Author Topic: Cracked exhaust manifold , weld it or replace it?  (Read 3089 times)

thefairlaneman

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Cracked exhaust manifold , weld it or replace it?
« on: September 30, 2010, 07:15:52 PM »
The kids 99 civic has a cracked exhaust manifold. It seems to be a common issue with these models and a new one is 200 bucks and up. I have never needed a mig welder or even a cutting torch and only have a stick welder . I want to fix it as cheap as I can. Any ideas ?thanks

Offline stevejh82

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #1 on: September 30, 2010, 07:26:14 PM »
Longest term solution is to replace.  Manifolds are especially tough (I'm assuming cast iron) because the heat and carbon from the exhaust make the metal even more brittle than regular cast.  I have been successful welding up tractor manifolds with nickel rod, but you have to clean it till it is spotless, preheat (I used my grill and then a torch), weld, and then cool as slowly as possible (more time in the grill).
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Offline J.A.F.E.

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #2 on: September 30, 2010, 07:33:40 PM »
I'd likely be inclined to grab one from a pick and pull. Around here they'd be in the 20-30 range. That's cheaper than what it would cost to pay someone else to weld it up.

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thefairlaneman

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #3 on: September 30, 2010, 07:36:04 PM »
Thanks.  For me it looks like buying one is the only way . Rock auto has for 179 the same one autozone and advance has for 229. Im in Charlotte. If I order it on friday I wonder how long and how much extra for shipping....maybe I should call and ask. The kid needs his car monday. I am guessing that because these things are so common a salvage yard might not have it but I will call several in the AM............let me even think about going fishing and this sorta thing will happen every time...gezzzzz

Offline Uncle Buck

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #4 on: September 30, 2010, 08:01:10 PM »
Unless the guy welding it is the real deal deal, forget it. In fact, even if you do have a real crackerjack of a welder  forget about it! I have had this issue before and the guys that can actually pull off welding cast manifolds back together and making them stick are few and far between! I know there are a few guys that can pull it off, but that number is a whole lot less than the number of guys that think they can pull it off!

Yes, get a replacement and save yourself a heck of a lot of frustration!  ;)
You boys better hold on cause i'm gonna have to stand on it!

Offline Aunt Phil

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #5 on: September 30, 2010, 08:40:48 PM »
In your case Flowerlane, go to the hardware store, buy a can of furnace cement and trowl the repair on.
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thefairlaneman

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #6 on: September 30, 2010, 10:15:51 PM »
I have done a little looking and found some folks have used the JB weld to repair some small cracks and if I were getting ready to sell it to some sucker I would jackleg it back together even if it took bubble gum or some of aunt phils prescription hemorrhoid cream . Wife said tonight "You poor thing. After you fix Jrs car you should take off to the beach"  I plan too. :) :)

Offline Aunt Phil

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #7 on: September 30, 2010, 10:25:26 PM »
Laugh all you want, a hell of a lot of manifolds run 40,000 miles to the junkyard with furnace cement holding the gas in.

You best check on the beach, news here tonight is it got washed away by the storm.
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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #8 on: October 01, 2010, 03:54:24 AM »
I bet you can find some aftermarket headers for that 'performance" car for pretty cheap.  Check out some of those rice rocket parts slingers.
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Offline Matt_T

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #9 on: October 01, 2010, 05:13:37 AM »
If you've got a hot wrench just braze it.

Offline goodfellow

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #10 on: October 01, 2010, 05:32:43 AM »
If you've got a hot wrench just braze it.

It's not that easy with a cracked manifold. Cleaning the carbon out of the crack and pre-heatng is very difficult, and it is equally hard to prep the crack to ensure that it doesn't spread.

Fairlaneman, since you only have access to an arc welder, then you might try a nickel rod. That said, the prep work, pre-heating, welding and peening may require more work than what it's worth. Better to get a nice used part.

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Offline scottg

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #12 on: October 01, 2010, 10:36:07 AM »
First off, the 2 day deadline is toast.  2 days is convenient, this is all.
   
 Furnace cement is pretty gritty.   Muffler glue is the same thing minus the grit.
I love muffler cement for small repairs, 2 bucks, Napa parts!  Wet scrub with a wire brush and water first until its clean.
 I have some on my woodstove for years now.    I use furnace cement inside on the firebrick.
   They both are basically sodium silicate, IE: water glass. 

But...    Junkyard Dude!   What are you thinking?  This is no classic that is going to be kept for another 2 decades.  A 1/2 decent junker and you are good to go until he is tired of the car.
 
Your worst problem is the bolts. They are guaranteed to be screwed.
 Without a torch you better be real good welding nuts onto snapped bolts and quick spin them out while they are still red, or easy outs.
 
  Try soaking all the bolts in penetrating oil now, while you are planning the repair.  The more you can stall and keep squirting those bolts, the easier it'll be.
I soaked my Pacer 3 days straight, 3 times a day, in Kroil and they all came out in one piece.
  yours Scott

Offline Uncle Buck

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #13 on: October 01, 2010, 12:26:47 PM »
I have always found that exhaust manifold bolts on a car that is currently in operation generally come out fairly well, it is the bolts holding the manifolds to engines quietly sleeping in junk yards that are a real pain to get out!
You boys better hold on cause i'm gonna have to stand on it!

thefairlaneman

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #14 on: October 01, 2010, 03:29:41 PM »
Thanks for the ideas. I removed it and the crack makes almost a 360 around one of the pipes. I bought one at autozone  this am and will stick it on tonight , No problems so far and all of the nuts came off ok . This thing has the converter made with the pipe and was a bear to get out . even the oxi sensors came out ok . I still think he got a good price on the car with me being his mechanic because the girl he got it from would have HAD TO HAVE SPENT ABOUT 2 K  on it to bring it up to the condition it is in now. So far I have replaced the radiator, timing belt and water pump. fuel filter and caps and plugs with new wires,2 new tires and now the new manifold.When I fix stuff its done rite.

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Re: Cracked exhaust manifold , weld it or replace it?
« Reply #14 on: October 01, 2010, 03:29:41 PM »

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