Engine Knocking???

I have a 1994 GS300 that I recently made a few repairs (New water pump, thermostat, timing belt, serpentine belt) to. After drivng it for about 20 miles, it has started making a knocking sound that sounds like a valve or lifter towards the back of the engine. Also, about a min after I shut the car off after driving for some time, It starts to make a boiling sound in the water system. Unfortunately, my temperature gauge on the dash does not work. It drives good and coolant does circulate trhrough the system while driving. Any ideas on what the problem could be? I did just put some sea foam in the crank case and water wetter in the radiator to see if it might help....prob not but I'm crossing my fingers. Will some of you DIY veterens please offer some ideas and solutions. Thanks-

looks like you have a bad case of the hacks aka grease monkey (thay fucked your car up) sound like the timing may be off.  above all take it back and bitch like thirs no tomaro tell thay fix what thay broke!

engine knocking hey tell me something,(only those who know what they''re saying abt engines).My car knocks sometimes,is it the plugs or the distributor.Reminding you that my cars distributor has never been changed it like 14 years old???