I've had a lot of issues with exhaust leaks at my manifold. Abe sanded it after finishing the welding, and it came off warped the first time I removed it. Had it belt sanded, and it warped again the next time it was off. Had it touched up a 3rd time, and now I'm getting an awful ticking sound.

I'm trying to figure out if its an exhaust leak or bearing issue.




It doesn't make noise at cruise or decel, only when the throttle opens.

Feels absolutely amazing despite noise. Many of you may have seen in my build thread that the turbo flange was pretty warped. After fixing that, although the ticking developed, it feels much more punchy at lower RPMs.
https://www.miataturbo.net/build-thr...-63204/page11/

Seems to have a bit of a whistle along with the clicking.

It seems to go away once warmed up, and is a little worse when really cold.

I'm using a three layer exhaust gasket that's ~6 months old. Two thin "bubbled" layers on the outside and one flat thicker sheet sandwiched in between.

I cannot find any leaks or cracks in the manifold, and the flange doesn't seem warped at all. I'm stumped.

 

Boy, I sure don't hear bearing noise. Good luck with your search.

Richard

 

Had a friend listen as well, he's on the same boat thinking it's just an exhaust leak. Just need to figure out how to fix it. I'm waiting to hear back from Abe on the topic of relief cuts.

 

Seems like a combined tick + whistle to me. I also think exhaust leak. Beyond the engine flange, how are the turbo and DP connections?

Wonder how many of Abe's customers track as often as you do?

 

I can't see the vid so I'm gonna ask, does it look like this?


if so I'd ditch it and replace with mls.

if that's not it, then its still only a matter of time til that's one of the leaks

MLS or nothing

 

It's an oem gasket. Stamped steel, one layer about .03" thick, and two about half as thick on either side. Hard to describe.

 

So Multiple Layers of Steel?

 

Yup. Like so:



I always get three pieces when I buy a new one. The thicker one with a thin one spot welded to it, and a separate thin one on its own. I've tried just the two piece one, and currently have all three layers installed, no difference.

 

So I finally got tired of it and took it apart again. Here's the manifold at a few different angles, since it's hard to photograph.




And the head:



If you can't tell, it's leaking pretty bad from cylinder #4, and #1 a bit. So the manifold is bowed.

Here's the ends of the manifold. 1st pictures are just sitting there, 2nd set of pictures is with the opposite end pushed down against the workbench.






Before anyone asks, yes I realize my workbench isn't a perfectly flat surface. But I can repeat these results at any angle on the work bench, on the garage floor, and any other flatish surface I can find.

Should I get it sanded again? Or have it chopped off and a new flange weleded on?

 

I mean... sanding it again would pretty much be the definition of insanity.

 

So you're saying I should sand it?

 

You DO have a turbo 1.6 Miata. So.... yes!

 

Curly, it looks like as that manifold ages, it wants to pull #1 and #4 inward -- hence the bowing/leaking. Maybe you should make some relief cuts in the flange to let it move? I know on my Greddy manifold with relief cuts, what was originally 1/16" gaps have completely closed up -- but no exhaust leaks or cracks.

 

+1 on relief cuts.

 

I'm thinking that's my next step. The question is, should I get it sanded before or after? or not at all. And this was my idea for the relief cuts:



This gives ~2.5 holes per port to hold it all down. I wasn't going to cut the middle since it seems to not have an issue.

 

I'd cut the middle just to be safe. But that's just me.

 

Well you can always go back and cut some more later...

It all depends on how much you like taking the manifold off. lol
Cut two, sand it, tighten it down, get it good and hot, check bolts. Be good.

 

One other thing that happened to me is that when the relief cuts closed up, they also caused the hole with the relief cut to grip the stud. Made getting it off difficult. My machinist buddy redrilled the holes to make it easy to install/remove again. I'd keep an eye out for that.

 

We'll see how this goes. Middle two runners seemed fine, so I only cut between 1&2 and 3&4. It's at the shop now to be belt sanded. Missed the machinist by 15 minutes, otherwise I'd be showing y'all pictures of the finished product.

Edit: yes hornetball, my greddy did that. I drilled the holes out before selling it. If that happens to this one, I'll do the same. My cutting left a decent sized gap, I certainly hope it doesn't close all the way up.

 

Yikes I have an artech side mount setup in the garage waiting to go on this summer. All your manifold problems makes me nervous! Hope this works. If it does, maybe I should do some relief cuts in mine before I install everything...