Temp sensors and overheating issues

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ARCHIVE_Michael121

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ZL 600 lots on EBAY

There are a lot of parts on Ebay for the 6'rs

Starters, coils, wheels...etcc... all starting around 9.99

Some higher even the engine I think about 49.99 plus 50 ship
 
Hi Guys'

A couple of times, I've had the bike dump coolant (as happened just recently at a rally) and I'm perplexed by the way the temp sensors on my bike seem to operate the thermofan.

I had previously installed a fan bypass switch (#13 on the circuit diagram), so I can activate the thermofan manually, for example, whilst I'm coasting in slow moving traffic, basically to overcome the lack of airflow, but I've been wondering, shouldn't the temp activation sensors/switches do that anyway, based on the coolant temp, with the ignition on and the motor running, as they would normally do in a car, for example.

Ever since I've owned the bike, have I never heard the thermofan kick in independently whilst the motor is going, even after a long time at idle and when it is hot. The only time I've ever heard the thermofan activate independently, is when the ignition/motor has been turned off, and by then coolant has already started to overflow from the reservoir.

Please tell me if I understand this correctly, but as far as I can understand the circuit diagram below, (...and with a mild understanding of electrical components) the 97c temp sensor/switch (#8 is the temp sensor/switch at the bottom of the radiator, as far as I'm aware), as connected within Fan Relay #3, is normally closed (on), so basically, a rudimentary coolant monitoring circuit is activated (on) by the ignition switch, and the 97c temp sensor/switch (#8) is constantly monitoring the coolant temp within the radiator.

cooling_system_electrical_web.jpg


The other higher temp sensors/switches that are in the circuit diagram are normally open (off), within Fan Relay #3, with the ignition on.

#9 temp sensor/switches is to monitor the engine coolant, through the both sides of the thermostat to the radiator and which also activates the red "idiot light" in the tacho & #10 is to monitor the oil temp, which also activates the red "idiot light" in the tacho, (another reason why independant gauges are needed as "idiot light's" usually tell you somethings wrong AFTER the damage has already been done).

When the coolant temp around the 97c temp sensor/switch (#8), breaches the temp threshold (approx. 97c), a temperture sensitive, bi-metal spring contact inside the temp sensor/switch touches another contact therefore closing the circuit and providing (-) negative/ground to the already (+/positive) activated circuit, and therefore activating the thermofan.

The length of time the thermofan will continue to be activated will depend on the other temp sensors (#9 & #10), and if they are also over their temp thresholds, then the higher temp sensors/switches will activate the relay in their favor and they will supersede the lower temp sensor/switch, by default.

Once the higher temp sensors/switches (#9 & #10) have cooled below their respective temp thresholds, the relay will de-activate and automatically switch back to the normal temp sensor/switch (#8), but the fan will continue to operate until the 97c temp sensor/switch (#8), is cooled, making the bi-metal spring contact to open, therefore collapsing the circuit and the thermofan will stop operating, therefore bringing the circuit back to it's normal monitoring status.

...very logical, I suppose, but have I got my understanding of it right?

As I've explained, the fan circuit should be active (power on) only with the ignition switched on, but it seems as if this has been reversed on my bike and it's only activated once it's switched off.

The only reason I can forsee the fan not to come on, is when the bike is moving at normal road speed, the fan could affect the natural flowing effects of the cooler air passing through the radiator, as you're riding. The fan should, theoretically, only come on when there was insufficient airflow through the radiator and the motionless air/ambient air temp was unable to successfully cool the coolant down to below the 97c temp sensor/switch's (#8) threshold, which was the just scenario I had the other day.

...anyway, I've checked the fuses, the wiring, the fan relays, and the temp sensors individually, either in circuit or on a bench-test and they all work within acceptable parameters, so I'm wondering if anyone has had some experience with this before and what did you do.

I "sort-of" know how to fix this, re-wire the circuit to the way it should be, but it seems to be an electrical/circuit design fault, but I'm curious to know if others have noticed this and is it supposed to be normal?

Mick.
 
temp fan

hey Stormy, I am sure not going to write a response as long as your post so my answer to you is if I let my ZL sit and idle on the patio the fan will come on while the bike is running and also will run if temp is hot enough upon shutdown of engine. Don't know if that is what you wanted to hear but both of my 1000's do that and also my 600 responds the same way.
 
Hey furchin,

Yeah, sorry about that, I was trying to get my head around it and try to explain if I was on the right track, and I've given myself a big headache because of it.

