OK, I'm used to a 10 year old car having rattles and whistles and creaks.
But this one has me stumped. drive the car and it gets upto temp and stays there fine, and drives great, although the temp drops on motorways so it suggests the stat is stuck open (which might help the crap economy when fixed). But when in traffic and at town speeds, the temp stays at the right place, and the fan kicks in keeps things proper, no hint of overheating. Coolant is still good, clean clear and red.
But Ive noticed, that when at traffic/town speed/fan cycling, if I boot it, it still boosts as before, but there is occasionally a little bit of a rattle from somewhere that only happens when at the upper end of normal temp (fan cycle). If you get moving again, and then boot it so air is flowing, no rattle.
I thought pinking, but I noticed yesterday after doing a bit of work, that it did it sometimes when not at boost, and even when at idle.
Also, it is really loud if in the car with the window down, or lieing on the floor next to the sill while revving the engine, but not do loud, or barely audible if you stand over the engine revving it.
I'm sure I can even hear it louder at the tail pipe, that at the engine.
In the car, it seems to come from down, and infront of the drivers seat. basically exactly where the engine/trans/exhaust runs.
The sound is hard to describe, it sounds like a pea in a coffee can being shaken arround, or as if someone had placed a ball bearing on a biscuit tin lid and put the lid on a subwoofer, so both the lid and the bearing are vibrating at different frequencies and both increase if it is revved.
If it is pinking, why is it doing it at idle. I'm changing the fuel filter tomorrow, as I already bought it and the one on there looks like it has been arround since pr-ice age. But surely it couldn't be leaning out too badly or it wouldn't boost fully, would have exploded in the last 3 months, and would run far hotter than even the fan could handle?
Little help hear guys.