This is why you take care of your cooling system

Capital

Capital

Joined
Aug 30, 2020
Messages
114
Location
LTU
Bike
2002 ST1300A
Had a wonderful moist morning today, we headed out at 6AM, to visit a sightseeing place (partisan bunker - it deservers a separate story but not this time around). After around 90 kms riding (outside temperature around 15C), having the usual temperature gauge reading at "10 o-clock", we turned to a very bumpy unpaved road for ~10 kms. At the end of it I noticed, that my temperature went up to around "1 o'clock". Well, that is unusual, but I did not care too much, as we were doing a lot of riding at 2nd-3rd gear on a higher rpm trying to stay on the [unpaved] sandy road.

On the way back (10 more kms of unpaved road), back on the tarmac at around 110 km/h I notice the temperature gauge going back and forth, all this movement happening at "12-2 o-clock", not getting too close to the red line. Something suspicious, I ask the guys to stop at the next gas station. And what do you know - as I stop, shut it off, my overflow tank's overflow tube starts spitting coolant. First thought - "what the hell", but 2nd though "it can't be true - I did so much to overhaul the cooling system in winter!".

Turns out, that the bumpy road hit the nail to the electrical contact at the radiator fan plug (see pic below). That looks like the only thing I've overlooked, apart from changing: all hoses, radiator, thermostat, cap, checking overflow tube, etc. That foolish mistake I've made ignoring the connectors!

I'm almost sure, that if I was still riding with coolant hoses back from 1991, I would've had a longitudinal split on one of the hoses and my trip was over. Or if I decided to keep the old "whitish" radiator.

Nonetheless, with the fan back on (after playing with the connector) I returned safely back home the next 50 kms, and now need to do a flush and make sure that normal coolant (not some generic from the gas station) continues to flow in the system. Also properly clean and add some dielectric grease to the connectors :)

Take care of the coolant hoses, but don't forget the connectors!! ;)

IMG_1998.jpg IMG_1999.jpg
 
I'm not sure that a boil-over as shown would happen with a dead fan, especially as you say the temperature gauge never went near the red. My guess is that your cap needs to be replaced first, if it won't hold pressure you get localised boiling at lower temperatures, and the steam generated will push coolant out of the reservoir tank.
 
I've said this before. Dielectric grease is an insulator. If you smear it on say a pair of spade type connectors, when you put the connectors together, the grease gets scraped off the metal as they go together, allowing the current to flow. I suggest you clean or replace those connectors, assemble them and smear the grease around the outside to seal out moisture.
 
Thanks for all replies! Yes I will pick the right coolant. And the cap was new - will give it a try to buy another one maybe. Will also take care of the connector.

After returning and the bike cooling down for half a day, I checked the levels both at radiator and overflow - everything in order as I left it before taking off.

Will continue monitoring after maintenance, let’s see. The air is only getting warmer :cool:
 
Ordered OEM cap (other options are chepest automotive brands for Hondas, one of which is possibly failing now…). And will grab type 2 coolant at the dealership. Hope to do maintenance later this week and forget the jeating problem. Again thanks all!
 
I'd also have another look at the overflow line. A tiny crack anywhere along it will remove the possibility of antifreeze returning to the radiator.
 
schlep1967 said:
I'd also have another look at the overflow line. A tiny crack anywhere along it will remove the possibility of antifreeze returning to the radiator.
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Indeed, a known issue. I eliminated a small crack at the thermostat during winter. Also it is returning as it should so no issue there for now.
 
Capital said:
Ordered OEM cap (other options are chepest automotive brands for Hondas, one of which is possibly failing now…). And will grab type 2 coolant at the dealership. Hope to do maintenance later this week and forget the jeating problem. Again thanks all!
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Type 2 coolant at a honda car dealership is cheaper than at your local honda motorcycle dealership.
 
