6G72 Water Pump Outlet O-Ring Spec

Hello,

I had the pleasure of changing my oil pump, timing belt, and water pump last spring. The new water pump didn’t come with the o-ring that seals the outlet of the pump where the heater line connects. I gambled and reused the old o-ring. I lost. It leaks. None of the auto parts stores near me can tell me what the part number of the ring is, or what the specs are for it. I could buy a new pump just to get the o-ring but, even though the image of the pump shows the o-ring as included, the description of the contents doesn’t account for it. Ugh. I think I’ll order a handful of o-rings of a similar size and pick the one that fits.

I wanted to start a post in case someone has run into the same issue and can tell me the specs, or just to have an archive in case someone runs into the issue in the future. Measuring a worn-out o-ring is imprecise but here’s what I’ve come up with: Cross section 3.0 - 3.5mm, ID 16.5mm. This probably a common o-ring for heating/cooling systems but no one I know seems to know.


Always learning,
Geoff

Follow-up: I installed a 3.5mm x 16mm Buna-N 70 Duro o-ring from o-rings.com. So far, so good. No leaks.