the other day I noticed that when starting the 400 that it made a squeking noise while the starter was turning over.I dont know if its the starter or something else.Any ideas?

 

The older Polaris quads have a poorly sealed starter and if you open it up I'm sure you will find it has been sitting in water and that it's rusted. It even says in the manual, that after riding deep water, you should drain the starter.

 

If it isn't rusted bad, you can take the drive apart & grease it. It is all to common with the older 400s. Polaris even makes a special 'starter drive grease' just for it.