I've only done this with Subarus so far, but it definitely makes it easier to find the sneaky ones. Take off the vacuum bulb, suspend the tester and plumb it right into the reservoir nipple. Any combustion gases in the radiator get forced right through the test fluid, without coolant contamination or the hassle of holding the tester at the radiator neck while also revving the engine.

[Easy]

Leo from Virginia

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