Still Overheating

[briansteinkerchner]

I have a 1995 Patriot with the 8.3 Cummins.  The engine and transmission both begin to overheat when driving highway speeds with a temperature over 95 degrees.  I cleaned out all debris between the radiators and it helped the overheating a little.  There is not guard/duct/? between the vents on the side of the motor coach and the radiators.  There was nothing there when I purchased the unit.  It looks like something was there originally.  Is something supposed to be there?  If so can someone provide a description or picture?  Could that be the cause of the overheating.  The radiators are 22 years old also.  Should they be replaced even though they do not leak?  Any ideas or help would be appreciated. 

[Steve Huber Co-Admin]

Brian,
I'm not familiar  with your particular coach but have a couple of general observations. First clean the radiators. Wet them down and spray them with a mixture of Dawn dishwasher detergent and water. Let it work a few minutes, and hose it off completely. Try as best you can to get both sides of the radiator. Use a garden hose, not a pressure washer as they can bend the fins. Most of the debris will probably be outside the diameter of the fan itself. I think there should be baffles around the radiator to cause the air moved by the fan to come through the radiator and not around it. Maybe a member with a similar coach can confirm this.
Steve

[Gerald Farris]

Brian,
The only guard/duct that is needed is the fan shroud that forces all of the air that is drawn by the fan to travel through the radiator assemble.
 
To diagnose your overheating issue, you need to determine that the cooling system is full of coolant first, then determine that the fan control is operating properly (fan engages at operating temperature, and obtains high speed). These two things are the most likely issues, and they are the easiest to check. However, if both of these items check OK, you will need a more involved diagnostic process to check coolant flow rate (thermostat, restricted radiator, water pump, and belt), and fan RPMs. 

There is no reason to replace your radiator on an age basis only. However, if the fins between the tubes have deteriorated excessively, you loose cooling efficiency from the radiator and a recore may be necessary even if it is not leaking or restricted.       

Gerald

[Dave Atherton]

Brian, it is possible on your heating problem you could have a Check valve on your engine
oil cooler sticking or stuck. Next engine thermostat not operating correctly. Engine oil cooler
location on the right side of engine looking from back of engine to front or on driver side and
engine thermost top front on driver side. Both easy to get to. Dave Atherton Retired Cat Mechanic

[briansteinkerchner]

Is there a way to easily check the fan to make sure it has two speeds?  Does anyone know what controls the fan speeds and where that control is in the engine bay?  I tried cleaning the coils and that helped some on the last trip.  However it still goes to 200 then overheats on long climbs when the temperature is over 90 degrees.  It also looks like I am missing some sort of cover that goes between the bottom of the side vents on the exterior of the RV to the bottom of the radiators.  The other three sides are all ducted to the radiators and some plastic is broken on the bottom and there are screws with nothing attached.   Thanks

[Dave Atherton]

Brain, the pieces missing from bottom of fan shroud yes would affect your cooling on engine.
The fan shroud the way it is made and mounted allows for max cooling while engine is running.
It sounds mainly under load engine temp comes up and it will with parts of shroud missing.
Dave Atherton Retired Cat Mechanic

[Gerald Farris]

Brian,
If you are referring to the air dam between bottom of the radiator and the outer coach panel, it is only there to reduce the amount of dirt and grime that is sucked up into the radiator from the roadway. It should not effect the cooling system performance, except that the radiator will get dirty faster, so replacing it is a good idea.

The hydraulic cooling fan is controlled by a wax valve (thermostat) that will be located in the coolant flow between the engine thermostat (upper engine coolant outlet) and the radiator or in the radiator tank on the inlet side. If you need help in locating it, Spartan chassis technical support should be able to tell you where it is located. Since wax valves are so expensive, I would make sure that you properly diagnose the system before you start throwing parts at the problem. Throwing parts at a problem without taking the time to diagnose the issue is usually the most expensive repair method.

Gerald