496: How often to change anti-freeze.
 

I have an '02 496. I just bought it, and I'm not sure when the anti-freeze was last changed, if ever. Should I just test it and if it comes up good, then leave it, or should I change it anyway?

Thx

I believe the red Dexcool a/f is good for 5 years

If it's a 2002 I would simply change it and be done with it. Better to start off with the knowledge certain things are fresh like oils, serpentine belt/s, anit-freeze (for corrsion protection) and other items you personally did not change or clean like electric connectors on your trim pumps, stern light connectors, etc. etc.

Pull some plugs and check for proper gaps and any of the other things you don;t want to leave to trust or chance. Don't forget to grease your coupler bearing as well inside and out.

Done!

I have changed the plugs ($18 a piece), outdrive/engine oil, water separation filter, greased the coupler, and gimble bearing (with the correct, two different grease tubes), 2-4-C on the steering. Checked torque on the gimble ring bolts (55Lbs). The impeller is shot, so I back-flushed everything and waiting for the rebuild kit from R and R Products. Bought a Livorsi sea strainer on ebay, waiting for that.

You are right, the only thing left is the coolant. I'll do that, too. I will do the thermostat while I'm at it.

Anything else, I'm all ears.

Thx!

Tom

Well done!! Not enough guys do preventative maintenance and then wonder why they are stranded or miss a weekend.

Enjoy the boat!!

I have a 2003 and now i will change mine too. I heard there were issues with that antifreeze.

Preventive maintenace is always a plus, just don't get carried away with to many things that don't need service as often as oil, lubrication and manufacturers recommendations.
As for loosing an impellor on a raw water pump on a 496 or similar closed cooling engine, if the impellor breaks up into loose pieces and gets into the raw system, ie heat exchanger and oil cooler many times backflushing will not get all the pieces of debris and rubber back out of the system. Since its not a hard thing to do, remove the ends carefully from both ends of the heat exchanger and check for debris there and remove the hoses from both ends of the oil cooler on the lower left side of the block and flush it both ways to remove any debris. These two actions should make sure your raw cooling system is clear coupled with a normal backflush. The SS kit and impellor from R&R is a great way to save a 496 raw water pump with scoring on the end plates and will las longer than a stock mercury rebuild kit.
As for changing DEX-Cool coolant in this engine as Mercury installs it should not be neccessary until Mercury recommendations unless it gets badly diluted or contaminated. By the way the clossed cooling system on a Merc 496 uses approximatly 4.5 gallons of coolant.
Have Fun! Be Safe!

Best Regards,
Ray @ Raylar

What's the best way to completely drain the antifreeze on a 496?

Two pipe plugs one at the bottom center of the block on each side. One is a real b***h to get to. A little will be left in various low spots unless you flush with clean water but then you will be introducing non distilled water if you use city water etc.

Roger that, thanks. We couldn't find any plugs on my neighbor's 496 but his block is very inaccessable. He screwed up and had used a cooling system cleaner last fall and had one hell of a time getting it all out and getting the right mix back in.

I was getting ready to change mine but I have much easier access to the engine bottom. I'll look for those plugs.

Thx, Ray! One the back-flushing, I actually did just what you recommended. It took a long-time and I was pretty wet after, but I got everything after I 'pieced together' the old impeller.

Also, I did buy the RandR kit, per your recommendation on another thread, just waiting for it to be delivered.

Great having you on this board, thx for all the great advise in your responses.

Tom