over heating after engine out?

i have a ranault traffic camper van. The clutch went. I took it to a grarage who had the engine out. The garage rang me and said you need a new radiator. I said "the radiator was OK when I brought the vehicle to you, put the old one back." The garage phoned me again and said you need a new clutch slave cylinder, so I paid for it. when i got the vehicle back it overheated badly and the water bubled in the resevoire. i took the thermostat out. this did ot solve it. there is no emulsified oil on the oil filler cap or on the dip stick. the head gasket was ok when i took it to the garage. did the garage get "a lump" and steal my engine and replace it with a bummer with a u/s head gasket. is there a special way to bleed the water system. is there anything else it could be. my vehicle is petrol, 1985 1647 cc