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

Uncle Phil

Uncle Phil

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Joined
Feb 26, 2007
Messages
10,936
Age
72
Location
In The Holler West Of Nashville, Tennessee
Bike
4 ST1100(s)
2024 Miles
029048
I am stumped on this one so here are the details -

1. The temp gauge started registering at 12 o'clock or more even (straight up) when running down the slab with plenty of air flow (normal is about 1/4 from the right).
2. Anti-freeze level was good, hose from overflow tank to radiator was brand new, engine only has 40,000 miles on it.
3. Changed the thermostat with a brand new Honda one and it appeared to fix the problem.
4. Various test rides and the problem was fixed and I was happy.
5. 750 miles later on the trip to OHSToc, the problem is back.

Details -
Evans waterless coolant at proper levels (open the radiator cap and the coolant is up in the neck, overflow bottle between the high/low lines).
Brand new Honda Thermostat and o-ring installed as noted above.
Engine has 40,000+ miles on it (water pump should be good).
Radiator appears to be clean and good (visually inspected).
No leaks that can be detected.
Brand new hose from overflow bottle to the radiator cap neck.
Thermostat 'fixed' the problem for about 750 miles.
Engine smells and feels 'hot' (no temp 'gun' handy to check actual temps).
The gauge appears to be working fine as it registers through the ranges.
Electrical grounds are cleaned.

I have a hard time believing a brand new thermostat went bad in 750 miles or that the water pump is toast with those few miles on the engine.

Ideas? Other tests to run?
 
Mine's been doing the same thing for years, and my grounds appear to be good, like yours. I think its just something that happens to the gauge over time. Mine doesn't do it all the time either, similar to your thinking that it had been fixed when it stopped doing it temporarily.

I was surprised to see that the gauge itself is a separately available item (don't have to buy a whole instrument cluster) if you're interested in replacing it.

oops, checked the fiche and its no longer available.
 
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I also swapped out the temp sender, which didn't help either. I have one that I can mail to you if you want it. It probably won't fix the problem, but you can give it a try and if it doesn't fix the problem mail it back to me.
 
Mine never reads past 1/4 over from cold when I am pushing air over it (e.g. "actively riding...:). When I get stuck in traffic it goes to about 1/2 (mid-gauge) then the fan kicks on and it stays there, then back to almost full "cold" when I get moving again. It has done this since it was new way back in '93 so I just figured this is the way they are..... seems to run fine "cold" with the choke on for the first mile or two. I figure if the thermostat is stuck open, better than stuck closed!
 
I would guess the thermostat was not the culprit and that there is another cause that creates an intermitent problem ?

Was it cooler outside when it worked OK ?

Liquid coolant apparently becomes very corrosive after a few years. This is why we need to replace it every 3 to 5 years. So, eventhough the engine is only 40 K, could it be the water pumps fins that are gone, eated by acid coolant?
A possible easy way to check that, could be to run the engine on center stand, without the radiator cap, and watch if there is a good flow coming back from the engine.


Other Ideas :
- Not a chance there is some air pocket traped inside the engine, right ?

My ST1100 seems to be a bit sensitive to the outside temp. If it's 10C / 50 F, the temp gage stays at Cold. when it's 20C / 70 F, it is at 1/4 on the open road and 1/2 in slow moving city traffic. At 30 C / 90 F, it is at 1/2, or 12 oclock, even on open roads.
 
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IndyRob said:
Mine never reads past 1/4 over from cold when I am pushing air over it (e.g. "actively riding...:). When I get stuck in traffic it goes to about 1/2 (mid-gauge) then the fan kicks on and it stays there, then back to almost full "cold" when I get moving again. It has done this since it was new way back in '93 so I just figured this is the way they are..... seems to run fine "cold" with the choke on for the first mile or two. I figure if the thermostat is stuck open, better than stuck closed!
Click to expand...
This is exactly the same my 2 STs run in all the time I’ve owned them (no change in the thermostat, ever and 50/50 Prestone coolant). I did have an issue yesterday with the 2000 in that in traffic it heated more to the red but not in the red…all of my fuses were oxidized (I guess related to age) and now all is well after switching them all out for new (this occurred on the 94 ~ 2 years ago- fan was not working when sitting still in traffic- changed the fan fuse with all the others and fan kicked on well as expected). Is the bike running hotter than expected? Evans doesn’t pressurize the system like regular coolant, and has a boiling point of 375 degrees F. I’m wondering if it‘s a lack of pressure that may be problematic (just trying to figure out how).

