transmission Line Rubbed Hole in Coolant Resevoir

[DWestfall]

I noticed a little oily film on drivers side front frame while rotating tires today. Here is what I found. One of the transmission lines is leaking, where it also rubbed a hole in the coolant resevoir. Also, the other transmission line is rubbing on the intercooler boot. I didn't have time to tear it all apart today, so I will save it for the end of next week. I just thought I would post this to give a heads up and see if this happened to any one else.

 

[DWestfall]

By the way my coolant in the resevoir is below the Minimum Level. My radiator is full though. Will this hurt any thing till I get to it next week? Providing of course I watch my temp gauge closely.

 

[rbattelle]

Usually once the coolant is in the reservoir it never returns to the radiator. It won't hurt to leave it below minimum as long as the radiator is full.



-Ryan

 

[Turbo1Ton]

Usually once the coolant is in the reservoir it never returns to the radiator. It won't hurt to leave it below minimum as long as the radiator is full.



-Ryan

Are you serious? That is news to me. The one on my '85 CJ goes back and forth. If you check the level in the reservoir you had better check it hot(has a full and add mark) because if you fill it up while she's cold you'll puke antifreeze all over the place.



Now I don't know if I've taken much notice of my wife's '04 Jeep. I check to make sure its above the add mark but other than that I haven't noticed.



Thanks Ryan. Now I'm gonna have to go and drive all 3 vehicles around just to see! :-laf



BTW, I agree with the comment about the radiator being full.



Jeff

 

[rbattelle]

Are you serious? That is news to me. The one on my '85 CJ goes back and forth. If you check the level in the reservoir you had better check it hot(has a full and add mark) because if you fill it up while she's cold you'll puke antifreeze all over the place.

Well, maybe I'm wrong but here's my logic:



The radiator cap has a pressure relief spring on the bottom of it. It uses a rubber seal to keep the coolant from flowing out to the overflow until the pressure is high enough to depress the spring, which brings the sealing ring above the little hole that accesses the overflow tube. So when the coolant expands enough to exceed the relief pressure (16 psi in our case), the valve opens and a small amount of coolant is released until pressure returns below 16 psi. At that point, the overflow tube is sealed off from the cooling system.



When the system cools, the coolant volume decreases, thereby creating a partial vacuum in the radiator (assuming the system is sealed well). In the absence of the radiator cap sealing ring, that vacuum would suck fluid back out of the overflow reservoir and into the radiator. But since we do have a sealing ring on the radiator cap, there's no air connection between the overflow tank and the radiator, so the system doesn't suck any fluid back.



Having said, that, I think there is some small sucking action that occurs, because after a coolant flush the level in the overflow tank does seem to drop after the first few drives until the system stabilizes.



I could be wrong.



-Ryan

 

[Turbo1Ton]

Ryan, I'm not real clear on how the pressure cap works either. I would assume that it opens up somehow once it cools off.



Great, just what I needed, something else to look up on the internet!



Jeff



Edit: Apparently there must be another spring loaded valve in the pressure cap. http://auto.howstuffworks.com/cooling-system7.htm

 

[rbattelle]

Ryan, I'm not real clear on how the pressure cap works either. I would assume that it opens up somehow once it cools off.

It doesn't open back up when the system cools... the spring prevents that. Go remove your radiator cap - I guarantee the spring/valve assembly is fully extended.



-Ryan

 

[Turbo1Ton]

Alright, I think I've got it figured out. I went and took the one off of my Jeep and am examining it.



Yes the spring/valve assy that you are talking about is fully extended and seals the overflow off from the radiator. But, have you ever noticed the metal disk in the center of the seal? The metal disk is spring loaded to close against the seal. It appears that this metal disk will pull open with a vacuum, therefore allowing the fluid in the reservoir to return to the radiator, once it has cooled and creates the necessary vacuum.



Hope this clears things up a little. If it still doesn't make sense, as soon as you pull the cap and look at it, it should be clear. Thanks for the motivation to learn something this morning!



Jeff

 

[HOBrian]

If you squeeze the upper hose a couple of times you should hear the opening and closing of that "disk".

 

[rbattelle]

Alright, I think I've got it figured out. I went and took the one off of my Jeep and am examining it.



Yes the spring/valve assy that you are talking about is fully extended and seals the overflow off from the radiator. But, have you ever noticed the metal disk in the center of the seal? The metal disk is spring loaded to close against the seal. It appears that this metal disk will pull open with a vacuum, therefore allowing the fluid in the reservoir to return to the radiator, once it has cooled and creates the necessary vacuum.



Hope this clears things up a little. If it still doesn't make sense, as soon as you pull the cap and look at it, it should be clear. Thanks for the motivation to learn something this morning!



Jeff

Brilliant! I didn't read this post until just now, when Brian brought up the thread again. That explains things nicely, thanks Jeff.



-Ryan