A job in Billings made me rethink my whole take on those 'stop leak' additives for coolant systems.

Got a truck in last month with a slow leak the owner had been fighting for a year with a bottle of sealant every few months. We did a full flush and found the radiator tubes were almost totally blocked by the gunk from the additive. Cleaned it all out, replaced a $5 hose that was the real problem, and the temp gauge dropped 15 degrees on the test drive. Now it runs cool and steady. Has anyone else seen a 'fix' like that cause way more work down the line?

3 comments

3 Comments

carter.terry2mo ago

Yeah, that gunk from the sealant is the worst. I've seen it completely clog heater cores, makes a simple leak fix into a full system flush.

nancybailey2mo ago

Those additives can even mess with the water pump seal over time. The gritty stuff in them acts like sandpaper on the spinning seal face, turning a weep into a full blown leak. You end up replacing a major part for a problem that started small.

adam_adams2mo ago

Had a Ford F-150 with the same issue last spring. The clogged heater core made the cab cold and the repair bill hot. A proper pressure test found the real leak in seconds.