Exhaust Issue - pre-cat

smetzger

03 P5 (x2), 09 Miata, 07 Mazda3, 13 Fit, 09 Ody
So, got some issues with rust and where the bolts attach has rusted off and I have a leak...
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I was able to 'crack' all the bolts.
47653828751_63ea15d03d.jpg


Well... broke this one off...
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Whomever put this on put a different sized nut...
33776407508_1742a00c04.jpg

in between 13mm and 14mm ... ???

Is this nut supposed to come off? Or is it welded on and you just screw into it?
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So... question time..
1) What parts do I need? I'd like to get all new nuts and bolts? Is there a piece (like a gasket) that fits in between the two where it is leaking?
Looks like there is a gasket on the other end closer to the engine.

2) Can I just take this one piece off without dissembling the rest of the exhaust? It looks like I can, just want to make sure.

3) Are those nuts in the last pic supposed to come off?

4) What SAE size is in between 13mm and 14mm? I don't have any SAE sockets. So, I'll need to get one.

Thanks
 
Yes they can come off. The cat can come off from the header and the downpipe. I've taken mine apart when I was taking it off for a aftermarket header.
With rust it's not going to be easy you might have to drill into it if you can't get a socket on it for it to come apart.
 
4) What SAE size is in between 13mm and 14mm? I don't have any SAE sockets. So, I'll need to get one.

Those nuts may have been 14 mm but shrunk due to rust loss.

I had some 14 mm bolts on my strut that were so rusted the 14 mm was loose and striped it, so I hammered a 13 mm on it.

You may need to use a visegrip on them.
I've found that the original Vise Grip brand by Irwin work way better. The cheaper visegrips are crap and the jaws get all sloppy and falloff the bolts.

You may need to cut them off and a grinder with a cutoff wheel can work, if you can fit it in there.

A Dremel tool with a cutoff wheel will work too for tighter spots but it's slower going.

13 mm is slightly bigger than 1/2"

 
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Well since the bracket holding the front bolts rusted completely off and the back nuts have to come off... I don't need to worry about that weird sized one. Which is good because 17/32 = 13.5mm. Amazon and ebay didn't have any 17/32 deep sockets.

I'll have to get under their later this week and see if I can break free those back nuts.

Looking at parts... many do not have that middle bracket
https://www.rockauto.com/en/moreinfo.php?pk=2478650&cc=1430264&jsn=375

How important do you think it is?
FYI - this is my 02 LX with 311k miles, burns 2 qts of oil every 4000 miles and has lots of rust.

I am thinking just get the cheapest pipe because the pipe will most likely far outlast the rest of the car.
 
I am thinking just get the cheapest pipe because the pipe will most likely far outlast the rest of the car.

I hear that.
This is what I did. I didn't spent any money.



There's a donut style metal gasket in there too.
 
I hear that.
This is what I did. I didn't spent any money.



There's a donut style metal gasket in there too.

That is pretty impressive. Cars are getting old, many of us are just keeping them alive. Maybe we should have a thread on "doing it wrong, but I don't care"

The front rad support on the car was knocked in a little bit in minor accident. I have some 1" pieces of wood for spacers so the grill fits on.
 
If I would've tried to replace that same part,
(which obviously I should have done), I could well have ended up replacing my entire exhaust.

Fricken Rust Turds !!
 
I do not want to thread-hijack but better that than start a whole new one so here goes;

I bought a steel exhaust header and noticed that the post cat O2 Sensors' wire is grounded to the cat or the wire is attached to the cat so the wire doesn't move around as the cars in motion or to simply protect the wire from heat? Whatever the reason the wire is attached, not plugged in, in 2 places on the cat.
My question is can I disregard the brackets that holds onto the post-cat O2 Sensor wire when I install my steel header? whatdo
 
I would suspect that if the cat is fully grounded to the rest of the exhaust through bolts and nuts and continues to the engine ground and ECU you should be fine.

If unsure, connect a ground wire.

The "shield wire" needs a good ground.

 
I've been spaying PB Blast on a few stubborn bolts on that exhaust so haven't been on here but thanks for the info.
I was also reading about EGR Valve related threads on here and was considering deleting it but now I don't want to. Every modification I make to this car someones likely talked about it on here
 
...
My question is can I disregard the brackets that holds onto the post-cat O2 Sensor wire when I install my steel header? whatdo

If by bracket, you mean this thing, then no, you don't need the bracket as a ground because the wire is insulated by plastic anyway.



You may need the bracket to hold the wire out of the way though.
 
I've got the impact driver but I still need to get a set of bolt extractors. They've been on my shopping list for a while.
 
I bought a set of bolt extractors.

13 sockets for the price of 5 Irwin sockets.

I'll see how they work out, I won't be using them too often.

 
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