fluid in overflow tank different from radiator green

[Joesprocket]

Hey everyone, quick question about coolant fluids.

I'm getting ready to replace my temp gauge sending unit and to do so I'll need to drain the coolant from the radiator petcock. The fluid in the radiator is fluorescent green however the fluid in the reserve tank is orange...like GM Dexcool orange. I've had the truck a little over a year and this is how it came. Anybody have a guess as to why the 2 different fluids? They should both be the same no?

I appreciate the help for the 'new guy'.

[Grumpy old man]

It's not dex-cool it's probably rust , Dex-cool just causes problems with aluminum heads and radiators .I wouldn't buy it for any car/truck .

http://www.consumeraffairs.com/news0...m_dexcool.html

[geezer#99]

Or the different colors might be because your overflow tank isn't returning the coolant to the rad when it cools down.
It's just sat there for a year turning ugly brown.
The return hose needs to be immersed in the liquid.

[Joesprocket]

thanks! the return hose is definitely submerged but perhaps you're right that coolant isn't being returned for some reason.

I'm going to start by draining the system and replacing the temp gauge sender. Then refilling both tanks and see where that gets me.

If only i could find the correct sensor. Looks like sunpro has discontinued them.

[BLT gmc]

Make sure you have the correct radiator cap, so the overflow system can work as intended. Take care, Bruce
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[piecesparts]

Dex Cool will turn into a sludge, if exposed to air and it sits for a period of time. Flush the collection can and fill with green and mix what you need in the radiator at the proper mix.