Mercedes Sprinter 311, 2002 model, no internal bulkhead. Rear part of exhaust was replaced with a shorter version some time ago, which has a short bend at the end pointing to the RHS of the vehicle, terminating about one foot behind the trailing edge of the sliding side door. Side door does not seal properly and the bottom edge has a gap about 6-10mm wide between it and the body. Could fumes be coming up into the van through this gap while driving? The van is used to transport dogs and the driver complains of fumes in the vehicle. Some dogs have shown signs of inhaling fumes also. The door has always had this gap but the problem has only started some time AFTER the exhaust was changed.
The driver has said that she believes that the exhaust fumes, when she was aware of them before (eg, standing near the exhaust exit) were not always as noxious as they appear to be now. Is there anything I can do which would affect the content of the exhaust fumes (clean EGR valve, air filter element, injectors, etc.)?
Vehicle has covered approx 180,000 miles since new.
Hello and welcome to JustAnswer!
With the exhaust exiting under the vehicle now and the gaps at the door it will definitely allow exhaust fumes to enter when sitting or possibly at low speeds. When stopped with the engine running the exhaust will collect underneath and then move upward and can definitely come in the gaps at the door. I would highly recommend having a tailpipe installed to get the exhaust out from under the vehicle, preferably all the way to the rear bumper.
If exhaust fumes are stronger now it could be a few things. The catalytic converter may have lost efficiency and is no longer doing it's job. It's possible that injectors could be an issue, especially at high mileage, but that would often come with excess smoke, higher fuel consumption possibly some hard starting and extra combustion noise. I'd definitely check the air filter if it's in question and cleaning the EGR valve won't hurt. These do get plugged with carbon and it impedes their operation, I've seen them come in not working and no fault codes had set.