My 400 overheating too - Polaris ATV Forum
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post #1 of 13 (permalink) Old 08-08-2019, 09:22 AM Thread Starter
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My 400 overheating too

I've got a 1995 Sportsman 400 and it overheating too. Here's what I've done for trouble shooting; changed the antifreeze, new cap, new fan, washed the radiator. What else am I missing?
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post #2 of 13 (permalink) Old 08-08-2019, 10:14 AM
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Coolant circulating and blown head gasket?

The 400 was notorious for broken water pump shafts and blowing head gaskets

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post #3 of 13 (permalink) Old 08-08-2019, 11:14 AM Thread Starter
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water pump eh. Is there a known way to tell if its working? I also replaced the little sensor on top of the radiator.
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post #4 of 13 (permalink) Old 08-08-2019, 11:25 AM
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Easiest way to tell if the water pump is working? With the radiator cap cap off and the coolant just covering the top of the core tubes, start the engine and rev to about 2000 RPM - coolant should flow over the top of the tubes indicating coolant flow which indicates water pump is working - if there is bubbles or foam in the coolant it indicates a head gasket leak - I've seen them bad enough just pulling on the recoil rope would be sufficient to get bubbles in the coolant and you could hear compression leakage into the cooling system.
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post #5 of 13 (permalink) Old 08-08-2019, 12:15 PM Thread Starter
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I'll try it when I get home. I don't think its a head gasket. Seems to have plenty of power and get up and go - pep. I pretty sure I remember the coolant having a good flow when I had the cap off a while back. But since I'm heading out for a caribou hunt in three weeks I need to know.
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post #6 of 13 (permalink) Old 08-08-2019, 01:13 PM Thread Starter
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Since you're answering questions, as I'm pulling hills after the atv is warmed up it sound like the chain is slipping on some sprocket. I changed both sprockets on the main and the chain, but it still happens.
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post #7 of 13 (permalink) Old 08-08-2019, 01:14 PM Thread Starter
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I'm working on replacing the starter before the 1st too.
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post #8 of 13 (permalink) Old 08-08-2019, 04:04 PM
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Originally Posted by latebird View Post
Coolant circulating and blown head gasket?

The 400 was notorious for broken water pump shafts and blowing head gaskets
In what years was this a problem please? I have a 2014 and havenít had any problems. Thanks
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post #9 of 13 (permalink) Old 08-08-2019, 07:23 PM
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In what years was this a problem please? I have a 2014 and havenít had any problems. Thanks[/QUOTE]


They're referring to the 400 Liquid cooled two stroke, not the later model four stroke.
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post #10 of 13 (permalink) Old 08-09-2019, 07:24 AM
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Yes - we are talking 2 stroke engines - all years of the 400L engine

The chain slipping? There is a chain inside the gearcase that will wear out and start jumping the sprockets inside the gearcase or (if it's not the chain), the shift dogs inside the gearcase can be damaged or worn and the transmission can be jumping out and back into gear also sounding like a chain jumping.

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