Rage

BINGO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

That fits my symptoms to a T.

Since the purchase in 2005 winters on the lake have been mild except the last. I used the 496HO automatic sea water drain valve system every year thinking it was failsafe.

How do you now prevent the HE from freezing as you described even after draining per instructions?

Have you tried to have the HE repaired by a local radiator repair shop? Results?

Reckless32

Been doing some time-killing surfing in the archives prepping for winterization, and was curious what you found out on this problem? Was it the exchanger after all? Or head gasket?

lowfunds

if you run the boat for a extended time and keep it on the rev limiter it will blow the head gaskets. had a customer lend his boat to his nephew and he held it wide open for over a hour and it blew the head gaskets. he also had it over trimmed causing it to hit the limiter. spoke with mercury tech support and they told me that is what will happen. the rev limiter is not designed to be run for that long. to many thing going on like retarding the timing and injector pulse width changes.

Reckless32

Looks like though this guy has (had) a problem with increased water volume and pressure inside the closed loop of the block itself causing an overflow event in the coolant bottle. I'm guessing the two probable causes are head gasket blown allowing more water volume into the water jackets (though not in the cylinders/oil pan)?.....or the heat exchanger has either frozen or rusted thru in one of its' internal tubes allowing external raw water pressure to "enter" the jacket loop pushing the existing coolant out thru the reservoir cap?

This is an old post (4/2007) I was just curious to see which problem it was should it ever happen to me or someone I know.

Rage

It was the latter. Freeze damaged HE.

Reckless32

Ouch! That's what I figured most likely was the cause. What kind of temps did you experience last winter, and how far did you go winterizing? Just curious to see what the lesson learned was and how far is not enough. I'm in a moderate climate area, so we don't really get the sustained cold stuff like a Michigan, or Indiana, etc. does. But I don't want to be caught off guard by not doing enough with regards to the Heat Exchanger.

Sydwayz

The 496HO air pressure purging system is good enough to get your through a couple overnight dips below freezing without doing a full winterization.

HOWEVER, a full winterization of the system with traditional antifreeze filling the sea water side of the system is MANDATORY. This prevents any issues, and also includes a rust inhibitor. If you just push all the water out via air, you are exposing all of the internal passages to air and introducing potential for rust.

Rage, I am glad you nailed your problem down. Its not just the H.E. that is vulnerable to freezing issues, but also the oil cooler and exhaust.

Rage

Yes, this was a total screwup on my part. The boat is on a Hydrahoist year round on Table Rock Lake. Three seasons/mild winters using the Merc drain out system only with no problems (also the lake never does freeze and acts as a heat source to moderate the air temperatures near the water). The fourth season on a warm and sunny Sunday day in Fall I was in a hurry just before sunset and just before my four hour drive back to St Louis to make some A/F data runs for ECU recalibration. I was planning on being back the next week end and had also not looked at the weather forcast. Well we got a brutal cold snap all that next week and I had not drained or winterized anything. I eventually dissassembled and pressure tested everything, manifolds, cool fuel, PS oil cooler, HE, etc. The HE was the only fatality.

Reckless32

Good point about the rust inhibitors of nothing else. Typically whenever we get a warm spell (such as lest year's entire January) I will fire up the motors and let them lubricate themselves (mine is on a lift out back).

Thru reading some crafty posts on here abouth using buckets, hoses, spickets, etc. for flushing anti-freeze into the raw water system I have decided to make my own variation. Since I now have the flsuh kit installed it should be easier at the lift vice trying to do it with flush ears.