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2004 Yamaha Kodiak cooling system


bstorm
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  • 1 month later...

I am curious to see if you bled the system........I never had a problem with overheating until I changed the fluid.......I did exactly what the book says but when I ran the machine after changing the fluid it overheated on me......I assumed it was due to air in the system but have not looked at it yet.......If anyone else has had this happen let me know.

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When thermostats have been in service, and then the coolant gets drained and they remain empty long enough for the thermostat to dry, the thermostat can jamb closed sometimes. I've seen it plenty of times. Even brand new ones can stick on their first run. Once they have opened though they seem to come right.

Mostly if you are watch them and be ready to take some sort of action like drive or cool the radiator with a hose, they will come right after they get to a higher temp than they are meant to open at. It seems like it takes time more than temperature, but then once they have opened and got over the dryness they are ok..

That said, thermostats are a part I reckon should be changed every few years as a preventative bit of maintenance. They are too cheap, and critical, and can cause so much damage for the small cost of a thermostat, that it's best to change them before they play up.

The manufacturers these dayssay after two years, but I reckon up to four years.. Or when the coolant's being changed.  

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I'm not familiar with those bikes but if the manual says they don't need bleeding then presumably not.. In some vehicles though the air is bled back to the header tank by a small diameter hose, and those can get blocked, kinked or misrouted so there is an air-lock and can sometimes mean air doesn't get out.

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The manual does not say anything about bleeding the air......I was curious because someone else had mentioned that after they filled the new antifreeze they ran the bike and waited for the thermostat to kick in and the coolant level fell........The only way that could happen is that there was a gap in the system and thats why I questioned it.......I have not had a chance to change the thermostat because they are pure gold right now and I can not find one......I guess I will try ebay///////Thanks for your response......I do appreciate it......Hope you and yours have a great Christmas.

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Thanks Krominator, and to you and yours too.

Yeah the bike ones are dearer than auto ones.. 

If a thermostat is going to cause an airlock in the system, then the thermostat for that machine has a small hole it it to let the air out. The hole needs to be at the top. Other than that though the cooling systems these days are generally designed to self bleed.. But sometimes on a bike that might require a small hose from the top of the motor going straight up to the radiator. If that hose gets blocked or kinked it can cause an air lock problem..  Sometimes some of the radiator hoses look like if they were routed wrong it could cause an air lock too.

 

 

Edited by Mech
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  • 1 month later...

Well after all of the great things I have said about the Kodiak, I have been having problem after problem.......I still think it has been a great machine and I have had very few problems with it for twenty years so I can not complain.........After I did some maintenance on the bike like changing the coolant and the thermostat, it is still overheating.......I noticed the fan is not coming on when it should.......I checked the fan with the battery and it runs fine.......I replaced the battery, the main switch and the thermostat.......I checked the continuity of the radiator switch and it does click on when heated and clicks off when cooled down.......I guess the next item would be the relay........Any suggestions out there what else I should check........I noticed that my temp light does not come on either.......This is always what happens to me when I open my mouth too soon........However, I still think the Kodiak is a great machine and I have been extremely happy with this purchase. 

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If it has more than one relay you could try swapping them and see if it causes the other circuit to play up or the fan to come right.

It might have a broken wire. Wires mostly break where they go into the metal terminal on their end. You could bridge the wires where they go onto the temp sensor, or if it only has one wire you could earth it out, which should cause the fan to come on. If the fan doesn't come on then go around wriggling the wires near their ends, perhaps flex them very gently, hoping it does come on. If it's still got the original relay at that stage try giving it a few taps with the handle of a screwdriver.  If the fan did come on, wriggle wires anyway making sure there isn't an intermittent contact. You could also look into the wiring plugs looking for green corrosion.

