6.2 Diesel Info

[Swampthang]

Lots of attention has been given to the 6.2L G.M. diesel concerning head gasket problems. I worked at a chebby dealership during the 6.2's heyday and here is some info that some of you might find useful. When the 6.2 was introduced in '82, dealerships began hearing complaints of headgasket leaks almost immediately. This problem stemmed from poorly designed head castings. The factory cast a hole in the mounting surface of the head which was sealed off by the headgasket on installation. However, over time coolant began to weep out of this hole past the headgasket. Chebby fixed these under warranty by supplying the dealerships with a repair kit consisting of a pair of kidney-shaped freezeplugs (one for each head), a driver to install them, and a tube of locktite to insure they stayed put. We installed a buttload of these and as far as I know they were all successful. However, I can see how over time they could corrode and fail again. Beginning in the '83 model year the design flaw was corrected and all later heads are golden.

The second problem lies with mechanics trying to "poor boy" repairs and reuse the old head bolts. G.M. was very specific about replacing the headbolts any time the heads were removed. Their reasoning was that the bolts will stretch enough during torque-down and use to give improper torque reading and not seal properly when reused. This is most often seen when head gaskets are replaced and seem fine for a while then suddenly start leaking. Also, the factory bolts (iirc) have the threads coated with sealer for the ones that screw into a water jacket.

The 6.2's were never powerhouses, but they are fairly durable. Detroit Diesel was still a part of G.M. at that time and was given the nod for design work. In my opinion, G.M. should have gone to Isuzu, Cat, or Cummins instead and had them draw up an inline turbo diesel.