496 HO coolant?
 

Had a 1 year old water pump impeller come apart, so i am pulling all the coolers to clean out and inspect. I do not know how old the closed cooling coolant is but i figure it should be changed or is there a recommended time interval. When you take off the end caps, do you loose coolant?

I did order the Hardin stainless pump to replace my factory pump which is pretty bad,

2001 496 HO

Thanks

Marc

No you won't loose any when you remove the end caps raw/ sea water will come out if you don't drain .

+1

If you do change it, it needs to be the orange Dex-Cool. Sombody should chime in but I think the first change interval is 300 hours. The only real way to change it is by removing the hex plugs in the block.

However, I take off the reservoir every 3-4 years, clean it and put it back on.

Coolant is good for 5 years then it needs to be changed. If it is dull in color it is done. I used premix dex-cool instead of using tap water and mixing myself. The block plugs are not easy to get to because the auto drain valves are in the way so you may have to unbolt them from the block to make a little room.

50% orange Dex
50% distilled water

DEFINITELY do not let it go more than 7 years/seasons
If it is not bright pink, and has a metallic or dark look as described above, it's starting to silt up; and no cool as well.

IF you are changing antifreeze, I strongly suggest replacing the thermostat as well as both grommets on the heat exchanger to crossover.

its take 19 qts of coolant for the capacity - buy 3 gallons of Dex Cool and 3 gallons of DISTILLED WATER mix it all evenly either gallon per gallon or however but a 50 / 50 mix.

Change timeframe is every 5 years or 500 hours which ever comes first. If not using DEX Cool extended coolant - pink / orange color- then its 2 years / 200 hours whichever comes first.

All grommets and end caps and o ring gaskets needs to be changed every 5 years or if seen they are leaking or starting to deteriorate before that timeframe.

If you ever have overheated the engine pretty hard then all of this at that time frame needs to be changed out including the T Stat. The T stat is missed alot times especially when the engine has been overheated / pretty hard.

Thanks guys.

End cap seals and T-stat ordered. Will pick up DEX cool. I start tearing it apart Tuesday for the July trip to AR and MO!

has anyone thought to change over to the newer OAT coolant? seems like it would be much better for the entire system and would last just as long.

2003 496 mag with 800 hours, never been changed. Still looks good though. I cannot find the block plugs for the life of me. Anyone have pictures of what they look like? I've looked online with no luck. TIA.

They are down low, on the sides of the block, just above the oil pan. They are a brass plug that screw into a hole drilled into the block, and they have an allen head 6-sided hole bored into them. Sorry, no pics; that was recollection from when I pulled them out years ago. They are definitely not easy to get to. Of the 4 on my twin engine 496HOs, I could only get to 3 of them. The center stringer was in the way of one of the inboard plugs.

Thanks. Are the plugs on an extrusion from the block or are they flush with the face of the block?