Hi

I have a recently-purchased `78 300D, in general in very good condition.

My only small gripe is that there is an unusual intermittent smell. Presumably coming from the airvents but difficult to tell precisely as it seems to intensify at random times (i.e. uncorrelated with brake or gas) while I'm driving.

The smell is hard to identify. Not diesel. Nothing burning. I had just put it down to `old car smell' when I test drove it, and maybe it is, but it isn't dissipating after a couple of weeks, afaict.

Other possibly salient facts are that it disappears when I run the heat or the aircon (which still works perfectly, btw). Which I find slightly baffling. Maybe the air vents just need a good clean out. But if there are common leaking fluids or just a list of common odour-causing problems I should check for, I'd appreciate it. Don't want to be gassing myself while I drive!

Thanks forum,
-J

Dead rodent in the heater ducts?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I thought about it! I'm probably just going to give them a good clean-out, to make sure

But with anything like that, wouldn't the smell get worse when I turn on the heat or ac? It's confusing.

We are having the same problem on the 300TD right now. I noticed that the AC isn't draining much water with the AC on, so I think it might be funky wet AC vents due to a clogged drain?

The smell isn't there with ACC off. Too hot here to test the heat part of it.

I looked under the car for the AC drain tube last night, but didn't find it. I will try to look for the drain with the AC running (look for the drip) next time I fire her up.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

I'm thinking mold or mildew in the ductwork. I've driven several vehicles that didn't have a smell from the climate control as long as you had either the heat or the aircon on, but when you switched it to vent, it stank, especially if you had just been running the AC.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

A mouse crawled up in my wagon last summer and died!! It was just unbelievably horrible!!!! I couldn't drive it for 2 months, and there was still a faint odor a couple months after that.
I never did find the dead body........
I hope your smell is something else!

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Could just be the old horsehair seat pads, they have a distinctive "old German car" smell.

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

typical things that off gas will give of a set number of scent molecules regardless of how much air is rushing over them (dead animals excluded). It takes so many molecules for your nose to be able to smell them so when you turn the heat/AC on it has the effect of diluting the smell. It is still there probably, just not in sufficient quantity for you to smell it. I would look at window seals and the afforementioned AC drain.

__________________
2003 Dodge Ram 2500 Cummins - Georend fully built trans, Banks Big Hoss Bundle, Smarty Tuner, 5" turbo back exhaust. 500 HP and 1100 ft/lbs to the ground.
1979 Mercedes-Benz 300CD - Lost to a four car pile up on 275, Thank You Michigan Drivers.
1986 Mercedes-Benz 300D - Sold, Euro non-turbo car.

I have the same problem after eating certain foods.:-}

__________________
1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

I wonder if insurance covers Legionnaire’s disease.

Once while driving an old Neon, a smelly fog came out of the vents. Turns out it was freon.

__________________
1982 300CD Petrol/Black Leather

My 1985 300td had similar problem. The short piece of drain sleeve that leads out of the bottom of evaporator box had rotted. It seems as if it were made of foam or something? This was causing water to seep under the floor mats on the driver side everytime the ac was used. The car had a terrible musty smell that would take a week or more to go away. After quite some time, I finally found the source. The tube was located just above the transmission and sandwiched under the evaporator box. The right driver side kick panel covering had to be removed for access. As I recall, it was not easy to remove and replace this tube. I also had to carefully measure the length of the new tube as the space would not acccomodate excess length. The tube material needs to be flexible yet water proof. I found some handle bar covers that I removed from my old Puch 10-speed bicycle that worked great. They were made of neoprene - like scuba suits, sewn into a tube of the proper diameter (Spenco, I believe). The water seemed to drip from the back of the hole so I put the stitched side facing forward. I was lucky to find a suitable tubing material and think that is critical unless there are original replacements available. That was about ten years ago and I have not had a water problem or musty smell since. Except, the other week when my stupid flexible coors light promo cooler leaked melted ice water in the cargo area. Old wet wool carpeting does not smell good!

I was chasing a fan vibration on my old W123 240D, and I found a petrified mouse inside the blower.

Try some Febreeze inside the housing. Worked for me.

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Great inormation robk!! I am going to go dig around for that tube today.

__________________

Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT