Overheating/ cooling system problems

S

shogun

New member
Joined
Jan 14, 2004
Messages
4
Help, I have a 98 xtc 700 that is having cooling problems, it started off this year with the temp light going on and off during a 40 mile ride, I bled the system using the bleeder under the seat, while in the garage the system seemed to be working as it should, I filled the overflow bottle up to the full mark and warmed the sled up, once warm I checked the overflow and it had gone up about 1/2 way to the top, let it cool down and the coolant would go back to where it started, so I took it for another short ride and the system pushed coolent up to within 2" of the top of the overflow but when I squeezed the hoses it did not seem to have any pressure in the system, I went back home and let the sled cool down, no coolant went back into the system from the overflow, after cooling I took off the pressure cap, there was no pressure in the system and no coolent to be seen in the hose. I also see very little coolant in or under the sled, and other than this the sled runs great. I should say that I have had this sled to the dealer every year since I bought it in 99 as a leftover, once the o-ring for the pump was bad and last year they thought it was a small leak in a hose, they showed me the hose and I couldn't see anywhere it would leak but the sled seemed ok, since this happened late last year this was only the second time the sled was driven since then. Sorry this is so long but I'm really getting frustated, It has been to 2 different dealers and the problem persists, other than when they fixed the bad o-ring we can not seem to see where the leak may be coming from, any ideas where to go with this??? Thanks in advance for any help.
 
Are all the heat exchangers getting warm along with the engine? That would tell you if the coolant is circulating through the system. I don't
know if your sled uses a thermostat or not, but if it does and it's stuck
closed that could be your problem.
 
Thanks for the reply, I checked and the heat exchangers are getting warm, not sure about the thermostat, I don't think the xtc's came with one.
 
Have you done anything with the carbs? What about PM. Are the jets dirty? Is it possible your running lean and a little too warm?
 
More help needed

Still having problems, I put a new cap on, took the pump off and checked impeller, put a new o-ring in, pulled the head off everything looked good, the gasket looked good so I cleaned the head, gasket, and jugs, used hightac and put it back together. I'm still having problems, going thru the steps to bleed it, seemed to be going ok, all coolers where warm, I lifted the back and ran it at higher rpm's and noticed the overflow filling up pretty quick, noticed bubbles coming up to the top of overflow when it was reved up, at idle no bubbles. Let it cool down thinking it was just air in the system so I let it cool down, no fluid was pulled back out of the overflow, tried rebleeding again seemed ok again and the same thing happened. At this point I'm thinking bad head or gasket, can anyone confirm or any other ideas.
Also I pressure tested the system cold and it held 15lbs fine, no obvious leaks.
 
Thanks for the reply Doug, When the system is warm it is holding pressure, is it possible to have air pushed from the case into the cooling system without having coolant pushed thru the seal the other way ? I guess what I'm asking is what has more pressure, the cooling system or the crankcase when the engine is running? The reason I was thinking the head or gasket was the high pressure in the cylinder. Once again thanks for the help
 
Yes, if the seal behind the impeller is leaking it pushes air into the system(not crank case air but air from someplace, the impeller crankcase housing is seperate from the rest of the inside of the case). This pushes the coolant into the overflow and then when it cools it will not go back into the system because it was easyer for the system to pull more air from the leaking gasket. Which gasket it is is a question you will have to answer. It can be the ones behind the impeller, the O-ring on the impeller housing or head gaskets. I personally have only had this strange one-way-valve problem when the gasket behind the impeller goes bad. My headgaskets just caused the motor to run like crap. Also in my big service manual it notes that there is 2-stroke oil in the pump shaft housing inside the crank. It will push that oil into the coolant and stain your coolant. Doug
 
i'm hoping it was my head gasket.

i pulled the head and the mag side piston was a lot cleaner then the other two. and the dome had just about no carbon on it compared to the others.


i ordered gaskets and dropped the head off to be milled.

i'll know in about a week and a half if this fixes it.

i also sent my pipes to be ceramic coated.... woo hooo!!!
 
It started overheating real bad last night at the cabin and you could see a leak around the head. I tore it down and cleaned everything up, sprayed the gaskets with copper spray, let it sit overnight and it runs like a top now. Quick fix but new gasket Monday.
 
wow, there have really been a lot of problems with headgaskets this year for some reason. I smoked a set too earlier in the season, but mine were thinned out.
 
I've read a lot of the posts about these NPV 700 with cooling system problems. I have the exact same problem as this original post had. It's in a 2001 mm700. I did the head gasket and things seem to be not bad. I haven't been able to take it for a real good rip due to time and lack of snow here right now. I do have a question about the over flow that I hope someone can answer. Under normal cooling system operation is it normal, after doing the head gasket and bleeding, for the over flow level to go up and stay up. It doesn't seem to be pushing it any higher. it went up about 2 inches from the original fill and bleed and now it seems to be staying at that level.

This post seemed to fizzle out and nobody finished up with what their problems turned out to be.

Any help would be greatly appreciated.
 
I did the head gasket and took it for a few good chews. Everything seemed fine. Went on a big trip this past weekend and it started pushing the coolant out again after about 15 miles of WOT on semi packed trails. We stopped and had a weiner roast and I filled the cooling sustem back up and let some of the coolant run back into the system while the cap was off. We had some spot were there was a good 3 feet of powder. I did some WOT pulls in the powder and for the rest of the trip it was fine.

I am not getting any stain in the coolant and the plugs are not grey, which would be the tell tail sign of a head gasket.

The only time this seems to happen is when I do WOT runs on trails. There was abundant snow on the trails so I don't think I was over heating by any means. The temp light never came on.

Any ideas?
 
You must log in or register to reply here.


Back
Top