Jim Grant's Tech Tips
'91 Chevy Blazer S10, Stop Leak Additive
Q: I own a 91 Chevy S10 Blazer that has a coolant leak in the heater core. I know it is the heater core because the windshield fogs up on the inside when I turn the defrost on. I want to know if a leak stop additive is worth trying or will it cause other problems?
A: The biggest problem weve seen from stop leak additives is blockage of the heater core passages from adding too much. If your heater core is failing/leaking, the stop leak additive is only a band-aid that may fend off the inevitability of replacing the heater core. The bottom line? Youll be replacing the heater core to correct the problem. The sealer may just give you time to plan for it.