The h/g on BlackSheep was seeping out the h/g underneath the t-stat when I bought the truck with 239,000 on the clock and over time it finally got worse to the point I was adding a 1/2 gallon of coolant per week (3000+ miles). Last summer I changed the t-stat to a 180* in lieu of the 195* unit to help control coolant temps on long grades while loaded. Instantly the seeping (by this time it had become a genuine leak) stopped. Zip. Zero. Nada. Having already purchased the parts I went ahead and replaced the h/g last fall and saw the damage to the h/g directly under the t-stat, but it was still not leaking with the 180* t-stat. My theory is that the coolant psi increase caused by the 195* t-stat during high boost/high rpm events is what causes the h/g to become weak under the t-stat. Anyway, 80,000 miles since new h/g and no seepage at all with 180* t-stat. During winter the cabin heat is not sufficient with the 180* t-stat so I put cardboard in front of half the rad and it increased the cabin temperature to my satisfaction.
Godspeed,
Trent
Godspeed,
Trent