slow coolant leak???

[gradylaw]

The coolant level in my overflow tank has dropped to 1/2 inch below the add mark over the last couple of months but I can't find any leaks. Been all over & under the truck. I smelled coolant in the cab real strong a couple of weeks ago (I'm sure it had to be me because I was driving along the coast with a sea breeze). Haven't smelled it at all since but the level keeps dropping.

I'd like to have a clue what's up before I turn the dealer loose on it.

Any ideas?

Thanks









2001. 5 2500 Quad 4X4 6 spd, 16k mi. Totally stock for now

 

[JPittman]

Mine ('99) was doing that. Had it pressure tested and it passed, no leaks. Just had Cummins do a change of coolant and they told me that it would take a few heating cycles for the level in the overflow to stabilize, just add if needed. They also said that the level may vary depending on the ambient temperature. To have a peace of mind do a pressure test just in case.

 

[LSMITH]

I would get an oil analysis ASAP to make sure it is not going in the oil. If you run it for longer drives you can boil all of the water and glycol out of the oil from a small leak, a larger leak will obviously make the oil milky and cause a lot of damage. Run the oil for at least 2K miles and sample it, see what it tells you. At least at that point you will know if it is safe or not to continue driving. If it is a small leak internally you will be looking for TBN depletion and potassium and/or sodium levels to be elevated as the water and glycol will likely not be present in quantities large enough to be detected. I found out I had an internal coolant leak about 6 months ago, it is very small and I change the oil at 4K miles or less to keep the oil healthy. If I had not done an analysis I would have not known and could have done some damage. I still have the leak and have not fixed it, but I sample regularly to keep an eye on it. It will be fixed soon as I have all of the parts on hand now.



BTW, call the analysis company and make sure they sample for potassium and sodium, as well as report the TBN or you could waste the money on a sample without adequate reporting. Hope this helps.

 

[gradylaw]

I changed the oil a couple of weeks ago and it looked normal but I will get a sample checked after I run the new oil a while. Better safe than sorry!

Thanks for the advice.







2001. 5 2500 4X4 H. O. 6spd, 15k mi. totally stock for now

 

[TomGolden]

As LSMITH recommended, take an oil sample as soon as reasonably possible.



My 2001. 5 ETH truck did the same thing, at about 5 or 6K miles. I posted the same question here. Several members suggested it was likely just air in the heater lines, and that after I had run the heater a good bit, and kept re-filling my overflow bottle, it would likely reach *real* full level (no more air), and it did. I haven't had this problem ever since.



I also remember a few others posting the same question, so we are not the only ones to see this.



Tom