I filled the res. to the full mark when I replaced the thermostat, then topped it of after I drove around to make sure it was full. Today I see it's 1" above the low mark after about 11 days since the last fill. Don't see any smoke during idle first thing or after it's warmed up. Temp gauge holds steady, heater blows hot, w/ no temp fluctuation. I don't see any leaks around the water pump, along w/ no puddles under the truck. I figured it used about a gal. in the time frame. Last time I had it in to have it looked at was for an injector problem and they found an overboost condition. Had something like 50lbs recorded in the ECM. Anyway, I hope I didn't weaken the head gasket, or stretch head bolts, which I'm sure I can re-torque, maybe? So where do you suppose it can be going?

 

was the radiator full when you topped of the res??

 

Yep! I even went as far as leaving the cap off and started it while cold. Never seen any bubbles or coolant run over. Maybe it is the water pump and it's real hard to see the leak. FIIK!!!

 

The 06's were prone to leak out of the rubber connectors on the passenger side of the block. I'm not sure it would actually pouddle up though. You might want to crawl under your truck and look at the block near the wastegate of your turbo. There will be two hard lines that have rubber connectors on them. Check to see if there are signs of leaking. Other than that the only other leaks I know that were common was the overflow tube as it leaves the filer neck. The hose leaks around the nipple. I ziptied mine and it hasn't leaked since. I know guys boosting these CR's into the 60's all the time and not heard of one gasket comng loose. Too much drive pressure, injector timing and things like water/meth and NOS kill headgaskets. Boost alone is not so hard on gaskets. Especially at 50 PSI or less.

 

what has your oil level been like i know 06 diesel has a head gasket that is allowing antifreeze to leak into his oil. i would get a oil analysis and see if the potassium level is high

 

Stays just under the full mark. One gal over 11 days, that's a pretty small leak.

 

I would leave it at that mark, put a small mark on the tank and see if it gets lower over the next week. Also get some dye and put it in the antifreeze. This way you can find your leak easier. I would also recomend a oil analysis just to be on the safe side. That is how I found out about my HG being blown. I smelled antifreeze for a while before noticing the oil level being high, then the sample confirmed this. I am pulling my head tomorrow to confirm the HG failure, hopefully this will be the first and last time my head comes off.

 

Good time for studs. Good luck.

 

I had the same problem with my 06. I found exactly what staarma described. I bought my truck used with 25k and wondered why there was a line marked on the resevoir. I found the leak on the rubber hose on the passenger side of the block, tightened the clamps, and have had no more problem. Never saw any drops on the ground, noticed any smell, etc. Also had the leak on the overflow hose, just clamped it with a ty-rap too.

 

I have an 03 cummins in a American Tradition RV. We took a trip out west from the east coast this summer and were losing coolant, about 2 Quarts every 200 miles all the way to Denver. Had it pressure tested in Denver, no leaks. continued to leak about the same amount as we drove around out west. No white smoke, engine purred. Ran about 190 degrees on hills, about 160 otherwise. We were figuring it was a head gasket, but the last 600 miles we did in one day, all down hill or flat, running at 160, we didn't lose any coolant. Now I wonder, is it is possible that running under load is going to cause me to lose some coolant? How to explain this? I think I will have the oil test done. Any ideas?