Overheating, but not the engine?????

[rtiqulatendisco]

So, this past week, I was on a trail here in CO that was uphill the entire way. About 30 minutes into the trail, I smelt coolant and noticed some steam coming from beneath the hood. The coolant overflow tank was hissing and spraying coolant from the cap. The engine temp was normal. I waited until it stopped hissing, 3 minutes, and then drove on. 20 minutes later the same thing happend. From that point on, I turned the heat on and lifted the hood every ten minutes and the problem never happend again. On the way down the trail, the truck was fine without the heat on and no stopping.

Things that I've noticed:

It only does it when the truck is in low and under medium power to get up the hill. The harder the engine is working to get up a steeper incline, the quicker the coolant boiled over. The engine temp remained at normal.

Under normal driving conditions during the summer (80degrees) it takes 3 minutes of driving to reach normal engine temp.

It only happens when I've been on the gas for a period of time.

Road driving presents NO problems.


So, what the hell is going on???


Thanks,

James

 

[warner0188]

I would have to say a combination of things are probably going on. Disco temp gauges are junk. Mine has never gone over about half way up the gauge even when it was overheating. When you are driving around at road speeds cool air is pushed through the radiator. When you are moving slowly or sitting at idle the engine heats up and the viscous fan clutch pulls cool air through the radiator allowing your engine to stay at a normal operating temp. When the fan clutch doesn't come the engine overheats causing your expansion tank to spew coolant everwhere. Leaving you to wonder why in the heck since your gauge is lying and telling you everything is "cool." Those expansion tanks are bad to rupture at the seam that goes horizontally around the middle. If your tank is white I think it will be the updated (improved?) one. If it is black probably not. I replaced my expansion tank, expansion tank cap and the fan clutch.... 95 degrees yesterday and no spewing coolant.