Double-stacked O-ring

Tips to keep your Midlana in top-notch shape
Midlana1
Site Admin
Posts: 2716
Joined: 19 Dec 2008, 16:44
Anti-spam question: 4
Are you a spammer: No
Location: Southern California

Double-stacked O-ring

Postby Midlana1 » 30 Apr 2018, 07:18

O-rings are elegant sealing solutions for many situations; they don't stick, don't get destroyed when removed, and they're inexpensive. There are, however, failure mode that can be caused by maintainers and assemblers that happen often enough that there's a term for it: "double-stacked O-ring". I got bit by this over the weekend.

My oil is cooled by an oil-to-coolant heat exchanger. As the engine warms up, coolant temperature rises faster than the oil, so the heat exchangers helps warm up the oil faster. Once up to temperature, the heat exchanger keeps oil temperature from climbing much higher than the coolant. This weekend's drive was accompanied by a slow realization of an oil smell, but at first it was so slight I thought I was imagining things. By the end of the drive though, it was clear there was a problem, and once back in the garage, found the back end of the car drenched in oil, and a line of oil all the way up the street. If it wasn't for the 8-quart capacity of the dry sump system, the engine would have been toast.

The most common way this happens is when a maintainer doesn't remove the original O-ring before replacing it with a new on. In my case, it was assembled this way at the factory, probably because two O-rings sticking together and the assembler didn't notice. Lasted 5 years it did!

Image

Image

Return to “Maintenance”

Who is online

Users browsing this forum: No registered users and 1 guest