I have a 1998 Mazda B2500 that has clocked more than 211,000 kms already.

My first question is before I had my 210k+ PMS, I started to hear a kinda weird and loud rattling/clunking like sound in the engine bay. At first I thought it was the flexible so I went to the shop where I had it replaced with a brand new one. They said that my flexible is still good and no signs of wear and tear and they think the sound is coming from the engine. When I brought it to my trusted shop for PMS, I told it my trusted mechanic and he said that by the sound, it needs calibration. I just don't remember the part that he said that needs to be calibrated, but it sounds like "injection" something. He also added that the car will not stall but the longer it takes, the louder it would become. More 1k+ kms after, it's still there and yah, I think it's getting louder but the duration of the sound is the same, I guess.

That sound appears 10 to 15 seconds every time I start the car, most especially when turning the aircon on and after that, I will not hear until the next start up. The sound is like a worn out or about to wear out flexible. There are times that it wouldn't make that sound.

For my second query, at the bottom of the passenger side, I noticed that something is leaking since it is making this circle wet marking. At first I thought it was just water dripping from the bed but it left a stain and everyday that same parking spot, it has wet marking. I tried to smell it and it's has a mild gas smell. From the naked eye, I didn't see any leaks.

The third inquiry is at an uphill, I could feel that it is somewhat having a hard time going up. I don't know if I am just used to the common rail engine but really, I have to rev up to more than 3000 rpm just for it to go up.

On flat roads, once it gets its momentum, I don't have any problems with it. The only thing is once it gets to 80 kph, it takes a very long time to get to 100 kph and even longer time to get to 120 kph and once it reaches 120 kph, that's it, it couldn't go any faster.

I have just replaced my fuel filter with an original one from Ford about 5,000+ kms ago and it has pump. Air filter, I haven't replaced it since but a lot of mechanics told me that it's still good and it doesn't need replacement yet.

I just wanna know what's your stand on my questions especially on the 1st and 2nd questions. Thanks!