That CAT 3406 in a 1990 Peterbilt taught me a hard lesson about oil coolers

I was doing an inframe on a 3406 last summer at a shop outside Bakersfield. Pulled the oil cooler, pressure tested it, everything looked fine so I slapped it back together. Owner takes the truck 80 miles down the 5 and it starts pushing oil out the dipstick. Turned out there was a tiny crack inside the cooler core I missed because I didn't hot tank and inspect with dye. Any of you guys trust a visual check on oil coolers or am I the only one who learned this the hard way?

2 comments

2 Comments

faithwalker13d ago

Dye test's the only way to catch hairline cracks for sure.

jennysullivan13d ago

Feel for you on this one. Had a friend ignore a tiny crack in his engine block last summer because he couldn't see it with the naked eye, and it cost him a whole rebuild a few months later. Dye test is a pain but it really does catch those sneaky little fractures you'd never spot otherwise. Hope yours holds up better than his did.