98 XC - overheating?? - what to look for?

LoTecRacing · Mar 2, 2008

Rode on Saturday - borrowed my 98 XC to another guy. He stops me after about 2 hrs and says she's overheating... Sure enough - antifreeze shooting out of the overflow... So we cool her down with snow then run her up the hill and she overheats again after 3 mins... Same scenario all the way back to the truck.

I haven't looked inside yet, but if I remember right, there is a belt that drives the water pump, correct? That will be the first thing I look at.

Any other thoughts? Things I should inspect?

Any input will be greatly appreciated.

ivar · Mar 3, 2008

Definately check the wp belt.
some more info on the water pump belt here:
http://snowest.com/forum/showthread.php?t=66287

BTW, how was the snow conditions when it overheated the first time? If it was hardpack and the speed was slow, it could overheat b/c of not enough snow hitting the exchangers. Then, air pockets may have formed in the cooling systems , causing it to overheat afterwards even if cooling was plentiful

Norway · Mar 3, 2008

belt of course.

T-stat could be broken.

The pressure cap on your coolant bottle much secure tightly to the bottle, or the system wont pressurize and the coolant will boil much earlier.

Also, look for leaks. If you leak coolant then air will be sucked back in.When you get airbubbles passing through the engine you get instant hotspots in the head wich boils the coolant.

But start with the belt! Has it ever been replaced?

RS

rocket · Mar 3, 2008

98 Xc

The '98 motors had no t-stat, so that isn't going to be the problem. I really suspect either the water pump belt or some other internal problem with the water pump itself. I've seen air bubbles cause the symptom you describe, but only if there is something else wrong in the cooling system (leaky o-ring, hose connection, etc.) where the motor pulls in air every time it cools down. If you bleed the air out of the system and the problem comes back only when the motor gets run hard, you may have a leaky cylinder o-ring.

Nolimits · Mar 3, 2008

I had the same problem a couple of weeks ago, The bearings went out in the waterpump shaft which threw the belt off. If it is just the belt be sure to check the bearings on the pump.

THRILL_SEEKER · Mar 3, 2008

Another simple thing to check is MAKE SURE YOUR SNOW FLAP IS STILL ON THE MACHINE. We see it time and time again, people take it off for some reason, they think it lookes cooler or something. When the snow conditions are less than perfect, they will over heat every time. The snow flap is intended to help throw snow up to heat exchangers.

LoTecRacing · Mar 4, 2008

ummm yep... snowflap is still there....
thanks for the comments guys. i will update with my findings later this week.
-j

markoo · Mar 4, 2008

Head gasket?

Shocker · Mar 4, 2008

I had 1 a few yrs back that the nut backed off the impeller of the water pump and pushed it against the outer housing and quit turning. Just another thing to look for. Not sure if the 800's & the 700's are the same ( i believe they are) but if it broke the belt it also loses the oil pump along with the water pump.

LoTecRacing · Mar 4, 2008

cracked her open

opened it up and the belt was right off the drive sprocket on the water pump... couldn't see any damage to the belt. can't turn the sproket on the pump by hand... is that a bad sign? bearings gone? maybe that's typical since it is trying to push antifreeze through the whole system... what could cause the belt to jump off the sprocket?

i put the cover on without the oiler and i could see the end of the shaft turn slowly when i pull the rope. so i know the pump isn't siezed. when the belt was off i must have run it a bit without the oiler working... could that cause problems?? what should i check next?

this is a 700 btw - don't think that really matters though. far as i can remember 6's, 7's, and 8's were all the same in this department...

thanks.
-j

sodfarmer · Mar 4, 2008

If you can't turn the waterpump by hand you'd better tear it apart. When the pump seized it threw your belt off.

LoTecRacing · Mar 6, 2008

cant get the %@^# water pump off...

Ok I need help.
Tore into it tonight - sure enough water pump definitely is siezed. Started taking the bolts out around the pump that face the exhaust manifold. I got all of them but one. Check out these pics:

Mag side view with shroud & oiler removed.

Closeup PTO side view from below exhaust manifold. Got the other bolts out where it's all shiny and clean... One tricky one left.

Closeup PTO side view #2 from below exhaust manifold. Stupid nub in on crank case - keeps me from getting a socket on it.

Overhead Mag side view - remaining bolt directly behind and 4" below Polaris sticker.

Closeup PTO side view - remaining bolt - can't get at it from any angle.

I'm guessing I have to pull the entire housing off that the pump mounts to? Anyone done this before? I found 4 bolts that run from inside the housing into the crank case. Those have to come out I'm betting. Also, I'm guessing that I need to pull the coil off the crank (is it called the coil? used to call it the magneto.) I tried breaking the nut on the end of the crank loose but couldn't budge it... anyone know if it's threaded normal or backwards? Suggestions on getting it off? Do I need any special tools to get the coil off once that nut is off?

any thoughts? how much is a new water pump typically?

thanks guys.
-j

ivar · Mar 7, 2008

You'll need a flywheel puller to pull the flywheel. The nut holding the flywheel is often reverse threaded, can't remember is it is on this engine.

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98 XC - overheating?? - what to look for?

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