8.1 Vortec Roar

[LETMGROW]

Originally Posted by MIKEBEQ

Make sure you check your coolant properly and regularly. Our fan was coming on regularly the first day or our trip last summer. It was pretty hot so not unexpected. We checked the coolant before heading out the next morning and had to add a fair amount of water. Later that day when heading up a long low grade into WY, steam suddenly came pouring out of the front end. We shut it down right away and subsequently spent $3000+ to replace what we were told was likely a partially plugged radiator. Without going into detail, I learned a LOT about how cooling systems work and suspect now that the problem was that we simply ran low on coolant because we didn't know the correct procedure to check and fill it. (Even though there's enough coolant in the overflow tank it doesn't mean there's enough in the radiator.)

I have seen cases where there was a very tiny leak in the radiator so the coolant would escape but the reserve tank would remain full. Normally when the coolant cools down it forms a vacuum in the cooling system which pulls the coolant back into the radiator which had transferred to the tank as the coolant expanded in the radiator with normal operating conditions. Even the tiniest leak will prevent the vacuum from building enough to do what it is supposed to.
Chances are in this poster's case the leak was supposedly repaired by pouring some "miracle fix" in the radiator to seal a leak and eventually plugged the tubes in the radiator.
It is always best to check the levels in both the tank and the radiator just to be sure. A full tank and a radiator with a low level is an indication you have a problem looming down the road.
Lynn

[MIKEBEQ]

LETMEGROW - You're exactly right about a small leak being one potential cause of the problem. In this case there was no visible indication of a leak, and a post-event leak test of the cooling system and cap were also negative. I think it was just not filled properly (by us or our mechanic, not sure which) when the coolant was changed before our trip, and we didn't know enough to check the coolant level in both the tank AND radiator.

We have never used stopleak in any of our vehicles, though, for the very reason you mentioned. It's possible a previous owner put stopleak in it, but the maintenance records don't show any cooling issues. Of course, you never know...

The mechanic decided it was a partially plugged radiator based on various IR temperature readings at various points across the radiator. I happen to disagree that his readings proved there was a restriction. Why? Because I AWAYS think I know better than the mechanic. According to my wife anyway. Had it changed anyway just in case.