ST1100 - She's Giving Up Smoking Like A Cigar But Now She's Hot!

Yes UP, the negative ground by the grab handle. The rubber fitting that the bolt passes through. Sorry I know what I mean. lol
 
I did run it a bit in my shop with the radiator cap off just to check the flow.
Flow looks good but there were a few big 'bubbles' that came to the top.
So I buttoned her up (thinking those air pockets were the problem) and took her out for a good 'thrashing'.
At first it did a little better but by the time I got home it was back to where I was before.
40 miles on the slab at 75+ and the gauge never dropped below 12 o'clock - it should have been just off the left mark about 1/8".
Engine is running great and it is not 'overheating' as into the 'red zone'.
But if the gauge is to be believed, it is running way hotter than it should (compared to the other 3 ST1100s I have).
It's as if it cannot dissipate the heat once the engine gets past a certain temperature.
Anybody know how to 'burp' a ST1100 coolant system (in case there is more air pockets)?
And any advice on how to clean the inside and outside of a radiator - or check it for flow?
I don't want to just throw parts at it but I am running out of ideas.
 
You could hook an ohm meter to the temp sender to verify the gauge. I would have to look up the values for when the thermostat would open and when the fan comes on. It’s something like 64 ohms when cold, 30 for the thermostat around 16 ohms when the fan kicks in. I will confirm in the morning.
 
You do have a secondary temperature device, namely the fan switch. If that is not comng on then you can be confident the coolant in the radiator is less than 212F/100C which is normally 6 O'clock on the gauge.
I would point the IR gun at a solid part of the radiator (not the fins).
 
Same radiator with the 3rd engine? If so, seems radiator is a common denominator. Radiator not flowing properly? :think1:
 
The only way I could see it being the radiator is if the coolant cleaned out the engine and clogged the radiator reducing the flow of coolant. Did you compare the flow (rad. cap off) on a good and a bad one? I know it would be by eye and don't know if you could see a difference.

After it has set and cooled down, roll a good ones over next to the bad one. Start them both and set a fast idle on each. Note the temp. gauges as you go along. Check a point on both and compare. I would try to get a number in several places. Like header pipe #1 then #2 then #3 then #4, matching points on radiator-inlet corner, middle of radiator, outlet corner, inlet hose, outlet hose. Make a chart to see if you can spot something.

Maybe another temp. sensor? Verify it's a temp. sensor not a fan switch (aren't they phyically interchangeable?).
 
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ST1100Y said:
corrected that for you... ;)
Click to expand...
Hi Uncle Phile,
Been watching your posts now for many years, and you have probably forgotten more than I will ever know, but a suggestion:
This problem has returned after your engine swap? Have you used the original engine temp sender, or the one that came with the replacement engine. Maybe swap them out. Also, might there be a wire under strain somewhere from the engine swap - the one from the sender? All the time i am presuming that the engine is not actually running too hot, which as noted in above post, should mean the fan would stay on much longer.
 
Uncle Phil said:
Anybody know how to 'burp' a ST1100 coolant system (in case there is more air pockets)?
Click to expand...
I always have the bike on the side-stand, rad cap off, slowly filling to the brim, squeeze all hoses a couple of times (this already burbs out a lot), refill, squeeze again, etc...
with rad cap still off I start the engine (don't blip the throttle), letting it idle, warming up slowly while peeping down the filler neck, topping coolant off when needed...
you can observe when the thermostat opens (the small "pee-stream" through the pinhole changes to a large wallowing), once this appears the rad cap comes on (two clicks for fully close), engine idles along further till the fan kicks in... while warm I fill the reservoir to MAX...
kill the engine, letting it cool down again, the reservoir level should drop to/near the MIN mark... perfect...
 
gcos said:
Hi Uncle Phile,
Been watching your posts now for many years, and you have probably forgotten more than I will ever know, but a suggestion:
This problem has returned after your engine swap? Have you used the original engine temp sender, or the one that came with the replacement engine. Maybe swap them out. Also, might there be a wire under strain somewhere from the engine swap - the one from the sender? All the time i am presuming that the engine is not actually running too hot, which as noted in above post, should mean the fan would stay on much longer.
Click to expand...
The 'gauge' (hence the sending unit which is the one that came with the engine - 23,000 miles) seems to be indicating properly.
It's the 'problem' gets worse the longer I ride.
 
TerryS said:
You do have a secondary temperature device, namely the fan switch. If that is not comng on then you can be confident the coolant in the radiator is less than 212F/100C which is normally 6 O'clock on the gauge.
I would point the IR gun at a solid part of the radiator (not the fins).
Click to expand...
Please note the fan is coming on - Post #56. ;)
 
Here's 'new' oddity - the neutral light comes and goes.
The bike will start when it is in true 'neutral' but the light does not come on.
Bulb has been replaced and it worked for a while.
IIRC, the neutral switch circuit and the temp sensor circuit are in the same harness ..... hmmm ... :think1:
Problem is I am running out of time as I'm off to ArkanSToc tomorrow.
 
ST1100Y said:
I always have the bike on the side-stand, rad cap off, slowly filling to the brim, squeeze all hoses a couple of times (this already burbs out a lot), refill, squeeze again, etc...
with rad cap still off I start the engine (don't blip the throttle), letting it idle, warming up slowly while peeping down the filler neck, topping coolant off when needed...
you can observe when the thermostat opens (the small "pee-stream" through the pinhole changes to a large wallowing), once this appears the rad cap comes on (two clicks for fully close), engine idles along further till the fan kicks in... while warm I fill the reservoir to MAX...
kill the engine, letting it cool down again, the reservoir level should drop to/near the MIN mark... perfect...
Click to expand...
I've seen the 'pee-stream' already and I'll check again the 'wallowing'.
I'll also squeeze all the hoses as I still suspect there is air in the system.
 
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