650 running unusally warm, plugged cooler?

[hilbile]

I'm stumped on my 1988 650 its been running unusually warm as of late. It was my dads sled he bought from its first owner in 90. Right away he put a manual temp gauge on it, it would never run above 120*F on a 20degree day. this week same type of day it wont run below 160*. Thinking the gauge was off we checked it with a infrared, digital, and a meat thermometer, all agree with the gauge. We flushed the system with air, and water, backwards and forwards. Each time we flushed the system we bled the air. Changed the water pump, checked for cracked heads, cylinders gaskets. It runs just as good as it always has. While running it the running board coolers will be warm, and the center cooler while iding will be cold to the touch and won't melt snow. If you run it hard it seems to be working better. but consistently that cooler is colder than the others, like it is not doing its job. Could it be plugged? Anybody have any ideas to why it would do this?

 

[BB454]

Sounds to me like a bubble. Coolant comes out of the head through the brake and into the right cooler. Then out of that cooler into the crossover and out of it into the left cooler. Out of the left back into the engine. Pretty straight forward. They were known for getting a bubble. Coolant would just flow through the bottom of the crossover into the left cooler. You can try tipping it on it's right side and see if you can get it to burp. While it is over see if you can loosen the hose clamp on the left side of the crossover and let the air out. They will overheat without that crossover cooling right. The crossover has larger openings than the running board coolers so I don't think it is clogged. Also alumimum system so not much to clogg it. Still think it's a bubble.

Also make sure the water pump belt is tight. I assume it is because you changed the pump. Mine would over heat when the belt got worn. Common to the 600s and 650s as well as storms.

 

[cowboy181d]

I am voting for a bubble also when I built my last 650 it did the same thing Till I got that bubble to pop, Try rolling the sled over to the right and burping it, and If you have a mighty vac or vacuum pump you can try pulling 15" of vac on it to suck the bubble out, I now use a coolant fill system on the wedges to take out much of the "bubble trouble".. If you happen to know any mechanics most of us have a coolant vac and fill setup for filling automotive cooling systems, that works like a charm on sleds as it pulls a vacuum on the system and then seemlessly fills it with coolant(this is how the manufatures do it). hope my ramblings help!

heres a link to what I use http://www.costplustools.com/Kent-Moore-GE-47716-Vac-N-Fill-Coolant-Refill-Tool_p_8176.html, Spendy rig but it is a good example,
sears and snap-on both carry much cheaper versions...If you have a GM dealer in your town they should have the one in the link as it was a factory tool supplied to GM dealers in the late 90's, and most service departments would probably suck down your system for minimum charge!

 

[hilbile]

Tonight we tipped it to see if it would burp, it did nothing so we're guessing there was no air. Next, we decided to test the water pump, we unhooked the inlet where it comes from the coolers and on top where it comes out of the rail from the heads. Sucking water from a bucket and pumping it through the heads and out the top, at idle it had small flow, shot it out about 6inches out the end of the rail at most and a slow pace. Does anybody know anything about how much flow in GPM or other measurement a water pump is supposed to have, or if they make/made a high flow version. The belt is tight we checked before we started.