Coolant level, radiator overflow questions.

[domano 68]

I was checking the fluids on my "new" 72 LWB C10 and noticed the radiator fluid was low. Looks to be about 4" below the top of the radiator.

I know these old trucks do not have overflow containers, they just puke out to the ground from an overflow tube. Where is the tube located? I must be overlooking it.

How much fluid should the radiator contain when cold? All the way to the top of the filler neck, 1" below the neck ?

Is regular Prestone ok to use or should I use Dexcool? Thanks in advance!

[Ironhorse]

Correct in that these old trucks do not have an overflow canister, dump to the ground via the tube, mounted on a nipple on the radiator fill opening. The rubber line may be missing. These were built before the EPA got worried about nasty old anti-freeze hitting the ground.

Start at about 2'' below the fill neck with your anti-freeze and keep on eye on the temp,(should be good at that level) also watch to see if the rad "pukes" any to the ground. Doubtful at that level of fill. Use a 50/50 mix of water and the ethylene glycol green anti-freeze. DO NOT use the pink DEX-COOL if your engine is an older original to the truck. I don't even use that crap in my '99 Tahoe, flushed it out and went back to the old green ethylene glycol.

It is possible to add a overflow or catch can to your truck. Do a search, it is quite a popular mod. I did it to my truck a couple years ago using a windshield washer tank and bracket, mounted to right side behind the battery, looks stock and works fine. Just be sure to use a radiator cap of the correct lb. pressure and specify a cap for the newer style "closed system". Hope that helps.

[domano 68]

Originally Posted by Ironhorse

Correct in that these old trucks do not have an overflow canister, dump to the ground via the tube, mounted on a nipple on the radiator fill opening. The rubber line may be missing. These were built before the EPA got worried about nasty old anti-freeze hitting the ground.

Start at about 2'' below the fill neck with your anti-freeze and keep on eye on the temp,(should be good at that level) also watch to see if the rad "pukes" any to the ground. Doubtful at that level of fill. Use a 50/50 mix of water and the ethylene glycol green anti-freeze. DO NOT use the pink DEX-COOL if your engine is an older original to the truck. I don't even use that crap in my '99 Tahoe, flushed it out and went back to the old green ethylene glycol.

It is possible to add a overflow or catch can to your truck. Do a search, it is quite a popular mod. I did it to my truck a couple years ago using a windshield washer tank and bracket, mounted to right side behind the battery, looks stock and works fine. Just be sure to use a radiator cap of the correct lb. pressure and specify a cap for the newer style "closed system". Hope that helps.

Good info, thanks much.

From the engine code off of the head it appears to be a 350 from a 69 Impala. I believe it is a 16lb vented cap. Do not know if this is what is recommended for this engine.

Just to clarify, will standard green Prestone do the trick?

[Gonepostal]

Standard green antifreeze is fine

[FirstOwner69]

My 69 owners manual states: "On crossflow radiators, if the engine is cold, the coolant level should be three inches below bottom of filler neck or up to the mark on the side of the radiator."

I have always maintained mine that way (mark on the side of the 4 row radiator tank) and have never had an overflow or overheat in the 45 years I've had the truck.

As stated above a 50/50 mix of green ethylene glycol and distilled water is what you should use.

[jjzepplin]

I have always wondered where I could get some "distilled water".

[FirstOwner69]

Originally Posted by jjzepplin

I have always wondered where I could get some "distilled water".

Grocery stores sell it by the gallon. Reverse osmosis would be fine also. Just don't use "distilled spirits" in the truck's radiator. It's made for your radiator.