Hi All, First time poster after being a BMW CCA member for several years! My ‘99 E36 M# (S52 engine, Z4M radiator, Stewart water pump) has been showing traces of coolant spray after several HPDE sessions. Traces of coolant around the expansion tank cap, and sprayed around the right side of the engine bay. Stock temperature gauge stays solid in the “Normal” range. Also get the “Check Coolant” message, with no significant coolant loss. I have swapped the expansion tank cap, bleed the cooling system several times, and have pressure checked the cooling system. (Pressure solid at 1.5 BAR for an hour). The coolant level seems to increase with a cold engine that has been sitting overnight. I heard some pit talk that there could be possibility that the coolant may be reacting with the metals in the engine block, creating hydrogen gas? I appreciate any thoughts on this! Thanks, JBM
This may not be your problem, but...the stock coolant expansion tank filler neck threads do not extend completely around the neck. Over time, the opening can become an oval instead of round, possibly causing the expansion tank cap not to fit properly. So you might be putting your new, round cap over an old, ovate opening. Worth checking, perhaps.
The car has the Z4M radiator with the side expansion tank; those have the issue with the necks deforming too?
