N/a overheating..

[Guest Roger NE]

It would because without the cap on its not pressurising so if done for long enough the water will boil

just like it does in a kettle and it only has 1 place to come out which is the rad neck.

 

Yes but it usually only comes out GENTLY . . . . it doesn't start spurting out ! (and in practice the coolant doesn't actually boil . . . it usually reaches around 90 degrees)

 

Sure, if you had the Rad Cap ON and then took off it would spurt out, because of the pressure build up that you are then releasing . . . but that's not what we're talking about.

 

Like others, I have done this DOZENS of times, without any problems . . . . . in my experience the only time you start getting torrents of coolant spurting out the top of the Radiator is when the Head Gasket has started leaking.

Edited September 1, 2013 by Roger NE (see edit history)

[Nic]

Yes but it usually only comes out GENTLY . . . . it doesn't start spurting out ! (and in practice the coolant doesn't actually boil . . . it usually reaches around 90 degrees)

 

Sure, if you had the Rad Cap ON and then took off it would spurt out, because of the pressure build up that you are then releasing . . . but that's not what we're talking about.

 

Like others, I have done this DOZENS of times, without any problems . . . . . in my experience the only time you start getting torrents of coolant spurting out the top of the Radiator is when the Head Gasket has started leaking.

 

Very rare for the headgasket to go on a 2JZ motor. Overheating is almost always down to depressurisation of the coolant system, be that leaking rad cap, split pipe, leaking heater matrix, core plug or cracked radiator.

Edited September 1, 2013 by Nic (see edit history)

[Guest Roger NE]

I'm very aware of that . . . . in fact I wouldn't be replacing my 7M with a 2JZ if that wasn't the case! But of course it CAN happen on ANY engine.

 

Actually I've personally never found that a failed Head Gasket actually causes much overheating . . . . only if you lose a lot of coolant if it's being sucked into the engine, but that doesn't seem to happen much on these engines. The main issue is the huge pressurisation it causes . . . . which as I've explained is usually seen when you run from cold with the rad cap off.

[Al Massey]

Yes but it usually only comes out GENTLY . . . . it doesn't start spurting out ! (and in practice the coolant doesn't actually boil . . . it usually reaches around 90 degrees)

 

. in my experience the only time you start getting torrents of coolant spurting out the top of the Radiator is when the Head Gasket has started leaking.

 

 

 

Actually I've personally never found that a failed Head Gasket actually causes much overheating . . . . only if you lose a lot of coolant if it's being sucked into the engine, but that doesn't seem to happen much on these engines. The main issue is the huge pressurisation it causes . . . . which as I've explained is usually seen when you run from cold with the rad cap off.

 

Two very contradicting quotes here :/

[Guest Roger NE]

What exactly do you think is contradictory about those statements Al? Please explain . . . .

 

The reason the Coolant comes spurting out the top of the open Radiator when the Head Gasket has started blowing is NOT because the Coolant is really hot . . . . it's because the exhaust gasses getting into the coolant cause a build up of gas pressure which blows the coolant out.

Edited September 1, 2013 by Roger NE (see edit history)