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Cooling system issues

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Good evening Thumper,

I'm having a cooling issue with my klx400. I've had the temp gauge come on twice on me now. First time was during slow trail riding. Figured the coolant might be old (purchased the bike used). I flushed the system (vinegar/distilled water) and replaced with engine ice. Today is the first time actually using the bike for a bit after coolant replacement and temp gauge went on again at end of my ride. I spent the last 5 minutes crawling slowly around my neighborhood and let it sit for 1 or 2 minutes while I went inside to open garage. As soon as I parked it in my garage the light came on and I noticed the overflow tank boiling. Both times the fan did not come on. Would the fan not working be reason enough for the bike to be getting this hot? 

Thanks in advance. 

 

5nq2d1.jpg

Overflow full. I had put about 1 1/2 inch of coolant in overflow tank just in case I had an air bubble. 

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Need to test the fan switch on the left radiator and the fan itself.Jumper the fan to see if it works and then check the current feed from the switch. The switch should close when the coolant gets near or at boiling.

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18 minutes ago, bumtarder said:

Need to test the fan switch on the left radiator and the fan itself.Jumper the fan to see if it works and then check the current feed from the switch. The switch should close when the coolant gets near or at boiling.

I’ll attempt to troubleshoot the fan. Hasn’t came on once so pretty sure it’s not working. I question why the bike gets hot so quickly. I’ve read of people running their drz without a fan 

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Update:

 

took off shroud, took off fan and noticed it was warped preventing it from spinning. I guess the previous owner had a spill and bent the radiator and fan a bit. Tried to persuade it to original shape as much as possible.

 

reinstalled, let idle for around 4-5 minutes and fan kicked on. ??

 

Still feel like bike gets hot FAST, but hopefully the fan working helps a bit 

 

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Glad you got it resolved. At least the fan and switch as a system is working.

 

My fan cycles on and off normally during hot summer weather when in slow traffic or going real slow down a logging road. The big tank shrouds and the plastic louvers in front of the radiators are designed to channel air in slower conditions to aid cooling.

 

I even have a manual override switch to the cooling fan that allows me to keep it on constantly when the traffic is really bad.

 

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I've had several cooling switches fail on me in the past. Including a new replacement. I now test them at every oil change by letting the bike idle until the fan comes on. This is how I found one of my failed switches. The way I ride, my fan almost never comes on, and I think they may fail from non-use as much as getting worn out. So I think it's a good habit to make sure it does work when needed. I also wire a fan switch bypass. 

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You got something cooking other than the fan issue.  No way your coolant should hit 205F in 4-5 minutes of idling.  Your bike has two different sensors: in the top of the right rad there is the warning light sensor: this is the rad that has the hottest coolant in it as it comes directly from the engine.  When the sensor hits 243F it puts the red temp warning light on.  In the left rad you will find the other sensor: the fan switch: it cuts the fan on at 205F.  I suspect that you have an issue with coolant flow: either the pump is not pumping the coolant, or there is a blockage somewhere.  This is trapping the coolant in the engine, which would cause the overheat to happen as fast as you are saying.  

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4 hours ago, dad2u said:

You got something cooking other than the fan issue.  No way your coolant should hit 205F in 4-5 minutes of idling.  Your bike has two different sensors: in the top of the right rad there is the warning light sensor: this is the rad that has the hottest coolant in it as it comes directly from the engine.  When the sensor hits 243F it puts the red temp warning light on.  In the left rad you will find the other sensor: the fan switch: it cuts the fan on at 205F.  I suspect that you have an issue with coolant flow: either the pump is not pumping the coolant, or there is a blockage somewhere.  This is trapping the coolant in the engine, which would cause the overheat to happen as fast as you are saying.  

Thank you sir, I was still left uneasy even after "fixing" the fan situation. the left radiator is a bit pinched along the outside edge.

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I had temp issues with my bike when I first bought it - mine is an E model so no fan to begin with. Turns out it was jetted so lean it would overheat very quickly. I searched around and found the recommended jetting here on the forum and after changing those it has been much better. Not sure if this is your problem, but thought I would suggest it as something to check. Good luck.

