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Radiator Overflow Tank

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nevets

nevets

Jedi Knight
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I read a bunch of prior posts on this subject, which were very informative with some creative solutions. Just installed an aftermarket radiator expansion tank. I believe I followed all the requirements concerning venting, partially pre-filling the tank, tube configuration, etc. I think it's working, but I'm not sure. My question is this: Is it necessary for there to be a solid column of coolant in the tube to the tank? I'm pretty sure the answer is no, but I thought I would see what others have to say. Thanks

picture shows the setup. It's a little dark but if you look carefully, you can see an air gap in the column of coolant in the clear plastic tube.
 

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Re: question about radiator overflow tank

I've always had black rubber tubing between the radiator and the tank, so any bubbles are unseen. Am assuming any time I remove the rad filler cap bubbles form in the line. Setup's worked fine for many years.
 
No need for it to be solid water--A vacuum is a vacuum.
 
nevets said:
One more question...Does the radiator cap provide a good enough seal without any modification?
Click to expand...
There needs to be a seal between the cap and top of the neck. The standard cap seals at the bottom of the neck only, and there is a springy metal disk at the top that doesn't provide a vacuum seal. You will need put a rubber seal between the springy metal disk and the top of the radiator neck. Caps for modern cars have these, but the radiator neck height is different on a Healey.
 
Nevets - I originally had a plastic tank somewhat similar to yours. It had a thin rubber seal inside the cap, which I cut a hole in the center of and used as the seal as John describes above. The seal was no longer necessary in the plastic tank as it was open to the atmosphere anyway.
 
nevets
i would be interested in if this works as planned. i have the same set up but a different bottle. i added the rubber seal in my cap. it does send fluid to the bottle but i can't say it pulls any back. so it has really become just an overflow bottle.

as far as air in the line: My TR6 had the same set up and it always had air bubbles in the line. but you could see the bottle had more fluid in it when it was hot and lower when the engine cooled. main thing was to keep some fluid above the transfer tube at all temps.

i wondered if the reason mine does not work right... is the bottle is too low compared to the radiator cap? or too far away for a 7LB cap? or is my seal just not working as it should? either way i don't see it pulling coolant back to the radiator. good news though is no coolant on the floor.
 
My setup was originally identical to Nevets' above with a square tank in that position and it worked perfectly.

I kept enough coolant in the bottom of the reservoir to cover the outlet and kept the radiator full to the brim. It would stabilize with the coolant about 1/2" down from the filler neck. It would pull the overflow back when the radiator cooled.

Now I'm using an MG brass tank clamped to the shroud support. It works equally well.
 
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I borrowed tje entire system from my P1800 Volvos and installed on my Healy ,never lost a drop of water or overheated since.-
 
I also had that setup and it worked perfectly. The way to test if it's working is to see if the coolant level in the plastic tank is higher when the engine is hot than when cold (which may not be easy as the change in level isn't much), or, after running the engine and cooling off, see if the coolant is full in the radiator neck.
 
YEP:

You are spot on John .
 
mine will put coolant out in to the overflow but not pull it back when the engine cools.

it may be my cap though. i put a rubber seal under it but i think i can hear it losing some air when i shut the car off and the engine is hot. if it is losing air it is likely sucking some back in, as opposed to pulling back coolant when cooling.


now got me to thinking. read about the NAPA cap that works for recovery tanks #7031411. going to stop by tomorrow and pick one up to try.
 
Hi All,

I have used a non-pressurized recovery tank for years with success. The tank used is mounted on the left side of the radiator sitting on a home made bracket and the recovery container is a used rear end oil container with a small hole in the cap to accept the tube. To incorporate a recovery cooling system in my Healey and, as Drone Dog mentioned, I acquired special recovery-capable radiator pressure cap with a 1” drop, for my original radiator. Although this is a non-common item, they are available for bothLBCs and older American classics through NAPA (Balkamp 703-1411) and a number of other suppliers.

https://drive.google.com/file/d/0Bx4EjcJmfaScY0NLdlB0YjEwRFE/view?usp=sharing

It has been a traffic and inexpensive addition,
Ray(64BJ8P1)
 
This is the cap I purchased from NAPA. Not sure if it's 7031411, but it does have an upper rubber seal, as well as a spring loaded lower seal. Hopefully this will maintain a vacuum without an additional seal?
 

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nevets said:
This is the cap I purchased from NAPA. Not sure if it's 7031411, but it does have an upper rubber seal, as well as a spring loaded lower seal. Hopefully this will maintain a vacuum without an additional seal?
Click to expand...

That'll work fine as long as the depth is correct. This 1/16" rubber gasket's been working well for >10 years on the stock cap.

screenshot.2275.jpg
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Steveg, thanks for the pictures. If the NAPA cap doesn't hold a seal, I'll add a gasket similar to yours.
 
nevets
i tried my new NAPA cap yesterday and it worked fine. First time the car has pulled coolant back out of the bottle. in fact it sucked the bottle dry. So now i have added more coolant to the system. will see where the new norm is.

maybe the old cap, from Moss, had an issue. Or maybe putting the rubber seal in did not let it seat right. either way it did not work for me.
 
Steve G. and Randy F. both have the brass MG overflow tanks.
Anyone else?
How exactly did you mount it to the shroud support?
I have the tank and the bracket that came with it.
Thanks.

Douglas
 
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