I've just read the article in the Tech section about the Cooling system on a GPz900 / ZL900 by moab and one of the questions were answered, that it's normal for the fan to come on with the ignition switched off and the engine hot.

I've checked out the whole cooling electrical system, back to front and it checks out ok electrically, so all I can assume is the bike WILL get above 97c when idling, but not above 110c, so the fan won't come on with the ignition on.

The internal cooling system of the bike is in immaculate condition, as is the radiator, so with the motor running and the coolant flow from the water pump through the radiator, it must just be enough to keep the temp under 110c and therefore not activate the 110c sensor.

Either that or the 110c sensor is defective, but then it would default back to the 97c sensor and activate the fan, which isn't happening either, so the only logical conclusion is it just isn't getting above 110c. It's possible I suppose, the daily ambient air temp has been around 25c or less lately and this area rarely get's above 39c, because of it's altitude, so I suppose it is plausible.

...anyway, it's got me???

Mick.
 
I think Kawasaki made an error on these sensor wires and i have repaired it by:

changed the 2 wires across from the relay

yellow and white/green

and it works as it should be in first place :dancingfool:
 
Hi Stormy,
Sounds more like your 97c sensor is faulty. The temp would rise once coolant is dumped and air enters system, then the 110c sensor kicks in. Have you tried swapping these two wires at the sensors?
 
Yeah, LUMI, I see what you are saying, swap the 97c sensor wire and the 110c sensor wire around in the relay plug, so the fan will now cut in at 97c with the motor on, rather than at 110c.

...yeah, it makes sense.

...and that would almost make the 110c sensor totally redundant, because the temp should never get above 97c, but if it does, the 110c sensor is still there as a back up.

...good thinking, LUMI, thanks.

Mick.
 
I haven't yet, panther, but I'm going to try them tomorrow, using LUMI's and your suggestions.

The problem is the fan doesn't kick in at all if the motor / ignition is on, but it does if the motor / ignition is switched off, so I'd say the 97c sensor works fine, but it doesn't get hot enough to get above 110c.

The biggest problem I think here is, is altitude, the higher the altitude, the lower the boiling point, I'm 2099 ft above sea level, so the boiling point will have dropped, not much, but a little bit, which means it must be somewhere below 100c, but still somewhere between 97c and 110c, maybe the amount of coolant concentrate may have something to do with it also, as coolant is suppose to raise the boiling point, hence the glycol anti-freeze / anti-boil that is only available here in Australia, we rarely have freezing problems, normally overheating problems.

Mick.
 
Stormy said:
Yeah, LUMI, I see what you are saying, swap the 97c sensor wire and the 110c sensor wire around in the relay plug, so the fan will now cut in at 97c with the motor on, rather than at 110c.

...yeah, it makes sense.

...and that would almost make the 110c sensor totally redundant, because the temp should never get above 97c, but if it does, the 110c sensor is still there as a back up.

...good thinking, LUMI, thanks.

Mick.
Click to expand...

i have been running like this on all of my 900´s in the past for years with no broblems
and i think Kawasaki made an error on it :D
 
:detective: Have to agree with you Stormy, (8) has power all the time, therefore should switch fan on when temp reaches 97c regardless of ignition. Swapping wires with other sensor (9) will result in no change except temp. fan switches on. Fault most likely is in one of the relays or the way they are wired up, do they have special connectors preventing them from being wired incorrectly? is it likely that two of the wires got swapped? eg the left two bl & w/bl on (2) Have you checked the circuit with a multi-meter to determine power output ,cold and hot? At a guess i'd say it's fan relay (2). 12v 4pin relays are relatively cheap and easy to obtain, hours of riding enjoyment...priceless. And if you haven't tested the sensor you could connect the earth wire from the fan directly to the sensor and use your bypass switch, this will tell you if it works but not the temp that activates it. This can be done in hot water with a thermometer and multi-meter to test resistance. Hope this helps you and doesn't make it more confusing than it is. (i'd rather be hands on than looking at a diagram)[/i]
 
Hi Kawa-Krazy,
I had considered this, having read this post previously but discounted it as the cause of the fan not operating when ignition is on. It is clearly an electronics issue (in my mind) i can't always be right (damn) lol. I can see where you are coming from, a faulty cap would lower the boiling point therefore possibly boiling over before optimal temp is reached at the sensor to switch fan on. :good luck:
 
Hey Panther,

If you read the circuit diagram, it shows the ignition is off, and the main relay and both fan realys are also not activated, when the ignition is on, the main relay activates and throws the fan relay #3 from the 97c sensor/switch circuit to the 110c sensor/switch curcuit. When the bike shuts down (ignition off) it reverts to the 97c sensor/switch circuit.

