Thanks, Ed.
My hydraulic reservour had a new filter and fluid last year, thermostats are less than 10 hours old, and the air restriction guage runs at about 8"Hg, so I've mentally eliminated those as causes. Also the radiator and CAC fins are clean.
If I read you right, you're saying that once the wax valve turns the fan on, it stays on, but speed does vary with engine (pump) rpm.
I have read about folks with a 2 speed fan that goes to "high" when the engine temp reaches normal levels. Am I misinterpreting something there?
Thanks for the help
Andy
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I'm not sure if all coaches are similar. I believe the way mine works, based on several temperature monitors on my computer, is the wax valve sends little or no fluid to drive the hydraulic fan motor until your engine reaches temperature. In my case that is 194F, in Gerald's case maybe 188F. It would appear that once the fan motor is turned on it stays on and the engine thermostat then controls the engine temp.
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Given the hydraulic fan is run off of the hydraulic pump, there would be some variation in pressure with RPM, but you were holding high RPM so one would expect adequate pump speed and pressure. You may want to start looking for simple things that can change over time that could limit the cooling before going to the main components. The radiator is clean so next might be the hydraulic filter. If it was plugging some that may cut the fan speed you could achieve. The engine thermostats may be not fully opening is also a possibility. Not sure if a restricted air filter might limit the speed you could attain and impact intake air flow and cooling affect and help drive the temperature up. These are some of the things that come to mind.
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Later Ed
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