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Discussion Starter #1
I have an old '98 Cat ZL500 and when I bought it I noticed that plastic inlet where the cap locks onto it was out of round and worn. By being really careful I was able to keep it from leaking. But then I topped it off the other day and once it was hot it started leaking and today my temp light came on, luckily I was close to home so was able to limp in with no problems.

A quick web search revealed that Cats have had problems with their coolant reservoirs on various years-models. Seems like the inlet hole should me metal or at least metal lined. So my question is does anyone know if they made an upgraded and/or after market replacement or am I stuck with a stock replacement tank and if so where is the best place to order on online?
 

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Discussion Starter #3
Thanks. Found a (hopefully) good used one on ebay for 15 bucks, having the part number helped since multiple years-models have the same reservoir.
 

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Discussion Starter #4
I installed the new tank and after riding close to home for about 20 minutes, the overheating light came on. I had overfilled the tank a bit but figured it would go out the overflow tube. So I stopped to let it cool and some fluid was coming out the overflow and I drained some more out bringing it down to the proper level. I let it cool off for about 15 minutes, rode it around for about another 15 minutes and so far it hasn't over-heated again. However, I am concerned that I may have air in the system. I found some links on how to bleed the system, but upon quick inspection could not locate a bleeder near the thermostat housing? help
 

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Discussion Starter #5
I should note that this sled has never overheated before and this is the first time the warning light has come on, except for the last time I rode it prior to replacing the tank. Plus, yes, it is definitely over-heating, the warning sensor is not the issue. I assume that over-filling the tank would cause it to over heat?
 

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The bleeder is on a Polaris (Ive added them to my Cats)
Just jack the front end as high as possible with the engine running and then open the radiator cap and let it run!
 

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Discussion Starter #8
Thanks, no wonder I couldn't find the bleeder, I will try that tomorrow. Another quick question, I went to start my old Yamaha and the choke cable was frozen, then started the 'Cat and the throttle was cable was frozen...I blew on it while the motor warmed up and it came free after about 10 minutes. It was not all that cold out (14 degees F at night) and we have low humidity here in N Idaho...so, is would a cable lubricant help a lot and if so which type?
 

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Try a dry graphite
But get them inside and thawed out, the wet snow inside the cable is tough to get out,
most will just replace cable
 

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Discussion Starter #10
Ok, I jacked up the front end and let it run for about 10 min with the cap off...rode it about 20 min and the temp light came on again and just before I got it home it began running really rough. So then I rode it up a steep snowbank and after letting it cool, did the same process as before, letting it run about 10 min w/ cap off. Rode it around for about 20 min and it was running fine but the temp light came on again. This is getting a bit baffling as I said, in the 5 years I have had it the temp light has never come on. The first time was a couple weeks ago when I added a bit of coolant, but then had a lead due to the tank cap inlet being warped and cross threaded, that's when I installed the replacement tank. Weird problem.
 

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Ride it around then remove the cap on a snow bank,
it has to be at full temp with cap off to get air out and keep burping the throttle too
 

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Discussion Starter #12
Ok, I will try that tomorrow and also read that rocking it back and forth helps? Plus I will check to see if the head exchangers are getting warm. Fluid is circulating to and from the tank so I assume that the pump must be working? Then if that doesn't work I suppose I will check the sending unit and thermostat.
 

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Discussion Starter #14
I did what you suggested and the light still comes on after about a half hour...the heat exchangers warm up so there must be good flow. I am beginning to think it might be a faulty sending unit, is there any way to test them?
 

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Discussion Starter #16
I guess boiling-testing the thermostat would be the next step. The light seems to come on consistently after about 20 minutes or so, not intermittently, so the sending unit is likely good. We had some warmer weather here so the snow is compact, no fresh snow or powder on the groomed trails. Still, since it has never over-heated before, that seems to be a questionable cause.
 

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Discussion Starter #17
Ok, pulled the thermostat and found that it is supposed to open at 122 F or 50 C...so heated the water in the pan to 122f dropped the stat in for a few minutes and nothing happened. I am kind of confused as to the open and closed position. At the bottom of the stat the shaft with the markings on it protrudes about an 1/8" below the housing...would that be open or closed? I would just buy another one but could not find on ebay, one online parts place wants $65 and the local dealer wants $80...so obviously I want to be damn sure it's bad before purchasing another. I am going back to fan or free air sleds, too much crap to go wrong on newer sleds!
 

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Discussion Starter #18
"If you suspect a faulty thermostat, run a few checks. With the engine cold, remove the radiator cap and start the engine. Look to see if the coolant is swirling/flowing immediately — that means the thermostat’s stuck open. If the coolant doesn’t flow after 10 minutes or so and continues to be stagnant after the temperature gauge indicates it’s hot, the thermostat’s likely stuck closed. " The coolant is flowing in and out of the reservoir so I guess that means it's not stuck closed?
 

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Discussion Starter #19
Stopped by the local sled dealer and had a mechanic look at the thermostat and he explained the open-closed position to me, so apparently it's stuck closed.
 
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