yes most old diesel engines have this little tube about 1 or 1 1/2 inch in dia installed in exhaust pipe. mostly found in jeepneys but i also have this in my van, very useful to clean the exhaust pipe. Just fill up until water comes out from the tail pipe, for better result yu can add kerosene it will soften the carbon deposits. Mas maganda kung ibabad mo muna for an hour before starting your engine. Then rev your engine up to 3,000rpm. This is proven effective.