I have a 93 3500 w/6.5 td 3 days ago started having excessive blowby---pulled oilpan took inspection miror and checked all pistons, no damage and no holes-- vent is also clear!!!! WHAT ELSE SHOULD I CHECK!
Cracked head or blown head gasket are also possibilities.
Compression testers exist that thread into the glow plug holes, which can narrow down your search. You can also open injector lines one at a time an look for a big decrease in blowby when the effected hole is deactivated, but you're probably going for the full teardown no matter what's causing the blowby.
A forum community dedicated to Chevrolet and GMC diesel truck owners and enthusiasts. Come join the discussion about duramax engines, performance, builds, modifications, classifieds, troubleshooting, maintenance, and more!