6.5 Durability With High Power and Harsh Conditions

6.5 durability has mixed reviews. With the various problems stemming from poor design showing themselves over the years like…

Sounds like a pretty terrible engine, doesn’t it? 

Then why are they so darn popular? Well first, we need to take into consideration that the majority of the times that we hear about others vehicles is when they are having problems. They are either just complaining out of sheer frustration or are reporting so that they can find a solution to their problems.

However, there are 6.5s that have upwards of 200, 300 and even 400,000 miles on them and more, so we can’t forget the thousands upon thousands of healthy 6.5s out there that have been bringing millions of miles of enjoyment to their owners. We don’t hear much from them because there is nothing to report. No news is good news. 

So what can we do if we are one of the ones who have issues with our ride? 

All of the major issues with the 6.5 durability have been addressed over the years by GM, the aftermarket industry and people like you and me who drive them every day that have come up with our own solutions and share them with others like us.


The 6.5 Durability Fix!

Cracked heads have been addressed by TSB #1564165. And can be done by ourselves in a decently equipped home shop, or by competent machinists like Ted and Ron at Portland Engine Rebuilders.

Cracked blocks can be fixed by a process known as Lock-n-Stitch. Portland Engine Rebuilders are capable of this repair as well.

A failed PMD is almost guaranteed in a ’94 and up 6.5. But it is also one of the easiest improvements to make since it is only a matter of heat causing the failure so merely adding cooling capability and remote mounting solves that incredibly frustrating problem. Leroy Diesel has a great kit for this.

Running hot when towing or after adding performance mods is something many 6.5 turbo diesel owners do not have to deal with. One advantage in owning a GM vehicle is the interchangeability of so many components. After thoroughly cleaning the coolant system, we can swap the water pump, fan clutch and fan from a newer model and see our coolant temps drop dramatically. After all this, if you still need more cooling, I was amazed to see the difference that the Champion radiator made on the cooling of my rig while towing and even more so, Twisted Steel Performance's thermal dispersant coating on the Champion Radiator.

The early model DB2 injection pumps had a head and rotor design that caused a hot start failure when pumping thin fuels, whether it was thinned from heat or just thinner alternate fuels. GM put out a fix for that with an improved head and rotor design and is standard for all quality new rebuilds. But you should check with whoever did the rebuild to make sure that it comes with a new head and rotor. Some may try to sell a cheap rebuild by skipping this vital part.

One of the most common problems with the 6.5 turbo diesel (or for the Ford Powerstrokes too for that matter) is blown head gaskets. GM worked closely with Fel-Pro to come up with an improved gasket design that solved the issue entirely under normal conditions. 

But we’re not normal. 

When we want to go to the higher power levels (and we do) we are going to be pushing way more air into the cylinders to burn all the fuel that we will be dumping into it. So that means we’ll have to handle more heat and more pressure. 

Welp, there’s an app for that. 

It’s called ARP head studs. Replacing the stock torque-to-yield bolts with more strength and holding pressure, ARP head studs are all you need to hold her together. We show you how to properly install them here.

So, as you can see there are really no major problems that haven’t been addressed and solved over the years. You CAN have that 6.5 durability with a reliable and powerful turbo diesel in your truck.


Above And Beyond Problem Solving... Making Your 6.5 Virtually Bulletproof

In addition to the solutions above to the most common failures, there are several things that you can do to add much more durability to your truck. 

  1. With a gear drive timing set, you will never have to replace another timing chain again. And will improve performance in addition to that.
  2. A Fluidampr harmonic balancer will stop vibrations that are known to break cranks with the stock balancer installed. Read how to install  your Fluidampr here.
  3. A partial bypass of the oil pressure switch and upgrading to heavy duty wiring for the lift pump will almost eliminate lift pump failures from a worn oil pressure switch.
  4. Stainless steel braided Teflon oil cooler hoses will be a life-long addition to your truck and prevent engine failure from a hose that has popped loose from either the block or the cooler causing a total loss of oil pressure. 
  5. Big batteries will do nothing if you can't get the power to the starter. Installing heavy duty battery cables will allow the batteries to do their jobs. We show you PT Wiring Solution's huge 2/0 battery cable set that is the best you can find.
  6. Keep her cool! Overheating is an all to common issue with our rigs. We go through a full install of the best upgrades to your cooling system here.

6.5 durability is not impossible to achieve in our engines, so follow along as we address each of these issues and more. Then jump in and get that 6.5 turbo diesel of yours running as reliable as it can be!

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