Use the Correct Radiator Cap!
billofdurham » This post is to be read in conjunction with Update your Radiator Cap! 2/7/9/series.
The following models, year and engine designation DO NOT take the later cap which is rated at 1.5bar. Using the later cap WILL cause damage to these cars.
240
B200K ’84 – ’89 0.75 – 0.85bar
B230A ’84 – ’88 0.65 – 0.85bar
740
B200K ’84 – ’89 1.0bar
B200E ’88 – ’89 0.75bar
B200F ’89 – ’92 1.0bar
B230K ’84 – ’86 1.0bar
B230E ’84 – ’89 1.0bar
B230F ’86 – ’91 1.0bar
940
B200F ’91 – ’95 1.0bar
Why Will A Cap Damage an Engine?
waydar » Can you explain why the 1.5 bar cap will damage the engines on your list? Thx., Wayne
billofdurham » The engines listed are designed to run at lower pressure. Using the green cap will increase the pressure, in some cases to double that recommended. A high-pressure radiator cap puts greater stress on the rest of the system (clamps, hoses, gasket surfaces, and so on).
Raising your radiator cap’s pressure above factory specs increases your cooling system’s maximum operating pressure above design parameters. While raising your cooling system’s maximum operating pressure does raise it’s boiling point and, therefore, helps to avoid boil-over, it does not lower your operating temperature prior to boil-over, and simply allows your engine to continue to operate at temperatures higher than it is engineered for. Water boils at 212 degrees, and for each pound you raise the system pressure it raises the boiling point 3 degrees – Example: The 0.75 bar (11 psi) cap will have a boiling point of 245 degrees. The 15 bar (21) psi cap will push the boiling point to 275 degrees. Operating an engine at higher than acceptable temperatures can destroy it.
Bill.
