You cannot make a weak password stronger without using some additional entropy source. Hashing it does not add any entropy and therefore the resulting password is just as weak as the one you started with.

Also using some "secret" hash algorithm is a bad decision since you are basing you security purely on keeping the algorithm secret. This means you cannot discuss it with anyone or give someone else access to you algorithm. Once it leaks out, you need to change your complete setup since all secrecy is within the way the algorithm works. This is called security by obscurity.

You cannot make a weak password stronger without using some additional entropy source. Hashing does not add any entropy and therefore the resulting password is just as weak as the one you started with.

Also, using some "secret" hash algorithm is a bad decision, since you are basing you security purely on keeping the algorithm secret. This means you cannot discuss it with anyone or give someone else access to your algorithm. Once it leaks out, you need to change your complete setup since all the secrecy is within the way the algorithm works. This is called security by obscurity.