NEW thermostat stuck open?

Joined
Aug 8, 2015
Messages
456
Location
CT USA
Bike
07 ST1300
Just went through the whole rigamarole..flush coolant blablabla.. New honda thermostat.
Run it in the garage with no tupperware. Warms up to 3 bars in a jiffy..cycles the fans. Put it together and test drive in 23f weather. Warms up to 1 bar then NONE then 1 then 2 then 1. Idle a bit it gets to three.
Is it just the damn stinking cold weather?
And my furnace has no fire.
And my burgle alarm went off by mistake.
And the cops showed up..
Argh..
 
No, I have ridden in below freezing weather and kept three bars the whole time at 65 mph.
Sorry to say....But I think you got a bad one......:confused:

ToddC
 
If I ever have to replace the thermostat I'll test the new one in hot water first. Lesson learned though I'd never expect a new one to be defective. Sorry for your troubles but you may have helped others down the road.
 
Well it's going to be a while before I change it again. The one I took out was probably fine..ughh..Think I will test the old one now
 
Sure enough the old one opens at about 180 plus then closes right back up at about 180 all give or take a couple..
Well it was a fun exercise.
OK not really.
But I did get to rip out the dying HID lights and associated crap, and hook up the volt meter that has been collecting dust. I hope the new LED's don't suck.
It's POSSIBLE that it was so cold and I was running so mildly that the little bit of coolant running through that little hole in the tstat..I don't know. But I'm not ripping the plastic off anytime real soon. I rode this morning and now there is 3 inches of snow and counting on the roads.
Also possible I didn't burp the coolant properly..
 
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OK, so I am lazy...Have been riding my '04 for years with, I assume, a stuck thermostat.
Just didn't want to open the Tupperware to fix it.
I get 3 bars in the summer, but riding in the 40s or 30s...never above 1 bar.
I get a little hi weird idle but other than that, what is it gonna hurt to run with the thing open?
Fuel mileage?
In cold weather the dash still says I am getting upper 30s maybe 40 MPG?
Thanks for any input.
 
Also possible I didn't burp the coolant properly..
I haven't done any more than check the coolant level so I don't know the (if there is one) bleeding procedure for the cooling system. I do know that a few cars I've had had a bleed nipple on the back of the heater core (usually at the highest point of the water cooling system) for just this purpose. Does the ST have a similar bleed nipple to burp the system?

I get 3 bars in the summer, but riding in the 40s or 30s...never above 1 bar.
I get a little hi weird idle but other than that, what is it gonna hurt to run with the thing open?
Fuel mileage?
In cold weather the dash still says I am getting upper 30s maybe 40 MPG?
Thanks for any input.
I don't have extensive cold weather riding experience, but have taken the bike out on a 150 mile ride when it was in the mid 30's to low 40's and several 130 mile rides in the same weather. I have never seen the bike's temp at anything but 3 bars (excepting warm-up). Mine is a '10 ST.
 
^^^
Best advice there is. Always test it first before installing and putting tuperware back on.
Hope it just an anomaly.

For the record in 45 years of replacing thermostats as needed, I have NEVER tested a new one. Ever. And I have never had one go bad at 15000 miles. In fact I still havent. Also I have never heard anyone suggesting to test a new one before installing.
I hindsight of course it's great advise. Thermostats are not new technology for crying out loud. Hyundai can provide a working thermostat you would think Honda could as well.
 
I work in the automotive industry and I also work on my own vehicles. Stuff like this is one of the reasons that I pound into my group that there is NO grey area when it comes to tolerances.
 
My thermostat is leaking by. I don't get 3 bars in cold temps. Anyone want to come change it for me? Lol
 
You didn't install it upside down did you?
I tried but it kept falling out!
OK no..
If I did, it would never open I think. Maybe it would?
This makes me wonder if it's possible to install the thermostat right side in, but not seated perfectly so that some coolant slips by, but it does not leak.
That's not possible is it?
I generally don't make history.
 
