I got some TII parts yesterday and I started to clean up the exhaust manifold in the sink. It was really greasy and had some weathering on it, but after a fair amount of scrubbing I got it as clean as it was going to get.

I wanted it clean becuase I was going to get it powdercoated at the same time as my other parts when the time was right, however, I noticed this hairline crack on it, that runs a little...
Im not blaming the seller, it was impossible to see when it was dirty, but im wondering how bad it is




How long will this last? whats the worst that will happen, it will crack off or start leaking?

lmk
thx

 

Any exhaust leak is a bad leak especially when it's before the o'2 sensor, it will pull in unwanted air and send false signal to o'2 and cause it to burn more fuel. recommend that you take to welding shop and have them repair it. rx7doctor

 

I see.

The way that this manifold is designed is weird, from what I can tell there is an internal and external layer of metal. The external is the cast iron housing, and the insternal seems to be a 4mm lining of some other metal on the inside... So as long as the crack is on the outside it shouldn't leak right? or do I have this all wrong.

thx

 

i didn't think rotaries relied on the O2 sensor much if at all for the for fuel trim.



the crack may be external right now but depending on how you tune your engine it might enter the exhaust soon enough. the internal layer i believe is a light layer of ceramic to keep the heat in the chamber, this was also layered in the exhaust ports of the housings.

 

shhhh, your going to get people a-ngry

 

but i'm so good at that.


added another note, i'm always doing that also. ^

you may be able to fix the crack or keep it from spreading, i would ask a machine shop for their opinion.

 

I would think the guys here would know more than a machine shop on the second gen TII exhaust manifold. I wouldn't be surprized if there are a shitload of peole out there with a crack in theirs as well.

I was thinking of getting a brand new aftermarket one, but I know NONE that have the t03 flange, all are the t04 flange. If I get another used one i'll probably have another crack on their somewhere, or is the cracking rare?

thx all for your input

 

well i have about 4 cracks in mine atm, they leak but the engine runs and idles perfect it just sounds funny in the morning.. most people don't bother with cracked manifolds they just find good replacements but these days it is becoming tough to find good manifolds that aren't cracked, i would be suspicious of those who claim theirs are not cracked, i sometimes look at my manifold and see it glowing at night, these manifolds get abused worse than a redheaded stepchild..

as a side note, i knew they were cracked but i put them on my rebuild anyways.


for optimum performance and sound though you will want no cracks in your manifold though, i plan on replacing mine at some point.

 

nope the cracking is not rare on TII exhaust manifold. my boy bought one off of ebay & it was crackedtoo. he thought he got bamboozeled by the seller but the seller said he didnt know it was cracked either. so we went to the junkyard to buy one from there & that one was cracked too. so he said **** it & just took the manifold to get soldered at a speed shop. i cant tell you if it held or not because he had to sell the car a couple of months later because of personel problems.

 

thx! So it isn't rare.. thats what I thought. I've decided to repair it.

My dads a pretty good welder, hes not a pro, but I think he has taken some training on it. Would he know how to fix it up good enoughe? hes sleepin so I can't ask.

I would think that you would just clean it up and then run a bead along the crack, am I correct?

 

problem with welding it is weakens the area around the weld, i may experiment with some type of metal bonding agents to see if there is a patchable way to seal the cracks without welding or pinning. these manifolds take in so much heat there isn't many ways to try and keep them in one piece once they start to fall apart.