The other thing that could cause the temp sensor to not operate is if it's siting in a bubble of air. It's not likely that will be caused by a bleeding issue after all this time, but it could be caused by having a blown head gasket or the water pump  letting bubbles into the cooling system. You could take the radiator cap or reservoir lid off and look for bubbles coming up in there. If it's a radiator cap the bubbles will probably come up as small bubbles, possibly as small as pin heads, or they could accumulate and come up as a bigger bubble every few minutes. If it's the reservoir it will  probably only give one bigger bubble every few minutes so you need to be watching carefully without taking your eye off it. You need the motor hot and idling and you need to keep watching for quite a while, ten minutes will probably show something. If you find bubbles, you need to figure out whether it's the water pump or the head gasket. The easiest way to do that is to check for the presence of hydrocarbons in the bubbles, which mechanics do by doing a Teekay test.. Most workshops have a teekay tester. You can read up on them online. If you don't have access to a teekay tester you have to make a pragmatic decision about which to try/repair first. Generally a head gasket will make more bubbles when they are warm, and they make a lot more bubbles if you can put a heavy load on the engine, so if you sit on it with the brakes on and in gear and then start to load the motor with the clutch engaging you may see a sudden increase in bubbles. Water pumps don't respond like that, but they do tend to make more bubbles at certain revs.. so you might be able to rev it in neutral and get it to bubble more. Telling the difference between pump and gasket is often difficult though.

Edited by Mech
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The fan comes on and runs fine when I bridge the wires that go to the radiator thermo switch so I assumed that the switch was the problem.......However, when I tested the switch in a pot of coolant as described in the manual, the switch worked fine......It had continuity when the coolant reached 185 and no continuity when it cooled down to 165........I ran the machine for more than ten minutes and watched the coolant in the radiator.......I did not see any bubbles but it did get hot and the radiator never kicked on........Does the power from the radiator thermo switch run through a relay or a circuit breaker before it goes to the fan motor because this is the only thing I could think of that might be wrong.......But then why would the fan work when bridging those wires....... I am a wee bit illiterate when it comes to reading diagrams so I can not tell if power goes from the switch to the fan or it runs through something else first.......I really appreciate your help because I am stumped.

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First thing is.. did you change the thermostat in the end, and/or, are you sure the thermostat is opening ?

The other thing is, if the fan's not coming on, why do you think it's getting too hot ? Perhaps it's not.. Have you tried reading the temp right close to the sensor to ascertain if it is actually getting hot enough to turn the fan on. Where the fan switch is may not be the same place as a temp gauge sensor, or where you may be measuring the temp. The bike's temp gauge(if it has one), may be reading wrong.

Not sure if there is a relay but I'll have a look. If bridging the temp sensor makes the fan come on though then it doesn't seem likely the relay(if it has one) would be playing up. The temp sensor may have dirty contacts so that even though it shows as having closed with an ohm gauge, there might not be a good enough contact in there to run the fan. You could disconnect the wire at the fan and check it doesn't have power cold, then use a test light on there until the sensor switches on and check there's enough power coming through to run the light. A headlight bulb would be a better test than a tiny test light bulb.

The other simple cure to the problem is to rig up a handlebar switch to turn on the fan.

 

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I couldn't find a manual for your exact model which I think is a ymf450fas or fahs. I had a look at the parts though and there is no relay shown, just a thermal/bimetal circuit breaker before the sensor/switch..  That must be going ok if bypassing the sensor makes the fan go.

So far it's looking like either the sensor is defective even though it passes the test, or, the engine is not getting too hot, or not too hot where the sensor is anyway.

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My feeling is that the radiator thermo switch is strong enough to read continuity but too weak to turn the fan on as you have stated.......It is the only thing that makes sense to me as the fan would not work if something else was bad........I ordered a new thermo switch but I am going to apply heat to the switch with a heat gun to see if it works......I will take it out of the radiator but keep the wiring hooked up when I apply heat to it.......This should let me know for sure.......I will post the results.......Thanks again for your advise......

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Hey Mech it looks like we were right........When I tested the radiator thermo switch out of the bike in coolant I was getting continuity at the 185 degree point and no continuity at 160 just as it should but when I put it on the bike it would not turn the fan on.........Ordered a new one and it works as it should.........I thought that was pretty strange but there are a lot of strange things out there........Just wanted to thank you again........I am goin ridin

 

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