In

Make sure you drill each end of the crack and clean it up nice. If you can acid etch the crack area first it will help you, as cast gets full of nasties. It is also sensitive to localized heat. If you can get maybe a good hot BBQ grill going to preheat it or put it in your oven at 500 degrees (if you do this in your house oven you will be dealing with an angry wife by the way). You want it preheated up fully. Work the torch around an area at least 2-3 inches from the braze joint first, then move in and braze up the crack. Then immediately get it back into either the grill or the house oven. For the grill method, just make sure it has plenty of charcoal, put the lid on and come back the next day. For the oven, reduce your heat by 50 degrees per hour until your oven gets to 200, then just shut the oven off and leave it be until all has cooled to room temp. You can also make a good hot bed of charcoal on the ground or in a steel box, set the manifold on it then bury it in sand to control the cooling but then you have to make sure you get all the sand out of it before install. I prefer the oven method for more precise heat control, but I have an understanding girlfriend who is used to things like that from me.

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