Where can you find instructions on how to install a heater core in a 1990 Oldsmobile 88 Royale?
chiltons auto repair manual
remove both hoses from the heater and join them with a short piece of pipe about the size of the inner diameter of the hoses. use 2 hose clamps to sealed and hold the hoses on the pipe. Or- cut the hoses and do the same type joining. later you will need another pipe and two more clamps if you want to rehook it to your heater core.
I have a 1992 Olds with the 3800 engine; the block heater is almost inaccessible. The engine is sideways and the block heater is in the frost plug location just over the frame at the back. Suggestion: unless it is leaking just take the frost plug out in the front of the engine and install the block heater there where it is accessible. Duane