OK, so I am lazy...Have been riding my '04 for years with, I assume, a stuck thermostat.
Just didn't want to open the Tupperware to fix it.
I get 3 bars in the summer, but riding in the 40s or 30s...never above 1 bar.
I get a little hi weird idle but other than that, what is it gonna hurt to run with the thing open?
Fuel mileage?
In cold weather the dash still says I am getting upper 30s maybe 40 MPG?
Thanks for any input.
As a Auto tech please let me tell you what happens when your thermostat is stuck open. The cylinders can run as high as 500 F. but usually in the 250ish F. The coolant should run between 180 and 210 F. Below 180 coolant temp and thermostat closes. ( these are just average numbers, please don't attack)
Now imagine below 100 F coolant going to fast ( yes, thermostats second job is to control speed of coolant flow ) past 300 F metal and you get cracks. Big and bad cracks.
I hopes this helps someone.
 
I am not suggestion inside out, but turned upside down. The little piece that looks like a loose rivet should be at the top.
I have found a couple that were installed incorrectly and not trapped in their slot, and work themselves around and wear a deep groove or pit in the cover.
I was thinking that maybe as you were installing the cover, the T-stat may have slipped out of its notch and be tilted, jammed, or turned.
 
I am not suggestion inside out, but turned upside down. The little piece that looks like a loose rivet should be at the top.
I have found a couple that were installed incorrectly and not trapped in their slot, and work themselves around and wear a deep groove or pit in the cover.
I was thinking that maybe as you were installing the cover, the T-stat may have slipped out of its notch and be tilted, jammed, or turned.
Man it's hard to believe that it will snug down with the thermostat cocked and then not leak. If it's possible, then it's very easy to do as you can't see whats going on in there. Didn't know about the rivet being at 12:00 either.
When I put it together I ran it with distilled water till the fans cycled a few times. Warmed right up quick to 3 bars BTW. Then drained again, removed radiator etc. Refilled with blue stuff and ran it again. Again warmed right up quick to 3 bars. Fans cycled a couple of times. Let it cool. Topped up radiator and warmed it AGAIN..right up to 3 bars same as ever. Fans only would run for very short time, AT a time. All seemed good. Never occurred to me the Tstat could be in wrong, as I had read SO much about changing them and never a word about that. Also never a word about NEW Tstats being defective. I think anyone at this point, would call it good.
So back on went everything and here we are.
Oh also the black paint in the hose connections was perfect and not flaking but I removed it inside and out anyway. Gave the radiator a good flushing in the kitchen sink. No leaks at any clamps but snugged them a bit anyway.
It was 10f this morning and I dont like riding in below about 28f. I really want to giver her another chance thinking that MAYBE possibly there was an air pocket in there. Or something. Maybe..
But for now we are in deep freeze with snow and salt everywhere.
But..the brown truck just dropped off my new garage heater!
Tell me Igo, if you really think it's possible that Tstat is cocked in there.
 
You can do a really basic functional check on the thermostat while it is installed. What should happen is the coolant stays within the pump/block circuit warming up until it exceeds the thermostat opening point. Then the now hot coolant should start to flow through the radiators. If you keep your hand on the radiator (top left) this first rush of hot coolant is very distinctive and easy to feel.

If you start the bike from cold and let it warm up, if the radiator stays cold for a few minutes then suddenly gets too hot to touch, your thermostat is probably fine.
If on the other hand the radiator slowly warms from the time the engine is started, then the thermostat is probably stuck open.
 
The hole is supposed to go at the top. Its purpose and the tickler in the hole is to allow burping the block - lets trapped air pass the t-stat and out of the housing. I doubt that if it is oriented other than 12 o'clock it would pass enough coolant to act as an 'open' thermostat.

The cover to the housing is indexed to the stat with a landing and wouldn't bolt down and not leak if the stat was cocked sideways.
 
The cover to the housing is indexed to the stat with a landing and wouldn't bolt down and not leak if the stat was cocked sideways.
Thank you.
Also it's possible that the bleed hole is not at 12:00
Sooo..Guess I will pull the plastic.
Thanks all.
 
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Pulled the new thermostat out. My new garage heater works great BTW.
The bleed hole was at 3:00. My bad. Manual clearly say's 12:00.
Brought it inside for testing. Tested with the old and the new together. They both open at the same time and close at the same time as water heats and cools. Open at just over 180. I did it over and over. They are both the same. I am moderately flummoxed.
I think my old thermostat was fine and that was not my problem. I will reinstall the new thermostat properly. I guess.
I'm open (and asking) for suggestions. This is not as epic as I make it seem. Half hour I had it out. All coolant caught clean and ready for re issue.
 
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