New Radiator - Unknown out/inlet

[Eriedor]

Silly question here, just bought a new radiator from Coolex and it has an extra very small port on it at the top that my current radiator doesn't have. What's it for? What's the best way to blank it off?

[Graham King]

Looking at the size of the connector (looks like 8mm), the only thing I can think it's meant for is the 8mm connection to/from the header tank but I haven't seen one there previously and if you used it you'd have to blank off the current connection. Could it maybe intended as a bleed off point?

If you want to blank it off then maybe something like this would work https://www.carparts4less.co.uk/search/203660010 or connect a short piece of the correct diameter hose and insert a blanking plug in that. 

Personally I'd be inclined to contact the manufacturer and ask them what they intended the use to be.

Graham. 

[Eriedor]

I've reached out to Coolex, I think you're right it's 8mm which matches the header tank's small inlet and it's position suggests it's there to vent air in the rad. However my current setup doesn't have one, and the header tanks small inlet is connected to the inlet manifold which I've since read has a Jiggle Valve (unless mines been removed which I can't tell without pulling the inlet off I guess) which is designed to capture air bubbles moving around the system and feed back to the header tank. 

So feels like I can probably just blank off the 8mm outlet on the rad.

https://andrewrevill.co.uk/JiggleValveReplacement.htm

[Wrightpayne]

When fitting the new rad, check how it presents to the 4 bobbins. Mine needed some washers adding to stop the rad being pulled to the shape of the chassis brackets! 

[WobblyWeb]

I encountered the same issue on my K when I bought a new all-ali Rad from Caterham (it came with the spigot not on my old steel Rad) and I used an 8mm brass (in preference to plastic) tee to allow you to join both the bleed spigot from the new Rad, and the existing bleed from the inlet manifold, together, and thence into the header tank. You'll need some suitable hose from the header tank to the tee and tee to the Rad, and some clips. That's what I run - self-bleeds air from the top of the Rad. There are some threads on this in the archives I think, and general advice not to go with plastic tees. Don't blank/block it up!

Something like this:

https://www.ebay.co.uk/itm/264529990988?hash=item3d9737554c:g:rrEAAOSwRu5dycjK

Later car/header tank, but linked pic shows the tee:

http://2.bp.blogspot.com/-ezsrprWZa50/Te_dsnrkHrI/AAAAAAAAABQ/GA_NBLlhQ4A/s1600/2011+05+07_0417.jpg

[Eriedor]

I like that idea, having both is surely the optimum solution. I'll be installing a PRRT with the new rad so should be straight forward to add this as well.

[Jonathan Kay]

"When fitting the new rad, check how it presents to the 4 bobbins. Mine needed some washers adding to stop the rad being pulled to the shape of the chassis brackets!"

Wise words. I'm pretty convinced that some of the problems with leaks from aluminium radiators have been caused by stress from the mounting. 

Avoiding that might include opening up holes in or bending the chassis brackets and packing with washers. The radiator shouldn't be hauled into position by the bolts.

Jonathan