Hi gang,
Been noticing my 450 ISM Cummins has been running either normally at around 185-190 or slightly warmer at 205-210 regardless of OAT. Of course pulling hills it goes up some, never over heats and returns back to one of the two temps once crested the hill. It only resets to either normal or hotter after engine shut down so I thought maybe the thermostat was hanging up. Installed a new one and for the first few trips seemed normal, then returned to running normal or warmer again.
I did install a new radiator a few years ago, all new hoses, rebuilt one hydraulic fan and resealed the pump. Baffles are all new, no dirt in the radiator, all looks good.
I ran through some testing that I thought I would share to help others.
The side radiator has a Wax valve or temp control valve mounted to the top aft inboard side.
Being certain the system is being regulated to either normal or slightly higher and knowing the thermostat has been changed figured this Wax valve looks suspect. I called Monaco and they agreed, they said it was a 85 day wait for the part and about $1200.00
I searched the local Sauer Danfoss distributor and found the same 85 day wait but a better price at $411.00
Searched the internet via Google and found a couple over seas in England for abour $100.00 plus shipping.
I ordered the valve from Whitehouse Hydraulics in England via Fed X, two days later I had it in hand, $160.00
I am almost positive the engine is being "regulated" to either the normal temperatur or the elevated one because it goes there and basically stays there till the engine is shut down and recycled through a cooling period. In either case I thought I would test the fans before ordering the valve by testing the hydraulics at the valve.
I assembled a test gage and ball valve to change the fan speed manually and test the pressure.
What happens is the hydraulics run from the pump, to the fans and back again. When the temp or Wax valve detects elevated temperaturs it starts to restrict flow to the control valve on the master fan (I have two fans, others might only have one) which directs the flow of hydraulic fluid into the fan motor to speed them up. The hotter the coolent in the radiator, the more the wax valve restricts fluid to the motor which speeds the motor up. Another way the control side of the hydraulic fluid is regulated is a full on electronic valve which is in series with the wax valve. Basically if the ECM detects a certain coolent temp, it turns that electric valve on which causes the hydraulics to be blocked off thus causing the fans to run full speed.
At full speed the pressure should be about 3050 P.S.I. or 210 BAR at the fan inlet.
I measured the pressure at the Wax valve inlet which tends to be slightly less and measured 2700 PSI, fans full on (and REALLY screaming, wow) at 1700 R.P.M. engine speed, warmed up.
The little red valve on the test gage is very sensitive because the flow to the control circuit is very small, just a slight movement and you get a big fan speed change.
Basically just moving the valve from open to closed causes the fans to run very slow (open) to very fast (closed) with a linier operations between open and closed. The fans work great.
It might take several trips to determine if this corrected the issue so I will report back later.
Also, in trouble shooting this I found that some people have similar issues however normally the Wax valve tends to fail in the closed position causing the fans to run in the full on mode all the time, hot or cold.
Hope this helps someone
Windecker
Linear Mode
