Engine Cooling System Question

Don't get all caught up in it. The cooling system shouldn't leak at 16psi or even 25psi for that matter. Just make sure it's not a hose that's connected to the radiator that's leaking.

Kurt
Hey Kurt,

Thanks for the post and the advise. I purchased an oem rad from autozone along with a new upper & lower hose, and clamps. I wanted to cover my bases as best as possible.
 
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Good call man. Especially on the new hose clamps. Those stock hose clamps are only good for inventing new swear words. I swear the company who makes them gets a kick back from Band-Aid brand. A lot of people swear by the stock size radiator. Just remember, 50/50 antifreeze and distilled water. Hose water will clog your radiator up again.

Kurt
 
Good call man. Especially on the new hose clamps. Those stock hose clamps are only good for inventing new swear words. I swear the company who makes them gets a kick back from Band-Aid brand. A lot of people swear by the stock size radiator. Just remember, 50/50 antifreeze and distilled water. Hose water will clog your radiator up again.

Kurt

Got it. In fact, I have all 50/50 antifreeze ready to go. I was thinking of filling the overflow take w/straight antifreeze. Yes, no?
 
Got it. In fact, I have all 50/50 antifreeze ready to go. I was thinking of filling the overflow take w/straight antifreeze. Yes, no?

You're supposed to fill it to the cold line, which by this time will covered in crud, and un identifiable. Just fill it with 50/50, same as the rest. Put as much as you want in there, and don't worry about it. It will just push out what it doesn't want through the overflow tube.

Kurt
 
You're supposed to fill it to the cold line, which by this time will covered in crud, and un identifiable. Just fill it with 50/50, same as the rest. Put as much as you want in there, and don't worry about it. It will just push out what it doesn't want through the overflow tube.

Kurt
Yes filled with crud is right! In fact, it was so nasty that there was hardened crud in the bottom of and a film all over the inside. I couldn't tell where either line was. So, I made a tool to clean it and used Castrol Super Clean, then bleach, then Super Clean again on the inside. I then painted the lettering and marks on the outside of the overflow. While I could not get approx 10% of the crud off of the inside, there is a huge improvement. Thanks for the info. What do you think?
image.jpg
 
Ah, I think I understand what you are saying. When you say, "When you are doing the pressure test, it causes the coolant to pressurize to the point where it will find any leaking point regarless of its height." do you mean that when I pressurized the system w/the pump to 16psi that it forced the coolant level to rise up to the point that it "found" the hole and leaked out?

I'd like to not stumble upon the right answer, but be able to critically think through what happened. Thank you for all your input 95GTTech.

By the way, I ordered a new cap from motorcraft. Its a bit more $$, but I trust the quality a bit more than, say, Stant...


Yeah, pretty much what I mean. If I have a hard time finding a leak that I KNOW is happening with the pressure test I let the vehicle get ice cold and re-do it - sometimes the expansion from heat can temporarily slow down certain leaks. Stant isn't bad - I work at a parts store for some part time money around my 9-5 job at Acura and I don't see any defect returns from that brand. For the rad, it'd be a good excuse to upgrade to an aluminum 3 core and a set of slimline fans.
 
Man, that looks awesome. I need to do mine the next time I change the coolant. You can fill it a little higher than the full cold.

Kurt
Thanks, Kurt! It took a lot of patience to clean the thing. Do you see the darkened area on the right, right above the "Full Cold?" Imagine that 2-3Xs darker and covering most of the tank. That's how it looked before I started. The previous owner really let the maintenance slide. The car only has about 60k miles on it, but the cooling system was full of rusty water when I got it.

I flushed the system when I first got it, but in the overflow tank there was this rusty looking sediment stuff that was clumped at the bottom, and covering the sides with that dark film. I'm thinking that it was stop leak or something of the sort. The car just needs some TLC and a little patience.
 
Call me crazy, but I'm returning all my autozone replacement hoses and getting motorcraft hoses. The motorcraft hoses are direct fit, not cut to fit, but some of the autozone hoses are cut to fit, and they seem a bit squishy. After my experience with the autozone rad cap I'm a bit shy to pull the trigger with them. I like repairs to last a LONG time.
 
