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Putting it back together after installing a new head gasket


All together after my first ride with my new head gasket (sorry for the blurry pic)


After playing in a little mud


This seemed much higher in person than it looks in this picture




Ok now that I have the pics out of the way let me fill you in on the problems I'm having. It is overheating like crazy. I replaced the head gasket and it overheated and blew another one fairly quickly after. Before it blew the first head gasket it was spewing coolant out of the overflow after it would warm up. I could still ride it for a few hours at a time though. Before I blew the last head gasket it was doing the same thing but I could only ride for about 15 minutes and it would overheat. Is the water pump the problem? I bought a new one and it should be here on Monday. I already have another new head gasket for it (my second new one). I just want to make sure I'm not missing something. The cooling fan has a bad bearing in it but it still runs. It is just a little weak. I mostly ride at 30mph and above so I didn't think it would be a big deal if I wait a week or 2 to get a new cooling fan motor.

This is my first ATV. I am very good at fixing cars so I understand how they work. I know I can do all the work on it myself. I don't know everything it needs maintenance wise. I might need help there. I plan to buy a Haynes manual for it soon.
 

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Mornin man,
These Scramblers are good looking an fun machines!The 400 2stroke can be quite a motor, hitting almost 100HP with head, intake and exhaust mods!!!

Anyhow, is the coolant flowing? How about the gasket surfaces, is anything warped causing the continued leaks/overheating? Also be sure you have all the air out of the system as that too can cause overheating. Either change the bearing in the fan or get a new fan too.

Good luck,
CW
 

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I thought the air in the cooling system was the problem at first. When I put my new head gasket on I made sure the coolant had no air in it. I lifted it up on its rear bumper a few times, filled it some more, ran it for a minute, then filled it again. I did that until I didn't get any more air. The second it got warm it started spewing fluid out of the overflow tank. Does this unit have a thermostat? Maybe its not opening. I plan to buy a new fan motor but I might get a used one for now.
 

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I got my new water pump in the mail today. I did not expect it to be so tiny! I've never seen an ATV water pump. Does this engine have a thermostat? If it does would it be a bad thing if I just removed it? I've done that to a few cars over the years and it just makes them run a little cool.
 

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The 400 2 strokes do not have a thermostat. In order to burp the cooling system, there is a air-bleed bolt on the top of the head , while the engine is cool ,remove the bolt add coolant in rdiator and you should be fine.
You most defineately need a cooling fan,and you could try a universal electric,mount to the radiator style, as they are cheaper than oem and only require wiring end mods. get at least a 9" diameter, 10" better
 

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also, check the temp. overheat light is working
 

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Overheat light doesn't work. The switch that turns on the fan doesn't work so I wired it to the ignition temporarily. It runs but I think its weak. Next time I get paid I think I'm just going to buy a new fan motor. I will start tearing it down at about 8am. I hope to at least have it running by the afternoon. It should be done before that if I don't screw around. Thanks for the info.
 

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It was cold and raining this morning so I decided to wait until now to start fixing it. The classic cars are taking up the garage so I'm going to be doing this outside. It should be 60 out by now and I hope the rain can hold off for a few hours so I can get it fixed. I can't wait!
 

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I didn't really hard wire it. I just removed the wires from the fan switch and bridged them. I'm off to get a puller. I completely forgot to do that.
 

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need to take bolt out of side of head while running till anti freze comes out, can get new fan from e-bay, look under polaris fans, make sure radiator is clean.
 
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