Rad Caps

[johng]

My Portuguese has a Rad fitted with 30lb cap & an expansion tank with a blanking cap. Haines Manual shows it other way round. Its never overheated. The pipe from the rad enters the top of expansion tank so water can't be drawned back into rad if required. It doesn't make sense why it has an expansion tank. Anyone tell me why ?

[Nigel(no top)Sykes]

I think the pipe grazed into the expansion tank goes to the bottom of it on the inside of the tank. The blanking cap should be on the rad and the pressure cap on the expansion tank (I think)

[grantourer]

I think the pipe grazed into the expansion tank goes to the bottom of it on the inside of the tank. The blanking cap should be on the rad and the pressure cap on the expansion tank (I think)

On my Aussie it is that way round, blanking on the Rad and pressure cap on the expansion tank.

[johng]

The obvious way is blank on rad & pressurise expansion tank except why is pipe on top of tank. Coolant can expand over into tank but can't be sucked back when cooling. Took this tank off over winter & it was third full of rust and cr"p. But since its never overheated , I'll follow the old addage - If its not broken ... Don't fix it

[grantourer]

John, clean the tankout, half fill with antifreeze solution, top the rad up as full as possible, put the blanking cap on, connect the expasion tank, with out the pressure cap, warm up engine until bubbles stop appearing in the expasion tank. Fit the pressure cap, and you should be fine. That is what I did on my Aussie.

[Dean]

The coolant can (and does) get sucked back into the rad. There's an internal pipe inside the expansion tank that goes to the bottom of the tank allowing the coolant to syphon back when needed. The rad will always remain full. There is a fill level marker inside the expansion tank.
Oh, and as the others said, flat cap on the rad and spring cap on the expansion tank.
Dean