Just a couple of things that I believe need clarifying. A leak is important to recognize as the coolant will slowly disappear. What happens then is the overflow bottle will empty as the engine cools and if the level falls below the overflow hose air will be drawn into the cooling system and/or the system will draw in air at the leak as the system cools. These air pockets can affect the coolant flow and become superheated steam chambers causing rapid temperature increases. The pressure rating is only important to the extent that the boiling point of the coolant mix is raised as the pressure increases. In this regard it's only important when operating conditions exist that cause the coolant to reach temperatures that would cause the coolant to reach a boiling point lower than what would be the boiling point at 16 psi. We are probably looking at a difference of less than 5* between 13.5 psi and 16 psi. You may remember a science experiment where water boils at room temperature under vacuum (pressure less than 1 atmosphere).
 
Just a couple of things that I believe need clarifying. A leak is important to recognize as the coolant will slowly disappear. What happens then is the overflow bottle will empty as the engine cools and if the level falls below the overflow hose air will be drawn into the cooling system and/or the system will draw in air at the leak as the system cools. These air pockets can affect the coolant flow and become superheated steam chambers causing rapid temperature increases. The pressure rating is only important to the extent that the boiling point of the coolant mix is raised as the pressure increases. In this regard it's only important when operating conditions exist that cause the coolant to reach temperatures that would cause the coolant to reach a boiling point lower than what would be the boiling point at 16 psi. We are probably looking at a difference of less than 5* between 13.5 psi and 16 psi. You may remember a science experiment where water boils at room temperature under vacuum (pressure less than 1 atmosphere).

Ok, thank you toyman. So, your point is that the issue that I was most likely experiencing was due to air pockets in the cooling system somewhere, not necessarily did the faulty rad cap have too much to do with it. Am I understanding your point correctly?

If I'm understanding your point correctly then I'm failing to understand how my cooling system seemed to demonstrate a lack of air pockets when I let it cycle with the cap off and the heater on high. Can you please help me analyze what was going on? I find this very interesting. Also, i know that in science two concurrent facts do not necessarily prove a related truth. For example, people in 1853 ate carrots. 100% of those carrot eaters are dead. One cannot take those two concurrent facts and surmise that eating carrots is deadly. So, I am fully open to the possibility that because the system seemed to demonstrate no air pockets it doesn't mean that there were none. Thank you for any help you can supply.
 
UPDATE: regarding my decision to return the autozone radiator hoses in favor of getting motorcraft radiator hoses; GOOD decision. The lower radiator hose from motorcraft comes with the spring inside of it. The autozone hose does not, and it feels weak to start with.

It's clear that Ford believes that the lower radiator hose ought to have the spring in it. Now I know that the lower will not collapse. If anyone is interested in the motorcraft lower radiator hose the part # is KM-2831 or F4ZZ-8286-A. The upper radiator hose part # is KM-2432 or F4ZZ-8260-A.
 
The cooling system is a closed system to the extent that the cap holds a specified pressure. As the coolant heats it expands. If you have the cap off at operating temperature then put the cap on the system will draw either air or coolant from the degas (overflow) bottle. As there is a leak it's likely that air is drawn back into the system. As a general rule you will not see any bubbles or air escaping by watching the water flow with the cap off. After the leak is repaired, fill the system to the top of the radiator neck, put the correct cap on (16 psi) and fill the degas bottle to the top. So long as there is coolant in the degas bottle air will not be introduced during the cool down phase. Ford calls it a degas bottle for the very reason that any trapped air will be expelled from the system as the car warms up into the bottle.
 
The cooling system is a closed system to the extent that the cap holds a specified pressure. As the coolant heats it expands. If you have the cap off at operating temperature then put the cap on the system will draw either air or coolant from the degas (overflow) bottle. As there is a leak it's likely that air is drawn back into the system. As a general rule you will not see any bubbles or air escaping by watching the water flow with the cap off. After the leak is repaired, fill the system to the top of the radiator neck, put the correct cap on (16 psi) and fill the degas bottle to the top. So long as there is coolant in the degas bottle air will not be introduced during the cool down phase. Ford calls it a degas bottle for the very reason that any trapped air will be expelled from the system as the car warms up into the bottle.

Very helpful info, toyman. Thank you!