i purchase a lightly used 2004 trek 7500 a few months back to start riding again. ebayed a bike stand and the couple of specific bike tools need i went thru all the mechanics and have it working fine. Today i heard a crunching clicking noise sounding as if it my be from the crank area. There is no noise when run on the stand.

question 1 : is how do i check this out ?

question 2 : are the bearings serviceable or just replace ?

I did google it but did not find any usefull information

Thanks for any help, Larry

To check out, first check your pedals and make sure if you have cages, that these are tightly bolted onto the pedal body.

Next, if the problem persists, you need to open the BB to inspect cups, spindles and bearings. Read up on BBs with Sheldon Brown for your type of spindle. Basically, you'll need a tool to extract your cranks, then one or two to loosen and remove the BB cups to then look inside. If you have a std. sealed cartridge bearing BB, usually the spindle is fine and it's the bearings that have pitted inside. With traditional cup and bearings type of BB, you should check and replace the spindle if pitted. It may be cheaper (around under $20) to get a new UN55 type BB if that's the type your takes.

Thanks for the info, it's greatly appreciated. I have no problem with replacing any parts, how do i find out what type BB i have ??? Email Trek or just take it apart ???

thanks again

Look here to determine which type you have.
https://www.parktool.com/blog/repair-...ottom-brackets

or here
https://www.sheldonbrown.com/gloss_bo-z.html#bottom

Most likely that is a cartridge type. specs say "isis" type spline
something like this.
https://www.google.com/products/catal...ed=0CFkQ8wIwAQ#

Once you determine what you have you need the proper tool to remove it. Then inside they are usually marked with the specifics like "68x113" "shell width x spindle length" That bikes bottom bracket is without much doubt English threaded.

Thanks for the helpful info and links ... guess i need to order a crank puller and go from there ...