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Thermo -Bob Testing and results - Excellent

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DieselTwitch

Well-known member
Dec 23, 2007
308
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40
Gunnison, Colorado
I agree that it does take out less heat from the engine, so that helps - but for something in such cold environments, keep in mind that the freezing point is at 10°F. Be careful! See attached plot.

Should have mentioned, propylene glycol not ethylene glycol. I'm good down to -75*F

ethylene-propylene-glycol-protection-comparison-chart.jpg
 
Last edited:

jrusher

Well-known member
Lifetime Membership
Dec 1, 2007
498
285
63
Edmonton
Good info Im running thermo-bob and blocking rads and temps are still low and take quite awhile to climb.. Oil is still getting diluted with gas
 
D

DieselTwitch

Well-known member
Dec 23, 2007
308
112
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Gunnison, Colorado
Diesel- good idea! are your rads blocked? and I take your not running a t-stat with this set-up. Did it lower the boiling pt?

No blocked rads, no t-stat either. It lowered it slightly im sure but with the system under pressure im sure its some where around 220*F not much data on pure glycol
 
D

DieselTwitch

Well-known member
Dec 23, 2007
308
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Gunnison, Colorado
I take that back Propylene GLycol has a boiling point of 370*F.

The reason I believe it works as well as it does is it lowers the efficiency of the cooling system by 30%
 
M
Feb 6, 2014
1
0
1
Lacombe AB
I now have CRF450X (2005-2014) and CRF450R (2005-2008) kits on the shelf, I need to put them up at the website but they're available- just send me an email and phone number.

Same goes for YZF450s, 2006 and up. On the shelf.

ANYONE KNOW "MARC V" WITH A 2007 CRF450R? His e-mail is bouncing so my replies are not making it to him.

Thanks,

Hello Watt-man I must be the guy in this quote, Marc V
 

sidehillsam

Active member
Lifetime Membership
Sep 24, 2008
159
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28
Post Falls, Idaho
Thermobob not stopping coolant

On 450SX, coolant is warming immediately after startup. Wasn't a problem late last year in the warmer weather. Now trying to make it work right. In a pot on the kitchen stove it seems to open and close correctly. When I took it apart I was hoping to see small bypass holes that some have said needed plugged. No holes. Does the KTM 450SX build enough coolant pressure at the thermostat to open it prematurely? Help please!
 

sidehillsam

Active member
Lifetime Membership
Sep 24, 2008
159
31
28
Post Falls, Idaho
Temperature Probe

Yes, temp probe is in the brass bypass T. Temps rise constantly to 190 where fan is set to come on. Radiators should not warm immediately. Maybe the crude metal to metal seal in closed position is leaking a little coolant to the radiators?
 
W
Mar 10, 2010
97
11
8
Any updates on an install in a 2010 KX 450? I was told that there wasn't an exact install guide for that bike, and that the hoses needed to be cut. I have a thermobob that I bought less than a month ago, but it's not a precision fit I've been told. haven't had time to install it yet.
 
W
Any updates on an install in a 2010 KX 450? I was told that there wasn't an exact install guide for that bike, and that the hoses needed to be cut. I have a thermobob that I bought less than a month ago, but it's not a precision fit I've been told. haven't had time to install it yet.

I haven't heard any leaking issues with just clamping down the 7/8" hose on the 3/4" barb on the Thermo-Bob, but I think the most professional thing for me to do will be to include a short section of 7/8" to 3/4" hose reducer with every KX450F kit. All kits that ship after today will have one, and the price will not change.

Wakeandsnow, if you'd like me to mail one to you a reducer, send me an e-mail at watt-man at cox dot net.
 
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mtn-doo

Well-known member
Feb 26, 2004
1,315
661
113
Kalispell, Mt
On 450SX, coolant is warming immediately after startup. Wasn't a problem late last year in the warmer weather. Now trying to make it work right. In a pot on the kitchen stove it seems to open and close correctly. When I took it apart I was hoping to see small bypass holes that some have said needed plugged. No holes. Does the KTM 450SX build enough coolant pressure at the thermostat to open it prematurely? Help please!

No, the Stat opens toward the incoming pressure. Pressure won't open the stat. The bypass prevents excess pressure. No leak ports needed in the Stat. You're good.
 

sidehillsam

Active member
Lifetime Membership
Sep 24, 2008
159
31
28
Post Falls, Idaho
Thermobob

Watt-Man sent me another 180 thermostat. In the shop it seams to seal better now. Radiators still get warm before thermostat opens, must be from warm coolant convecting up the bottom two radiator hoses. Great service, thanks Watt-man.
 
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