The same question has been asked at islam-qa and answered Sheikh Muhammed Salih Al-Munajjid
My parents have taken out a mortgage for a house sometime ago, they are currently paying interest on this loan. But now they have decided to go on Hajj, they still have 15 years left on the loan. Is it permissible for them to go on Hajj even though they owe money? Or will they have to wait 15 years first? Can they in the meantime do Umrah if it is not permissible to do Hajj? Answer:
It is permissible for them to go for Hajj if they pay the installment that is currently due, and they do not have to wait until they have paid all installments. If they are able to pay the current installment and are able to go for Hajj, then it is obligatory for them to do so. The same applies to ‘Umrah. They also have to repent to Allaah from the riba which they have taken upon themselves. And Allaah knows best.
Sheikh Muhammed Salih Al-Munajjid (www.islam-qa.com