496 Coolant Issue/Question
 

I had all of the coolant leak out of the tanks on my 496HOs this winter. About how much coolant will I need to refill them both.

Also, is the Mercury Coolant from their website the best stuff to use? I keep seeing the DEX-Cool being thrown around, but haven't had luck finding that stuff.

Thx.

dex cool is whats in there, the red stuff most auto part store carry it, as for how much ? that depends on how muchyou lost..

The clear tanks are pretty much empty. So the Merc stuff is a no go?

Like he said, you can get Dex-cool at any auto parts store. But, the real question is, why did it leak out? You'd better fix that.

Question is how did you loose it?? Find the leak?

There is no differents at all between the mercruiser name brand or the Texaco/Havoline's Dex-Cool and Prestone's Extended Life 5 year/150,000 mile antifreeze.
http://shop.advanceautoparts.com/web...=21-55668250-2

The compleat cooling system in a 496 engine will hold 19 (US) Quarts.

X 3 on why they both went low in the first place.


There is a really good read about half way down in this link about the difference in Antifreeze chemistry if anyone is interested, Titled Under The Cap, Larry Carley, Tire Review, November 2000
Today's Coolant Options Require Close Attention, Different Techniques.

http://www.automotivehelper.com/topic406907.htm

The difference will be if you happen to find the Mercury branded "pre-diluted" coolant you do NOT add water.

If you buy Dexcool at any parts store including Walmart, you would typically mix it 50/50 tap water and coolant.

As already stated, you better find out why it leaked before you are quick to fill it back up. That system doesn't just "dry up". It went somewhere.

If the mixture was not strong enough and you live in a cold environment, you could be looking at some damage (heads, hoses, block etc).

Pour a little in and start looking for leaks. Pull your plugs and crank the engine. This story sounds familiar. Best of luck!

Awesome, thanks for the help! I spent about 2 hours cleaning the bottom of the bilge as it was full of all of the Dex-cool that leaked out. I talked to a couple friends/mechanics and all said that the temperature swing in Ohio causes the seals to leak just bellow the heat exchanger. Would tightening the clamps up fix the issue once it gets warm out again?

While diluting the Dexcool is the way to do it, I would reccomend using reverse osmosis water, distilled water, or deionized water to dilute it with. Tap water is usually saturated with hardness minerals (calcium carbonate etc.) that scale the HE and the inside of the engine and reduces heat transfer.
I usually open the bottle of anti freeze and dump it into a 5 gallon bucket. Then I fill the the bottle with pure water and add it to the bucket. Mix thouroughly and use. If you're into the second bottle of anti freeze mix, put any excess back into the second bottle and keep it around to top up with.

The leak is most likely between the heat exchanger and cross over, there is a seal that you can't tighten. Mine leaks every winter too even though I've replaces them. Come spring they seal back up with no problems till the next winter. I just live with it, but if someone knows a solution I'd love to hear it.