Engine Cooling/Thermo-Bob Questions - Kawasaki KLR 650 Forum
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post #1 of 75 Old 05-11-2011, 09:59 AM Thread Starter
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Engine Cooling/Thermo-Bob Questions

I've been considering putting a Thermo-Bob on my KLR and would like to throw a few questions out there that maybe can be answered by somebody with a lot more technical knowledge than I have.

I would first like to note that I am in no way casting doubt on the efficiency or quality of the TOB and most likely will go ahead and install one. It's obvious the TOB is endorsed and used by a very large number of KLR riders so I figure there must be a good reason for it.

I understand the general theory behind the thing: it will stabilize the engine temperature, warm the engine up quicker, supposedly make the engine last longer, all cars use thermostats to stabilize their coolant temperature, etc.

With that in mind:

As long as the engine temperature stays within safe limits once warmed up, do these swings in temperature really reduce engine life? Or is the biggest benefit getting the engine up to temperature quickly when it's cold?

What engine components are supposedly most susceptible to these temperature swings? The oil? Seals, like water pump seals? The actual metals themselves?

I understand that all car engines have thermostats, but a car engine has a lot more mass than a KLR engine and I can see how warming up the coolant quicker would get more heat into remote areas of the engine to keep them from "running cold." Also, I think you have to consider that perhaps another reason for thermostats on cars is to get them hot faster so the heater will work more quickly when it's cold out.

Does anybody know if any study has been done to see if a TOB-equipped engine will last longer than one without a TOB? I would think this would be almost impossible due to the length of time/miles required and since even under the exact same conditions, slight variances in either engine, manufacturing defects, etc. would make it impossible to tell if the TOB helped or didn't make any difference at all.

Again, I'm not knocking the product and I understand the theory behind it and that theory makes sense to me, but does anybody have any more details about how, specifically, these things help, besides the general idea of "a temperature-stabilized engine will last longer than one that isn't?"



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post #2 of 75 Old 05-11-2011, 10:08 AM
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The KLR has a thermostat from the factory. What it doesn't have is any sort of bypass at the thermostat. Here is a writeup that explains it.

http://www.klrworld.com/index.php?op...193&Itemid=286
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post #3 of 75 Old 05-11-2011, 10:43 AM
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i spoke with a few guys that are very up to speed on this kind of thing i was a skeptic....
put mine on my self two weeks ago...
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post #4 of 75 Old 05-11-2011, 10:52 AM
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I believe the Temp. swings effect the cylinder and if it gets heated and cooled quickly over time it can go out of round causing loss of compression etc. This is only what I have read and seems pausible to me.
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post #5 of 75 Old 05-11-2011, 11:20 AM
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I wager that between now, and the end of time, not one soul can come forth with evidence that they lost an engine due to the lack of a thermo bob being installed on their bike. Not submitted out of opinion, submitted with supporting evidence from objective, professional sources. In specific, information supplied by a forensic engineer.

By installing this modification, one will increase the useful lifespan of their KLR 650 by how much? In what conditions? ...And as evidenced by what?

I don't know if it is useful or not. I can't find any independent, objective testing on this item. I think some of my skepticism is due to some of the wild claims made by purchasers. 20 degree difference in maintained operating temperature may have affect on a heat sensor, and heat sensor activated functions, but it sure won't make your seat softer and increase the realized rear wheel horsepower by 30%. 35 degrees difference in operating temperatures will correct oil consumption from a liter lost in 200 miles, to no oil consumption at all? Thats kind of like telling me that if I buy this certain dog collar, 'ol Bowser will be able to count and speak Greek.

If it makes you feel good, I see no harm. As far as a "you got to or yer engine will fry", the bullshit flag is down on the play. I think it might be a nice thing to do for your bike, allowing it run at even operating temperatures. But we're not talking 700 degree differences here. I;ve toyed with the idea of installing a radiator bypass from an Aprilla or Ducati, which would require minimal adaption, and would cost under 20 bucks. And I will try it. Just as soon as I understand WHY I'm doing it.

****

And when Brother Damocles see this, order the large tub of popcorn. His dissertation on the Thermo Bob is as long and intense as Doctor Zhivago.


****

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post #6 of 75 Old 05-11-2011, 11:40 AM
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I can see where benefit would occur more so in colder climes than in warmer. I can see that it would lend some stabilization to the temperature of the coolant. However, there will likely never be a peer reviewed study based on scientific method. There is not enough demand for it. I think it will come to what makes you feel better. I don't go for those who posit that the bike is junk and everything on it must be replaced. Nor do I go for those who assert that Kawasaki is always right on the maintenance etc. There is one thing a buddy of mine once said though. 'Butch, clean oil never hurt an engine.' I think that that may be an absolute truth!
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post #7 of 75 Old 05-11-2011, 11:44 AM Thread Starter
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Thanks for directing me to the review: lots of information there. I find the claim of "potentially adding years of service life to my engine" claim a little out there, though.



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post #8 of 75 Old 05-11-2011, 11:52 AM
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I have an air cooled 1982 xj650 maxim. It has over 50k on the clock without a rebuild. BTW, liquid cooling has extended the life of most bike engines.
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post #9 of 75 Old 05-11-2011, 11:53 AM Thread Starter
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The one downside I see to it is more components to fail; i.e. more hoses and clamps. I suppose no more susceptible to failure than the ones already there, though. Its location seems to protect it well and it's reported to be of very high quality.

efigalaxie, I'm a big proponent of what your buddy told you: I change my oil (and filter) every 1,000 miles. Maybe overkill, maybe not, but it's cheap and takes all of 15 minutes to do.

I don't know if it's stuff our Dads theorized, something maybe read in a manual somewhere or what, but, although it might not be based on "fact," I always let the engine in anything warm up before I put a load on it and I always cut it back to idle for a couple of minutes before shutting it off.

On the other hand, I used to run wheel loaders in a battery plant that actually had German made, air-cooled diesel engines which require even closer tolerances and massive compression and forces generated inside the engine. These things would run all day long and the engines lasted for thousands and thousands of hours with no liquid cooling at all. I suppose it's all about design, materials, etc. I'd never even seen an air-cooled diesel before I saw those things.



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post #10 of 75 Old 05-11-2011, 12:12 PM
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I installed the thermo bob at 53000 kilometers on my 08. Prior to the install, the engine temps fluctuated from showing stone cold on cold days to 3/4 from hot. I know from experience these wide swings in coolant temp is not a good thing at the best of times. Engine performace and longevity is determined to a great extent on proper and consisstent operating temps for both cooling and oil temps. With the thermo bob, temps remain consistant at all times. That alone gives me comfort.

byker
2008 KLR 650 (108,000 kilometers and rising)
1987 K100RS
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