overflow tank problem

[willy]

Have the overflow tank that was in the kit a 2"x13"(20oz), is that a little small when I run the engine to temp it fills the tank and kicks out some then when it cools off it sucks the tank dry and then air, at first thought it was a headgasket presurizing the system but no water in the exshuat or oil and no bubbles , so am thinking the overflow is just to small for that much coolant seeing that the couple does have more coolant than a normal car.

[michael everson]

I think you can buy a 3 " one. That might help
Mike

[riptide motorsport]

I dont believe your system is full, you have air in it , get all the air out of it and it should stop puking and refilling....Steven

[willy]

Have the fill at the highest point and ran it at idel to make sure it was full and when it fill the tank there are no bubbles just fills the tank till it over flows and then when it cool down suck it dry then suck some air in to the system ??

[willy]

looking at OEM tank they just look like they hold more than the 2" x 13" one in the kit

[crash]

We have huge volume cooling systems on the GTMs and it only drops about 2-3 inches from the top on a 1.25 quart tank. If you are seeing more than this, there is likely a problem.

[willy]

Did a little experiment today filled everything to the rim and ran it till the fan kicks on just drips till then as soon as the fan kicks it stops, I collected the water that came out of the overflow and was 25oz, so the overflow is only 20oz let it cool down and it suck the tank emtpy then used the othe 5oz and it filled the filler neck to the right amont, so cannot help myself to think the tank is a little small. crash said he has a 1.25qt tank that = 40oz so 2-3 inchs could be 20-25oz. We wll see I ordered a 52oz
3"x16" one figered even if that does not solve he problem it cannot hurt and was not that expersive.

[DARKPT]

Can you give us some details on the tank you found, Willy? I'm experiencing the same thing with my 302.

Thanks

Dan

[willy]

Did not want to spend a lot of $$$ foun on E-Bay $44 with free shipping , good to hear somebody else has the same problem was starting to wonder if I was the only one.

[loeffler1]

I had the same problem, only I had a sizeable Canton tank with sight glass. Solved by filling 2/3's full and it sucked down to about 1/2 full.

Bill

[willy]

loeffler my problem is I can fill the rad and tank to the top so when it heats up it overflow out of the tank, when I turn off the engine the tank is full then during cool down it sucks the tank dry and then some air , did think of a head gasket problem ie presurerizing the system but has no bubbles and as soon as the fan kicks on it stops kicking out fluid out of the tank. and the overflow tank the 2"x13" is only 20oz not much to work with

[parnelli]

Willy
Your overflow tank is too small. The one that came with mine a few years ago holds more than 2 quarts.
It is much like a windshield washer reservoir. When cold there is about 1/5 fluid. When very hot, it is
about 3/4 to 7/8. If you have sucked air back into the system, it will take a couple of cycles to burp
it all out. Oh yeah, the burps can be forceful, resulting in very hot coolant blowing out of the tank.

Greg

[skullandbones]

I measured my stock 92 GT overflow tank. It has a capacity of 1.5 gal. I don't know what you can get away with minimally but I am thinking 2 to 3 quarts would work most of the time. Extreme conditions might require a little more. The reason I worry is because AZ is as extreme as it gets in the summer. WEK.

[willy]

Have a bigger one on order the small one I have now is the one suppied with the kit do not know way they send such a small one (20oz) the one on order is 52oz think that sould be big enough I fill everything and ran it till the fan kick on and it only lostt 25oz out of the overflow tank so think 52 sould be pleaty

[MikeJones]

I have had similar problems in the past, and the problem is with air still in the system. Put the front wheels on blocks to lift it up, and make sure your filler cap is the highest in the system. Uncap and fill completely. Then slightly open each of the plugs on your intake until you see coolant coming out. Do everything back up and run it through about five heat cycles (run engine until hits operating temp and allow to completely cool), and top up your overflow bottle each time. I did this twice before all the air was out, and id drove me nuts.

Good luck, Mike

[willy]

got my 52oz overflow today and tryed it out, filled verything up and ran it till the fans kicked on then let it cool down left abotu a 1/2 of the bottle so think I have it licked

[EBarnes]

I was wondering the same thing Mike...wondering the mixture that expands like that, but you are right, air in the system, even small amount, would expand greatly and not necessarily be what is initially purged - fluid would be. Then with the tank dry it would repeat itself.

I'd be interested in knowing how much the variation is with the bigger tank, AFTER a dozen cycles.

[smithtlw]

The volumetric thermal expansion coefficient of water is 0.00012 per degree F and ethylene glycol is is 0.00032 per degree F. For a 50/50 mix the coefficient would be 0.00022 per degree F. Values found at http://www.engineeringtoolbox.com/cubical-expansion-coefficients-d_1262.html

Assuming a 4 gal system capacity (not sure here) the volumetric expansion calculates to be 14.6 fl.oz. when going from 70° F to 200° F.

If you look at a bit more of an extreme case going from 40° F to 220° F the volumetric expansion is 20.2 fl.oz.

I Used an online calculator found at http://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html

Unless the 4 gallon system capacity is far off I think Willy may still have some air but the 20 fl.oz. overflow tank supplied is marginally usable at best! I wonder how the 20 fl.oz. tank was selected by FFR?:confused:

[willy]

8904 when I checked I was using water ( did not want to consanly fill the garage with coolant) and it lost 25oz so if the tank is only 20oz it sucked 5oz of air every time, with the bigger tank and does not suck any air now think that will take care of it. Here is a pic of the new tank

[massawax]

[Hi WillyI
I DAQUOTE=willy;57118]8904 whWilly
en I checked I was using water ( did not want to consanly fill the garage with coolant) and it lost 25oz so if the tank is only 20oz it sucked 5oz of air every time, with the bigger tank and does not suck any air now think that will take care of it. Here is a pic of the new tank[/QUOTE]

[massawax]

Hi Willy

I had the exact same problem. Tried and purge air pockets from the system several time, but it would invariably suck new air from the small overflow tankduring cooling down.
How did it work out for you with a bigger overflow tank? did it sove the problem?
max

[willy]

No problem now the bigger tank works good, one other thing I did was to use a radiator hose 90* elbow were the hose comes out the top of the engine makes a much better elbow and is lower than the metal hose can.

[massawax]

hi Willy,
I did that too: I bought a 90 preformed rubber elbow from Breeze. It sits exactly out if the thermostat housing neck. That helped, but I still need to install a bigger overflow tank.
I just bought The Canton racing, 2 quarts capacity. Hope it works. Thanks for your help.
Max