As an update to past posts I have been having trouble finding an internal antifreeze leak on an 03 600 Sportsman. I recently tore it down and couldn't find anything wrong with the head gasket although I suspected it to be the problem (I couldn't see any signs of washing of any part of the gasket by antifreeze slipping past). I then decided to go deeper and removed the cylinders to find the base gasket in poor shape. So I replaced both the base and head gaskets and put everything back together. To my dismay I haven't found the leak. A local dealer (who actually doesn't mind people that work on their own bikes) told me that the way to check whether the leak is in the top of the engine or the bottom is to remove the rad cap with the engine running and look for fine bubbles (I am kicking myself for not thinking about that sooner as I knew that from working on cars). I did so and found that there are bubbles. Now I am really starting to be baffled. I checked the cylinder head for warpage and it didn't appear out. The head was meticulously torqued down with the new gasket. I didn't see any cracks in the cylinder when I had it out. In thinking hard on this one before I go back in I remember that it started to use antifreeze after it had been driven about a hundred miles without an exhaust bullring (I blew it while moosehunting and continued to ride). Any ideas?

 

Since I don't remember the details of your first post I hope I don't repeat anything you already know or checked. Assuming the problem is not the mechanical seal on the waterpump shaft, it sounds like you do have some sort of internal leak. Also, I am not sure if you paid a lab to do an oil analysis, but that might prove very helpful. If they find a high concentration of antifreeze in your oil that will help narrow down the problem. Another thing that might help is adding dye to your coolant. If I am not mistaken, you can buy dye to change the color of your antifreeze and that might help show where it's going. Perhaps you will see a particular gasket get colored by the coolant and watch the color stain across it to show the leakage. Also, maybe lightly pressurizing the cooling system with compressed air will reveal the issue.

 

If you have your cylinder and heads off it might be a good idea to have them dye penetrant tested. This is 3 part process, first a cleaner is used to make sure area to be tested is very clean. Then a red dye is sprayed over the area you want tested, leave it soak for 5 mins or so. Wipe off the dye down to bare metal. The final stage is to spray a white substance which dries very quickly to a powder. If there are cracks the dye will penetrate the crack then leach out into the white powder. This makes the crack very obvious. If you have a friend in the metallurgy inspection field he should be able to help you if not call an inspection company in your area.
Hope this is of some help.

 

Thanks for the replys. In regard to the mechanical seal on the waterpump I have had past replies and one local dealer telling me that the waterpump leaks externally through a weap hole in the bottom of the waterpump cover. However, I made a call to a northern New York State dealer who is well respected in my area that said there is another seal in there that it could be. He said he had a 600 in this past summer with the identical symptoms and that is what it ended up being. I am still baffled as to the air bubbles in the antifreeze with the engine running. Unless the waterpump seal allows base pressure gases into the waterpump when it is running I don't see how else I could be getting the bubbles except for top of the engine. The dye idea is something that I will try next.
Thanks