I just received my coolant overflow tank and was surprised to see it with a sealed air tight cap. I thought the overflow was unpressurized ambient? I should drill a hole in the cap as it’s a bottom fill right?
Coolant Overflow Tank
- Thread starter 340inabbody
- Start date
-
dano
Evil Handy Man
Is there just 1 port?
Yes
So a port at the top as well to direct the coolant to the ground is a correct configuration?
IIRC some racing sanctioning bodies require a sealed tank. The whole point is to NOT dump coolant all over the tarmac. I agree that for normal street use a vented tank is standard and operationally better.
DartGTDan
'71 Dart GT Fan
I chose the Dorman 54002 overflow system. Works great!
mderoy340
Well-Known Member
I just use a Zip spray bottle.
OK, cool thanks guys. That’s what I thought.
another thing to add is with a sealed overflow the system is mow going to pressurize higher than the rad cap pressure. radiator builds pressure to 16 psi, then it vents air or coolant that air or coolant has to go somewhere so it goes into the overflow tank. the air pressure in the tank quickly reached 16psi and then if the coolant keeps getting hotter the entire system pressurizes higher then 16 till something blows (hopefully the overflow hose and the hood is shut)
Remember myth busters and the flying water heaters, all they did was close off the overpressure valve and the in and outlets and allowed the heater to heat
Remember myth busters and the flying water heaters, all they did was close off the overpressure valve and the in and outlets and allowed the heater to heat
PV=nRT
No, you need a port from the rad that goes to the bottom of the can, so when cooling down, the rad sucks the tank contents back in. A second port at the top of the can with a hose overboard acts as a vent and directs overflow out of the bay.
I’ve used for years a cleaned out quart oil can with a 3/4” hole in the cap zip ties to the radiator support. The tube drops in and leave an air gap. I can read the clear sight line to tell when I need to empty it.
Local tracks have had no issues doing this. Again - keeping the antifreeze off the raceway.
But if you want to be fancy….
Local tracks have had no issues doing this. Again - keeping the antifreeze off the raceway.
But if you want to be fancy….
JDMopar
Well-Known Member
Mine WAS fancy back in the early 90's....lol. I won a plastic water bottle as a door prize at a car show. It said Hemi on it. I just yanked the plastic straw out, stuck the overflow rubber hose in, and stuck it down beside the radiator to get thru the tech at Bristol. 71 Challenger conv, and it is still in there since 92 or 93! That reminds me....I need to check it to see if it still holds water/antifreeze!
My 71 vette had a pressurized recovery tank made of brass. Was a nice piece when polished up.
I just need an overflow can like the one I have. A good thing about it is the fill tube is at the bottom. I am going to drill the cap and put a rubber tube in it for venting burping pukeing and the like if it overfills which it wont.
I just need an overflow can like the one I have. A good thing about it is the fill tube is at the bottom. I am going to drill the cap and put a rubber tube in it for venting burping pukeing and the like if it overfills which it wont.
- Joined
- Mar 6, 2008
- Messages
- 1,131
- Reaction score
- 803
I have one of those, drilled a hole in the lid to vent it. It is a bit small, but it's priced cheap enough its real competition is a Coke bottle.
I may switch to the Dorman while doing my radiator swap - @DartGTDan, thanks for the part number. It looks a lot bigger.
I may switch to the Dorman while doing my radiator swap - @DartGTDan, thanks for the part number. It looks a lot bigger.
Ant
Well-Known Member
20oz Pepsi bottle works good with some holes in the cap. It's also track legal at the drag strip.
My dad used orange juice bottles.
I just leave the factory recommended 1 inch air gap at the top of the tank. Haven't spilt a drop in years
I just leave the factory recommended 1 inch air gap at the top of the tank. Haven't spilt a drop in years
You guys are so low tech! Here's mine that I used 35 years ago. Easy to see after I pulled the front end off my 69 Charger.
Some random plastic bottle from the trash with tape holding the hose in. Sitting next to my Cool Can (remember those?) and my DC chrome ignition box. Ran it that way on the street and track for better than 10 years!
Oh, and my junkyard A/C condenser that served as a tranny cooler too!
Some random plastic bottle from the trash with tape holding the hose in. Sitting next to my Cool Can (remember those?) and my DC chrome ignition box. Ran it that way on the street and track for better than 10 years!
Oh, and my junkyard A/C condenser that served as a tranny cooler too!
It is a combo expansion and overflow/recovery tank. It connects to the rad cap neck overflow relief fitting. Cold, the rad should be completely filled and the tank filled to the hose connection (because they did not put it on the bottom for some reason) and no higher with a nonvented tank cap. When the radiator relief valve opens allowing flow to the tank, the air in the tank compresses. There is no minimum level to maintain in the tank because it is under pressure to return except what is below the fitting.
If you've already drilled the cap to vent, it works like a traditional overflow/recovery tank.
A non-syphon return due to a leaking cooling system will not overflow the unvented tank. A traditional overflow/recovery (or if you drilled the cap) will overflow. It's just another way to do it.
Last edited:
I haven’t had time to drill it yet. So you’re saying it can be used as an expansion pressurized tank by not relieving it? This tank is bottom fed btw. Would this pressurized expansion tank work with a single line?
Yes. The hose would need to handle pressure and have clamps versus a typical thin wall hose that just slips on. Also the capacity will be less than if it were the traditional type since the air will have no where to go. I prefer the big plastic type. Here is one I put in a geo tracker with a chevy v6.
I think I’ll just make it ambient overflow tank. It doesn’t burp much so it should be fine.
I am curious what is the approximate pressure of the release valve in the cap?
-
Similar threads
