Engine Overheat Issues

[Ebeard4]

@SupraSabre Helpful pic! I’ll bet that was a bit of a mess. How many miles on that particular bike?

@Igofar Just arrived home, Sir. Plan to take the ST on the road early tomorrow, check temps and report…

Appreciate y’all’s input so far!

 

[Ebeard4]

Morning!
Took the bike out for a bit before work:
Ambient temp was 48°
(Following temps measured with IR gun, facing front of bike, on top left and top right) Distance/Speed/TempBars/TopLeft/TopRight
- Idle temp after 6 min warm-up: 0/0/3/252/108
- .5mi/45mph/5/122/241
- 2.5mi/60mph/5/230/235

Though I didn’t get to go too far, hopefully this is enough information. Looking at these facts based on what you all have said is making me think it’s an electrical issue, indeed!

 

[SupraSabre]

@SupraSabre Helpful pic! I’ll bet that was a bit of a mess. How many miles on that particular bike?

@Igofar Just arrived home, Sir. Plan to take the ST on the road early tomorrow, check temps and report…

Appreciate y’all’s input so far!

That engine had 74K on it. I know there was some work done it at some point, I know that the clutch in it had to have been replaced, but came out toasted. But cop bikes were treated pretty hard, even with low mileage.

 

[RVtraveler48]

Sure sounds like a stuck thermostat.... but since you replaced, can you hear the fans kick on? let it idle for a while until they come on.

I have had my ST for 15 years and for the first time, after a stretch at 50mph, stopped at a light and the temperature began climbing. It does have a minor coolant leak somewhere never located, and I carry some extra antifreeze, but I'm thinking that since the temperature came down as soon as I started moving I am suspecting the relay that turns the fans on. It happened again on my ride back - as soon as I came onto the RV campground in 2nd gear the 4th led lit up but 50 yards later when I stopped the fans were running. I'm thinking they are intermittent - does anyone know the location of whatever tells the fans to come on?

I am wondering if the water pump on an ST1300 can be ... intermittent? At highway speeds it's generally fine (3 leds) but stuck in traffic, I can hear the fans so it's not what I thought - but to me water pumps either work or they don't. Could something be slipping that at higher rpms takes hold, but at lower speeds not so much? Today at 4 leds waiting out a light I gave it some throttle and it came down. So now I'm thinking water pump, but again - how could it be intermittent? Any ideas appreciated.

 

[RVtraveler48]

Sure sounds like a stuck thermostat.... but since you replaced, can you hear the fans kick on? let it idle for a while until they come on.

Because I wear ear plugs for the wind noise, I couldn't tell when it was indicating overheat conditions - but today I clearly heard the fans. At highway speeds it's fine but stuck in traffic 4, then 5 (highest so far). I gave it some throttle and it came down - can a water pump slip??

 

[Andrew Shadow]

At highway speeds it's fine but stuck in traffic 4, then 5 (highest so far). I gave it some throttle and it came down - can a water pump slip??

It doesn' go any higher than 5 bars- You are in danger territory.

The water pump can't slip but there have been a couple where the impellers were so disintegrated that they no longer moved enough coolant at low RPM's. This is the extreme however.

 

[dwalby]

Have you checked the coolant level at the radiator cap? Especially since you claim there's a coolant leak that hasn't been identified, your first priority is to make sure the radiator is full. If the fans come on, but the radiator is half empty, its not going to cool it down sufficiently. Perhaps by blipping the throttle you increase the flow through the radiator enough to compensate for it not being full.

Another possibility is if you didn't change the coolant frequently enough your water pump impeller may have corroded and lost effectiveness. Higher RPM may help there.

I don't know about the 1300, but the 1100 water pump is driven by the timing belt, so no chance it would be intermittent unless the impeller somehow came loose from the pulley driveshaft, which is probably next to impossible.

 

[Al st1100]

Ya might want to try a blue water test, would verify head gasket one way or the other. I have seen radiator hoses bubble on the inside restricting flow, just a thought.