Selling a vehicle without disclosing the details

I have bought a car from an British person by seeing advertisement in facebook. Hr have mentioned in the add good condition. When I go for checking he have informed he is the second owner. We have transferred the vehicle without any further negotiations. But next day itself car started to emit plastic smell and smoke, I have taken the vehicle to service centre for checkups and they have informed there's oil leak for engine also engine overheating they have suspected along with radiator leak. I have informed the old owner to take the car back and pay my cash after some deduction 150. He have refused saying it was in good condition. When I checked found that the car was imported to Oman and he didn't inform us that. Also found some leak under the car in his Facebook post which he used for sale. Any possibility to get the money back as he have not disclosed the details and vehicle was not in working condition.

No chance. Once the transfer happens it means that both buyer and seller have agreed on the "as-is" condition of the car.  Its your mistake to not check the car before......when buying used cars, the buyer has the right to have a garage check the car (at his own cost).