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garcenw

Beating a dead horse - thermostats and 5th gen operating temperture

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KevCarver,

 

Sorry, I should clarify what is meant by "steady state" for the non-engineers here. The temperature indicated was steady state which means I was running long enough and in relatively stable conditions so that the temperature leveled off. In the particular run you asked about, I did about 20 minutes of city driving before hitting a flat and non-curved section of limited access highway. Temperatures got as high as 206 F (briefly) in that city driving. Once on the highway, I maintained about an indicated 65 mph (true speed would be a bit less) until the temperature leveled off at 165 F (bouncing back and forth between 165 and 166, but spending more time at 165). I repeated the test going the opposite direction on said highway on my way back and temperature also leveled off at 165 F. 

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I did a similar idle test, but this time, I put the thermocouple in the center of the oil cooler. Ambient temperature on the dash gauge was 82 F, while my thermocouple indicted 84 F. Let's call it 83 F. My results are plotted below. As you can see, at least while idling from a cold start, oil cooler temperature asymptotically approaches water temperature and the oil is slower to warm up than the coolant. I'm not sure if this would be the case while running on the road. I was expecting warmer temperatures in the oil with all the fluid shearing going on. The up and down cycling of the coolant temperatures after ~800 seconds is due to the fan cycling on and off.

 

VFR_temp_graph2.jpg

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Although I've not paid much attention to temps at lower levels after warm-up, I have seen 160s (F). I never worried about temps in the 105,000+ miles on my first one. And the engine was in great shape at the end. See my oil sample in my albums. The sample was taken immediately before I left on the trip that was seriously interrupted by a hooved forest rat.

 

Seems much ado about nothing at times. :beatdeadhorse:

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I lived in Roseau for 4 years when I was an engineer for Polaris. It seems that northern MN has more than their fair share of hooved forest rats.

 

 

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Now it's my turn to beat that horse!

First long ride on my '99 today after changing the cooling system. New AS3 silicone hoses, new water pump, new t-stat, new rad cap, new O-rings, and new Honda Type 2 coolant. And it ran hot all day! Worst was going up the Cherohala from NC side. Once I got to the sorta top area (kinda plateaus a bit) I switched from air temp (68F) to water and it was 224! Was probably running 7-8k on the tach, not that extreme. Stuck it into 6th and got the temp back down. Rest was mostly downhill, so not bad. Only really cools itself on downhill or level in 6th with low revs, like 4-5k max.

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The radiator design on the 5G and VTR is crap. 

All is well on clean air or straight roads, but get traffic ahead or lots of corners and the air flow drops of dramatically. 

Mine can run on a 42*C day without a problem, but even on a 26*C day on tight stuff temps go up. 

Last time I did a track day at Eastern Creek was 26*C, it would cool down down the straight, but would climb back up to 98*C by the last corner. 

Saying that, it's been doing that for 120,000km without a problem. 

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1 hour ago, VFROZ said:

The radiator design on the 5G and VTR is crap. 

All is well on clean air or straight roads, but get traffic ahead or lots of corners and the air flow drops of dramatically. 

Mine can run on a 42*C day without a problem, but even on a 26*C day on tight stuff temps go up. 

Last time I did a track day at Eastern Creek was 26*C, it would cool down down the straight, but would climb back up to 98*C by the last corner. 

Saying that, it's been doing that for 120,000km without a problem. 

Yeah, I know all that as I've had both (on track). I just feel like I'm 10 degrees Fahrenheit too high at the moment, and it was fine before I went and "improved" it all... 

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Front mount. 

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KevCarver,

 

Did you happen to test the old and new thermostats in a pot of hot water before installing the new thermostat?

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No, I'll probably get to that pretty soon though. Definitely can test the old one, not looking forward to tearing it apart again to see about the new one.

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Kev, did you replace the radiator cap?  Pressurization of the cooling system leads to higher coolant density and better heat transfer.  At least it's an easy swap...

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3 hours ago, MadScientist said:

Pressurization of the cooling system leads to higher coolant density

 

Methinks you misspoke. Pressurizing raises the boiling point of the coolant which helps keep it in contact with the hottest metal of the engine.

 

More here: Cool under pressure

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Just curious as to what you are using for coolant.

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Sriracha chili sauce to keep it hot

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Kev,

 

I know you know, but at those ambient temps My 99' runs 180's, or 190-200 if running hard. Only in stop and go traffic or very slow cruising speed 25mph- does it get to 200++, so feel like the thermostat could be the culprit. I use Red Line water wetter product, and silicone hoses, everything else OEM. 

