What are the most common problems associated with the 6.5 Diesel Engine? Problems, Oh where shall we start? #3. Crank Breakage/ Failure. This may occur for two reasons:
#1.The first problem most 6.5 owners will face is injection pump problems, (usually the PMD module), (the little black box on the side of the pump).They cook down there in the valley of the engine. The truck may experience stalling or a no start condition. The fix is the improved PMD and a remote mounting kit.
#2. Cracking of the Castings. The results can be: coolent loss, white smoke, overheating, hydro-lock or cylinder miss. The fix is a new long-block engine, preferably with the new updated castings, designed to alleviate the cracking issues.
a. The lower end of the OEM block is weak. The caps or main bearing support/s develop cracks and no longer support the crank, (Automotive 6.5's use cast cranks, the don't flex, they snap).
b. The harmonic balancer fails. The results are obvious, the fix is the improved block and new harmonic balancer. Our new block has heavier main webbing and main bearing support to greatly improve bottom-end & crank durability and longevity, they also come with new harmonic balancers.
#4. Overheating under heavy prolonged load, due to poor design by GM. In 1997 the water pump, radiator fan & thermostat housing were improved, and these improvements do help. The new casting heads feature improved coolent passages. The 6.5 cools best when the '97 upgrades are used in conjunction with the improved heads available on the NEW Longblock.
These are by far the most common problems we run into. Most people get between 120K & 180K on there factory engine before catastrophic failure, some of our customers report as much as 400K some as little as 60K!! Ouch!! ...this was in an H-1, the most expensive platform a 6.5 came in! - hardly seemed fair.
The good news is that with new, improved and innovative products, we can now offer a solution to these problems and make the 6.5 diesel a great engine to own and operate. The 6.5 is still one of the most fuel efficient diesels ever offered in a full size pickup. Our customers routinely report 18-21 mpg in their 1 ton truck chassis, this is far better mileage than the newer 6.0/6.4l Ford or even the 6.6l Duramax!