Are they any cooling lines be hind the engine of 1997 surburban?

Yes, a 1997 Suburban (assuming a Chevrolet or GMC model) will have several cooling lines behind the engine. These lines are part of the vehicle's cooling system and carry coolant (antifreeze/water mixture) to and from the radiator, engine block, heater core, and possibly a transmission cooler if it's an automatic transmission. They're usually rubber hoses and/or metal pipes. The exact configuration and number of lines will vary slightly depending on the engine (e.g., 5.7L, 7.4L) and options (e.g., towing package).