I own a 2006 v8 Jeep Commander. I had the radiator replaced about 1 1/2 months ago. I drove it across country and then was careful to check all the fluids.

About two weeks ago, I checked it and the reservoir was up to the fill line, I opened the radiator cap and couldn't see any water in it. So I filled it full. The next day I checked for leaks after I left work and nothing. I went home checked the radiator again, and again I had to add more water.

The vehicle hasn't overheated at all. I am having to refill the radiator every night. I can not see any leaks and there is no puddles before I drive. Please help I would like to keep my jeep and fix the problem.

  • Welcome to the site. If you are near the exhaust while the vehicle is running, can you smell antifreeze? Have you checked the oil to see what it looks like? Jul 4, 2017 at 23:43

2 Answers 2


Sounds like your coolant system has air in it, as was mentioned by Daniel. He may have told you what was wrong, but did not provide a solution. Technically it's an answer but obviously it's not quite satisfactory.

First, try putting a piece of cardboard under your engine to be double sure no coolant is leaking out. Even a small leak or loose hose can drain significant amounts over night. The cardboard not only shows more clearly if you have a leak but also where it is coming from.

Next, to purge the air from your system, take off the radiator cap and run your vehicle from cold or warm (NOT HOT). Turn your hot air in the cabin on to full blast. This will open the valve that prevents coolant from leaving the engine before it is warm and circulate your coolant, and in turn will expel the air from the system.

If you continue having problems, have your oil looked at by yourself or a mechanic to check for coolant in the oil. An internal leak could mean no drips on the ground but still loss of fluid. Your oil will look white and milky if there is coolant in it. If this is the case you will want to have a professional look at it to assess whether it is a head gasket, etc.

I hope this helps you in identifying and remedying the problem!


It could be there is still Air in you cooling system. Do a proper draining of all the air in your cooling system. Some cars have drain valves for that. Remember fully engage the heating while doing it.

If you still lose water and see no leaks, have your coolant tested for co2. You might have a blown head gasket.

  • Welcome to the site. If you believe this may be the issue, you might want to tell the OP how to go about purging the system of air as well as what to do to test for hydrocarbons in the radiator. A well thought out complete answer will go a long way with the community and be looked at as a "good" answer. Jul 5, 2017 at 12:58
  • As the OP had the radiator replaced e.g. did not do it himself, i´d suggest he does not do the other things himself either. Find someone with the knowledge and the tools to do it. Failing to do it properly can wreck the engine.
    – Daniel
    Jul 5, 2017 at 13:15
  • That's why we answer questions, to pass the knowledge onto others. That's what this site is all about, bringing the knowledge here for others. Jul 5, 2017 at 13:31
  • Yes the question is: "Why do my waterlevels drop after changing radiator?" not "How do I do reapir procedure XY?"
    – Daniel
    Jul 5, 2017 at 13:36
  • It's just a suggestion to provide an answer which will be better accepted. Jul 5, 2017 at 13:37

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