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Hey guys,


I recently bought a new header. When I take out my stock one, is it necessary to spray penetrating oil on the bolts to loosen it or can I just unbolt them without using oil?

 
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if theyre stuck spray them.

 
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^word.

Use a new gasket, and if the bolts/nuts on the head dont come off easily, use a wrench and tap the end with a hammer to get loose. Also use a criss cross pattern between the bolts so they dont wrap the side of the head.

 
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Can't I re-use the old gaskets? What would happen if I did?

 
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Your header wont be sealed properly to the head of your engine and you could have exhaust leaks that give faulty readings on your O2 sensors that mess up the ECU's logic to keep your car running smooth and efficiently.

 
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Does the 2003 civic come with a donut gasket? Because I tried looking it up at the honda e-store, but it doesnt show that it is equipped with one.

 
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Yes. at least its in the EX exhausts between the header and the downtube, as for the dx/lx... I dont know actually because I didnt really take that close of a look at it when I did my swap. I dont think honda will list it as a donut gasket on their parts page.

Also FYI if your replacing it, the donut gasket melts to make its seal and smells like its burining or that there is something wrong with your engine, there isnt- its normal.

 
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what model civic do u have.the dx does have
a donut gaskit. but remeber if u intstall the header u loose the cat and will throw a cell light.you will need a o2 simulator .

 
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Take a look at my exhaust FAQ that is linked in my sig. It should give you a very good understanding of the exhaust system.

 
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you can reuse gaskets unless their bent dont use them but its wise to buy new ones you dont have to its smart also you shouldent need pb oil unless their rusted and you cant crack them but if their rusted replace them

 
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I have a 03 civic ex and it's a 4-1 piece header. Thanks for all the advice guys!

 
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One more question... do I have to take off the 02 sensor?

 
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Nope, the sensors are in the down pipe.

Unbolt the header in a criss cross pattern with an impact wrench. If you dont have one, use a socket wrench and tap the end with a hammer to break the nuts off the studs loose. They will be stuck, if you got any muscle and try to man handle it then you'll split two sockets in half like me. Use the hammer, soak it in PB blaster an hour or two before you take the header off. (oh... be sure to make sure ur engine and exhaust is completely cooled before putting PB blaster on and attempting the removal.

once they are loosened to the point you can take the nuts off by hand, move down to the two spring loaded bolts. The top nut is welded to the stock header, and the head of the bolt is accessed from under the car that holds the downpipe to the header. these bolts will be easier in PB blaster as well. They are relatively weak bolts so dont be surprised if they snap on you when you remove them, they suck. Mine was siezed to the nut and when I was loosening it, I was basically unwinding the threads and it snapped in half. Whatever.

basically just do the reverse process to put it all back together with the suggested new gaskets.

 
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yea the donut gasket makes a difference cause when i put the header on my 04 civic with ned gaskets we forgot the donut and didnt put it in and exaust leaked like **** and had to go back in and put the donut in and no more leaks