Header nut problems.

Hey fella's,

I had a set of 4-2-1 stainless headers sitting around for a few months, and finally got them installed last friday, along with a 2 inch cat-back system the week before on my EK1 Civic (D16Y4).

About half an hour of driving around after the header install, I heard a massive metal on metal ting and limped the car home in fear of the worse. Got it up on the jacks on the weekend and discovered a bolt missing from where the cat connects to the backpipe, and also found a missing nut from the stud the header connects to. Sure enough, went back to the shop that did it today, and apart from finding 3 leaks from a dodgy weld job done by the ****wit apprentice that worked on my car, they replaced the missing bolt and replaced the all the head nuts with washers and welded up the leaks.

Again, I took the car out for a blast afterwards and within the hour, heard another ting , pulled over and found another head nut and washer missing.

What's the go from here? Apparently the holes in the header are larger than the studs them selves, leaving room for movement, which would explain the loosening of nuts, but is there any way to ensure they're not going to come off mid-drive again? I'll be heading back tomorrow to see what's the go, and hopefully the bloke (who's been nothing but nice) can fix the problem. Seriously considering taking it somewhere else for a second opinion.

Any others had the same problem? Any input would be appreciated!

Never heard about this problem before, Are you using the bolts with springs in the middle and nuts to tight it ? or you are using just a bolt with the nuts

As far as I'm aware they've just put standard open head nuts with stainless washers. I didn't research much into it as you would assume a licensed exhaust repairer would be aware of such problems and use the correct equipment for the job. Have spoken to a few people since who have responded with the self locking nut argument.

red loctite ?
you dont need washers if your using oem exhaust header nuts

sounds like a dodgy work shop to me

the problem is there is movement between that joint, either the engine is moving around or the cat back is moving too much. You have a few options.

1. Flex Pipe between cat and header
2. More rigid engine mounts if its the engine moving about
3. Exhaust bushings that are more firm if its the cat back moving.
4. Higher tensile bolt and nuts. I use red loctite and double nuts on each bolt.

mine ended up being a blown engine mount and weak nut/bolt combination. no flex pipe needed :) Honestly, that exhaust shop should know better.

Yeah, I've gotta head back tomorrow and tell him he's ****ed up twice now. I'm not really looking forward to it. I'll make sure he does something about it, whether it be better bolts and washers, or I'll just get some decent nuts myself and loctite them up. He pulled the argument that if I were to try and remove the bolts with loctite I'd break the studs, but I can't see why I'd want to remove the header in the future short of failure.

I'll swing by tomorrow morning and get his input, failing that I'll be taking it to another shop.

It's a fairly rigid system as well, but my mounts have been checked and are fine, I've observed the engine under hard throttle and it doesn't move very much at all. The roads are pretty crap around here, but I haven't got any suspension mods so it's like floating on a cloud most of the time, bushes are brand new. I just can't see why his best suggestion was to just stick washers underneath the nuts though, just seems like he's trying to get me out of the shop and out of my pocket.

I'll keep you guys posted. Thanks for the input so far!

Ask them to do flexpipe and use red loctite. Flexpipe is a win-win IMO, especially if you're unfortunate enough to bump your cat on something, gives you a little bit of flex so it doesn't pull on the header so much.

Bushings and engine mounts would be a passive PITA for a D16 header lol

Well, I ended up not taking the car back to the place I had it done at. Had recommendations from 3 of my mates to head to a new shop. Ended up heading to the new place, had it up on the hoist for 20 seconds and told me it was an incredibly dodgy job in the first place.

He replaced the head studs with longer, alloy rod and used self locking bolts with loctite. Welded up the rear muffler connect, as the previous place had simply made a slip joint, tack welded it and threw a shitty clamp to tighten it, which didn't work and was still leaking. Replaced the cat bolts with spring bolts and nuts/washers as they were just normal 2 inch bolts and welded another leak that was found. Apparently the hangers were only tack welded on as well, so he did them properly and pulled the system down as much as he could as it was scraping on my rear bar and may have melted it in the future. Also discovered a over bend in the back pipe, in which they'd simply bent it back into place. Bloody nightmare come true.

Pretty ****ing pissed about the first job though, I'll be heading in there and giving 'em an earful about it, and have a few words to the guy who actually installed the system.

Cheers for the input, didn't expect this much of a headache from a exhaust upgrade D= !