I just texted my brother in Colorado. In his 1993 Nissan 300ZX, he runs the Evans court, and at one point, he stated that he needed to get a lower pressure cap since the coolant is not pressurized like normal coolant and has a higher boiling point than regular coolant. As soon as he gets back to me, maybe I will have some reasonable answers.
 
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I recall that pat white 1100 runs In the exact same way cause I question that this weekend cause mine rarely comes off of cold…. Maybe you just work that thing way to hard….
 
OK, here is his answer:

Evans potentially will run a little bit hotter. Nothing has is good transfer of heat as water. Plain water.
But Water also has areas where in boils and there is no cooling taking place. Evans will never do that. It always has liquid contact which means there's always a transfer of heat.

A low pressure (cap) Won't work with regular water. You need the high barometric pressure. With glycol coolants, and no pressure buildup, then you don't need a high-pressure cap. Because there's no pressure buildup anyway.

This was his (apparently verbalized) text response- not sure if this will help- he put a lower pressure cap on his Z as I guess a regular pressure cap wasn’t needed as Evans doesn’t pressurize like regular coolant/ water.

More:
’The purpose of the low pressure cap is to let it easily expand and go into the overflow tank. When it cools down, the stuff in the radiator contracts, and it sucks it back in. It's to let it do that "easily." With zero pressure.

Anything other than water will have extra heat in it. That's just thermodynamics. But the better cooling properties is because you won't have steam pockets within the cooling system that are not picking up the heat. Hard to explain over text.’
 
This is my first time using Evans and the key is that when I changed the thermostat, it worked as 'normal' originally and for about 750 miles after the 'fix'.
I've got three other running ST1100s so I am comparing the 'performance' to 450,000+ miles among them all.
Since I have plenty of 'spares', I'm thinking the temp sensor and the gauge first.
It may have something to do with the Evans stuff, but then why did it work fine for a while, go south, change the thermostat and then it worked again for a while?
 
Phil, you said it smells and feels hot. I don't think it's the guage. This is a shot in the dark but maybe radiator cap? Maybe drain the Evans and go with something like Honda type 2? I have no doubt you'll get it sorted out:)
 
Erdoc48 said:
Evans doesn’t pressurize the system like regular coolant, and has a boiling point of 375 degrees F. I’m wondering if it‘s a lack of pressure that may be problematic (just trying to figure out how).
Click to expand...
The lack of pressure due to the Evans coolant should have no role in @Uncle Phil's problem. The cooling system works on temperature, and while an open system (no radiator cap) will allow straight water used as a coolant to boil off, the Evans will not.

The so called moving parts involved in the system include the temp sensor, temp gage, coolant, water pump, thermostat, and hoses. Lets look at them one at a time. Hoses - years ago I remember reading about cars that had soft hoses that collapsed preventing cool water from the radiator from flowing to the engine block. I've not heard of that happening with modern engines let alone our ST's so shelve this part. The sensor and gage have not been checked yet, so they are suspect. The stat has been changed and while it is not likely to be faulty, I think many of us have installed a new part and had it fail much sooner than expected, so this is also a (low probablity) possible culprit. I think I've read only one thread in which someone posted a picture of his water pump that had completely corroded away, so it is unlikely Phil has the second one.

My money would be on a bad ground - double check this, it cannot hurt, or the gage and sensor.
 
This temp sensor thing has been a minor issue with most Honda cars and motorcycles as many use the same sensor. My 2000 GW has had 3 OEM sensors that have failed in 55k miles. 2 years ago I put a cheap ($17) eBay sensor in and it has been spot on ever since.
 
When I had an 1100 I had a problem where the gauge would climb to redline over a period of under a minute when stationary. Seemed to be the ground connection or the battery connection so that when I tightened them up. the problem went away. They did not look particularly loose.
 
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