Okay guys, I installed a new stator, got my battery charging prob solved. When I dismantled the water pump I found a broken impeller. So, found the source of my overheating problem.

Ordered the new impeller from yamaha, installed it on the old gasket/seal set, no oil leaks seamed okay.

Now, I have constant flow of coolant from the vent hose. I have checked every hose for a blockage, found the thermostat was stuck open; the darn stem the spring moves on got tilted, moved it back with a screwdriver, it closed right up. Will get a new thermostat Tuesday or ASAP.

Just can't figure out why there is so much pressure on this vent? Maybe I forgot to tighten down some internal limiting screw? Is there an external one?

There is no sign of coolant in te oil. Oil is branc new 5/30 synthetic for AK Fall/Winter use.

The old impeller just snapped up inside the impeller body. How the hell does that happen? No leaking or pumping of coolant til I replaced the impeller. Without an impeller, the machine would not overheat for a pretty long time.

Anyway, if anybody knows how to cure this situation, I'm all ears. The pump housing all looks excelent. The impeller breakage seems not to have done any damage, it just sat in the housing with the shaft spinning, nothing jagged on the shaft impeller looks like it could be from the factory in two pieces.

I am stumped and really hoping someone has seen this before.

Thanks

 

You probably have air in the cooling system, and you need to purge it out. To do that:

1. Raise the quad by the front end until the radiator is in a straight vertical position.
2. Put a pan or tub underneath the radiator to catch any fluid that blows out.
3. Remove radiator cap, start the quad and let it idle until the thermostat opens and you can see water flowing through the cap opening. -You might need a good light to see.
4. Turn off the quad, top off the radiator and reinstall the cap.
5. You should have a little air bleed screw in the thermostat housing. Locate it.
6. Restart the quad, let it idle; slowly open the bleed screw and bleed off air until only coolant comes out. Close the bleed screw.
7. Turn off the quad, let it cool completely; and top off the radiator again.

You should be all set. Since it's an '02 I would replace the radiator cap too. The spring and seal in the cap get old and don't let the pressure build up that's necessary to have the cooling system work properly.

Hefty

 

THANK YOU! will give this a go!

 

HeftyLefty,

No vent screw on the thermostat housing. The temp sensor/switch is right behind it. Will give that a try.

thanks

 

Here's a site that has the manual for the '02 Grizzly 660 available for download. It is on page 2 of the Yamaha list. You will need a .pdf reader like Acrobat to view it.

http://manuals.dqt.be/index.ph...om_frontpage&Itemid=1


Hope this helps.

Hefty

 

I have the cd-rom manual. I have loosened the temp sensor about 3 times now and the coolant still comes out the vent tube.
I think I will pull the thermostat, fill the upper hose as full as I can, reattach to radiator, fill radiator and see if that gets the job done.
Am planning to replace the thermostat anyways. Just 170 mi in & back to the dealers, so it will be a few days... Maybe I just need to cap the vent and not sweat this? Oh well...

 

NO!. Leave the thermostat in place, you can warp the head if the quad gets too hot. Like I said in my original post, both the cap and the thermostat(since its damaged), may be the culprits.

I would replace both the thermostat and the radiator cap. If that doesn't stop the venting, the the radiator itself is clogged up and needs to be cleaned out by a radiator shop or replaced. I say that rather than telling you to try and flush it out yourself because I don't know what the chemicals in these radiator flush and fill kits will do to the engine.

You can buy parts online from www.mrcycles.com , put in your quad info and select 'radiator hose' . They have cap, thermostat, and radiator. Or, call 1-800-359-0567.

 

Update: spoke with the dealer on Tues after the holiday. Mechanic said the first rubber seal behind the impeller was bad, to replace it.
I asked the parts guy about replacing the seals on the impeller shaft and was advised against it.

Thanks Lefty for all your efforts and help.