Why does adding antifreeze directly to the radiator (without letting the engine warm up first) supposed to crack the engine block when antifreeze is already in the radiator and is about the same temperature as the antifreeze that is being added. In other words, why is it necessary to warm up the engine first before adding antifreeze to the radiator? Thanks.
Kevin

 

It is not necessary to do that. Somebody has given you some seriously confused information.

The thing you're not supposed to do is add cold fluid (AF or water) to a hot motor, especially an already-overheated one. Just like dropping a cube of ice into a hot glass will break the glass due to stresses from thermal expansion and contraction, putting cold whatever in a hot block may crack it.

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"So many Mustangs, so little time..."

 

My uncle told me however tho, that if you use a sprayer that spreads the water out, like a car wash hose then it shouldn't hurt. We do that a lot when his truck overheats. He has an 88 454 one ton, and we used to have cooling problems when dragging the Kubota around (we build swimming pools).

 

So say I added antifreeze to the radiator when the temperature of the engine was 160 degrees Fahrenheit (which I did). Is that not enough to make any difference? Thanks.
Kevin

 

I've had some radiator troubles over the years and when ever someone has helped me out (including mechanics), they always take off the radiator cap, turn the engine on, and wait a little bit before adding antifreeze to the readiator. So I'm confused here.
Kevin

 

don't think a garden hose would be any better, unless it's just on the radiator.

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ICON Motorsports
1st & 3rd

 

They take off the cap with the engine off irst so that if coolant spews out, it won't get sprayed everywhere by the fan. Then they start the motor to add coolant so that the water pump will suck all the coolant out of the cold-side tank (where the fill usually is), so they can fill it as full as possible. That has nothing to do with the temperature.

Topping off the system with either water or AF is OK for sure if it's not boiling over. What will really cause trouble though is dumping cold fluid into an overheated engine that's so low on coolant that there isn't even enough to boil over. In practice it's pretty unlikely you'd ever be in a situation where it's possible to hurt the engine in a car with a modern cooling system.

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"So many Mustangs, so little time..."

 

Thanks RB83L69.
Kevin

 

the reason they run the motor is to circulate coolant and get air bubbles out of the cooling system, this also resuts in a better fill up.

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87 IROC-z 305 TPI 5spd Borg warner 9-bolt 3.45 posi 4 wheel disc,8.8 Accel wires , bosch platinum +4 plugs,gutted air box,k&n oil filter,synthetic oil 10w30