with the overflow tank, just fill radiator to brim and it will puke out what it doesn't want. about 2-4" below neck is normal

 

Just make sure when filling to brim that the expansion tank is large enough to handle the overflow.

 

I always go about 1" from the neck...room for expansion and room for over-flow.

 

I fill mine to the neck and let the radiator/coolant recovery tank do its thing

if you are installing a "coolant recovery tank" than you need to have a 1"-2" of coolant in that tank so the pick-up part of the hose/tube than goes in it will be submerged so when the heated coolant expands and overflows into it the suction created by the cooling radiator will draw it back into the radiator

when doing a radiator flush or installing some new component of the cooling system (WP, radiator) it can take a heat/cool cycle or two for the cooling system to purge any air so you will need to "top off" the radiator after that

 

Thanks... Its a 13" X 2" tank and I'm rigging it as a recovery tank. It has two (2) 7/16 20 NPT barbed hose fittings, one has a tube extending up near the top, the other I think is just open on the bottom.

Capacity is about 13 ounces, so when I get it installed I'll the 1"-2" you suggested and also burp the system one more time with the Funky Funnel gadget. When you said it could take a heat/cool cycle or two to purge the last bits of air... will it purge air into the recovery tank or should I just open the cap when it's cold?

Mike

 

If you are changing the system you will need a new radiator cap so the fluid will be drawn back to the radiator when it cools.Radiator should be full. Expansion flows to the recovery tank and than is sucked back in when the radiator cools. Modern system vs ancient system.

 

Radiator Caps Explained

Radiator Caps Explained (coolcatcorp.com)

 

Any part numbers and brand of vented cap to use?

 

So once I install the expansion tank and plumb it, I'll need a cap like this?

I'm sure there are other brands... I have a billet cap cover on my regular 16# cap which is new... but I want the system to work the way SoCal described it.

Mike

 

one that says "closed system" on it. I use a AC Delco RC81

part# 25661994

 

Here's an interesting diagram showing what I think we're talking about.

Radiator caps aren't that expensive... I ordered the Delco you suggested. I've got the brand new one that came with the Cold Case radiator, but I don't know if its a vented one. And the one inside the billet housing... its probably a Dorman or Gates. I have to take it apart as the beauty cap just gets 3M double sided taped to the inside.

Mike

 

I've got the brand new one that came with the Cold Case radiator, but I don't know if its a vented one.

Mike

FWIW, Eric @ CC PM me saying the CC cap is a 16PSI vented cap...

 

I did order the Delco cap, I will compare it to the Cold Case cap. The cap I had on my old 4-core radiator has the billet cover on it. I don't recall the brand or model, but look at the difference in the springs. It looks like it has a vent hole but I'm not sure. I'm gonna use either the CC cap or the Delco to make sure its a vented cap. Expansion tank should be here in a couple of days, coming via USPS Priority which could take forever these days. Chris Cass had told me that #16 cap is fine with his radiators, and I've also read that #15 is normal for most older muscle cars. Go figure.-Mike

 

while CC (Eric) said the CC cap is for a closed (vented) system I just use the AC Delco RC33 (aka pink top) cap I had and it is 15 PSI. IMHO a CC radiator and a heater core are fine with 16 PSI

I did notice the CC cap did have a vent hole on one side but the RC33 has it on both sides but assume otherwise they function the same

With the recovery tank I see the coolant level in radiator stays about 1/2" below the fill neck vs about 2+" when it was just using a non-vented cap and coolant would just overflow to ground leaving the larger expansion space in the radiator. I notice no difference in operating temps between the closed and open systems. I did the coolant recovery because its needed at NHRA tracks to pass tech

 

Inquiring old minds want to know. . . . .these cars were not designed for overflow tank and none of my cars overheat, even my 05 Vette does'nt use the OT. So my question is what is the point?

 

My guess would be to keep Ethylene Glycol off the street.

 

Is there a rule of thumb or caution about how far from the radiator you can put an Expansion tank? I know some guys have mounted them on the opposite (drivers) side. My PS firewall is looking better and better bc it’s pretty empty, and I’ve already got my PS reservoir on the drivers side of the core support. I use a cover over the front “cavity” so I don’t want to bury the tank where I can’t get at it without removing all the tie down bolts.
The firewall isn’t much further than the DS of the radiator.

