Originally Posted by Ivanerrol

Have you had the cooling system pressure tested?


These are old cars. Water pumps have probably deteriorated on all three cars.
I've had the same problem on W124's I've owned and then made the misfortune to install a cheap PRC water pump. Replacing a water pump on the M103 is a job you only want top do once.


After two less than effective pumps I bit the bullet and installed an OEM Graf. Never had an issue after. Even 40+ degree (110F) days, the auxiliary fan hardly came in.

And I'll put my habd up as well and recommend the Sachs fan. Beware there are a lot of cheap fan knockoffs with the Behr name on them.