Fan shroud

i replaced a fan shroud on a 2000 mercedes benz s430 but it does not seem to kick in when it gets hot. what wrong?

A bad fan clutch? Is it electric or belt powered? The shroud only helps if the fan works like it should.

I’m impressed by your question decoding powers, you must have the patent Car Talk question decoder ring…

It’s possible the poster disturbed the water temp sensor or fan wiring connection when fitting the new shroud I guess. S430 has 2 electric fans, the left is the rad fan, the right is the condensor fan. The rad fan is activated by 1 one of 2 fan switches.

If the connections are good, he’ll need to chase the circuit with a meter to pinpoint the problem.