I've had my truck for a little over a month now and it won't heat up. It'll run about 150 155 tops. I've taken it on the highway for 40 miles turning 2100 and it'll only hit 155 (approx) on the temp gauge. I'm pretty sure it's the thermostat but not sure. It won't heat up, the heater blows warm never hot, and she's going through coolant. went through about a quart in 500 miles. Luckily there's no signs of coolant in my oil I've checked it a lot lately, all my hoses and everything are good and I've yet to find a leak anywhere other than the oil and I havn't seen a diesel yet that doesn't leak a little oil. But does anybody have any other Ideas on what it could be? This is my first diesel and I'm not too familiar with it yet and you guys know your stuff so I figured you're my best bet. any input is a big help. Thanks in advance.

 

change the thermostat, that is the heat up issue, and while your there it normally helps to flush the heater core with a garden hose, as far as loosing coolant, check all of your rubber hoses and clamps, i bet one has a small leak, and they normally only leak at first start up

 

alright, thanks for the answer i figured that's what it was but wanted some piece of mind. thanks for the help.