Everything in the Philippines wants to corrode or rust away. Even if your car is sitting in the garage and out of the rain, it will rust. It is easy to get pin-holes in sheet metal, especially the muffler and exhaust system. If this is the problem, you should replace it with stainless steel. I assume you'll want to keep this car around for many years, and stainless is worth the extra cost. You could have some fabricate a new exhaust system for you.

Anyway, it always smells like diesel smoke in the Philippines since everyone drives a diesel!