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HP Indigo Digital Presses - Imaging Oil Overheat


The HP Indigo Press reports the Imaging oil temperature too high message.
Chiller temperature, coolant flow, heat exchanger and cooling valve seem normal. Chiller water pump pressure may be higher than usual.


The hose that is connected from the imaging oil tank to the heat exchanger has a severe bend in it which is not visible because the hose is insulated. The hose will develop a crimp and needs to be rerouted to eliminate the crimp that is restricting oil flow to the heat exchanger and causing imaging oil overheat errors. Routing the hose to change direction will take out the crimp in the hose.
  1. Verify that chiller filter is not clogged, coolant lines are not kinked or otherwise restricted, ball valves are open, chiller temperature is in the 40 F degree range and pump pressure is normal.
  2. Verify cooling valve on heat exchanger is working, heat exchanger is not clogged.
  3. If you have the chiller flow and temperature jig MJX-1625-51, try placing it in series with the press, or remove a coupling from the jig and try it on the press. If the problem is solved replace defective coupling or couplings
In general, when the imaging oil filters have been used for average of 500 thousand impressions or clicks, it is time to replace them even if there is not any imaging oil overheating errors, as a preventive measure.
The customer can also empty the imaging oil reservoir and refill with fresh oil every filter replacement as a preventive action for all presses.
If after imaging oil filters replacement the overheating is not solved, check the chiller.
The following is applicable for customers who have an external water filter located at their chiller with two pressure dials.
The customer with an external water filter without dials should do a preventive change at 500 thousand to one million clicks.
The following is applicable for customers who have an external water filter located at their chiller with two pressure dials:
Both dials (in and out) should read almost the same at the external water filter. If the difference is too large, a strange noise may be heard at the chiller. The reduction of the flow will prevent the heat exchanger to have sufficient capability to chill the imaging oil down. Also on the newer presses, the ink temperature of the inks will be slightly raised due to the same reason.
Replacement of the water filter is required.
If, after imaging oil filters replacement, the imaging oil overheating is not solved check the solenoid.
Due to pollution it might be stuck and a light tapping on it might resolve it.
Or else initiate the solenoid multiple time using the software (version depended).
If the solenoid does not respond, then the replacement of the heat exchanger or flush is required.
On the 5000 and 7000 the temp sensor is on the IOC board. On the 5500 the sensor is in the IO tank and is connected to the IOC. The IOC board may need to be replaced.
Only send engineer with flushing kit after all previous is validated to be working fine.
Check the large brass quick connect couplings that connect the chiller lines at the press may be defective. There is a small spring loaded button valve inside the male and female parts of the coupling. When coupled together, these push each other open allowing coolant to flow. If the spring associated with these buttons become weak they may not open the valve completely restricting the flow of coolant which results in overheating. Also make sure the chiller input and output lines are correct to the press
The Figure below shows these valves:






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