Let's look at the numbers on keeping the old house.
If you sell it you will get €240,000
If you keep it, the annual cost of keeping it is:
€170,000 @2% = €3,400
€70,000@4%= €2800
Total interest cost c: €6,200
If interest rates rise by
2%, the additional cost will be €4,800
So it will cost you around €11,000 in interest.
What rental income after expenses can you expect to get?
We don't speculate about house prices on askaboutmoney, but if you think house prices will fall further ovre the long-term, you should add this to the cost.
Giving up a cheap tracker is tough, but unless you can rent it easily for at least €15,000 a year, I would be selling the property.