plaidseats

Add a cat? All I see is dual headers going to what I think is the presilencer followed by a welded pipe to muffler. It’s quiet and car runs great. No visual emissions but good lord does it stink right from the start.

mechanic found that brake cylinder kept leaking fluid and says he sees oil or something where it should be dry in the booster. That maybe the brake fluid is the cause of the odor.

brake fluid can get into the exhaust…??

anyway- more interested in controlling emissions than power - is the reco to add a cat? Is that what a dealer would do if The reactor went bad say, in 1989?

peejay

A cat won't work. A thermal reactor works by running the engine rich all the time so that there are lots of unburned hydrocarbons/carbon monoxide, then pumping hot air into the reactor to burn it off. Because the combustion temperature in the reactor is a lot lower than engine combustion temps, NOx isn't formed if you run "lean", so this strategy is actually really clean.

Catalytic converters require a stoich mixture in the exhaust to function, and they will melt down if too much is asked of them.

A dealer wouldn't install a cat, because they are not powertrain engineers. They would install a new thermal reactor, which was still available until 2000-2005 or so.

plaidseats

Ah yes that’s what I’m coming to understand. So if a TR goes bad or is just missing, and I can’t find a replacement that’s not shot, then there really is no other way to burn off those elements sounds like….. unless someone else has another point of view…. Thx

KansasCityREPU

iTrader: (9)

You could always install a 1981-1985 complete exhaust...If you can find one. Might have to also install the corresponding intake manifold.

For me, I'd just go to the Racing Beat exhaust when a change is needed.

mazdaverx713b

iTrader: (91)

When you have an aftermarket exhaust on our cars, especially the early cars with no shutter valve and coasting valve, you will have a mixture thats fairly rich all of the time and will get backfiring on deceleration. Its going to stink and burn your eyes. This is normal when the original exhaust has been replaced. I have a Racing Beat exhaust on my 80 and it will burn your eyes if you stand behind it while its running at idle. Personally I wouldn't have it any other way. I'm used to it after more than 20 years of restoring these cars. One of the few quirks that I love.

To remedy the smell, you will need a complete functioning stock exhaust system. Given the age, that may be tough to find. You can lean the mixture a tiny and see if that helps.

j9fd3s

iTrader: (3)

that doesn't work, the air injection ports are different in the engine, and won't match up to the newer intakes

j9fd3s

iTrader: (3)

so what problem are you trying to fix? the smell? does it need to pass smog? or the brakes?

plaidseats

doenst need to pass smog just would like to not have it smell that bad like something is wrong.

brakes operate fine - didn’t think related . But mechanic at local garage thinks brake fluid level drop and no sign of a leak other than in booster is somehow partly to blame for the exhaust fumes. As if getting into exhaust circuit, maybe vacuum faulty ?

That fluid drop every 100 miles enough to turn on the brake light is now more important than the exhaust of course. Replacing MC and BB soon as they arrive (got an ‘80 booster, all I could find, and was glad to see on forum that it fits and is actually better).

plaidseats

Maybe looking for a 79 wasn’t my brightness moment in life…. ! Not giving up yet though… either that or just buy carbon offsets!

peejay

That's what pre catalyst rotaries are like when you remove the thermal reactor.

You might be able to rejet the carburetor to '81-85 specs (don't use the whole carb, the '79-80 carb is superior) to get it leaner, but it will always be fumey because rotaries are horrible for combustion, so a good chunk of the air and fuel goes right out the exhaust, especially at idle. Rotaries also do not like to idle near stoich so it's going to be fumey at idle no matter what.

I buy fuel scent and dump some in when I know I'm going to be idling around people a lot. Vanilla and cherry flavors seem to work the best. It's like being around someone smoking a pipe!

plaidseats

i did NOT think that’s where this thread would lead but cover up may be only option !

Toruki

Fuel scent. lol. I had no idea that exists. Rotary vape.

peejay

Only downside is that a bottle that treats a full tank of fuel costs about half as much as the fuel does.

t_g_farrell

iTrader: (1)

There no way the brake MC/BB leak is causing the exhaust smell. Get a better mechanic.

So many memories of crusing at the back of a conga line of rotaries and getting out with watery eyes and that glorious hydrocarbon stench. Wouldn't trade it for the world! Its a badge of honor, wear it proudly!

LongDuck

Second vote for finding a new mechanic; the one you're using is an idiot.

The brake master cylinders are known for leaking past the seals down the INSIDE of the firewall. If you run your hand down the carpeting here, I'm sure you'll come up with a wet hand. Your brake booster is probably just fine. There is no way for brake fluid to get into the exhaust - they are isolated systems, by design.

Also, the Thermal Reactors are going to be very hard to find, as the nature of their operation causes extreme heat and they break down over time due to corrosion. The upside is that my 80LS used to throw fireballs out the Racing Beat exhaust at the slightest provocation, typically during abrupt downshifts.