Please explain why?

[Manxman]

My 2L motor has a thermo-wax driven faster idle when hot. This is a default feature. It's not working/adjusted correctly ATM. Can anyone tell me the faster speed at a specific temperature, so I can gauge how well it should work when reasonably adjusted. NB My thermostat is jammed open ATM, & I'm unwilling to disturb it as I fear the chamber corrosions.
I'm finding that in slow traffic on an hot day, my idling motor will boil the uncapped, water only filled radiator and the motor will falter and stop. I understand it's too hot, that it needs coolant, and a cap. ATM there is a cooling leak I can only stop by not presurising the radiator, which is adequately full. What I want to know is what precisely is killing the motor--is the fuel in the injectors boiling, or what? I understand this isn't good for my engine, but as that's terminal I'm not going to worry. I'll adjust the thermo wax gap and see it I can make the very worn linkages work. Pehaps this is why the heads were re-designed for the 3L and 5L--that they were running too hot at prolonged idle in hi temp areas. I note my 5L doesn't have a thermo wax, [or it's not plumbed on]. Thx all.

[trentmeyer23]

You are cooking the engine, I wouldn't be surprised if you melt a piston with what you have been doing, you have effectively made the cooling system null and void.

[CONROD]

May be all the **** that's jammed the thermostat open has also blocked the hell out of the radiator !!!!!!!!!!!!!!!!!

A radiator needs to be pressurised to raise the boiling point of the coolant.

As trentmeyer23 pointed out terminal damage is inevitable if you continue as is

[JDM-GTFour]

Maybe your radiator is so full of rust and dirt, mud, crap etc that it isnt cooling when vehicle not moving?... try another radiator...?

Speaking from experience on this one....

[Manxman]

Thank you for your answers. The motor is not trying to sieze, it's too worn for the pistons to grab, I would suggest. That it runs at all is a miracle to me. I suspect the thermostat has jammed because it's very old, and no longer regulating motor temp, and long warmups. Being usually brass, they don't corrode. I don't make a habit of doing this, I just noticed this behaviour when in the city on Friday & I'm wondering what is actually happening? The head gsk is leaking slowly at idle, but no contaminations anywhere yet. I can't stop the cooling leak, so I run with the cap loose to keep the water in the radiator-crude, but effective. If I get the thermo-wax adjusted correctly, the motor might not overheat again, as the faster idle will pump more cooler water through the motor and keep the temp below critical. At least, I think that's how it's meant to work, but the linkages are very worn, and may not allow operation. I see no reason to spend any more on it. It is running on sump oil atm, 1L/100km-burning it-and I'll change it & filter every 2000km til it dies or I have my other motor sorted and refitted. I am keeping it under 2500rpm.

NB all 4 cyl appear to die about the same time, [over abt 2 seconds] so I doubt its valve clearances, and it seems a precise temperature. The motor will immedaitely restart if given lots of throttle, but runs poorly under 2000rpm until the temp falls. The motor appears to have one good cylinder which always starts well, then the others catch on a few turns later. Could be bad injn. pump? The glowplugs are ok.

Edited January 18, 2014 by Manxman