If you are new to Mercedes Diesels and own a 1985 model 300D 300TD 300CD or 300SD you may often get asked if your engine has a trap oxidizer. This will come up when you try to order parts. We thought it would be helpful to show and explain the difference. Not all 85 models had a trap - even some early 1984 California models did! The EASIEST way to identify this model is by the location of the air filter housing. As you can see in the first picture the air filter assembly is mounted off the engine and up behind the right headlight.
Problem & Solution
Common among these chassis:
The reason for this location change is due to the fact they had to mount the turbo higher in order to get the trap (for diesel soot) under the turbo. In the picture below you can just make it out. Hard to see - silver unit just below the flexible coupling at the exhaust outlet of the turbo. Always let the parts supplier know you have a trap oxidizer when ordering engine parts.
If you have one of these models check with your Mercedes dealer to see if your trap has been replaced with the improved version under an old recall. If not ask if they are still honoring the recall on the trap. You may just end un getting a new trap and turbo. If the old oxidizer starts coming apart internally it can damage the turbo charger blades.
What about installing an earlier non trap manifold assembly on your engine and getting rid of the trap oxidizer all together.??? All the parts interchange except ...you will run into one small problem and that problem is on the oil pan. The oil pan with the trap system does not have the tube sticking up that allows the drain of the 83 air filter housing to go back into the pan.
If you can figure out a way to leave the 85 air filter on near the headlight you will be ok though.
So I hope you understand the challenge. If you have the 83 manifolds, turbo, exhaust pipe, etc. other than that pipe the change is straight forward. If you use the air filter assembly that mounts on the engine you will need to figure out a way to vent that air fillter housing tube back into the engiines oil pan. We have no recommendations as we have not done this conversion before.
PLEASE NOTE: The turbo rebuild kits we offer are the same for both the trap and non trap GARRETT T3 turbo chargers. Slight differences will be encounter when we removing the turbo from the engine.