JD 6415 Hydraulic light comes on after couple of hours bush hog work

Thomasstewart · Sep 27, 2013

Just changed hydraulic fluid and filters and everything works well but hydraulic temp. light comes on after couple of hours bush hog work. Radiator is clean and fluid is at proper levels. Only thing not done is check oil cooler. The drawing shows it inside a bell housing. The owner manual says clean the oil cooler but is there a way to get at this without having to take apart?

Zebrafive · Sep 28, 2013

The oil cooler is located behind the torsion damper on the flywheel. It is NOT in a bellhousing. It is aluminum and is water (engine coolant) to oil cooler. It has two oil lines and two coolant lines going to it. The drive shaft from the engine to the trans goes thru it. No fins to clean. The engine has separate thermostat for this cooler. The engine oil cooler and charge air cooler are also in this coolant circuit.

I would try replacing the temp sensor.

Thomasstewart · Sep 29, 2013

Thanks. I had thought of replacing the temp sensor. The thermostat by the water pump is for the engine cooling? Is the hydraulic oil side thermostat on the opposite side of the engine not where the water pump is but where there are sensors located? When the bottom sensor is unplugged the hydraulic oil temp light goes off but a beep begins to go off. I assume that is the sensor to replace. Could the thermostat on the oil side not be working properly if sensor is not the problem?

Zebrafive · Sep 29, 2013

In this drawing key #4 is the thermostat for the engine oil cooler, air charge cooler and hydraulic cooler.
Which transmission option do you have? I am thinking the sensor would be located on the transmission, but might depend on what trans you have.

tthopskin@yahoo.ca · Sep 30, 2013

if it runs good a after a few hrs it heats up i would say check your oil level and filters .ether one of these will heat up your oil good luck

Thomasstewart · Sep 30, 2013

Thanks. The drawing is very helpful. The sensor that turned the light off is on the side opposite the drawing you sent. A very large coolant hose is running out of the top of the part. I believe there were two types for 2005 6415. I have the latest type. Will get both sensor and thermostat today and try.

Thomasstewart · Oct 28, 2013

Thomasstewart said:
Just changed hydraulic fluid and filters and everything works well but hydraulic temp. light comes on after couple of hours bush hog work. Radiator is clean and fluid is at proper levels. Only thing not done is check oil cooler. The drawing shows it inside a bell housing. The owner manual says clean the oil cooler but is there a way to get at this without having to take apart?

Problem solved. Without notifying owners, JD redesigned the thermostat for the oil cooler because, you guessed it, the light would come on. After doing everything except replace the oil cooler (cheapest one I found was $1200.00) I finally decided to replace the oil cooler thermostat and found out that it would solve the problem of the oil light. It would have been nice if the dealer had told me that this was a problem on this model. It did show in their computer when I said I was replacing the thermostat because nothing else had worked, that the thermostat had been redesigned because of this very issue. Replaced, and now ok.

Zebrafive · Oct 28, 2013

Thanks for the update. What was the old and new thermostat part numbers? I guessing my 2006 has the newer part number, but in case I have the same problem, I would like to know. Thanks