Cracked Headers. How soon should i swap them over?

CheyneX5 · Postby **CheyneX5** » Tue Jun 04, 2013 12:01 pm

Hey All.

A while ago i fitted some Mazdaspeed Headers to my NA6. Over time they developed a bit of a hiss, especially when the car was cold. I eventually had this checked out and it appeared to be caused by a small crack. This was welded up and the noise mostly went away. This happened a couple of months ago.

Over time, the noise started to come back and it became worse. This was timed well as i was having my gearbox changed over, so i was able to remove the headers and take a closer look. My mechanic and i analysed them for a while and found quite a few small cracks (barely visible) near some of the joins and also at the very top where the piping meets the engine, most cracks were on the welds, but also on piping too. We welded up everyone we could find and refitted them back to the car. The noise was gone for a few days but now it's getting louder and louder which obviously means they are just cracking left right and centre.

Why i bring this up is that it seems when the noise is at it's worst, the car also seems to lack a bit of go. The idle can also feel a bit strange... smooth most of the time but occasional stutters.

Would i be correct in saying that all these minor leaks (especially the ones before the o2 sensor) are affecting the air & fuel mixture, therefore making the car perform a little roughly?

I'll be getting some Maxim Works headers on Thursday, should i be pretty prompt about fitting them?

Any feedback would be great, i know it sounds like i may have answered my own question, but i'm just curious to know if anyone can confirm what i am guessing or if i am way off.

Cheers.

emily_mx5 · Postby **emily_mx5** » Tue Jun 04, 2013 12:07 pm

You definitely answered your own question

The downsides are obviously rough idle, poor fuel economy, and lacking power.

There is no rush, as you can't damage anything by having a leaky exhaust.
Unless it runs so lean an explodes haha.
So fit them when you can, but no need to drop everything else immediately to do so

CheyneX5 · Postby **CheyneX5** » Tue Jun 04, 2013 12:11 pm

Cheers Emily, I thought it was the case.

I have always thought it was never really a problem until it started sounding like a tractor. I guess the same performance loss can come from lots of small cracks.

I appreciate the response.

emily_mx5 · Postby **emily_mx5** » Tue Jun 04, 2013 12:34 pm

Haha, when your mx5 sounds like it has an SR20 engine, you know something's wrong!

I am shocked to hear that the Mazdaspeed headers are failing, are they stainless steel?

zero00 · Postby **zero00** » Tue Jun 04, 2013 12:46 pm

emily_mxV wrote:Haha, when your mx5 sounds like it has an SR20 engine, you know something's wrong!

I am shocked to hear that the Mazdaspeed headers are failing, are they stainless steel?

My '89 NA has 'Mazdaspeed' headers and exhaust, still all original from new, even the engraved exhaust tip - the car was built by Mazdaspeed

CheyneX5 · Postby **CheyneX5** » Tue Jun 04, 2013 12:56 pm

Emily,

I got the Mazdaspeed headers by surprise when I purchased my Corns exhaust from YAJ a while ago. The looked to be good but had signs of repair.

Apparently these specific headers were known to crack due to the difference in materials used for the flanges and piping.

But my mechanic also mentioned that the piped were cracking because they have "hardened" a lot over time and have become brittle.

I also thought I'd ask if minor exhaust vibration should be a symptom of this kind of leak?

project.r.racing · Postby **project.r.racing** » Tue Jun 04, 2013 2:11 pm

welds cracking with ages is normal. pipe cracking with age is not. sounds like it is time to replace them. luckily the is 1000s of header available to replace them.

manga_blue · Postby **manga_blue** » Tue Jun 04, 2013 7:57 pm

Headers will crack up near the manifold flange when their bracket to the bellhousing is missing or not connected. That bracket is there to prevent the flex forces from being concentrated at the top flange, where the metal is already prone to getting brittle from heat.

CheyneX5 · Postby **CheyneX5** » Wed Jun 05, 2013 11:12 am

There is a bracket to the bell housing?
I don't think I have ever seen it.
Do most aftermarket headers have this?

emily_mx5 · Postby **emily_mx5** » Wed Jun 05, 2013 11:41 am

^ No, I have never seen an aftermarket header with such a bracket, only the stock ones do.

manga_blue · Postby **manga_blue** » Wed Jun 05, 2013 11:46 am

You can use a U-bolt and some creative metal shaping or else weld a piece on. Buggar of a spot to get to though.

manga_blue · Postby **manga_blue** » Wed Jun 05, 2013 3:22 pm

Back to the original question ... if you've got exhaust leaks near the engine and the seal on top of the firewall between the engine bay and the air collector area under the windscreen is not perfect then there's going to be some exhaust gas, including carbon monoxide, getting into the cabin. Personally I wouldn't drive it far and I wouldn't drive it top up.

CheyneX5 · Postby **CheyneX5** » Wed Jun 05, 2013 3:40 pm

I checked the seal and its pretty good.
I can smell exhaust fumes occasionally, but mainly when the roof is down and I come to a stop, or when I have a window down etc. I can also see black soot marks on a couple of places where one of the pipes joins to the flange where it meets the engine.

Mr Morlock · Postby **Mr Morlock** » Wed Jun 05, 2013 9:17 pm

just maybe some people do not know that exhaust fumes are toxic- cause sleepiness and can kill you. I really do not like the smell of exhaust fumes / unburnt petrol / diesel-- none of its good for your health.

lee · Postby **lee** » Thu Jun 06, 2013 1:24 am

Mr Morlock wrote:just maybe some people do not know that exhaust fumes are toxic- cause sleepiness and can kill you. I really do not like the smell of exhaust fumes / unburnt petrol / diesel-- none of its good for your health.

I'm sure Cheyne is well aware of the dangers of CO and CO2 inhalation, and I'd feel confident in saying he doesn't take pleasure in the prospect of inhaling exhaust gases.

It's a good thing you don't like the smell of exhaust gases and petroleum fumes. Many of those who revel in the scents of octane and its post-exothermic products tend to suffer deeply unpleasant consequences.