need for a radiator reservoir tank ?

[oukippy]

Hello,

 

I have a question concerning my 77 620. I'm thinking about replacing the liquid coolant. I saw on carpartsmanual that only the 78-79 have a radiator reservoir tank. Is it a good idea to add one to my 77 ?

Second question : any specification to follow for the liquid coolant ?

 

Thank you,

 

ouki

[datzenmike]

Most certainly is. AKA a coolant recovery reservoir. I installed on on my earlier 710 too. Hot water expands and if you fill to just below the rad cap it will over pressurize (certainly during heat soak after shut down and more so in warmer weather) and spit out the over flow. Every week or two I have to top up the rad. Coolant expelled while running or after shut down is collected in the reservoir. The coolant recovery system has a special rad cap so that when the rad cools and the water shrinks it sucks the displaced coolant from the reservoir back into the rad. I went from topping up every week in the summer to once a year. Right now if I go out and take the rad cap off the coolant is right up to the top of the rad. Any recovery reservoir from another vehicle that is convenient (or a boughten one) will do. The over flow hose MUST extend to the bottom of the reservoir and be submerged. I have one from a 720 but the rad cap is the important part. Has an extra valve in it.

 

 

Always use distilled water in your rad. Most tap water is 'hard water' in that there are dissolved minerals in it. The cooling system concentrates these by evaporating water away and adding more. Look inside an electric kettle and you'll see lime scale build up. You don't want this in your rad.  

[oukippy]

ok I understand how it works. The tricly part seems to be to find how to attach the reservoir correctly.

 

I checked mine and I think I need to had some liquid 🙄😁

My rad cap is similar to your picture but the seals are a little bit damaged so I'm not sure they will work correctly. Is it possible to change only the cap (I don't know if it's a standard replacement part like hoses). Edit: I think Iv'e found the cap I need with rockauto.

Edited July 17, 2020 by oukippy

[datzenmike]

It needs to be air tight to allow a suction to draw coolant back in. Once started it might siphon.

[vicdat]

A coolant recovery rad cap will have a black rubber gasket that seals up tightly letting the coolant go back and forth...the old style caps have a metal washer that releases the overflow down the tube losing it forever. The spring valves are probably similar for both caps. As Mike said be sure to switch caps.

Almost any type of container is OK for these DIY versions. (The later 620's would probably fit in the stock location)

 

Vicdat

[oukippy]

1 hour ago, vicdat said:

A coolant recovery rad cap will have a black rubber gasket that seals up tightly letting the coolant go back and forth...the old style caps have a metal washer that releases the overflow down the tube losing it forever. The spring valves are probably similar for both caps. As Mike said be sure to switch caps.

Almost any type of container is OK for these DIY versions. (The later 620's would probably fit in the stock location)

 

Vicdat

 

 I've found a good one on rockauto: https://www.rockauto.com/en/moreinfo.php?pk=100323&cc=1210138&jsn=24953

I'll try to find the 620 reservoir in order to have the best mounting part. I read somewhere that hot rods owners sometimes use Jack Daniel's Bottle. I like the idea but I prefer to have OEM part if possible. Or I'll maybe use an hydroalcoolic gel bottle. 😅

[datzenmike]

Go to wrecking yard and look. You just need something that will fit the 620 location you choose.

[gene knight]

oukippy: pm sent

[FrankRizzo]

My PO installed a ChaseBays overflow. Tucked it right next to the rad. It looks good and I have no problems with it, but dont know if I would spend $100.

 

https://www.chasebays.com/products/chase-bays-coolant-overflow?ref=yotpo_93

 

.

[Dguy210]

On 7/17/2020 at 4:04 PM, datzenmike said:

Go to wrecking yard and look. You just need something that will fit the 620 location you choose.

This

 

Stock one off a 210 is quite nice it has a metal bracket that the plastic bottle slides into and mounts almost anywhere.

 

Autozone and ebay carry cheap chinese copies (~$35) ones in CAN format (similar to the chasebays) or you can just get a generic plastic one for usually >$20 from a bunch of different places (Autozone, Amazon, ebay, etc...).