notaguru

This '83 US spec has only 68k miles on it, but the exhaust smells like a 49 Ford that needs a ring job.

It just passed CA smog. It drives perfectly and idle is smooth.

Where should I start looking?


...or is it just the smell of a normal 1983 car?

dr bob

If it just passed Cali smog, the offending fragrance may not be coming from the inside of the tailpipe. Unless it smells like rotten eggs, a sign of catalysts slowly setting in the west from poor fuel. Oil fumes generally don't trip the hydrocarbon limits. Does the car use oil? As much as that '49 Ford that needs the ring job? Telltale would be the mini blue-gray plume following you as you move through slow traffic.

notaguru

Burns no measurable amount of oil, but I haven't had it for long. No sulfide smell. No smoke.

No leaks, so nothing is dripping onto a hot spot.

I think it's all exhaust.

RennPartsDirect

My '82 stinks when the engine gets hot. Not so much from the exhaust but more of a hot engine smell. Like old rubber that needs to be replaced or fluids that have settled on top of the engine and are burning off as the engine heats up...

Mrmerlin

is the O2 sensor new? is it a factory part

notaguru

Records show that O2 sensor is 30k miles old, and is correct.

GlenL

This is colorful but is it accurate?

What color(s) of smoke come out the tailpipe at start and when running?

notaguru

After rest, a cold start produces a tiny puff, almost colorless - water vapor? When running, no smoke at all even under hard acceleration (observed from a parallel car).

GlenL

I'm not sure you have a problem.

notaguru

You may be right.
For decades, exhaust has been getting cleaner and cleaner. Maybe I should just tolerate this...

And yes -- the garage door was open.

The Deputy

Well...with the car anyway...lol.

But, seriously. What is the fuel quality like, has it been in the tank for a long period of time? If so, maybe add some type of additive of your liking and run a tank or two through it.

I've only noticed a peculiar smell in my exhaust when buying a bad tank full or burning off old winter storage fuel.

Brian.

notaguru

Refurbished tank, new filters, flushed lines - all at 67k when bringing the car back into service after years of storage. Which reminds me: no dead animals.

928 at last

I've run mine for seven years now......exhaust smells...worse in the morning when the car's cold.
No smoke and passes smog religiously.
I'd suggest ignore it and drive faster to leave it behind......

dr bob

There is always those first minutes after a cold start while you wait for the HEGO (Heated Exhaust Gas Oxygen) senor to actually heat up enough to run. The controls default to some set value until that happens. Some folks are tempted by lower cost into splicing in a non-heated one-wire replacement sensor, meaning there is a longer initial period after start-up when the LH doesn't get good feedback.

There's some cat 'light-off' delay, as the engine exhaust warms the catalysts to get them to operating temperature. From different experience, I know that the CO portion of the catalyst doesn't start working effectively until the support media reaches somewhere north of 400ºF. The NOx section has different requirements. I haven't lloked at the function of that part of the catalysts to determine the light-off requirements, nor those of the HC reduction section.

The fuel brain offers a richer mixture when the engine is cold, mostly to make sure that there's enough fuel vapor available to support combustion. A portion of the fuel spray ends up condensing on the cold metal surfaces of the head and the intake runners. Once that metal warms up, no more condensation and the mixture is brough to back to normal. Along with the light-off requirements of the various sections of the catalysts, this function drives the recommendation to make sure the engine is at full operating temperature when you have a tailpipe test done.

Any or all of these things can easily result in stinky exhaust when the engine is first started cold. It's also the reason why car manufacturers recommend that you don't sit and allow the engine to warm up slowly from cold. While the engine itself loves a slow warm-up, the exhaust is pretty ugly during that time, until everything is closer to design operating temps.

notaguru

Dr. Bob - as usual - has provided super information. Thanks!

But Rob's advice is perfect. Drive fast enough and you can leave the smell, and most problems of the world, far behind. Over 80mph, even a radio report on US politics becomes tolerable.