Private purchase do I have warranty? significant defect

A bought a car for 1000 euro from B Privat 4 days ago.A noticed on the same day that the car loses coolant.A Was after 4 days in 2 workshops the A made a cost estimate of 700 euro for the reperature or exchange of the heaterCooler is the defect.A believes the Privt salesman B hit him over the ear because B had driven the car himself only 2 weeks after he had bought it from a dealer.A believes the Käu A has now asked the private seller B to take the car back or to take over the repair costs, B does not want to do this.B says he did not know anything about the damage.In the purchase contract it says (Committee of Guarantees”>Guarantee”).This committee does not apply to claims for damages arising from liability for material defects which are based on intentional or grossly negligent violation of obligations of the seller.)Has A a c Is it necessary to give the dealer the B 1 year guarantee from which the car was bought from the B 4 weeks ago?Is the warranty of the dealer from B to A the third one?Or does A now remain on the harm as the last stupid sitting alone? I would be very happy about an answer. MfG Omega