will running tap water in coolant system in 2004 pontiac grand prix cause it to overheat?
Just plain water has a boiling point of 212 degrees adding a pressure cap will raise that some. Antifreeze has a much higher boiling point. Are the cooling fans running properly? Radiator's air flow not restricted?
Found your other post, it is a big no no to put any block seal in your system as it causes more problems than it cures, it radiator is usually what gets plugged up followed by the heater core, then smaller water passages in the engine. If it got that hot then it most likely blew the head gasket or cracked the head or heads, could have even blued the block. The only way to tell for sure is have a good shop do some engine block testing.
I have run plain water in the summer without a problem, but it is not the best ideal. Make sure you get some anti-freeze in there by fall. Do not use Dexcool!!!!!
Plain tap water is fine but it needs to be mixed with coolant as has already been said. This is important year round. If you're going to switch from the factory Dexcool your entire system needs to be properly flushed first to remove all of it as it is not compatible with other types of non- dexcool coolant. GM still uses it in their cars.
Tap water is actually better at transferring heat than 50/50 antifreeze, but it will boil at a lower temperature than the mix, and that can cause problems. So as a temporary emergency fix, tap water is okay. But do not leave it in the engine. The minerals in tap water will corrode internal engine parts and can quickly clog up small water passages with deposits. When I say 'quickly' I mean within a few weeks. Some people use distilled water to avoid this, but the anti-corrosion additives in anti-freeze are a vital part of the cooling system and shouldn't be neglected.
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