Hi all,
Just had the radiator flushed a few weeks ago. The next day I noticed some coolant leaking underneath the car, so I opened the hood and noticed the leak was occurring around the radiator cap. I replaced the radiator cap and took it back to have it checked. They observed no leak, but topped it off anyway. Now two weeks later, the overfill still has the coolant at the hot level whether the engine is cool or not, so it is not draining back into the radiator. Once again, I had a pressure check done, both when cold and when hot and still no leak was detected. Also, I checked the oil and it looks fine, so no internal leak noted. The car runs fine, although, I did notice that under mild acceleration uphill, I do hear something that sounds like air in the water pump. Any suggestions? Thanks in advance for any advice.

I doubt there is much of a problem if any at all. I would monitor the coolant temp via the diagnostic parameters just to see what temp the engine is running at when at NOT.

you need to burp the svstem,take the cap off when cold start the car, watch the neck of the radiator to see when the thermostat opens, when it opens shutthe car off , top it off if needed, replace cap, done

Hi all,
Just had the radiator flushed a few weeks ago. The next day I noticed some coolant leaking underneath the car, so I opened the hood and noticed the leak was occurring around the radiator cap. I replaced the radiator cap and took it back to have it checked. They observed no leak, but topped it off anyway. Now two weeks later, the overfill still has the coolant at the hot level whether the engine is cool or not, so it is not draining back into the radiator. Once again, I had a pressure check done, both when cold and when hot and still no leak was detected. Also, I checked the oil and it looks fine, so no internal leak noted. The car runs fine, although, I did notice that under mild acceleration uphill, I do hear something that sounds like air in the water pump. Any suggestions? Thanks in advance for any advice.

If coolant supplement has been added to the reservoir it could plug the hose which connect the latter to the radiator neck. Check it out.

How full is the radiator and the tank? If the radiator is full, it won't draw too much back in as it cools (some, but not a lot). If the tank was filled to the top, it will overflow when it heats and expands. It should be only about half full. Otherwise, the cap is bad or you replaced it with the wrong one. Does it have the little inverted bottle cap on the underside?

Thanks all. Per your suggestions, I will siphon the coolant from the overfill tank into the radiator. If it fills when heated, then I can rule out a clog. Will keep you posted. Thanks again.

Probably the wrong cap or bad design. You need a cap with a relief valve in order for it to expand into the overflow bottle and suck coolant back out. If you do not have a relief cap the coolant will simply boil over at the cap. Also, I used to have a relief cap with little arrows and it would only work when the arrows on the thing were EXACTLY lined up--if they were off by even a little bit the coolant would boil over at the cap instead. Last year I bought 13 lb relief caps from NAPA for both my vehicles and everything works perfectly. The only way to tell the difference between them is that relief caps are about 2x the price of non-relief caps.

Thanks all. Per your suggestions, I will siphon the coolant from the overfill tank into the radiator. If it fills when heated, then I can rule out a clog. Will keep you posted. Thanks again.

A formed plug can act as a valve. Will let coolant to the reservoir but would not let back. Check it out with a piece of wire.