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On 7/15/2018 at 7:04 AM, garcenw said:

I'm trying to establish what are the normal steady state temperatures are on cool days before I decide to pull my thermostat out and test it. The temperatures I'm seeing (a little below thermostat opening temperature) are in the gray area if one assumes the bypass allows some cooling to occur and also accounts for the acceptable error in the head temperature sensor (which is a thermistor).

 

 

I get 79-84C (174-184F) always regardless of external temps when running between 60-90mph. I don't normally ride this bike in winter, but when crossing the alps on a tour a couple of years ago with snow at the top & an external temperature at or below ZERO C the temp was showing 78C.  On the hottest days of the last few years & or when running in south of France, it sometimes gets up to 86C, that is with ambient temperatures of 35C (95F) at speeds in the 60-80mph.

 

I fitted a lower temp fan sensor switch that brings the fan on at 90C & off at 80C, I have another one to test that is supposed to come on at 95C & off at 85C, which would reduce fan cycling.

 

Either way I think what you are seeing is perfect for this bike & the difference is due to positioning & water flow. The thermostat is in the HOT outflow from both heads. The rear head runs hotter, but the temp sensor is in the front head. If you put your thermocouple on the rear head hose fitting on the thermostat (yeah I know it would be a pain) I think you will find the temp there (i.e. water to the thermostat) would be a few degrees warmer than the dash sensor shows.  You will also find it worth putting it on the hose connection to the front head, which should show the incoming water temp to be lower than the leaving temp & that cool water corrupts the dash sensor as its in the flow into the front head !

 

PS No two thermostats are the same & the tolerance is probably +/-2C so that would explain one bike to another in the same ambient temps. If its cold out & runs 10C lower than normal or takes a long time to heat up, then I'd worry.

 

Move along, nothing to see here, ride it & fix something that might be broken 😉

 

YMMV

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Totally agree with Mohawk above. OP should be ok. That’s what I was seeing before my updates. 

So I did this today. 

DCD54FB9-7B93-478B-8481-6503B4AA3683.jpeg

9D2C4D49-4356-4008-8B86-15D4B1BD9E9C.jpeg

6C0AD576-FB3B-49B7-859F-79E03DA0C717.jpeg

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And....air bubble?

 

Silicone hose clamps loosening themselves?

 

New 'stat good bad or indifferent?

 

Low coolant or adequate?

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4 minutes ago, CornerCarver said:

And....air bubble?

 

Silicone hose clamps loosening themselves?

 

New 'stat good bad or indifferent?

 

Low coolant or adequate?

Or you could reply to texts...

Old t'stat opens about 4 degrees sooner than the new one. Not sure that would cause 10 degrees higher running temps...

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That doesn't seem like it would cause that big a discrepancy in operating temps.

 

Was the new water pump the same as the old? no "improvements" inside...?

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16 hours ago, KevCarver said:

Or you could reply to texts...

 

Yeah... good luck w that lmao

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On 7/12/2018 at 1:15 PM, MaxSwell said:

I'll have to generalize here due to the long history of my experience.

I've experienced the same temps as you state above. But at times, slow traffic in 80F to 100F plus, I've seen 230+ engine temps. Nothing above 235F. I've ridden across Death Valley with out experiencing the temp above 225F. I'd only worry if it approaches 250F. I believe the engine will shut down a little above 250F.  (I thought I read this somewhere, like the owners manual, but I cannot find the reference now.)

On a ride from southern California to vegas in mid july, got up in the 225°f range, but it was evening when got on the strip, the ride back was stuck in traffic, peaked at 250, started blinking 250, pulled off, shut her down for a couple minutes, then said forget it and started splitting lanes, that kept her in the 235-240 range until i opened her up, ive found that my happy freeway cruise temp is 176-177, and living in hotter areas went to water wetter. Maybe i just need to replace thermo and hoses(never have)...

FB_IMG_1530499184897.jpg

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5 hours ago, dstride said:

Maybe i just need to replace thermo and hoses(never have)...

That's what I did and it seemed to make it hotter...

176-178 on the highway in open air is perfect, no issues. Stuck behind a car it'll probably head up to 185.

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3 hours ago, KevCarver said:

That's what I did and it seemed to make it hotter...

176-178 on the highway in open air is perfect, no issues. Stuck behind a car it'll probably head up to 185.

 

Forgot if you mentioned it, but have you tried cleaning the temp sensor, and/or measuring its output? 

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