Coolant Level, Overflow Tube
 

A little background first. I had no noticeable cooling problems with the car before I did all of this work. Over the winter I just replaced the radiator, air separation tank, thermostat, thermosensor, and most of the cooling hoses.

Now I am in the process of filling up the cooling system. I removed the throttle body hose, filled the AST, and the filler neck, and the overflow tank to its full level. After a couple of heat up, cool down cycles, the AST became completely full, and I was able to start adding coolant to filler neck when its level dropped down. It has been 5 days of driving now, and the filler neck is missing 2-3 inches of water everytime I check the car after it cools down, so I fill it back up to the top. It is still above the low coolant sensor each time.

I notice that when I fill the filler neck up to the top, and then I release the AST Pressure cap, the coolant in the filler neck goes down to the 2-3 inches low mark. However if I don’t release the AST Pressure, the coolant will remain to the top, until I drive it and check it and then it will be 2-3 inches low.

Does this sound like I am having a problem with the overflow tube? I had to remove my sheet metal intake shield when I replaced the radiator, so it is possible I damaged the hose then, but I don’t see any leaks anywhere.

Finally, my overflow tube looks pretty strange. At times it has some coiled plastic covering, sometimes it is just exposed, and othertimes it has a solid plastic covering. Is there any particular hose that is needed to replace the overflow tube?

Any possible suggestions would be appreciated. I will most likely replace the overflow tube this weekend, but I was wanting to get some opinions first.

Mine was bad. The overflow tube hose has three plastic spacers in the line. These can leak. Replace the entire line and remove the spacers. Keep filling the coolant level up until your system is completely free of air.

P.S. Did you remember to replace both of your turbo coolant hoses?

I did replace both turbo coolant hoses. I only have the heater hoses and throttle body hoses that aren't replaced. I figured I would do those next winter, when I remove the intake manifold to solve some vacuum hose issues.

On your overlow hose, did you just purchase some generic hose from the autoparts store?

Thanks

n/arotary, your car is perfectly fine.

The reason the coolant in the filler neck drops when you remove the AST cap is because once the cap is off the water on the filler neck can run downhill into the AST. With the ast cap on the coolant can't do that because the system is sealed.

Your overflow tube is also perfectly normal, you'll even find there are plastic fittings along its length that splice it together. In the interest of bulletproofing mine I used fuel injection hose from the AST to the overflow bottle. It's thicker and can stand the heat.

DamonB,

Isn't the coolant supposed to be at the top of the filler neck after the car cools down? I am concerned that the level isn't full after cool down. I really need to understand how the system works better. I fill up the filler neck to the top, run the car. As it warms up coolant will go into the overflow tank. Then after it cools down, shouldn't the coolant fill back up to the top of the filler neck? I was concerned that maybe the Overflow hose return line is letting air into the system, and that was why I was seeing the coolant level lower in the filler neck. Everytime I check the AST level it is completely full, but it actually sits lower than the filler neck.

I know how much these cars hate to overheat, so I trying to make sure that my cooling system is running normal. I do have a temperature gauge and it is sitting right at 180F right now, but I don't want to risk it running low on coolant.

No. It will be an inch or so below the level of the seat under the fill cap. This is perfectly normal.

You're being diligent by staying on top of things, but your car is fine.

Damon, how much fuel injector hose do you need?

Thanks again.

I will start driving it more, and see if the coolant drops at all. This car makes you question everything!

I don't remember exactly. From the AST, down to the crossmember, across to the overflow behind passenger headlight...maybe 6 feet at most? It's cheap stuff, just buy more than you need.