There is an old saying that says, “If it ain’t broke, don’t fix it!” For some who live by this creed, they are missing a vital preventive maintenance responsibility by not getting their overhead reset from time to time. Adjusting the valves and injectors, or the old phrase, “running the rack,” should be done every 200,000 miles – whether there is a problem or not! A good mechanic will look for any other problems when setting the valves and injectors, so if something is about to go wrong, they should be able to catch it before it becomes a major issue. So, about every 200,000 miles, make it a point to reset the overhead as a good preventative maintenance measure.
On a freshly-rebuilt engine, the overhead should be reset at 25,000 miles and the oil should be changed between 1,000 and 2,000 miles. Piston rings don’t seat into the cylinder walls – the cross-hatch of the cylinder walls seat into the piston rings. As a result, the metal that is scraped off the cylinder walls (along with all of the other break-in materials) end up in the oil, so drain it before 2,000 miles. At that point, the next oil drain should be at 10,000 miles, and then the third one should be 15,000 miles later. Once the engine has 26,000 miles on it, the oil should have been changed three times. Now the engine is clean on the inside, and if you’re going to run extended oil drains, start from that mileage. It’s so much easier (and cheaper) to maintain your equipment than to replace parts that fail as a result of neglect!
We are currently in the process of rebuilding a 60-Series Detroit because the engine would not hold a head gasket. Once the head was removed from the block, we then checked the liner protrusion and found that the liners were negative .003” – this is the worst case of a liner dropping in the upper counter bore that I have seen in 37 years! This engine would NEVER hold a head gasket, not even with new cylinder kits installed in the block (along with a new reman head). In fact, once this engine is taken apart and the block surface and upper counter bores are cleaned, it’s quite certain that we will have to install new upper counter bore repair sleeves. This repair actually makes the upper counter bore better, because the sleeve is stainless steel and harder than the cast iron block. We have been installing this type of sleeve in Big Cam Cummins engines since 1982, so this is not new science to us. Once the sleeve is installed and the counter bore cut to achieve the liner protrusion we want, this engine will not have a problem holding the head gasket any longer.
We’ve recently just finished a rebuild on a 6NZ Caterpillar that came to our shop from Mississippi with the same problem – a blown head gasket between cylinders #4 and #5. Again, we had to cut the block while the engine was still in the chassis and install a stainless steel shim under the upper liner flange to obtain the protrusion height we use, which is slightly greater than the factory setting, to eliminate the head gasket problem (see photo).
We recently installed one of our 6NZ “Signature Series” engines in a Pete 379. A lot of money was put into this build (about $36,000), but as you will see, it was all worth it. The truck’s stock engine had averaged 5.7 miles per gallon for 1.1 million miles, but the owner, a 64-year-old owner operator who has trucked for 40 years, really wanted to get better fuel mileage. Well, during his third week of operating this engine, his fuel mileage was now 7.6 miles per gallon – and that mileage was obtained with 44,000 lbs. on the deck of his trailer! That trip was from Texas north to Ohio, and tallied 1,300 miles using 171 gallons of diesel fuel. His old stock engine would have used 232 gallons of fuel, so his savings on that one trip was just under $250 in fuel. Plus, his new engine produces 775 horsepower. I guess my next question would be – what are YOU waiting for?
Our next step towards improving the fuel mileage on this veteran owner operator’s 6NZ Cat will be to install the FASS fuel system on it, and then our engineering department will study his ECM to see if we can write a better program to suit his specific driving style. The emissions of the new engine are much cleaner than the old engine, and, in fact, are even cleaner than the factory guidelines dictate for a stock 550 hp engine. It’s amazing what happens to these diesel engines once you allow them to breathe! Building a solid engine that is balanced, with a ported and ceramic-coated exhaust manifold, our high-performance turbo, and by using sound engineering in the programming of the ECM, makes for amazing results. These engines will not make smoke – in fact, we do not allow engines out of our shop until they burn clean and pass our emissions testing program.
On a completely different note, did you know that 53% of our population gets a paycheck from our government? This means that the other 47% of us work to pay for that! It’s hard for me to believe we are paying that much taxes, to the point where we are able to support that many people. With elections right around the corner, I think we should only vote for politicians who have been self-employed, have never filed bankruptcy, and have never worked for a company involved with any government contracts. In fact, I think we need more ranchers, farmers, owner operators, engineers, and other types of self-employed people to run for office! Just a thought – any takers out there?
