Overflow tank suddenly full

DanijelTodic

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Oct 17, 2019
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He guys,

I have been on the road for the last 5 weeks with the S10 and some things sometimes pop up.

One of these things is the sudden filling of the coolant overflow reservoir. It has suddenly risen almost to the cap. The last time I checked the level was between min and max.

It is hot here and I am in the Alps so there are some altitude differences. What could be going on here? Is this normal?

Greetings,

Danijel
 

elricfate

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It's entirely possible that while the coolant is extremely hot you can have some slight overpressurization - but that's designed into the measurements for min/max. Once the bike cools does the coolant return to a normal level?
 

DanijelTodic

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It's entirely possible that while the coolant is extremely hot you can have some slight overpressurization - but that's designed into the measurements for min/max. Once the bike cools does the coolant return to a normal level?
Exactly. I know that the tank is there for that purpose but it's seem a bit much coolant overflow if it almost reaches the cap...Or is this also normal?
 

gunslinger_006

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Let the bike completely cool, then remove the radiator cap and check if the level is near the top, while noting the reservior level also.

I would also check the lines to and from the tank, top and bottom.
 

WJBertrand

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Could be a bad cap. If it's not sealed against vacuum it may pull air back into the radiator instead of fluid back from the over flow tank. A couple heat cycles and your overflow tank fills up. As gunslinger recommended open the cap after the system has completely cooled and if the radiator is not completely full lower cap seal, this may be the problem. Cracked overflow lines was a common problem on the Honda ST1100, and would cause what I described; fluid out when hot, air sucked back in upon cooling. So far I've not heard of this issue with the Super Tenere, but worth checking the hoses for cracks, leaks or kinks.
 

DanijelTodic

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Let the bike completely cool, then remove the radiator cap and check if the level is near the top, while noting the reservior level also.

I would also check the lines to and from the tank, top and bottom.
I am going to this tomorrow after the bike has had a chance to cool off. Hope all is well and it's just a matter of maybe replacing the radiator cap. If the level is not near the top what should I do then? Do i add some coolant until she is full? What if in the morning the overflow reservoir is still full?
 

DanijelTodic

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Could be a bad cap. If it's not sealed against vacuum it may pull air back into the radiator instead of fluid back from the over flow tank. A couple heat cycles and your overflow tank fills up. As gunslinger recommended open the cap after the system has completely cooled and if the radiator is not completely full lower cap seal, this may be the problem. Cracked overflow lines was a common problem on the Honda ST1100, and would cause what I described; fluid out when hot, air sucked back in upon cooling. So far I've not heard of this issue with the Super Tenere, but worth checking the hoses for cracks, leaks or kinks.
I really hope that it's a bad cap and not the head gasket or something major. I am still learning about how this system works. What should I do if tomorrow morning the overflow reservoir is still full and the radiator not filled to the neck? Should is add coolant to the radiator?
 

WJBertrand

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I really hope that it's a bad cap and not the head gasket or something major. I am still learning about how this system works. What should I do if tomorrow morning the overflow reservoir is still full and the radiator not filled to the neck? Should is add coolant to the radiator?
Yes top off the radiator and then remove some from the excess coolant in the OF tank. Unless the fluid looks contaminated with oil, I would not worry about the head gasket. Make sure you’re confident you’ve identified the issue first though.


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DanijelTodic

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Yes top off the radiator and then remove some from the excess coolant in the OF tank. Unless the fluid looks contaminated with oil, I would not worry about the head gasket. Make sure you’re confident you’ve identified the issue first though.


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I just topped up the radiator. It was maybe 400ml of coolant that was added. I hope the engine die not get damaged because of this.

I also found some nasty white stuff around the radiator cap. What can this be?
 

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Nikolajsen

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Uh, the nasty stuff, should not be there.
And as far as I know, it is oil.. :eek:
Or at least waste products from the oil. Anyway coming from where there is oil.

Unless that someone put something in the coolant, have you any recall of that?
 

DanijelTodic

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Uh, the nasty stuff, should not be there.
And as far as I know, it is oil.. :eek:
Or at least waste products from the oil. Anyway coming from where there is oil.

Unless that someone put something in the coolant, have you any recall of that?
I don't think it's oil....I emptied the overflow reservoir and the coolant looked brand new. No signs of oil. I think it's evaporated coolant....
 

Boris

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That doesn’t look like the Mayo you would normally get with HG failure. Does the oil in the sight glass look normal?

If it does, I’d forget HG at this stage.
 

DanijelTodic

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That doesn’t look like the Mayo you would normally get with HG failure. Does the oil in the sight glass look normal?

If it does, I’d forget HG at this stage.
The oil looks completely normal. At this stage I really think is the cap. I am now looking for a new cap but they are hard to find in stock. These things are pretty universal right. Should it matter if I get one with a higher rating. 1.1 bar is not that high so going to 1.3 should not harm anything right?
 

Madhatter

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silicon residue im thinking . seen it before , not sure why it does it ,thinking some coolant has silicon in it and that's why the residue. just my best guess .
 

Jlq1969

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The oil looks completely normal. At this stage I really think is the cap. I am now looking for a new cap but they are hard to find in stock. These things are pretty universal right. Should it matter if I get one with a higher rating. 1.1 bar is not that high so going to 1.3 should not harm anything right?
The problem with the cap, is not the spring, it is probably the lower rubber that is marked by the radiator. Change the rubber ( or turn the rubber over while waiting for a new cap or rubber)... but don't buy a cap with more pressure. Without discussing the design of the "cooling system" and the working pressures ... if you change the cap for another with a spring with more pressure ... and the base where the rubber closes, is the same (the same contact surface) ..... the rubber will deform prematurely, conclusion .... it will last less
 

elricfate

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It's a silicone mash, or at least it looks like it, it's either really old (and needs to probably be flushed) or someone added a modifier to the coolant and it sludged up a little. So here's my concern for you at this point, your lines might have this same mash in it, which is normally fine as it flows with the rest of the fluid and is usually gone with a flush. But if it started sticking in a line somewhere, it's like an artery with a build-up, causing over-pressurization. If I were you, honest to god, I would just flush the radiator and overflow and refill.
 

pilleway

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I might think that what you found in the radiator neck migh be Coolant residues, (when was the pervious time you looked in to the radiator cap, for sure, too long ago) so it migh be there due to accumulation and of course the rubber of the rad cap. My recomendation is as said look in to the cap and as soon you can do a coolant replacement and take a good close look in to the coolant remove to see if there is any other indicator of failures (look for color, deposits, other different things) and compare it with the new coolant to be used. Using a higher pressure rad cap I would not recomend because you will increase the complete cooling sistem pressure and will harm your system somehow.
Hope you can solve your problem and keep us inform on your findings.
Have a great weekend.
 
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