So i finally removed the cats but in the process snapped the header bolt on the passenger side. As many of you may know the ends of the stock headers have a bolt that you supposedly cant remove. So when i installed my new high flow cats, i can't put a nut on that bolt because the end of the snapped bolt is level with the flange of the hfc. I thought that maybe just relying on the other two nuts and bolts would secure it enough but im thinking that it may be the reason why my car sounds a little wierd is because a potential small leak due to the fact that its not secure. I am not interest in aftermarket headers or anything to do with replacing them. Has anyone ever been successful at removing that bolt? I know this may be dumb but i was maybe going to get a small c clamp and try to clamp it tight which means driving around with a clamp that could fall off any moment.

 

The picture was just to show the bolt that i was talking about. Its not my picture.

 

Haven’t ever done this one before but....

Is the stud threaded (or pressed) into the manifold/header?

If so, perhaps a two or three day soak of PB Blaster then a “twist of the old two nut” method?

Just some good ol’ Mic The Mouse methodology. 😆

 

I believe that i snapped the bolt right where the threads were about to start. I dont know how the end of the bolt is attached to the header, but every search of "oem 350z header", the bolt is in every pic/video i see so i dont think its supposed to be removable or at least easily removable with average joe methods.

 

i think it is pressed in if i remember correctly

 

pressed means this? does that mean vice grips or a hammer shld knock it out?

 

Yeah....might be tricky and harder than you think

 

Yeah, press fit. Very similar to wheel studs.

Couple things.... penetrating oil/spray and heat (applied to the flange, not the stud to expand the flange threading) are your friends.

If there's threads left on the cat side, application of oil and either a press or other method (like the "two nut save" on an impact gun as used on wheel studs or "BFH Method" - big f'n hammer) might help here. Unlike a wheel hub however, be careful with a BFH as you can still bend the flange and that would be end-of-game.

Good luck!

 

they are not press fit. they can be removed. i am in the midst of installing longtubes (taking a break from hammering the **** out of primary for steering clearance ugh)

during this time, i removed all the studs for fun. it is threaded in to the flange. since i did not need them, i just used a vise grip and a hammer to knock it loose. since it's already off the car, blowtorch helps.

i'm sure yours are rusted to hell, but if they are perhaps not, the head of the stud should be star pattern (external torx). the exhaust manifold at the head is E8 i'm not sure about this one. see my attached image, you can see the threads in the flange



if you can't get it out, drill it out, replace with bolt and nut

 

Interesting, the pic OP posted must be a wheel stud then (splined for press fit). Thought it looked a little odd.

In any event.... Good to know.

 

Awesome..... good luck op

 

will the two nut method work if its threaded? dam im not looking forward to this...
thanks @Vitamin_B12

 

you said it is flush with the other flange when the high flow cat is on, right?

so i don't know if you have enough thread exposed for the height of 2 nuts to use that to back it out. since the stud is essentially useless now, i would highly recommend just using a vise grip and hammer. as tight as you can, like takes 2 hands and all your strength to set the vise grip. use a blowtorch at the flange around the hole

if it somehow fails or explodes, then you can always have the fallback option of drilling it out. either way, it should be done off the car unfortunately

* note that if you do manage to get it out, you would either need an OEM replacement stud (it is smaller than the head to header stud, maybe M8?), or equivalent bolt with matching pitch. if you don't have that on hand, may as well drill it out so you have free choice of fastener

 

As mentioned above, soak the hell out of it, heat the flange & try double nuts or vice grips first.

If that's not possible, here's a stud extractor set that I had some success using on a badly rusted cat.

i didn't remember them being this much when I bought them.

ATD Tools 6508 8-Piece Stud Remover Set
HTH

 

Ill definitely look into bolt extractors. Anyways i got under the car today and the weird noise i was talking about was from the exhaust resting on the rear brace which made that rattling noise.

 

Bolted- down bench vice might be easier, long screwdriver/cheater- bar between the pipes and unscrew it. And yes, lots of oil, gl!

 

I did the same thing on a Vette I was working on a few months ago. I had a little bit of stud left, but not enough to do anything with, so I ground it flat and drilled it out. I replaced it with a 3/8" grade-8 bolt and c-lock nut. Zero issues with it. Good luck.

 

after running my passenger high flow cat secured by two bolts out of the three to the end of the exhaust manifold, i had enough. with both windows down, i always noticed the passenger side give an air-y sound when flooring it with another car next to me. I used a dremmel with a metal cut off wheel to make a slit on the bolt so the drill bit has a nice place to stay. Then i went up by drill bit size and drilled tht btch out. Exhaust sounds way better now and has a better tone.

(a good way to hear the sounds your car is making is to drive on the express lane on the highway so ur next to the highway divider and roll down the window. cant explain the science but the noise your car makes will bounce off the highway divider so you could hear your car's noise better the same way you go under a tunnel.)

 

One ***** of a job, for sure. Glad you got it corrected. It's funny how we all think this stuff only happens to us, but it happens nonetheless.