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2002 Grizzly 660 OVERHEATING issues

4.3K views 12 replies 6 participants last post by  01 Grizzly  
#1 ·
Need help Guys
I purchased seized 02 Grizzly this Spring that had been sitting in a warehouse for almost 20 years. Other than a bunch of dust everything else was in mint condition. So, I order a new 686 Big Bore piston and cylinder kit from Niche. Replaced the valves, rebuilt the carburetor, new wheels, battery, replaced all the fluids. Assembled everything and started it up with no problem. Motor was running like new, and also seemed to be driving great. Then after riding for like an hour breaking it in, the heat light came on and steam started boil out. I then ordered a OEM thermostat and Radiator cap with temperature gage. Installed and started up, noticed after 5 minutes of idling the fan would start and never cut off. I montered the temp while idling and it would rise to over 200 in 25 minutes. Next I took the radiator off and cleaned it in a ultrasonic bath. Reinstalled the radiator and same problem again. I bleed the water pump for air and monitored the radiator while running and noticed it had air bubbles that were constant. Next i pulled the head again and got it re-surfaced and order a Cometic Head gasket thinking it was blown. Start it up, same problem. So i decided to take the waterpump off and inspect it, nothing wrong with it. Next I got a garden hose and connect it to the radiator hose and flush the engine and radiator for 20 minutes hoping to clear any debris. Start it up and same problem. I have tried liquid cool, and different antifreeze coolants and all the same outcomes. I have checked the timing and is set correct. Remember the engine runs great, no skips, pops, or stalls. I may have tried other things and forgot to include it. Any new ideas would be really appreciated.
Thanks
 
#11 ·
Last update I hope.
Installed the new radiator and monitored for 35 minutes while idling. The temperature reached 145 and the fan would cycle on and off. Then went for a 1 hr ride and the temperature never got 150. Looks like you guys have solved my problem. Thanks for everyone's help.
 
#9 ·
I had a great idea!
It sounds like your oil pump /water pump chain is so loose that is skipping the gear! I was taking apart my 700 griz and the same chain I’m talking about was extremely loose 1700mi.
Taking your water pump cover off and turn the pump impeller back and forth and feel for play. If there is excessive play, you should take that side cover off and change the chain and inspect your timing chain.
The service manual will detail what a either bad chain will look and feel like. Look at a parts breakdown to see what the chain drives.
I know you have a 660, but the oil pump chain is very similar to a 700.
Here is a picture inside my griz
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#7 ·
Feel the hoses going to/from the radiator. If the radiator is radiating heat, they should be significantly different in temperature. If both hoses are the same temp, then your radiator isn't working as it should.

A word of encouragement: your troubleshooting regimen seems rock solid - good work on this so far!
 
#8 ·
Feel the hoses going to/from the radiator. If the radiator is radiating heat, they should be significantly different in temperature. If both hoses are the same temp, then your radiator isn't working as it should.

A word of encouragement: your troubleshooting regimen seems rock solid - good work on this so far!
Thanks, I will check this weekend and let you know. Thanks everyone for the help
 
#6 ·
Running lean?? Consider checking jet and fuel level. Many rebuilds don't make the grade.
Proper heat range spark plug?

However in reality I would replace the radiator. A radiator sitting 20 years who knows what solidified gunk is in the tubes. An good aftermarket is around $120.00. I've installed 2 of these, great quality.
 
#4 ·
I've have tried the pump and it appears to be in perfect working condition. I can watch the fluids flow thru the radiator when warm, but I can't tell if the rate of flow is enough. I was hoping it was trapped air but I have bleed it and squeezed the hoses trying to force air pockets out. I am afraid it has something to do with the new cylinder.