Originally Posted by jauguston
Actually engine speed does vary fan speed in the most common hydraulic driven fans. The pump out put varies with its speed and that relates to varying fan speed.
I don't know if they're all the same, but my old side radiator fan does vary speed up to a point. I guess as the fluid flow increases, so does the fan speed but it seems to hit a max at a certain engine RPM which probably is related to some maximum fluid flow rate or pressure relief valve, etc.
FWIW my coolant temp stays at 180 degrees regardless of conditions. The transmission temp stays at 180 also unless I sit at a red light for a long time then it will increase to about 200. I've also seen the transmission temp rise a little bit when climbing steep hills at slow speed within a state park, etc. I try to speed up enough to get torque converter lock-up in 2nd gear to prevent the temp rise but it's not always possible.
Apparently, the torque converter makes a lot of heat until lock-up.
Sorry if my post rambled on.
1994 Holiday Rambler Navigator