you are not liable to pay debts of deceased grand father 

2) if you have inherited any property from your grand father you are liable to extent of your inheritance 

1. The residual Legal Heirs of Grand Father (GF) are liable for the third party Civil liabilities, ONLY IF the said legal heirs would stake claim/rights on the GF properties, as inheritance rights.  Further the Lenders can stake claim via a Civil court suit, ONLY upto Three years of due date of promissory note, due to the Limitation Act.

2. To the Exception of above, the residual legal heirs are NOT liable for the Civil liabilities left /created by GF, in anyway whatsoever.

No you are not liable to debts of your GF.

However, if you have inherited any property of your GF your liability will be to the extent of share you received.

Before concluding, check the date of said loan, if it is more than three years from date of execution and date of demand, then it will be time barred.

NO. 

Only in case you have inherited any property from grand father.

When debt was taken by grand father ?

If the properties left behind by your late grandfather devolves ion your father towards his share, then upon his intestate death the said properties shall devolve on his own legal heirs which includes you and your siblings including your mother.

Therefore, in view of the properties inherited from your grandfather and in the absence of your deceased father, you and the other legal heirs of your deceased father along with your father's siblings shall be jointly liable to repay the said loan, however it is has to be proved before court without any doubt. 

Your liability shall be equal to the share of property you have inherited and not beyond that.

It appears the loan was unsecured one and if that is so then on death of the person his legal heirs are not bound to repay it unless and until during his lifetime the court passed the money decree. 

So you are not liable to pay the debt of your gran father in the present circumstances.

Only if you have inherited property from him otherwise no

See you and other legal heirs of your grand father are liable to pay debts of grand father upto the amount / value of inheritance they received from the grand father.

You are not liable to pay the debts taken by your grand father . Recovery can be made from his estate which he may leave behind and which you inherit

1. Yes you are liable to pay the debts taken by your late grandfather.

2. But you are liable only upto the extent of assets inherited from grandfather.