2 temp. bars is OK?

[leonides]

Since I replace the ECU because of the constant code 26, my temp. bars were reading 2, on cold (Florida) temps like today it was 59 F and front wind and 70 mph speed.
When stoped at the traffic it went to 3 bars. I also replace the coolant fluid at the same time I did the ECU.
With the other (defective) ECU the temp was always at 3 bars.
Any thoughts?

 

[Al Gully]

I would take the rad cap off when your engine is cold and see if there is any air in there. Top it up with glycol if it shows there is air in there.
Next, make sure you have a full puke tank full of glycol.
Wait a few heat/cool cycles before changing the thermostat would be my advice
Does this bike have a bleed port at the termostat, not sure myself, I'll let others chime in.

 

[Kevin_56]

Historically- your T-STAT is stuck open. Known issue on the 1300's. Once at 3 bars, should stay at 3 bars. No bleeders on the 1300.

 

[ToddC]

Stat stuck open is my vote....

 

[ad.hom]

At 59F, your thermostat is likely stuck open.

Below 32F, I'd debate the issue, but not up at ~59F.

 

[Andrew Shadow]

Below 32F, I'd debate the issue, but not up at ~59F.

Why?
Regardless of outside ambient air temperature, a properly functioning thermostat will always keep a fully warmed up engine operating in the same temperature range- consistently at three bars.

 

[leonides]

Honda designed the ST1300 cooling system to operate at three bars, when warmed up.
I'd also say that you've encountered the common ST1300 problem of a 'twitchy' thermostat.

Is there any thermostat of better quality you can buy or just the Honda?. And while I'm in this area, besides de condt. of the hoses, is there something else I must check?

 

[dduelin]

Once you replace the thermostat it will most likely never have to replace it again. The factory supplied thermostats in 2003-2007 models seemed to fail between 15,000 to 30,000 miles but replacements and later model ST thermostats don’t seem give the same short service life.

There was an aftermarket part available for a while but that was years ago and the supplier went out of business.

Don’t omit replacing the thermostat housing O-ring.

 

[ad.hom]

Why?
Regardless of outside ambient air temperature, a properly functioning thermostat will always keep a fully warmed up engine operating in the same temperature range- consistently at three bars.

Keywords ... fully warmed up.... and debate.

This morning, I set off, maybe 6C...took a good 6 miles NSL speeds to see 3 bars.

I've had it before now (below 0c ambient) where 3 bars were showing, and it went down to two bars.

I've also had it in summer (30ish C ambient) where I've briefly seen 4 bars.

If the only worry is not seeing the 3rd bar for a while, IMHO, it's not a serious issue worth worrying about.

 

[caldercay]

Keywords ... fully warmed up.... and debate.

This morning, I set off, maybe 6C...took a good 6 miles NSL speeds to see 3 bars.

I've had it before now (below 0c ambient) where 3 bars were showing, and it went down to two bars.

I've also had it in summer (30ish C ambient) where I've briefly seen 4 bars.

If the only worry is not seeing the 3rd bar for a while, IMHO, it's not a serious issue worth worrying about.

Hmm. I have two STs that exhibit the exact same behavior: About five minutes after cold start, three bars are lit.

Down south Texas, our "normal" summer temps are in the high 90's, with occasional jumps to, say, 105 degrees. Three bars as usual - I've never seen four bars.

And on the flip side, we see temps below freezing (this time of year) and still, for my bikes, three bars - I've never seen two bars.

 

[Fawlty]

I have recently changed my thermostat. The old one was functioning correctly, but because I had the valves checked and other work, I decided to change it.

I have noticed that since the replacement, the engine takes slightly longer to get to three bars, but once it gets there it stays there.

 

[ad.hom]

Hmm. I have two STs that exhibit the exact same behavior: About five minutes after cold start, three bars are lit.

I don't doubt that my thermostat is sticky - in both directions.

It's just not enough for me to be bothered doing anything about it... yet.

 

[BakerBoy]

Since I replace the ECU because of the constant code 26, my temp. bars were reading 2, on cold (Florida) temps like today it was 59 F and front wind and 70 mph speed.
When stoped at the traffic it went to 3 bars. I also replace the coolant fluid at the same time I did the ECU.
With the other (defective) ECU the temp was always at 3 bars.
Any thoughts?

I've not read about your ECU issue; with that aside...

Nothing is normal about 2 bars at those outside temperatures, especially since you see it return to 3 bars while stopped for traffic.

Since you changed coolant, it would suggest there may be air in a passageway. Did you do the cap-off engine running per the service manual when you replaced the coolant? Is the coolant level still at proper elevation in radiator?

If yes to both of the above, you need to replace thermostat. If no to either of the above, chances still are that you need to replace the thermostat, but perform the burp procedure and repeat your ride test.

 

[Fawlty]

I've not read about your ECU issue; with that aside...

Nothing is normal about 2 bars at those outside temperatures, especially since you see it return to 3 bars while stopped for traffic.

Since you changed coolant, it would suggest there may be air in a passageway. Did you do the cap-off engine running per the service manual when you replaced the coolant? Is the coolant level still at proper elevation in radiator?

If yes to both of the above, you need to replace thermostat. If no to either of the above, chances still are that you need to replace the thermostat, but perform the burp procedure and repeat your ride test.

That's interesting BakerBoy. Wouldn't air in the system cause possible overheating as opposed to overcooling?

 

[caldercay]

That's interesting BakerBoy. Wouldn't air in the system cause possible overheating as opposed to overcooling?

Many mechanics consider air in the system as #1 cause of overheating; then of course, bad thermostat, not enough coolant, questionable pump.

 

[Larry Fine]

That's interesting BakerBoy. Wouldn't air in the system cause possible overheating as opposed to overcooling?

Is the temperature sender located where it's in contact with coolant even when low?

 

[Fawlty]

Is the temperature sender located where it's in contact with coolant even when low?

The sender is located at the back of the thermostat housing. Item 22 below:

 

[BakerBoy]

That's interesting BakerBoy. Wouldn't air in the system cause possible overheating as opposed to overcooling?

Likely yes, but...
Is the sender (item 22) in coolant (vs. air)?
Is the coolant moving properly (vs. being stalled and overheating locally)?
The temperature displayed on the dash is simply the temperature measured by the sender where it is installed, and totally dependent on coolant moving and the sender being fully immersed.

Key point is the OP likely needs to change the thermostat, but it doesn't hurt (is actually beneficial) to ensure no air trapped in coolant passages.

 

[Andrew Shadow]

Keywords ... fully warmed up.... and debate.

He stated that he had been traveling at 70 MPH so I was quite confident that the conditions that we are discussing are for a fully warmed up engine but he can confirm this for us.

If the only worry is not seeing the 3rd bar for a while, IMHO, it's not a serious issue worth worrying about.

I agree with you that this condition is not something serious in that it will not cause any permanent damage in the short term.
I may have misinterpreted what he is trying to find out but I think that his question is whether or not this condition is normal as a result of an ECU change. It is not. My answer for him remains that this temperature gauge reading is not normal.

 

[leonides]

He stated that he had been traveling at 70 MPH so I was quite confident that the conditions that we are discussing are for a fully warmed up engine but he can confirm this for us.

I agree with you that this condition is not something serious in that it will not cause any permanent damage in the short term.
I may have misinterpreted what he is trying to find out but I think that his question is whether or not this condition is normal as a result of an ECU change. It is not. My answer for him remains that this temperature gauge reading is not normal.

I already ordered a new thermostat and to play safe I also ordered the temp sensor.
Is there any video about the thermostat replacement?
It must not be too complicated, just guessing because I had never go in that area before.