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Discussion Starter #1
Hi All,

I run a 1998 (carb) blackbird and the temp gauge barely moves off the cold post (round town or at speed).

Does anyone happen to know resistances for coolant temp sensor (hot and cold)?

Any help is much appreciated.

Thanks
 

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The carburated Blackbird machines do tend to run cooler then the fuel injected machines. Part of the reason I believe is that the oil cooler location changed when the fuel injection came along in 1999 and the oil cooler was dropped out of the cowl nosecone inlet air stream for the FI bikes. On the early 97 and 98 Blackbirds the oil cooler has this inlet air stream directed more or less straigth at the oil cooler. On the FI's this airstream became part of the ram air trunking of the airbox intake system..so the oil cooler was placed lower on the chassis and might suffer a bit because of it. I find that my 98 model year runs just off the bottom of the indication during the start of the season when ambient temps are lower, but of course that only makes sense. As temps go up so will my indication and around town riding wll have it well within the middle area of the indication or slightly higher, this would be during the heat of summer. It may be that , a)your indication is in error, b) your temperature sending unit is in error or faulty..or c) the thermostat on the cooling system has stuck open and is therefore not allowing the engine temp to come up as it should. I'd suggest that you ensure the coolant level is to the correct point and then as a test ride a know route of fixed duration,..take note of the temperature indication. Then on a second run over the same route/distance place a cover over the oil cooler which can be easily removed, (cardboard and some tape might work here). See if you get a step change in the temperature indication. You may like to also check that the electric cooling fan is shutting down when the temp is cold. It should cycle on and off with the temp if it is working normally, they do not runn constantly. You could perhaps pull the related fuse to the fan motor circuit and thus disable the fan for a time and see again if a temp indication change takes place. Typical is that the fan only tends to come into operation with the stop-n-go traffic conditions. If your "at speed" then the forward motion of the bike, again dependent upon ambient temperature, is normally enough to keep the coolant cool so the fan might rarely to never come on. You could also give the coolant lines (rubber hoses) a feel with your hands after a ride...see how hot they are just to give you a indication of the base line system temp.

Tony
 

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Discussion Starter #3
Hi Tony,

Thanks for the reply.

I also understood the earlier models do run cooler, mine does seem a little too cool though.

Fan does not run at all times, you can reach the connector on the thermo switch for the fan through the fairing and have confirmed that fan does not run at all times.

Top and bottom hoses are nice and hot (as is all of rad), so assuming water pump is fine.

I'm with you, either stat is stuck open or a problem with the coolant temp sensor (resistance does change as the bike warms up, but, range seems low to me, 720 - 180 Ohms... but thought that would give a high temp output).


Think I will play about shorting the coolant temp sensor lead (through various resistors) to ground, see if needle moves.

Appreciate the advice,

Cheers,

Gaz.
 

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Approaching this from a different angle ..........
Have you looked at the circuit board and connectors on the rear of the clocks? In the UK 'climate' there have been lots of occasions where corrosion in these areas have caused strange clock readings ....... possibly the best place to start from if you haven't already.
 

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Before buying anything .. I'm with Duck on this .. check all connectors, also check for air in the system and as Heisti says if bike is running stationary for a while then gauge should rise to halfway or slightly over and then fan kicks in .....
 

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Approaching this from a different angle ..........
Have you looked at the circuit board and connectors on the rear of the clocks? In the UK 'climate' there have been lots of occasions where corrosion in these areas have caused strange clock readings ....... possibly the best place to start from if you haven't already.
 

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When all above checked is your thermostat held on its seat properly. When I got my bird (97) then thermostat was wide open. But now has a small spring, gently holding it down in place so water cannot go round the outside of it. It's fiddly to fit so check with a mirror up the outlet. The rubber seal supplied by Jaws was way too big. Temp gauge now sits at half eight and fan starts at half nine.
 

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min runs dead cold all the time, the gauge needle is correct as when its midway ( for example after a long idle period ) the fan kicks in i have read that the thermostat on the carb versions open in the mid 80s deg c so the engine never will get to a real running temp
the thermostats of efi open in the low 90s ...
 
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