blackcobra440

I have a C2 restomod with LS3 motor, reverse flow water pump, and Griffin radiator. Right now, the hose from the radiator vents to the ground. I am considering adding either an overflow tank or a true expansion tank in order to avoid coolant spilling on the ground.
1. Any recommendations on whether to go with an overflow tank vs an expansion tank? Is there an advantage to using a true expansion tank with a restomod?
2. Would the expansion tank be better at keeping air out of the system and therefore hopefully less chance of overheating?
3. Any specific vendors you would recommend? I would like an aluminum look if I add one.

Thank you for your help.

mark6669

I modified an original tank into a recovery tank by removing the radiator tube and replacing it with a tube that goes to the bottom of the tank. It uses a pressure cap on rad and a flat cap on the tank to allow the tank to vent. Radiator always stays full with no air.


Mark

Mike (Naples)

I installed an overflow tank, which works great for me. I mounted it on the driver side of the radiator.

mike coletta

Basil, I received your text, but decided to answer here. I don't run an expansion, overflow, etc., in any of the cars that I've built. I let the expanded water seek it's own level, and check it a couple of times each year. My water level runs about 1 1/2" below the cap when cold. Here is a good primer on expansion tanks and caps that I think will answer all of your questions. (including a correct definition of vented and non-vented caps). You said that your mechanic recommended a vented cap, so I'm not sure that he understands what the difference is. https://jimdinner.wordpress.com/2012...aps-explained/

Mike Coletta

I'm going to add that I doubt that you had a thermostat problem, but rather had air in the top of the intake. The reverse flow LS engines have to be "burped" to get the air cavity out of the engine. Most shops will jack the front of the car high in the air or use an air purge system. You basically have to get the radiator water level higher than the back of the intake. With an air lock in the engine, just as soon as the thermostat opens, the water cavitates at the air lock, and won't flow to the radiator. Sometimes if you boil it over real hard, it will push the air out, but it's really not a big deal to purge the system. There are several videos on you tube. I think that I would look for a different mechanic.

Beggers

Like Coletta, I haven't used an expansion or overflow tank on three LS3 cars I have built, I dont have any overflow or cooling issues at all. Many of the modern aluminum radiator set ups are delivered with tanks, but they are just not necessary once the system has been bleed of its trapped air. Brian

blackcobra440

Mark and Mike(Naples),

Thank you for sharing the photos of your engine bays. They look great, nice clean set up.

Mike,
Thank you for the link- excellent article. That helped explain a lot. I believe he meant that if I add a zero pressure tank(overflow tank) the cap on the radiator should be vented so that the coolant returns to the radiator from the overflow tank after cooling. Thanks for explaining burping. As always, your insights are very helpful.

Brian,
Thank you for sharing your experience. I feel better about not adding an overflow tank.