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Discussion Starter · #1 ·
My downpipe is beginning to rust through. A stock downpipe is $593 dollars at my dealership... and that's just the part. I was curious if anyone makes an aftermarket downpipe for our car or would it be cheaper to get something bent for it. I would like to upgrade since I have to spend the money anyway to pass state inspection (I live in Texas so I also have to pass emmisions). What can I do? Any suggestions would be great.
 

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Discussion Starter · #3 ·
huh?!!!

I don't understand your response b/c if my exhaust doesn't pass emmissions then byebye mazda. I need a new downpipe. It is obviously rusted. The tech guy showed me and it is literally falling apart. No way will I pass emmissions like that. The sound alone once it completely rusts through will give it away. Explain what you meant please b/c I don't get it.
 

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aggiedj02 said:
I don't understand your response b/c if my exhaust doesn't pass emmissions then byebye mazda. I need a new downpipe. It is obviously rusted. The tech guy showed me and it is literally falling apart. No way will I pass emmissions like that. The sound alone once it completely rusts through will give it away. Explain what you meant please b/c I don't get it.
aggie,

Perhaps you can try this (just thinking aloud here):

Contact Hotshot and see if they will sell you just a Y-pipe. It uses larger piping than the OEM one IIRC. Then, take the pipe to a good muffler shop and see if they can cut the ends off and fabricate up, using short lengths of pipe and a flaring machine, "tips" for the ends that will bolt-up to the OEM manifolds. Once trial fitted, they could weld the tips to the Y-pipe instead of using a slip-joint and clamp.

One possibility anyway, as I'm not aware of any specific, bolt-on Y-pipe upgrade out there.
 

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aggie,
I think what Jorge meant was just replace the exhaust mainfold and down pipe with a set of Hotshot headers. They replace everything fromt eh exhaust manifold to the cat, thereby replacing your down pipe in the process, not to mention they will give you some more power. That would be a cheaper option than buying just the pipe from Mazda. Or y0ou go also go with the other header options out there. Last choice woul be to find a junkyard MX-6 or Probe and if it still has the engine in it remove the down pipe from that and put it on yours. As for emissions testing you should pass the sniffer test with headers, I've done it here in CA and I know we have tougher smog tests than Texas.
 

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You say "rust" re downpipe.

o The downpipe is actually a low grade stainless steel. It
is non-magnetic and doesn't rust easily. Mine on a 1993V6
is still "white", apart from the welds which tack the two
halves of what looks like a pressing. That is despite 9yrs
of numerous winter/salt/UK-rain cycles. It sort of goes a
dusty bleached white metal colour.
o Now the /welds/ on the downpipe WILL rust, crusty orange
delineage of the two halves and what looks like tack bits.
o The flex-pipe is surrounded by a braiding which goes to
a clamp at each end, those clamps can rust through as mine
has. No leaks whatsoever and they'd be obvious & audible.

Thus:
o If the downpipe is leaking, it will not pass emissions
o Weld rust or surface rust is immaterial until it does,
and that pipe is actually very thick & heavy as a warning.

My Borla flange plate is bare steel and has thick crusts
of rust flaking off it's ~10mm thickness. Will last decades.

Other Sources:
o Email Roebuck/Trussville Mazda for the parts price, their
price may be quite a bit less than you have been quoted. It
is just a pipe after all and not a whole cat-back/muffler.

Since that piping is low grade stainless any shop should be
able to reweld it. I can't recall what grade, T4xx IIRC. Not
the T304 or (medical) T316 you associate with stainless. I
think partly because T304 is more susceptible to cracking
in "header" applications which this is to some extent.

Another Source:
Ask on http://www.Probetalk.com or here for anyone who has changed
from stock to headers, they may have downpipes available.
 

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Discussion Starter · #7 ·
thank you

Julian you're right about what is going bad on my car. The braids are unraveling and all the welding spots are a crusty orange and are flaking off. My exhaust is not leaking yet but it is close to it, and I know it won't pass emmissoins when it starts. I saw the rust myself and the problems with it, so I can tell you it is bad. I do thank you for the tips on getting it fixed though. I talked to guy yesterday who is willing to do 2.5 inch piping all the way through for like $300 (labor and all) if I bring him a muffler. I was thinking of getting a Prima Power muffler from Paeco industries since it is relatively quiet and doesn't have an ugly 4 inch tip on it. Any more suggestions would be great.
 

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Re downpipe...

o The downpipe can be rewelded - it's just a few welds,
the actual pipe itself will last as long as T304 in auto
use a colleague has confirmed. T4xx's just "cheap n cheap".
o Check the Wanted section of Probetalk.com / MX6.com for
any used stock exhausts (low mileage) or Borla/Greddy/etc.

A colleague picked up a used downpipe (Mr Brick & Mr Pipe
had a disagreement, along with Mr Brick & Mr Radiator), and
a stock exhaust for 120$US with 36k miles on them. Nothing.


The UK price on the downpipe is ~£230, it may be more or
less now as Mazda UK prices have changed (usually -50%),
so Roebuck/Trussville may do it for <<300$US. For the
whole thing "manifold-back" the price you quoted is good.
Do check what metal the downpipe is though, the heat is
severe (though not like a rotary which prefers Inconel)
and factory T4xx piping will never rust through. Colleague
did say it can be rewelded with a stainless wire, but he
did not say which one only "it's not so common to get".
 
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