Coolant question

[Like It's Stolen]

Hey chaps
Seems my Atom deposits a small amount of coolant when returning from a run. Not a lot, and when cooled down it stops, but enough to need the coolant topping up after 1000 miles.

It's an AA3 with a K24Z7 engine.

Questions:

1. Is this normal? A search on the forum suggests it may be.
2. What coolant do you guys use? Does it matter? As a mechanical noob I have no idea and any advice is appreciated. The manual doesn't mention any particular type and searches on sites like Autozone suggest coolant is coolant is coolant.

Cheers.

[atom ant]

That's not quite true. Here is the extreme short version:
First and for-most, water is actually the best coolant (this is why you often see people carry a jar of water in cars with coolant leaks). But water evaporates to quickly, when this occurs it will form vapor pockets causing metal to warp.
Coolant (Ethylene Glycol) has a much higher evaporation temperature and will mix with water well so in majority of applications people use a mixture of EG and water. The mixture proportion can go vary widely depending on operating temperature, ambient temperature etc.
Less common coolant (None Aqueous Propylene Glycol or NPG) uses no water at all. This has a very high evaporation temperature.
To complicate things even more, there is the pressure cap. The pressure cap (ranges from 8psi to 22psi) pressurize the cooling system, this in effect also serves to raise the evaporating temperature of the fluid to prevent flash evaporation. Because of the very high evaporation point of NPG, they can actually run with 0 pressure cap.
Cooling fluids will expand (some more than others) when the engine is at operating temperature. That is the reason for the overflow on the coolant reservoir. Depending on how much fluid was in the system, when you run the car hard it can expand to the point of overflow.

And by the way, why would anyone ask Autozone for anything other than a battery check .

Mike

[Like It's Stolen]

I just used their site to see what options were available, seem to all be mixes of coolant / antifreeze.

So you're saying I should just pick any random one and chuck it in?

[atom ant]

Typical cars including the Atom3 uses EG (the green stuff). 50/50 mixture is typical, you can purchase pre-mixed EG or mix it yourself. Any brand EG is fine.
Unless you plan on changing the system to NPG, that would require a system wide drain/flush/fill.

[Terry Kennedy]

I just used their site to see what options were available, seem to all be mixes of coolant / antifreeze.

To play it safe, I'd suggest calling TMI and asking what they use, then getting the same type.

In the past, it was possible to tell what chemistry a coolant had by looking at the color - green, yellow, pink, orange, etc. That is definitely not the case any longer, and there are chemistries that are extremely incompatible that have the same color.

The most severe incompatibility is between DexCool and anything else. Brammo cars generally were factory filled with DexCool except for the earliest, which got whatever was handy. I strongly doubt TMI is using DexCool as that's a GM-ism.

If you can't find out what's in the car and want to replace the coolant, the best thing is to flush with water between old and new coolants. Topping up a "mystery" coolant can be done with water (preferably distilled, but not essential).

[MadMaxAtom]

^What Terry said is spot on. Dex-cool was a dirty word in the 90's. Eventually they straightened it out..sort of.Best to just avoid it altogether. Use what TMI did originally or just add pure water. Many a coolant system has been damaged by improper fluids and neglect.

[Like It's Stolen]

Thought I would follow up on this. Turns out there was a small pin hole (2 actually) in the L-shaped hose under the engine and that was the source of the leak. Had it replaced and it's holding its level now.