Symptoms with a possible water pump failure?

[Kesnei]

Hey guys and gals.

Here is kinda what I am seeing and I think I have it narrowed down to a water pump failure or a water pump sensor (which I don't know if it exists)

But I figured I would let y'all take a look at it before I start the process:
So the bike is a 2008 Buell 1125r, upgrades at this point include:
KNN air filter
FMF slip on exhaust (No ECM upgrade yet, and the software is one version behind the 'current' software level)
De-noided
No Charcoal canister was ever on the bike since I owned it (either the previous owner removed it or it did not have it from the factory)
Lithium battery upgrade (stock one went out)
Updated clutch weep

The initial issue was the bike temp while running. I will be on the freeway and the bike's Coolant Temp would slowly drop.
I could reduce gears in order to rev the engine higher and make the coolant temp hold or slow the process but it gets down to 140 and the bike goes into 'cold' mode and reduces power etc etc.

The bike when coming to a stop seems to pull the temp up.
Last night I got gas and the bike was at about 155 or less on turning the engine off to get gas. A couple minutes later I turned it back on and the temp was at 190+ on start-up.

Any thoughts from the Buell experts? Anything you'd like checked?

My thought process currently is that the water pump is dying, given that the coolant would move appropriately on start-up and the engine would get warm, 10 minutes into the ride the weakness of the pump begins to show and the coolant temp starts to drop as a result of a lack of coolant flow.

Any thoughts would be appreciated!

-Kes

[mrlogix]

haven't ran into this on my 1125 before, but my experience with other engines would make me think air pocket in the system. Failing water pump would be more of a continually increasing engine temp till overheat. Had a Toyota truck that had similar symptoms and was a trapped air pocket. Just my .02. Keep us posted.

[Kesnei]

MrLogix -- I hadn't considered that -

Lets toy with the .02, if it is a pocket of air, wouldn't I see the temp steady then a sudden shoot up to some ridiculous amount 190-200+ for the coolant temp then back to normal? (I'll be honest I don't really know a ton about motors as a whole so I might be oversimplifying the problem)

[mrlogix]

typically if the air pocket gets around the temp sensor the temp drops because air is not a good heat transfer medium (hence cold weather clothes have material which allows for air pockets in the clothing for insulation. Any of the Jarheads out there remember the Mickey Mouse cold weather boots?). Like I said, just my .02. Anyone else have similar experiences?

[Cosworth]

Mine bike is always cooler when moving, gets down to 185-190. But as soon as I stop at a redlight it will spike to 214-215 which is normal for these bikes. I do suggest putting a tad bit of "water wetter" or equivalent in the system.
There is not much to the cooling system just a impeller driven off a engine gear or the right side of the bike but, I haven't seen an instance of the pump just failing all together in such a fashion as your describing but anything is possible i suppose.

Are you new to this bike or is this a recent development when riding?

[Kesnei]

This is mostly a recent development while riding -- I've owned the bike since March 2014, and the coolant in the system has been there since July.

I am used to the coolant temp going up and down as you described, but going to 140 isn't good as the bike then goes into warm-up mode and bogs down.

I'll check for pockets of air, see what I can do to burp the system.

[Cosworth]

Gotcha, I would suspect that or the temp sensor. Take a look at this thread, it seems close to what you are describing.
http://www.badweatherbikers.com/buell/messages/290431/491758.html?1251750361


You can take a ohm meter and test it I think its just a GM type ct sensor so this chart should match.
https://www.google.com/search?q=gm+coolant+temp+sensor+resistance+chart&biw=1024&bih=655&tbm=isch&