I'm playing with the idea of just removing and replacing the 110c sensor/switch with a brand new 97c sensor/switch, if it will fit, therefore having the fan run at a lower temp, like I reckon it should. That way the fan will cut in at the same temp whether it's switched on / running or not. Having the fan cut in earlier will give the bike time to cool down on really hot days, like over 40c.

According to the kawasaki parts diagram on the Kawasaki U.S website

http://www.buykawasaki.com/DefaultF...SITE/VIVEHICLEINFORMATION/VICHOOSEVEHICLE.ASP

The 97c "fan switch" #27010-1180 is on the bottom of the radiator, the 110c "switch warning" #27010-1188 is on the engine side of the thermostat housing and the 120c "oil temp" #27010-1191 is on the radiator side of the thermostat housing. That's the way I read it anyway.

Mick.
 
Too easy, problem solved. :cool10: Sensor switches are available in a variety of shapes and sizes it's just a matter of bringing in a sample of what you want to a decent parts shop, they should be able to get what you need.
 
...yeah, too bloody easy actually panther. I don't know why I didn't think of it before, DOH!!!

...anyway, after I printed out all the information you excellent people suggested, I went down to the shed and started on the bike.

I replaced the radiator cap with a brand spanking new 0.9 bar CPC job (right plunger depth and size) from the local "Supercheap Auto" parts shop for $15.00 (a new genuine kawasaki one is $146.49!!!) and popped that on.

...time will tell if it's fixed the coolant dumping or not.

I then moved onto the relay wiring, instead of cutting the wires and joining the whole lot together, as KK suggested, or joining them with a push connector as Ross suggested, I just grabbed a three inch long bit of 15 amp, red coloured, heavy insulated wire and soldered it straight onto the yellow wire and the white/green wire pullout female spade connections that go into the relay plug and insulated the solder join with some heat shrink of the original wires respective colours.

After replacing everything back (I had to take the tank partially off and the plastic shroud / cover near the head stem right off to get to the relay and radiator cap anyway), I started the bike up and let it get to full operating temp, as soon as it did, the thermofan kicked in and ran for about 30 seconds and switched itself off, no problems there, I let the bike idle for another 15 - 20 minutes and the thermofan proceded to kick in every now and again for about 30 seconds and switch itself off, EXCELLENT !!! working like a charm.

When the thermofan was still running, I switched off the bike at the key/ignition and you could hear a brief drop in the thermofan speed as the relay switched over, then it continued to spin at a normal sounding speed again, after about 15 seconds or so, it finally shut itself down.

:cheers: YAHOO!!!!!! :dancingfool: IT'S FINALLY WORKING LIKE IT SHOULD!!!

...thank you all for your excellent advice, I owe all that helped me out a beer or two at my place, anytime.

cheers.gif
, Mick.
 
Hi Stormy, just had a look in tech forum and guess what? Moab submitted an article on cooling systems last month complete with explanation of operation and diagram. Guess we should have looked there first eh :cool10:
 
panther said:
Hi Stormy, just had a look in tech forum and guess what? Moab submitted an article on cooling systems last month complete with explanation of operation and diagram. Guess we should have looked there first eh :cool10:
Click to expand...

...yeah, panther, I found and read that thread just before I made my second to last post in this thread.

...next time I'll look in the tech section before making a thread with such a long post. :evil3:


Mick.
 
thanks guys , great story.
it really helped me ,
have the same thing too and could not figure out what was going on. :?:
got the scedual from the other thread printed out,
and go look at it tomorrow, and set things right.
the guy at kawasaki in 1985 who did the wires , must have been sleeping. :?
but then again, it has been running for almost 23 years, they most have done something right :wink:
we'll see what happens
again guys , thanks for the thinking.

gtrz from sunny holland
Edd :cool:
 
Stormy,
I have also had my fan switch on with the motor running and (more often) after the engine is turned off. It is my understanding that both actions are designed into the
wiring plan. Have you checked your thermostat?
 
yeah, rkerg, I checked the thermostat and it checks out fine, I had another brand new car thermostat with the same temp, side by side with the original OEM one and popped them both in a pan with some cold water and set them on the stove top to come up to temp, they both opened at the same time, so I know it's working within acceptable parameters.

The mod I did to the relay wiring, along with the replacement radiator cap have both been working flawlessly now for almost a year. I haven't had any coolant dumping issues like I used to have, since, so I reckon the problem has been solved/rectified.

Thanks for the concern, anyway.

Mick.
 
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