Coolant issue

[rotohead]

I'm not certain on this but here's what I'm dealing with. I keep adding coolant to the radiator and it seems the level in my overflow bottle is increasing too. Why would that be? I'm not that educated on this issue. Can someone help me out? Is there a underlying issue here that I'm missing? Thanks for the help.

 

[NIsaacs]

You should not need to mess with your radiator cap other than an initial fill, after a coolant change. The bottle will/should keep your radiator full. If it don't, the cap may be bad or you might have a vacuum leak on the hose/bottle. How old is your cap and what pressure is it? They are more complex than you would think. They seal your radiator filler neck on the bottom and the top, with a high pressure relief valve and a vacuum valve. The hose to the bottle is in between the two seals, so under excess pressure the coolant can flow to the bottle. Then at overnight cool down the system creates vacuum and refills the radiator from the bottle.

Depending on elevation, water boils at 212*, with a 50/50 mix of antifreeze the boiling point goes up to about 223* then the pressure cap will add about 2 degree's more per 1 lb of pressure, so a 15 lbs cap will control your boiling point to about 253*

Nick

 

[rotohead]

Thank you Nick for that explanation. I didn't know that stuff. I'm pretty sure coolant is flowing from the radiator to the overflow bottle while the truck is driven. It never seems to flow the other way filling the radiator when cool. Why would it do that? I will troubleshoot some more today and the weekend. New radiator, cap, thermostat, coolant. All hoses are high quality silicone. No apparent leaks.

 

[rotohead]

So after removing the overflow tank and inspecting I believe there was debris in the molded channel on the side of the bottle. The rubber line was clear. This might have prevented coolant from flowing into the radiator. Going on a longer drive over the weekend and we'll see. I guess it makes a difference when you are removing the rad cap to view coolant level too.

 

[NIsaacs]

Are you making sure the cap is completely installed? It will stop/click half way then you have to get serious, push down and turn the rest of the way. You may have found the problem with the contamination in the bottle.

 

[rotohead]

Yes I'm sure the cap is fully seated. I bought the Mishimoto radiator and it came with a 19 psi cap. Seem like much better quality then OEM.

I'll figure it out.

 

[NIsaacs]

You can check the level anytime after an overnight shutdown. I am not sure why the liquid is not returning unless there is/was a restriction in the bottle. It is possible the cap is bad, you might try another one. Maybe the vacuum valve is somehow bad. The radiator should be full after an overnight shutdown. I doubt there is any issue with the head or head gasket as long as there is no cross contamination of oil or coolant. If there is an external leak I would think you would see it, however sometimes they can be so small the leak seems to vanish. The 24 valve is bad about leaking from the right front corner of the head gasket, check that area real good, use a flash light.

 

[rotohead]

You can check the level anytime after an overnight shutdown. I am not sure why the liquid is not returning unless there is/was a restriction in the bottle. It is possible the cap is bad, you might try another one. Maybe the vacuum valve is somehow bad. The radiator should be full after an overnight shutdown. I doubt there is any issue with the head or head gasket as long as there is no cross contamination of oil or coolant. If there is an external leak I would think you would see it, however sometimes they can be so small the leak seems to vanish. The 24 valve is bad about leaking from the right front corner of the head gasket, check that area real good, use a flash light.

Thanks for that. After doing all this cooling system work I sent in a oil sample to Blackstone Labs and they said zero sign of coolant in the oil so that made me feel a bit better. The next oil change will be the test. Thanks for all the advice. I do appreciate another knowledgeable persons opinions.