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Radiator not working

I have an 2003 honda odyssey that does not draw the antifreeze from the reservoir back to the radiator, took it to two mechanics first one flushed the radiator the second one pressure tested it, that came back fine they then fill it with antifreeze and said it was low this worked for about six months now its doing the same thing. It doesnt run hot but sometimes I get a gurgling noise when I take off. When I check the water level usually the extra in the reservoir tops the radiator off so it doesnt seem to be leaking but sometimes I smell antifreeze outside my vehicle

Sometimes the simplest of answers are overlooked. Have you put a new radiator cap on it? A bad cap can prevent coolant from being drawn back into the radiator. The overflow tank on Honda’s is not part of the sealed system, so if it’s overfilling with hot coolant, you might smell it. When the system is low, gurgling might be heard. Are you the original owner? Mileage? Has it ever overheated? The cooling fans on Honda’s do fail, has this been an issue in the past? I would have the most faith in a factory Honda radiator cap, not aftermarket. If this doesn’t solve your issue, let me know, and I’ll go a little deeper into possible causes.

Check for combustion gasses in the radiator…(blown head gasket)

I had this problem with a 1993 Oldsmobile 88. I found that the hose between the radiator and the reservoir would collapse when I shut off the engine and the coolant wouldn’t be drawn from the reservoir to the radiator. It was a quck 5 minute fix with $2 worth of hose.

If you do consider Caddyman’s suggestion about checking for combustion gases, it’s a simple enough test that you might be able to do it yourself. I found Autozone has a tool lending program where the tool for this test is available for free (but you have to buy a chemical for a nominal price). If you have an Autozone nearby, you might inquire about this simple testing device.

It has 187,000 I bought it with 122,000 from the original owner the second shop only works on Hondas they filled it with a special funnel. That worked for a couple months it doesn’t overheat. I replaced the radiator cap but it was an aftermarket one not a Honda one

Since you say you smell antifreeze at times it sounds to me that you may have a small pressure leak somewhere. That would explain why the coolant level was found to be low and not pulling in the coolant from the reservoir. Check for a leak while the system is hot, coolant level is full, and the engine is running. Some dye may need to be added to the coolant in order to find the leak.

It could be the radiator cap, but it also could be in the bottom of your overflow tank. Prior to 2003, the overflow tank had a hose that hung down from the overflow tank cap to the bottom of the overflow tank. If this hose either fell off or cracked near the top, you would have this problem.

But by 2003, I think all Honda’s were using an overflow tank that had the tube molded into the side of the tank instead. The problem with this is that the molded tube would go under the bottom of the tank and open to the center of the tank at its lowest point. Great for getting maximum use of the tank, allowing a slightly smaller tank, but if something that is heavier than the coolant falls into the tank, it can block the tube like a one way valve.

The quick fix here is to just remove the overflow tank and wash it out. Blow out the tube with compressed air or if it is cleaned enough, you can use your mouth. Make sure it is clear and unobstructed.

I had this problem one time, and in my case it was the rubber hose between the overflow tank and the radiator that had broken slightly, allowing the necessary vacuum to escape. Be sure to check that hose carefully, especially where it connects to the radiator, and to the tank, for any cracking or breaks. There’s also a possibility the fluid path is plugged up somewhere between the top of the radiator and the bottom of the tank. It may be necessary to remove the tank and test the entire path with one of those hand-held vacuum pump gadgets.

The overflow tank hose is a good point, Honda still uses a hose in it’s vehicles. I apologize for not suggesting it be checked, but a good Honda shop should know to check it, sometimes they will fall off into the tank,so coolant can’t be drawn back into the radiator. the next option, as has been suggested by Caddyman, is checking for a blown head gasket.