Done a compression test last week after fitting a civic rad. Got readings of 165 170 170 170. All seemed fine. Then today started it up gave it a little rev. Steam from engine bay. Both top and bottom hoses go rock hard. Pressure causing little bit of coolant to escape from turbo coolant pipe. Switch off engine to remove rad cap expecting it to explode in my face however comes off releasing the normal amount of pressure. Any other faults that can cause both rad hoses to have so much pressure. ???? HELP.