O/T Chevy 6.5 Turbo diesel

On ours, the fuel lines under the intake were the culprit. Noticed the leaks after a run and then a cool-down period--diesel fuel all over the slab. Remove the intake horn and the intake manifold and replace all rubber hoses under the intake. All low pressure hose but use good ss clamps. I also found what I think was a leak on the wirring connection into the fuel filter housing (water in fuel indicator). I degreased the area with carb cleaner, blow-dried the area thoroughly and then used oil resistant permatex sealant. Keep things clean and don't let debris get into the turbo. As RJ said--get the intake gasket set and keep up with the locations of each bolt--many of them are odd sizes and configurations for mounting brackets, etc. And BTW--being a small block chevy man, I "instinctively" drained the coolant--not necessary for this engine. Manifold is "dry".

BTW again--some of the hoses were leaking where they had chafed on the underside somewhere and a hole was worn through the hose wall. On ours there were actually three leaks including the one from the filter housing. While you're doing the job--its a good time to remove the filter housing completely and give the insides a thorough cleaning--you'll likely find lots of crud. Ours is at 210,000 miles and counting...