# 1998 Ski Doo max 440 Fan keeps quitting



## chasenabby (Apr 30, 2008)

I need some help with my 1998 Ski Doo Mzx 440 fan. 
The sled starts and runs great for about 10 minutes then makes a loud noise (sounds like an exhaust brake) then quits. 
When I try to pull start it pulls super hard. Damn near rips the recoil out of your hands. 
If I let it sit an hour or so it start right up again. 
Anybody know what's wrong? 
I'd appreciate any help I can get.


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## Hairybear (Feb 28, 2011)

If your sled has power exhast valves try taking them apart and cleaning them one may be getting stuck


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## scooter_trasher (Sep 19, 2005)

chasenabby said:


> I need some help with my 1998 Ski Doo Mzx 440 fan.
> The sled starts and runs great for about 10 minutes then makes a loud noise (sounds like an exhaust brake) then quits.
> When I try to pull start it pulls super hard. Damn near rips the recoil out of your hands.
> If I let it sit an hour or so it start right up again.
> ...


sounds like its getting HOT check your fan belt


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## chasenabby (Apr 30, 2008)

Thanks guys.
I read that it may be a crank bearing seizing and then cooling down and freeing up????it as good compression. 
What are you thoughts on that?


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## MossyHorns (Apr 14, 2011)

Sounds like your sled is overheating and causing the pistons to seize. This may be caused by the fan not working, or a mouse nest between the fan shroud and the cooling fins, or the oil injection is not working. Do you feel air coming out of the fan shroud? 

The engine will probably need to be rebuilt if it has been overheated to the point the pistons seized. If you pull the carbs off you can look at the pistons and you should see scoring if has been seized.


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## chasenabby (Apr 30, 2008)

I have pulled the air box and Fan shroud off and there Ian any blockage. 
There is good are moving across the cylinder heads. 
Checked the compression and both cylinders are at 105. 
Tried starting it again last night and fouled the plugs again. 
Will get new plugs today and get it back into the garage to work on.


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## scooter_trasher (Sep 19, 2005)

chasenabby said:


> I have pulled the air box and Fan shroud off and there Ian any blockage.
> There is good are moving across the cylinder heads.
> Checked the compression and both cylinders are at 105.
> Tried starting it again last night and fouled the plugs again.
> Will get new plugs today and get it back into the garage to work on.


If your fouling plugs you may have junk in your carbs causing the needle valve not to seat, or coil windings could be shorting when coming up to temp causing week spark, old boat motors used to be notorious for that, as are Harley Shovelheads


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## scooter_trasher (Sep 19, 2005)

chasenabby said:


> I have pulled the air box and Fan shroud off and there Ian any blockage.
> There is good are moving across the cylinder heads.
> Checked the compression and both cylinders are at 105.
> Tried starting it again last night and fouled the plugs again.
> Will get new plugs today and get it back into the garage to work on.


If your fouling plugs you may have junk in your carbs causing the needle valve not to seat, or coil windings could be shorting when coming up to temp causing week spark, old boat motors used to be notorious for that,as are Harley Shovelheads, are you running electronic ignition with non resistor plugs or wires, a dirty fuel filter, or cloged fuel tank vent will stop you also, but it wont foul your plugs


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## 2SloSHO (Jan 23, 2008)

Sounds like you have some bearings going out, assuming you let it warm up for a solid 5-10 minutes before taking off. Could be cold siezing if its dead within 10 minutes. Warm up is the most important part of the day.

posted using Outdoor Hub Campfire


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## MOTOMAN91 (Oct 26, 2010)

Crank bearing


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## chasenabby (Apr 30, 2008)

Motoman
I believe you're right. 
I just didn't want to tear it that far apart. 
Thanks


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