Why is my coolant reservoir full and the radiator appears to be low on coolant?

(2011-05-09 14:20:13) 1. Alex Says: I was checking my car's radiator because the car has been overheating slightly lately, and the water/antifreeze reservoir is almost in the FULL line, but I opened the radiator cap and you can see the radiator, it is wet, but you don't see liquid.... It's hard to explain, basically I can see the radiator holes, they are not bone dry, but there is no flowing liquid either.

Is this normal or what should I do?2. Michael Says: That happens when the cooling system is not able to build a vacuum to slurp the coolant from the reservoir when it cools. The usual causes are a bad radiator cap (the outer seal is bad) or a small leak in the cooling system. The drill is to replace the radiator cap first (with one from the dealer - aftermarket caps are not to be trusted) and then to look for a small leak if the problem persists. Because the level in the radiator was so low I suspect there is a leak, but rule out the cap first.3. bobweb Says: Congratulations on having removed your radiator cap in addition to checking the coolant reservoir level. Most people don't realize you need to do BOTH. All the answers above show understanding of what may be the problem. I read them carefully and hope changing your pressure cap will solve the problem, but keep monitoring it. Make sure the engine's not too hot when you use that big rag and glove to remove that radiator cap.4. Davey Says: You won't see any flow unless thermstat is stuck open. Have your cap checked at an auto parts store. A bad one won't hold pressure or won't suck coolant out of the reservoir when the car cools off. Some cars you have to bleed the air out of the system when coolant gets too low and after you top off the coolant too.5. Joe Says: It sounds like there may be some blockage in your system. You will have to have this remedied, as it can cause leaks. Take your car in for cooland service, and take it to your dealer. I know, it might cost more, but you don't want some Jim Bob putting just anything in there. The Dealer can be much more easily held accountable.6. cory l Says: your pressure cap is bad, your radiator builds pressure shoving coolant into your overflow but it doesn't put the coolant back into the radiator when the car cools off, simply get a new cap and your problem will be solved.7. Matt Hakes Says: Fill your radiator and not just your reservoir. Tag: Why is my coolant reservoir full and the radiator appears to be low on coolant?