Mike

 

Makes no difference imho. A lot of overthinking going on here. This is not rocket science. Radiator pressure beyond cap pressure rating pushes coolant into tank. When radiator cools resulting vacuum pulls coolant back into radiator. Don’t obsess over level, system will find its operating level.

Don

 

There should be no need to access the tank once it is installed.

Don

 

SoCal, I now have everything needed for the install as you have, my question is now did you put a hose on the overflow outlet?

 

This is where i mounted mine

 

I installed mine right next to the PS radiator and about 2" below the cap - it's bolted through the radiator support. Like Don said, it's pretty much a closed system - rather than venting a little coolant onto the ground, it goes in the tank instead and then gets pulled right back into the radiator as it cools down. Not much to it. One of these days I'll probably hard pipe it but it works for now.

 

I have a brand new engine and cooling system so i decided to go with the evans waterless coolant cuz they say it doesnt corroded the insides of the engine with electrolysis. And at $47 a gallon i dont want anything hitting the ground lol

 

No room on the PS, DS occupied by PS reservoir. The front section gets covered completely with polished SS cover. And my expansion tank is aroud 15" tall so it's gonna go on the firewall tomorrow.-Mike

 

Mike, I thought one thing you were inquiring about was the height of the OF tank vs the radiator. At least your post caused me to think about that. It did not even dawn on me until now and mine has been installed for about 6 mo. It appears that mine is lower than it might should be. I'll also look into a cap like you are going to use. I don't think mine is vented.
Brett🚀🚀🚀🚀

 

Tim... I'm going to use the Delco vented cap, mainly because I'm not sure the cap I was using was vented or not. The cap is mounted in a billet cover with 3M tape maybe 3 years now, and despite all my attempts with assorted solvents, I can't seem to budge the cap LOL. So I'm probably going to get a new Cold Case billet cap to go over the Delco. I sent Chris a DM asking about it but haven't heard back yet. My tank is now mounted on the firewall, working on the hose this afternoon, it'll be buried under the Heater/AC lines.

As Don had said, it could be in the trunk LOL... but I've actually seen many similar setups on Roadsters around here.-Mike

 

20210329_101920 by F G, on Flickr

 

To use as a recovery tank does the tank have to be sealed or vented?

 

Vented

 

View attachment 274787

 

there are coolant recovery and over flow tanks...and just over flow tanks. recovery type have a vented cap and the hose coming from radiator attaches to a tube that goes to the bottom of the recovery tank which keeps that end of the tube submerged in coolant so when the radiator cools vacuum draws coolant back from the recovery tank as it is vented so does not hold pressure, it is "neutral". The recovery type tanks also have a "overflow" port to allow coolant to spill out should they be overcome with coolant

over flow tanks just hold whatever is puked into them from radiator, like some who just use a windshield washer tank

IMHO the Nova 74-79 "recovery" tank looks like it "belongs" on the car and holds a good amount of coolant before it itself will overflow vs some of the aftermarket cylinder types that hold very little coolant

 

IMHO the Nova 74-79 "recovery" tank looks like it "belongs" on the car and holds a good amount of coolant before it itself will overflow vs some of the aftermarket cylinder types that hold very little coolant

I remember reading your discussion on installing the Nova recovery tank into your Camaro and I think it looked great!

But one minor correction (for those that may be trying to find this item)... The recovery tank you installed was for a 75-79 Nova (4th Gen).
The 73-74 Nova had its coolant recovery tank mounted onto the engine side of the inner fender and the shape of the recovery tank is different (see image below - 74 Nova Recovery Tank).

I really liked how you mounted your recovery tank tucked-up into the open space under the fender and have considered changing my set-up to copy yours.

What I really like about having a translucent recovery tank is you can tell if you're losing coolant by looking at the coolant level in the tank (should always be around the same level when the engine is cold). It's easy to inspect/view the coolant level in the recovery tank each time you open your hood. If the normal "Cold" coolant level starts to drop, then you are most likely losing coolant somewhere.

 

I found this illustration online and decided to tweak it a little bit with some arrows, copy and a few other things. BTW, that Delco cap does not like the neck on my Cold Case radiator.

 

BTW, that Delco cap does not like the neck on my Cold Case radiator.

you talking about this AC Delco cap?

fits my CC