Kevcules said:
Type 2 coolant at a honda car dealership is cheaper than at your local honda motorcycle dealership.
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In my town it is the same dealership :) And the cost is the same as any other moto coolant (e.g. Ipone). So I’m covered there :)
 
I was doing some tests during the weekend. What I changed - put on brand new OEM radiator cap, drain a mix of coolant and refill with distilled water (for now), clean fan connectors with contact cleaner. Also had a thought of a pretty dumb mistake I've made during the winter - I was taking care of the cooling fan housing and repainted it, as it was rusty... What I haven't thought of, is that electrical circuit (GND to be exact) goes from fan's housing to the radiator, and the through the fan switch turns on the fan. So I added additional GND from battery to radiator, as I am pretty sure that there is too much paint where it shouldn't be, hence my random fan work once all metals heat up.

Outside temperature was 30C (86F) - good occasion to test engine heating. The tests and results:
  • I was doing all tests standing still
  • System filled with distilled water
  • The engine still takes some time (at least 10 mins.) to heat up to "12 o'clock" holding around 3,5k RPM in Neutral
  • Fan kicks in just before "12 o'clock"
  • If I continue holding 3,5k RPM, the water starts going over the expansion tank (but my guess it is kind of normal having in mind pretty warm weather temperature)
  • If I warm it up and hold it at idle, expansion tank does not overflow. Fan turns on, runs for some time and turns of (no visible change on the temperature gauge, but it does not pass "12 o'clock". Expansion tank level goes up a little bit, but doesn't overflow
  • At all times, once the engine cools down, water gets sucked back into radiator. Radiator water level holds at top position after cooldown.
What I think to do next is take off the radiator and clean off the paint from fan frame where it touches radiator, to ensure it has proper GND connection. I also have a suspect of the fan switch, but looks like it works OK.

My biggest question to the public - is my radiator cap (again - brand new OEM) opening up at the right time, opening circuit to overflow?

P.S. was it hot? I guess it was:

IMG_2042.jpg
 
Capital said:
P.S. was it hot? I guess it was:

IMG_2042.jpg
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That happened to me once. Getting the bike off the center stand was not easy. The asphalt did not want to let go...That's how all those guy's perished in the La Brea Tar Pits. (Wonder if there is an old motorcycle in there with all the bones.... :rofl1:)
 
I'd like to ask a question on this subject .Today I went on some gravel roads - off the main road , mostly 1 or 2nd gear and up hill. Temp went up to 2 o'clock. The fan is kicking in and out (it hardly ever comes on with normal driving) . Well my question is -when you cut the ignition (key) should the fan cut also ? I does on mine. Just to end the story, I didn't have any problems on my trip.
 
yes, if you turn off the ignition the fan will shut off. If you turn the key back on immediately, the fan will continue running even if you don't start the bike.

I think the reason your bike heated up so much is you were doing a lot of low speed riding. The ST1100 temp will continue to climb until the fan comes on if you're not moving 40mph or so or faster.
 
dwalby said:
yes, if you turn off the ignition the fan will shut off. If you turn the key back on immediately, the fan will continue running even if you don't start the bike.

I think the reason your bike heated up so much is you were doing a lot of low speed riding. The ST1100 temp will continue to climb until the fan comes on if you're not moving 40mph or so or faster.
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Yea , it was my first take on these Norwegian cow paths , and it went slow.
 
JJames said:
Today I went on some gravel roads - off the main road , mostly 1 or 2nd gear and up hill. Temp went up to 2 o'clock. The fan is kicking in and out (it hardly ever comes on with normal driving).
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I've had that happen to me, also during slow travel in low gears on gravel roads. It's normal.

Michae
 
JJames said:
I'd like to ask a question on this subject .Today I went on some gravel roads - off the main road , mostly 1 or 2nd gear and up hill. Temp went up to 2 o'clock. The fan is kicking in and out (it hardly ever comes on with normal driving) . Well my question is -when you cut the ignition (key) should the fan cut also ? I does on mine. Just to end the story, I didn't have any problems on my trip.
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Did you notice what was happening with coolant level in expansion tank? How is the level now?
 
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