In some cases, for some cars, it is possible to get a clear suggestion if enough information is provided.
In other cases, it is nearly impossible to get an indication of the problem.
Noises don't come through the internet very well, although posting a recording will help in some cases. If the noise is a mystery rattle that no-one can find, then the internet probably won't help much.
If your car is overheating, again, posting in a forum may not help much. There are many things that could be wrong, from a thermostat to a head gasket to a leaky water pump. Shotgunning new parts at the problem based on guesses from novices isn't good practice, and isn't a methodical way to fix a problem.
The internet/forums can help if there is someone reading who is familiar with a specific situation that might be common to a certain model.
It can help if there is a bulletin that addresses the problem being struggled with.
It can also help if the poster is slightly more handy than average, with some background knowledge.
It is likely that some suggestions received, while well intentioned, will need to be ignored by the original poster, as people will post suggestions to check parts that the car isn't even equipped with.
Hopefully we can still help, just remember that the internet isn't a panacea. There is no replacement for a skilled repairperson getting good information from the vehicle owner, and the repairperson getting their hands on, i.e., getting a feel for and testing the car.
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