bertram31.com

Does anyone know the dimensions of the O-rings for a 6BTA after cooler? Looks approximately 5" ID x 1/8" thick...
Thanks,
--Marshall

Marshal,
I lurk here mostly, have replied a few times over the years on a few topics.
I assume you have the 330's? or at least the same after-coolers as the 330/ 370's use .
The O rings that Tony Athens sells for this application are .148" thick. I have looked for them and can't find any the exact dimension without getting custom ones made so keep getting mine from Seaboard Marine. If you frequent Boat Diesel.com, you know who Tony Athens is and his shop. Their prices and experience will really help you out.They are in Oxnard Ca.
Frank

I recall reading on the Boat Diesel forum a couple of years ago that there were more than one O-ring designs Cummins used.. be sure whatever you buy are specified for your engines.

Frank, The other size you are referring to is quite a bit larger . So much so that Marshal would not have mentioned that it was roughly 1/8 inch. I have seen several after cooler cores and have never seen the larger O ring used so all things considered felt safe recommending the size that I did.
Use lots of grease when you re assemble and you should pressure test the assembly when you're done Marshal. Red line synthetic is my favorite for this job.

Thanks guys -- I measured the thickness with a micrometer from work. It was deformed, but since I knew what the right answer was (thanks Frank) it measured right at .148". I'm going to give the local bearing house a shot...

Mcmaster Carr is another source.

Ya, Mcmaster-carr is where I go first, no luck.They will make custom ones but I haven't taken the time to find out how much a hundred or so of those would cost.Or maybe they have a minimum of a thousand , I really don't know. For now I buy them from Tony at about 15 bucks apiece, which is about half of what Cummins wants.