1991 Mercedes-Benz 420SEL Radiator Replacement Cost

A sub-performing Radiator has far reaching effects. An inoperative heater, loss of coolant, or engine damage from overheating could occur. Overheating causes severe damage to an engine, including failure of the head gasket. Continuing to drive an overheating vehicle may disable the motor.

Replacement intervals vary greatly by vehicle and driving conditions. We typically see the radiator replaced at approximately 80,000 miles. While the radiator does not wear the same as a belt or brake pad, the repeated heating and cooling cycles the radiator experiences will eventually cause the degradation of its plastic end-tanks and seals.

A comprehensive inspection of the entire cooling system will be performed, including the water pump, heater hoses, cooling fans, and thermostat. With the engine off, the technician may perform a pressure test to ensure the cooling system is sealed. Radiator hoses will be inspected and should be replaced if old or leaking. Brittle or oil soaked hoses will fail after radiator replacement, necessitating additional repairs. If the engine has overheated the shop will inspect for signs of engine damage. Modern engines commonly have composite (plastic) parts such as intake manifolds and thermostat housings that can warp from engine overheating. These parts, along with the head gasket, should be checked for leakage.

To replace the Radiator, the technician will drain the coolant from the cooling system and remove the Radiator and radiator hoses from the vehicle. This may also require removal of plastic shrouds and other engine bay cladding to reach the part. Where applicable, the cooling fan switch and electric cooling fan assemblies are transferred to the new Radiator. Once the new Radiator is installed, the cooling system is refilled with fresh coolant and the system is bled of any air, then rechecked to ensure all leaks have been fixed.

The coolant should be refreshed according to manufacturer maintenance recommendation, with the correct coolant type. If the repair is being performed by a shop, we recommend asking if the cooling system was pressure tested as part of the diagnosis. Also ask if the radiator was determined to be clogged or leaking. Find out why it failed (Separation of plastic end tank? Damaged fins?). Find out if there were any resulting damages from overheating, or if other parts like belts, hoses, or the thermostat should be replaced at the same time. You can also ask to see the old parts.

First and foremost, check that the Radiator or Coolant Reservoir are filled to the correct level of coolant! A low coolant level will continue to cause issues even after suspected parts are replaced. A proper diagnosis of any cooling system issues should be performed, including a pressure test to check for leaks. A stuck thermostat, leaking head gasket, or even a failed radiator cap could cause an overheating issue. Depending on the age and condition of the cooling system, related or conveniently located parts should be replaced at the same time. Hoses, fan clutches, thermostats and thermostat housings, and any other component that requires draining the cooling system to service and are near their end-of-service life should be replaced. Also, refrain from using any “leak stopper” products in your cooling system. While they may appear to save money in the short term, their ability to stop leaks will also eventually clog and stop circulation in the cooling system. This could affect the radiator, heater core, and engine coolant passages. This clogging will cause the engine to overheat from insufficient coolant circulation, and can be extremely costly and difficult to fix.

Repairing your own car is an extremely rewarding process that can also save you money. But before you dive in, it’s important to be sure the issue has been properly diagnosed. Seemingly obvious symptoms can lead the inexperienced down a rabbit hole of replacing parts that don’t fix the problem. Proper diagnosis can save more money than guessing at what’s broken! If you're unsure you have the right tools or experience to diagnose a problem, consider reaching out to a RepairPal Certified Shop. The vast majority of Radiators only require simple tools to replace. However, the procedures vary wildly from car to car. Before ordering parts or attempting this repair yourself, look online for guides on how to replace the Radiator in your specific vehicle. Some will require removal of the front bumper, or significant disassembly of the front end of the vehicle in order to extract the Radiator. Special procedures may also be required to fill the coolant and bleed the air out of the Cooling System.