I've been getting some unsavory smell inside my 1989 Volvo 240.
I have not been able to find any good discussions about how to clean
the cabin air or whether there is truly a cabin air filter on this car.
Any help on this would be greatly appreciated...

No leaks, no mice...
I'll try spraying with Lysol.

With all of my Volvo ( 144, 240 1981, 240 1982, 244 1991 ) over the years I removed the carpets and back rear seat during a couple of weeks or even more. This is to find the origin of any leak that will show when it is raining during the night or driving under heavy rain. Only the 1991 showed no leak.

This may show on the floor under front winshield or around the rear wheel bowl and draining on rear passenger floor.

I ended up eliminaling this rotten smell that one detect in summer when being in a car that has water leaks.

Of course it implies washing the carpets and under pads with soap and a little chlorox afterward. Then dry under the sun. Reinstall all tbat when I an convinced there is no leak left.

In your case you should make sure the heater box drain is free of debris or dirt. There are posts about how to clear it and clean as much as possible. I went there also and used a small vacuum flexible hose to suck debris and leaves through the reciculale flap. Not easy though.

Hi,

Mice would be my first thought, although their odours, both living and dead, are easy to recognize by those who live with them. An exception was one who perished somewhere inside my exhaust system and was slow roasted, but those aromas never entered the cabin.

I think there may be a potential source of foul air associated with the automatic transmission, if your car is so equipped.

Last summer I had my AW70 on the bench for a reseal and I noticed a white plastic barbed hose fitting on the very top of it, probably impossible to see when installed. Maybe a dental mirror could be worked in up there. I don't know.

The fitting faces the rear and is screwed into a 10mm tunnel in the casting that extends about 8 inches horizontally toward the front to about where the trans meets the bell housing. I assume it opens there to the inside of the trans and provides a vent.

I tried to remove the fitting but the brittle plastic crumpled under the wrench. While picking out the remnants stuck in the threads, a few pieces ended up out of reach in the tunnel. Fiddling with a wire only made it worse. I ended up vacuuming them out, but before that I very stupidly tried to draw them out with my breath using a piece of vinyl tubing that was lying on the bench.

I took a short tug and when I pulled the hose from my lips the fumes hit my nose and very nearly dropped me to the floor. It was the most vile, morbid smell I have ever experienced and far beyond transmission fluid. I don't know much about what goes on in there, but after that I don't think I want to know.

I've been meaning to inquire here since then if that fitting should have a hose on it directed to somewhere like the rear axel does. I know it's unlikely, but if those fumes were to ever find a way into the cabin even in a small amount, it would be unsavory to say the least.

regards, Peter

That's interesting! "It was the most vile, morbid smell I have ever experienced and far beyond transmission fluid."

Worse than well-used hypoid gear oil from the rear axle?
--
Art Benstein near Baltimore

I found I could say things with color and shapes that I couldn't say any other way - things I had no words for. - Georgia O'Keeffe

Hi Art,

Yes, many times worse. I deal with gear oil on a regular basis and while pungent, it's never caused me any distress.

When I was 12 or 13 years old, a wiseass friend of my brother handed me an open bottle of an ammonia product, telling me it smelt great and I should smell it. My reaction was similar. My body instinctively and violently reeled away from it.

The transmission had been drained for a couple of weeks when this happened. I wonder if oxygen or water from the air got to some place it wouldn't normally get to, and found something to react with. I don't know, but it was bad stuff.

Peter

Hi Peter,

I remember maybe 30 years ago participating in a National Geographic smell survey. It was a scratch and sniff test I vaguely recall. The results showed what a variety of reactions people had. Also within my recollection was a conversation with an engineer at Nicor, a midwest gas utility, regarding the research behind the choice of mercaptan as a warning additive, dependent somewhat on the unpopularity of its odor.

Living for a few decades, I've noticed my preference for certain smell memories have changed, mostly based on their associated meaning for my safety and life. For instance, ammonia turned from a diaper pail memory to one of window washing. Not saying which is more pleasant. But having never been directly sprayed, I enjoy skunky odors. Probably based on good time with skunky beer?

Now I dislike the syrupy smell of antifreeze, as it reminds me of a coolant leak. Diesel smells good to me because I know that's one smell that it isn't coming from my car.

I wonder if your transmission's odor is from burned ATF? Best guess I have, given how disgusting the smell of burning engine oil is to me. (Don't park the lawn mower on a slope during a break)

Daring to check the odor at this AW-71's vent nipple, all I detected was the reminder of a good experience, flushing the fluid, and a bad experience, taking a bath in it under the car. The latter is a much more distant memory, thankfully.


--
Art Benstein near Baltimore

Everyone seems normal until you get to know them.

I apologize to the OP for breaking in but just had to respond to Art's last post regarding odors. My own involved some well used gear oil spilling from the tailshaft of my $10 1960 Plymouth Valiant's 3 speed transmission. I was a 2nd year college student working in the school parking lot and had never changed a clutch before. I had no idea of what to expect when laying on the ground directly below and pulling the driveshaft out. Stupid me -- and my favorite shirt besides. 20 washings couldn't get the stink out. - Dave

Aside from a car sporting Swedish Baklava's cowl vent filter/cover design, a 240 has no provision to filter the incoming air.

Take care to keep homeless rodents from finding a way in.


--
Art Benstein near Baltimore

Birds are grouchy in the morning because their bills are over dew.

I was under the impression that the 200-series doesn't have a cabin air filter.
Not sure about the models with AC.

Check for damp carpets. I have encountered coolant leaks, windshield leaks, leaks on the wiper spindles...

First I'll get the obligatory response out of the way, which is have you tried eating fewer beans? Now that's done -- does your 240 have air con? If so, any blockage of the drain tube can lead to smells and overflow onto the carpet. The water on the carpet tends to flow all the way to in front of the back seat. The drain tank and tube can be accessed by taking the side panel off the center console. On my RHD car it's accessed from the driver's side. It's a very tight spot.