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If the flow was blocked only the motor would get hot , aka -no flow, so the radiators wouldn't get hot(till hot coolant slowly rises and makes it's way into the radiators) , soooooo, your system is working ,  verify jetting and make sure your fins are not bent so air can pass through both radiators as designed , also wouldn't hurt to put a new thermostat in with a lower rating . I run Engine Ice or Water Wetter in a few things and first thing I notice when going from coolant to the addatives is the extra heat coming off the radiators , it's the stuff doing it's job , getting rid of more heat than regular coolant . Nice in winter to help keep my legs warmer but sucks in summer with more heat blowing on my legs .

 

Remember, the old aircooled motors typically run 250-285°F-oil temps(I see 300 °F in putt-putt traffic with my built XT ), 205° coolant temp is really not "damaging" anything ,just a little warm for the DRZ .

 

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Edited by jjktmrider
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3 hours ago, azorr said:

I had temp issues with my bike when I first bought it - mine is an E model so no fan to begin with. Turns out it was jetted so lean it would overheat very quickly. I searched around and found the recommended jetting here on the forum and after changing those it has been much better. Not sure if this is your problem, but thought I would suggest it as something to check. Good luck.

Thanks for the suggestion, I will check jetting. As far as I know bike is completely stock besides the exhaust. 

 

2 hours ago, jjktmrider said:

If the flow was blocked only the motor would get hot , aka -no flow, so the radiators wouldn't get hot(till hot coolant slowly rises and makes it's way into the radiators) , soooooo, your system is working ,  verify jetting and make sure your fins are not bent so air can pass through both radiators as designed , also wouldn't hurt to put a new thermostat in with a lower rating . I run Engine Ice or Water Wetter in a few things and first thing I notice when going from coolant to the addatives is the extra heat coming off the radiators , it's the stuff doing it's job , getting rid of more heat than regular coolant . Nice in winter to help keep my legs warmer but sucks in summer with more heat blowing on my legs .

 

Remember, the old aircooled motors typically run 250-285°F-oil temps(I see 300 °F in putt-putt traffic with my built XT ), 205° coolant temp is really not "damaging" anything ,just a little warm for the DRZ .

 

.

Would the fan kicking in after a few minutes of idle be abnormal? The fins on my left radiator are a bit warped. 

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You have 2 radiators I think?  You have to make sure to get all the air out of them, if that tube connecting them has air, you're going to not pump much water.  I would chek that first.

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Bike getting so hot so fast while idling I'd suspect water pump doesn't pump much at all and heated water is just rising up on its own.

If that's the case, then there should be huge temperature differences between various parts of the cooling circuit.

If however the temperature of the cooling circuit is more or less very high everywhere, then pump is pumping but too much heat, more than the cooling system can remove, is generated somewhere inside the engine.

BTW, changing nothing else but exhaust will make the bike run leaner cause of the higher flow allowed by the changed exhaust. Thing is that bike was jetted lean to begin with, emissions regulations and all, so it kinda adds up in a bad way making bike run much hotter.

Just my 2c.

 

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I bought a used KLX 300 in California that was jetted so lean that it would overheat in mere minutes as well. I drilled out the sealed pilot jet screw access and fount it adjusted completely shut!  Also, there is a California needle jet and a 49 state needle jet available. I removed the California needle and replaced it with the latter.  Bottom line, maybe someone here may be able to advise you if you have a similar "California" set up on your model. My bike ran much better when it was "re-jetted" and didn't run hot.  Also, I had a friend that put effort into a JD jet set-up and seemed to get a bit more power out of it as well.  Good luck and let us know what you do.

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Thanks for your responses guys. Definitely helping me out as I am a complete noob to all of this. Isn't there supposed to be a fuel adjustment screw somewhere in this picture? Think it might have fell off or never been there. 

51wnde.jpg

picture of radiator damage

xd5b87.jpg

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I’m sure I’ve missed out on another discussion so forgive me if this is a bit dumb. Why am I thinking I’m looking at my DRZ400 when I see this photo? Is this the same engine?

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4 minutes ago, mojaveken said:

I’m sure I’ve missed out on another discussion so forgive me if this is a bit dumb. Why am I thinking I’m looking at my DRZ400 when I see this photo? Is this the same engine?

My KLX400SR is the exact same bike as DRZ400S, but with green plastics. Even my frame is stamped by suzuki.

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7 minutes ago, mojaveken said:

I’m sure I’ve missed out on another discussion so forgive me if this is a bit dumb. Why am I thinking I’m looking at my DRZ400 when I see this photo? Is this the same engine?

Its the exact same bike with green plastics

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