Overflow Tank question

[Excaliber]

That is the BEST setup Jim, and it will work perfectly. Some overflow tanks, like mine, simply vent or purge any excess from the tank out of the top through a vented cap. That overflow would then run all over the sides of the holding tank and spill out all around the engine compartment area and ground. I would much prefer a tank with a second hose from it's cap that directs any overflow straight to the ground.

It's important to NOT fill up your overflow tank when the system is cold because you need to leave room for expansion and additional filling of the overflow when the engine is hot.

Some folks say you should leave a little room, leave the water a little low, in the surge tank mounted on the motor. That way some expansion can occur within the engine without pushing the water out to the overflow tank.

[Archrms]

Jim,

It sound like you have the same setup I have for the overflow tank. I did the modifications as per Tim's link this past weekend. However, the setup you described by reversing the input hose to the bottom of the tank and making the top hose an overflow seems a better idea - and cleaner. Just make sure the vent hole at the top of the tank is plugged.

Also, I checked the cap on my expansion tank, and is was NOT a recovery type cap. I need to replace that next.

[patrickt]

Here you go, Ernie. This is a shot of the underside of my radiator cap that failed the Putnam Suck Test.

[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

[bkozlow]

As your OVER FLOW TANK look at a 1968 Mustang washer fluid tank about $40, hopefully the picture made it. I have used this tank on ever car since 1969, they look great and attach to any flat surface, can be drilled and tapped on the bottom for the radiator neck over flow and drilled at the top for an over flow to the ground. In the picture, you can see the amount of fluid easily.

Bill K

[patrickt]

Below is a note that the OP sent me along with two pics that he could not get to post.

Finally I can easily attach the pictures. See one of them is the white transparent canister, I never had any coolant in there, whether engine is hot or cold. The other picture is the right hand side of the radiator. The small leak is from the bottom of the radiator. I check the cap and little black side cap on the radiator and they feel dry. And no leak when the car is not running and cold. I don’t have two tanks like many folks mention in the posts. Just one white empty canister.

I also drove in the neighborhood for a bit and temp raises to 180 and stays there, no overheating. Important to mention, this is small block 400 chevy engine, I know people blame for that… but it was factored in the price.

[patrickt]

What I would do is fill the radiator up to the top when cold and then fill that white canister up about three inches from the bottom when cold. Draw a line on the canister where you filled it up to. Then drive it around and get it good and hot and see if the level goes up or not. If it goes up when hot, wait for it to get cold and see if the level goes back down to the line.

[Eyvazk]

Thanks Patrick, I will try it over the weekend. Getting to the radiator seems like will be a bit challenge given the location of it deep in the nose.