Expansion rad bottle, replacing with after market...Is overflow release required?

[supra_ufo]

I am fitting a FMIC and picked up a smaller expansion bottle from a old crx, however the bottle cap does not have the overflow hole (to release coolant i guess?), will I get away with not having an overflow hole?

[Dnk]

The tank needs to have an overflow hole/ breather hole or it will pressurize which

its not supposed to do.

It will possibly just blow the tank lid off or split the tank depending on its weakest

part.

 

The civic one i used had a hole in the side of the neck, actually in the threaded part

where the cap screwed on which let the pressure out and also let air get drawn back in

as the coolant cooled and returned to the radiator

 

Has it got a tube that fits to the cap and goes down into the tank ? if not it wont

be any good on supra as it needs one to let the radiator draw back coolant as the

system cools, like this one in the picture, the hose needs to go virtually to the bottom,

say 10mm - 20mm off

Edited July 24, 2014 by Dnk (see edit history)

[supra_ufo]

it looks like this mate

 

[Chris Wilson]

With cap and dip tube fitted to the bottle and the cap tightened, you should be able to blow down the pipe and hear air escape at some sort of breather hole on the top of the bottle or cap. If it doesn't, drill about a 2mm hole in the cap. Then it's fine.

[supra_ufo]

cheers chris I dont see anywhere air would exscape so I will drill a hole, 2mm doesnt seem that big?

[Guest Roger NE]

Personally I would drill at least a 5mm hole . . . if your car ever overheats badly it's not just air that needs to come out, it's fluid too!