Our charming 87 300TD has turned into an unbearable experience for my wife. It has developed a smell, rather like cleaning fluid, that appears under certain specific circumstances and then goes away . . we can start this car (and it runs fine thank you) and drive away and everything seems find. If we take it on the freeway all is good - no smell. As soon as we decelerate a smell akin to cleaning fluid appears in the cabin. Turning on the air recirc button will reduce the smell in the cabin. [Yes we also checked the drain for the condensate - it's clear]

I have removed and examined the vents on the cowl - there is nothing in these areas that could contribute to the smell. I've had a mechanic, that I use for the heavy projects that I don't have time for, investigate and he can't find anything. During this process the fan motor went south and had to be replaced - with that opportunity to investigate the innards, he again found nothing.

We recently had an issue with the 4-5-6 injector lines all rubbing on each other and eventually rupturing - replacing these did not solve the smell, though now it seems as though the smell is closer to diesel . . we thoroughly washed the engine compartment - nothing and it was pretty clean in the first place. I'm down to two possibilities: first that there is some problem with the fuel tank venting or second that there is some problem with the seal at the cowl to the hood (source of fumes?).

Thanks for reading and appreciate any feedback.

Craig
Santa Rosa, CA
83 300D
87 300TD

Pretty sure it diesel you're smelling.
Doesn't take much, just find where it's wetting under the hood. Look on the belly pan. Get under the engine bay and look up. Also
Watch for drips or spraying while the engine is running and everything is circulating.

__________________
Cheers!
Scott McPhee

1987 300D

Remove the trunk liner, inspect the fuel fill OVERFLOW HOSE for damage.

Inspect the trunk seal and all drain grommets for damage.

Inspect the turbo, exhaust manifold to head and exhaust couplings/pipes for damage or leaks.

Remove the fuel fill cap, inspect the gasket for damage.

Remove the fuel level sensor, inspect the O-ring for damage.

Inspect the steel - rubber fuel lines from tank to engine.

Remove the fuel tank vent valve, test drive to see if the issue is gone = plugged valve = developing tank pressure.

############################################

What is this valve and why is it dripping diesel?
http://www.peachparts.com/shopforum/diesel-discussion/317902-what-valve-why-dripping-diesel.html

Fuel tank vent pictures + location
http://www.peachparts.com/shopforum/2878700-post39.html

What happens when a tank vent gets clogged.
What happens when a tank vent gets clogged. - PeachParts Mercedes ShopForum

Imploded fuel tank - so sad!
http://www.peachparts.com/shopforum/diesel-discussion/314457-imploded-fuel-tank-so-sad.html

Why do I have vacuum in my diesel tank.....................?
Why do I have vacuum in my diesel tank.....................? - PeachParts Mercedes ShopForum


.

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

If not a fuel related problem, it could be a/c related. A small leak in evaporator can leak out a/c oil which has a strong odor. I had this happen on E320 and confirmed it by adding dye to refrigerant. A sniffer would have done it, but I took a digital pic of the evap drain tube - It shows up as fluorescent green.

__________________
Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Thank you for this.

Fuel overflow line has been inspected - no problem.

No trunk seal - it's a TD

Fuel fill seal is OK - no obvious damage.

--

Your last three items are the ones that I have on my list to inspect. I'll post the results. Thank you.

cg

O-rings in the Delivery valves on the ip. Common problem.

__________________
Dan
1981 240D
1987 300D Turbo
1973 220
Das Beste Oder Nichts

Hmm, not likely for the o-rings. New IP as of June 2011. Sad story is that the rear bearing on the IP camshaft disintegrated while about 150 miles from home. Going up a nice long grade on 108 to Sonora when it started running funny. But it ran sorta . . the bearing exploded and as the balls came out the cam pushed them through the access cover releasing oil on the engine. Not recoverable.

Are you sure it's not anti-freeze? This could be a leaky heater core or hose.

In a last ditch effort to have our guy take a look at it, just before we take it in I looked under the hood, and just as obvious as it could be, the return fule lines at the injectors are quite wet. Once they are replaced, it's alos apparent that the pressed in fittings on the #6 injector are also leaking which means replacing the injector. Funny thing, the smell is gone . . . so yes a diesel leak that couldn't have been more obvious. Thanks to all.