Overheating Possibility

vendredi 17 mai 2019

When I got my new-to-me 2015 X900 home I found a puddle of antifreeze under it directly beneath the drivers seat. It was a loose hose clamp where a rubber coolant hose connected to a metal tube.
Removed the clamp and caught the coolant in a pan, cleaned up the metal tubing light corrosions with a wire brush, cleaned the inside area where the hose mated and re-clamped it nice and tight.
Poured the drained coolant directly back into the radiator, not touching the reservoir which had about 3/4 full indication.
Let the wife try driving it and within a hundred yards it gave us overheat warnings. We turned around and returned to the house and shut 'er down.
Raising the hood I observed the reservoir to be empty.
Using a welder's glove I opened the radiatior cap and the radiator also appeared empty. ??? Made no sense... the same amount drained was returned... but now both the radiator tank AND the reservoir are empty?

I mixed up some 50/50 and serviced the radiator tank (took about a quart) and filled the reservoir (about another quart) and ran it …. everything has been operating normally ever since now, for about a month.... and the reservoir has remained full.

Today I was digging around and found HIDDEN (stuffed) within the left, rear ROPS, at the "box" just forward of the left cargo-release-lever a 3/8" rubber tube with a plastic-capped "vent" valve. It was not visible at all previously. The rubber line leads down beneath the cargo box to the thermostat housing on the top/front of the engine. Looking at the Messicks parts webpage... YEP! THA'R SHE BLOWS!... ref: A38000, item 70, "Air Bleeder Hose".
https://www.messicks.com/ku/90482
I'm reminded of the days when I was a Toyota Tech back in the early '70s. If the coolant was drained (even a little bit) the thermostat had to be "vented" before it was safe to run the engine. A "bubble" of air would be entrapped in the head and surrounding the thermostat. When the engine was started, the thermostat could not sense the coolant temperature because it was not submerged in coolant. Not until the engine was extremely over-heated would the internal steam of the hot coolant finally heat-soak the thermostat and (if lucky) it would open and allow coolant to flow through the engine.
If unlucky.... it'd be too late and the head gasket would blow … and the head may warp or crack.

Let my discovery be a heads-up to everyone... If you drain your coolant, be certain when refilling to have that breather hose valve OPEN to allow the air to escape the thermostat housing. After the radiatior, engine, and reservoir are all filled... THEN and ONLY THEN, close the breather hose valve.
Don't drive around until the engine has fully warmed up and stabilized, and the coolant level re-checked in order to avoid being away with an overheated RTV and no coolant or tools or gloves to deal with it.

(And for goodness sakes don't open a hot radiator cap willy-nilly or add cold coolant to a hot engine.) Hope this helps.


Overheating Possibility

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