OVERHEATED now running sluggish

[cvicek]

thanks for the info string.

[cvicek]

so the sign for Headgasket crack is blown white smoke from the exhaust?

i notice my car blowning lots of white smoke the other day after washing my car. i warmed the car ,but it still blown lots of white smoke, it was a really cold day that day, could it be because of the weather?

but on a nice whether, it hardly blown any smoke from the exhaust.

[Lukezen27]

so the sign for Headgasket crack is blown white smoke from the exhaust?

i notice my car blowning lots of white smoke the other day after washing my car. i warmed the car ,but it still blown lots of white smoke, it was a really cold day that day, could it be because of the weather?

but on a nice whether, it hardly blown any smoke from the exhaust.

White smoke at any times bad mate

Or heating problems

My blown HG didn't blow any smoke at all

[Mr_will]

Umm, I don't think so.

please explain why not

[DLO01]

or you may crack or warps the head block when you puring water into radiator when engine still hot.

Umm, I don't think so.

please explain why not

Because solid metal is an insulator, it will take time to warm up and therefore to cool down. Water transfers heat very easy. It warms up instantly and therefore have no affect on the metal.

[string]

If I heat a big billet of aluminium, then drip water onto a small section of it, of course that small section is going to lose heat to the water. Warming up and cooling down have far more metal to work with than just a small part of the head/cylinders which are coming into contact with cold water.

Perhaps you could be more specific about what you mean by "no affect on the metal"?

[Limbo]

Because solid metal is an insulator, it will take time to warm up and therefore to cool down. Water transfers heat very easy. It warms up instantly and therefore have no affect on the metal.

i disagree with this one Deano, what about warped rotors? The water causes them to warp due to cooling them too fast. I'm sure something similar would happen if you pump cold water into a hot engine

[Mr_will]

Because solid metal is an insulator, it will take time to warm up and therefore to cool down. Water transfers heat very easy. It warms up instantly and therefore have no affect on the metal.

noones really arguing that it will take time, whats relevant is that different portions will be cooling at different rates, and if the variation the rate of cooling is sufficient, the head can warp

[DLO01]

All good valid points. The question was, may the head crack/warp if you pour water in the radiator when the engine is hot.

I do not think it will.

[JohnL]

All good valid points. The question was, may the head crack/warp if you pour water in the radiator when the engine is hot.

I do not think it will.

If the newly introduced (cool) coolant stays in the radiator then you are correct. If the cool coolant contacts the hot metal of the engine then there's every chance the metal will distort.

If the coolant level is low, then when you top up the rad at least some cool coolant is likely to flow into the engine through the upper rad hose into the hot engine, and there will be significant risk of the metal being distorted by the sudden encounter with coolant that is substantially colder than the metal.

Even if no significant quantity of cool coolant flowed backward into the upper engine, if you introduce a substantial quantity of cool coolant into the radiator then start the engine, that cool fluid will be pumped into the engine from the rad in the normal manner. This means that there will be a sudden change in the temp of the coolant in the engine itself, which may be sufficient to damage the metal.

If the engine is very hot (i.e. significantly overheated) and coolant level quite low, then topping up with fresh water / coolant poses a very serious risk of damaging the engine, especially those with aluminium alloy castings (i.e. all Hondas).

This is known as 'thermal shock', and depending on all factors involved (disparity of temps, metallurgy of component material, etc) can result in no damage (at hopeful best), metal warpage, or metal fracture.

The danger of damage can be minimised by allowing the engine to cool down substantially before topping up the coolant, topping up with hot water, or by topping up the coolant very slowly with the engine running.

This means that fresh (cool) coolant is trickled into the rad as existing hot coolant is flowing through the cooling system, so the new coolant mixes gradually with the hot coolant and no 'slug' of cold coolant suddenly comes into contact with the engine metal. This shouldn't be attempted if the engine is severely overheated (be patient and wait for it to cool down first...).

[DLO01]

What about when you fire up your engine for the 1st time in the moring. Stone cold motor & extreme high temps in the combustion chambers. This is the same case but in the reverse direction. Does our head warp?