My 2008 LTZ400 is overheating upwards of 240 degrees if I don't turn it off.

There is more than enough coolant in the reservoir and it still overheats when I removed the thermostat from the cooling head and ran it open loop.

This happened right after I had to remove my thermostat one time to get my exhaust off so I could repaint the exhaust.

The fan does not turn on either. Is there some other thermostat that I do not know about such as the thing sticking out of the radiator itself?

 

look on the back side of the rad. kinda tucked up twords the top on the right side. my right not your right. should be two fuses in there one hot one spare. replace with good fuse then seal all around . water seems to get in there and short out the fuse. Good place to start. Seth 03

 

I swapped those fuses you were talking about even though the installed one appeared fine. No results. Overheated to 250f going for a cruise down my street. What else could it be? I see there are two different probes going into the radiator, maybe that is the culprit?

 

the four wheeler should not over heat that easily. if its moving the air flow is more than enough to keep it cool. you may wanna check and make sure your cooling fins in the rad are clean and that your water pump is pumping

 

I have a 09 and it did overheat due to a bad fuse. But once I got out onto the logging roads and got some air movement it cooled back down.Hillclimber is right check the waterpump.be sure to burp the cooling system. sometimes the sensors read funny if there is air in the system. a fan wont come on even if the temp is high. fill the rad and the burp tank and then let it idle with the rad cap off.run it long enough to open the thermo. Seth 03

 

You guys are right, I don't think my water pump is working. Anyone ever had one go out?

I removed the exit hose from the atv and let it run intil hot, not a drip came out. With the radiator cap off nothing came out either, it appears that the pump is definitely out of commission somehow.

I understood filling the radiator and letting it idle with the radiator cap off...How do you "burp the tank"?

This actually happened after I changed the oil filter and removed, painted, and then re-installed my exhaust. I then changed the oil to castrol 10w-40, which is great because it has stopped the light smoke trail it was leaving on acceleration occasionally. It ran at 160-180F max for hours on end before I did those simple modifications. I gave it a good pressure washing to, but I didn't concentrate on the radiator or anything out of the ordinary how I usually wash it.

I think it is just mad at me because I am going to sell it. lol

 

Now I really think it is a pump issue. The overflow tank will burp on its own if you burp the rad. I have never pulled a pump on a z400 but if its anything like my KLR 650 it is pretty simple. hope this helps. Why are you selling it z400s are a great all around quad. Seth 03

 

Right now I live in a rural area with tons of places to ride. I am only selling because I am moving into a neighborhood with many close neighbors and no trails with plenty of police. It has never broken down or had a hiccup. It just decided to die when I try to sell it haha.

 

Well I have great news for anyone looking up this thread with the same issue described above! The only thing wrong with mine was the fan controller probe found on the right back side of the radiator toward .(The lower probe) It cost $35 from suzuki oem parts. I bypassed it at first with a wire and found that with the fan on constantly temps never got over 142F!!! So the fan was the problem all along... that thing is critical.. without it temps quickly climbed to 250F!!!

 

glad to hear it was something simple. seems to be the way. look high and low and it is always the easy stuff.