Coolant Overflow Bottle Question

Dahoopd

Registered User
Are there two lines going in/out of the bottle? I don't have a reference picture to look at. I got rid of my factory bottle on the inside fender and put one in the core support. The problem is when I am driving, water blows out of the top of the bottle. Its not overfilled and the cap fits normal so I don't understand the problem. (yes, it has the cap on it)
 
Ahhh! There in lies the problem I assume. So the water does not get sucked back into the radiator when its low? Its pumped in?

The bottle I have is a straight bottle with no pump in it. The line is at the bottom.


I think I better find another SC for a reference since I took the wiring for the bottle out of the car.
 
What is the difference in height between the old bottle location and where you have it now? I suspect the new location is lower with respect to the radiator cap correct? Therein lies your problem most likely.

There is no pump in the line. When coolant in radiator cools it contracts and creates a vacuum drwing in the coolant from the overflow. When you start the car and the coolant warms it expands and flows the opposite direction until equalibrium is reached between temp. and volume.
 
Ahhh! There in lies the problem I assume. So the water does not get sucked back into the radiator when its low? Its pumped in?

The bottle I have is a straight bottle with no pump in it. The line is at the bottom.


I think I better find another SC for a reference since I took the wiring for the bottle out of the car.

Sorry, I knew coolant, but when I typed I was thinking washer fluid.

Duffy Clarified. The cooling system is a closed system. The fluid moves into and out of the recovery tank via pressure changes in the cooling system, higher pressure when hot, lower pressure when cold. It's used to take up the changes in volume that occurs when the fluid is heated and cooled.

If your tank is below the top of the radiator, it's possible that fluid will get siphoned out of the radiator and fill the recovery tank.
 
So as long as I keep the bottle to the correct level at temp, it should level the rad? I assume since its coming out when driven, I need to raise the height of the bottle.
 
I'm going by memory here, but I think the "cold full" line is level with the top of the radiator. That should be a good reference for ya when placing the tank elsewhere.
 
The overflow outlet tube on the radiator fill neck is 3" ~ 3.5" higher than the 'FULL HOT' level on the overflow tank (which is 2.5" higher than the 'FULL COLD' level). Technically, an overflow tank with this design will work as long as both levels & inlet are within the highest (operating) and lowest points of the radiator core.

Adjust the 'FULL COLD' level in the overflow tank only after the system has cooled completely...overnite works for me. Do not open the radiator cap when the system is hot/pressurized.

While you're messing with it, make sure the rubber tube from the radiator neck into the bottom of the tank is clear/clean. The tube/connection at the bottom of the tank has the smallest I.D, and I've seen them plug over time, especially if the car has suffered HG failure in the past, etc. Pull the tube off at the radiator and probe it with a piece of wire to confirm it will pass freely to the inside of the overflow tank.

If the tank is dirty/gummy, remove it from the car and find a way to much it out - how you proceed depends on what has collected...sometimes just a rinse and sometimes steam clean or you may find a hard residue that doesn't seem to want to come out.

In the worst case, find a replacement tank. When removing the level sensor, take care to not bend it, as it becomes brittle with age...the cover over the wires can break...if this happens simply seal it with silicone glue. Scrape clean the two metal probe tips on the end to help their function.
 
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The overflow outlet tube on the radiator fill neck is 3" ~ 3.5" higher than the 'FULL HOT' level on the overflow tank (which is 2.5" higher than the 'FULL COLD' level).

In other words, the coolant bottle HOT line needs to be higher than the radiator overflow tube outlet? Does the cap on the overflow bottle need to be tight to maintain pressure or is it suppose to release pressure.

Other than needing to check the overflow bottle level often and the water coming out when hot (see previous question) it shouldn't effect any other operations?

I know I sound really retarded with this but I like where my overflow tank is I just need it to function properly. Thanks for the help.
 
In other words, the coolant bottle HOT line needs to be higher than the radiator overflow tube outlet? Does the cap on the overflow bottle need to be tight to maintain pressure or is it suppose to release pressure.

Other than needing to check the overflow bottle level often and the water coming out when hot (see previous question) it shouldn't effect any other operations?

I know I sound really retarded with this but I like where my overflow tank is I just need it to function properly. Thanks for the help.

The cap needs to be on, but it isn't under pressure. The SC overflow tank doesn't hold pressure.

You need to think of this like a bubble level. The radiator and the recovery tank are on two ends of a line and gravity works to keep the fluid level across the two.

The pressure cap on the radiator maintains a set pressure in the cooling system. As the coolant expands, pressure rises, which the cap bleeds off, along with excess coolant. This coolant leaves the radiator at a pressure higher than ambient, which pushes the coolant into the recovery tank, allowing the tank to go above the balance level. The radiator cap works as a one way valve, keeping the balance from happening.

As the engine cools, the coolant in the engine/radiator reduces in volume and reduces pressure until the the cap relaxes and allows the coolant to flow back into the radiator, equalizing the pressure between the now slight vacuum in the radiator/engine, and the ambient pressure of the recovery tank.
http://auto.howstuffworks.com/cooling-system.htm This link might help.

So basically, you need to have the recovery tank set at a proper relation to the top of the radiator so that the cold level of the coolant is low enough that the recovery tank has enough room for the expanded hot coolant, but high enough that when it cools off, it doesn't suck air into the cooling system.

If you want it out of the way, you might consider getting an aftermarket recovery tank, and mounting it behind the fender, just cutting a hole for access to the fill cover.
 
In other words, the coolant bottle HOT line needs to be higher than the radiator overflow tube outlet? Does the cap on the overflow bottle need to be tight to maintain pressure or is it suppose to release pressure.

Other than needing to check the overflow bottle level often and the water coming out when hot (see previous question) it shouldn't effect any other operations?


On a stock SC, The 'HOT FULL' line should be lower than the overflow tube outlet on the radiator filler neck.

Top down...
A.) Top: radiator overflow tube outlet

B.) 3" ~ 3.5" lower than 'A': 'FULL HOT' level on the overflow tank

C.) 2.5" lower than 'B': 'FULL COLD' level on the overflow tank.

The cap for the overflow tank is just a lid...there is no pressure function for the overflow tank like there is for the engine cooling system.

The top/filler cap of the overflow tank sits at a level where it can be reached easily for service.

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As for other operations, some SCs have an overflow tank equipped with a coolant/fluid level sensor. This sensor reports to the VMM and is expected to trigger a 'LOW' indicator if the level in the tank falls close to empty.

As for fluid blowing out....sorry, but that sounds like a problem with the radiator cap or excess pressure in the engine cooling system - maybe/usually from blown head gaskets. Check the engine oil to see if it looks like a foamy milkshake.

Good luck w/your problems and keep us posted, etc. thank.
 

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