New 400 Cummins Over heating!!!

Lucchese1 · 07-20-2005, 07:31 AM

On the last trip with almost 10000 miles on my new 05 horizon coach 400 cummins, I was pulling the Sherwin grade in the Sierras towing my cherokee, even in third gear at high rpms the temp just started climbing untill i got the low ecu coolant shut down engine light (never saw the temp previous over 210 on any climb). I pulled over right away and high ideled to cool down, when checking the coolent level you can not see the level through plastic tank, so stuck a pencil to find the level, bone Dry, had to add two gallons of 50/50 mix to get it to register,and on the next trip it now wants to run at over 220 on almost any steep grade. I can not see a leak any where so did I get this coach 2 gallons low on coolant or is there a way for the coolant to slowly leak out. Going to factory in 4 weeks for one year appt. but is there somthing I shoud do before, Thanks for any help!!!

Lucchese1 · 07-20-2005, 07:31 AM

On the last trip with almost 10000 miles on my new 05 horizon coach 400 cummins, I was pulling the Sherwin grade in the Sierras towing my cherokee, even in third gear at high rpms the temp just started climbing untill i got the low ecu coolant shut down engine light (never saw the temp previous over 210 on any climb). I pulled over right away and high ideled to cool down, when checking the coolent level you can not see the level through plastic tank, so stuck a pencil to find the level, bone Dry, had to add two gallons of 50/50 mix to get it to register,and on the next trip it now wants to run at over 220 on almost any steep grade. I can not see a leak any where so did I get this coach 2 gallons low on coolant or is there a way for the coolant to slowly leak out. Going to factory in 4 weeks for one year appt. but is there somthing I shoud do before, Thanks for any help!!!

doc · 07-20-2005, 08:48 AM

Ben I cannot say what your problem is, but when we bought our Horizon new in 2000 there was a clamp that was not tightened right (or enough maybe) It would not leak until the engine was warm and then it was just a drop, but a slow steady drip. The guy at the diesel shop who changed the oil the first time found it and fixed it for us. I got a buzzer a couple of times for 'low coolant' on steep grades when the coolant would move away from the sensor in the filler tank. Quart or two of AF would fix it.
Two gallons sounds pretty serious however. I'm sure you have looked at the oil dip stick to make sure there is no milky looking oil on it, indicating water in the crankcase.
Good luck - let us know what the final is
doc

07-20-2005, 09:44 PM

....run a compression test and a coolent test and an an oil analsys also.....geofkaye

07-20-2005, 09:45 PM

also a fan cycle test...see if it is coming on under overheating/hot situations....geofkaye....it's a diesel not a gasser -there are differances

CalTex · 07-21-2005, 08:47 AM

Ben, you may not be the only one with this problem. I talked with a Monaco owner (his was brand new) a couple of weeks ago who was having serious overheating problems. He had been to the shop twice without any problems found. He was on a cross country trip and was having to stop every two hours to let the engine cool. I think his was a 500 Hp Cummins.

Lucchese1 · 07-21-2005, 08:56 AM

I checked everything that would make sence to check on the cooling system along with water in the oil, plugged or dirty rad. I just got off the phone with a diesel mech whom has the same make and year coach having the same problem witch he said sould not be occuring. He said that at the altitude that I over heated 7800', pulling a heavy load and at the high ambiant temp outside, fluid was probly low to begin with and the rest was released through the cap, and more that likely there is a design flaw with the cap, fan or fan speed and should look for a fix from freightliner coming soon as more people experience the same problems! Hope so until then I will watch it closer

Strega · 07-21-2005, 11:31 AM

Pressure test the cooling system. If you were 2 gallons low and reached that temp there is a good chance you cracked the head. A cracked head will make it run hot. Most auto supply chains (AutoZone , Advance and the like) have a tester and will check it for you

07-21-2005, 07:52 PM

....cracked head in a diesel will cause a miss like you won't believe....maybe a 50% power loss and the computer will go into limp mode and shut it down in 30 seconds it save the engine....red lites will almost blind you and warning horns will ring in your ears for days.....it's something simple you just got to find it!...fluid-fan temp setting/sensor-radiator cap-short in wirning circuit-program glitch.....otherwise you would be one the side on the road......good hunting....geofkaye