Overflow Tank question

[Eyvazk]

Guys- sorry for bringing the old topic here. Just got a replica 66 Cobra. Completely new to these cars. I noticed the radiator has a very small leak from the bottom passenger side after I run the engine. No leak while the car sitting in garage. I checked the white transparent canister, and no coolant in that - whether the engine hot or cold. I also opened the cap on the flexible hose (when cold) at the top of engine from thermostat to radiator and checked and noticed no coolant in the hose. Maybe it should be this way when the engine is cold. Anyway, my question is- should I add coolant to the engine and to what level. I am being told that transparent canister is just a catch can, unlike traditional cars with Min and Max marks… basically you shouldn’t expect to see coolant in there under normal circumstances. So then how do I know how much coolant should I add. Thanks in advance.

Originally Posted by timsullivan

Yes, you're right, the plastic overflow tank mounted on the right side fender well undoubtedly is the only source for the cooling system to literally and figuratively blow off some steam. Most likely you have the expansion tank (that sits directly above and in front of your thermostat housing) overfilled. They should only be filled to the midpoint of the expansion tank when the car is cold. That or you have some very serious overheating problems going on. Normal cooling system pressure relief shouldn't see water coming out of that very tiny breather hole on top of the overflow tank unless you have the puppy filled to the brim! Drain it all out of the oveflow tank and reset your coolant level in the expansion tank to the midpoint.

The valve on the bottom of the overflow tank should only move about 180 degrees to open or close the drain. If memory serves me it's just a press fit into the bottom of the tank.

[patrickt]

Originally Posted by Eyvazk

I am being told that transparent canister is just a catch can, unlike traditional cars with Min and Max marks… basically you shouldn’t expect to see coolant in there under normal circumstances. So then how do I know how much coolant should I add. Thanks in advance.

A pic of your transparent canister would help, I'm sure it's different than my "surge tank" that is pictured two posts up. I fill that surge tank up about an inch and a quarter from its floor and leave the rest of the tank empty. The coolant system will then find its right level by squirting coolant out the cap, and down through the clear plastic tube, in to my catch bottle that is attached to the oil pan. If I filled the surge tank up completely it would just shoot it out the tube and fill up the little glass bottle and dump the rest on the street. A pic of my catch bottle is below. Once my system has found its correct level it can go months or even a year or two without squirting anything in to the bottle. But if I take her out on a really hot day, and run her really hard, I can generally get a little squirt in to the bottle. I change my coolant every four years and that's the only time I ever add coolant to my system and when I do I try to put just a little bit more than it wants so it squirts a little bit in to the bottle but not a lot because the bottle doesn't hold all that much. It was mainly designed to protect my dog, who spent countless hours under the car with me. My system does not draw the coolant back in from the bottle like every modern car in the world does. If it goes in to the bottle, it's basically gone. I tend to keep an inch or so of coolant in the bottle, not for any particular reason, I just do.

[Blas]

The expansion tank will auto-level itself after driving a few miles. If you put you finger in it you will feel a plate inside the tank with a hole in it. That plate is the approx fluid lever when all is said and done.
Blas