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Wednesday, October 20, 2010

Letter Re: A Little Insight on Diesel Engines

JWR,
I can't wait to read the sequels to your novel. I'm writing on the topic of pre-electronic ignition diesel trucks -- preferably a 1998 model year or older Dodge with the 5.9 Cummins engine.
Having serviced and rebuilt several of these engines I am familiar with the design, and it is certainly my favorite. I won't go into much detail on the 24-valve engine because they may not be of use in the event of an EMP, or a grid-down collapse where diagnostics cannot be performed. (For reference, there is the 12 valve- '89-'98 5.9 Manual (non computer/electronic) Cummins Engine with 12 valves, 6 intake and 6 exhaust, and the 24 valve- '99-'08 computer controlled 5.9 Cummins Engine, having 24 valves,12 intake and 12 exhaust.)
First let's look at the difference in some of the engines that Cummins made for Dodge in the '89-'98 time table. '89-'93 12-valve 5.9 Cummins engines came with a rotary style fuel pump known as the "VE" pump. This small pump is considered undesirable by most performance/horsepower seekers because you are limited to how far you can "turn it up" These pre-'94 engines will also accept the '94-'98 Bosch style fuel pump, which I highly recommend. Just know what you are doing if you change one, or contact your local diesel repair shop and have it done. Timing is key, get it one tooth off and it won't run!
The '94-'98 engines are the most popular, mainly because they already have the Bosch-style fuel pump. These fuel pumps can be "tweaked" (by a knowledgeable service person) to almost unheard-of pressures. Considering that a stock pump will take 10 to 15 lbs. of fuel pressure from the lift pump and increase it to almost 4,000 lbs. for maximum atomization in the cylinder, you really need to know what you are doing doing before messing with the pump. I recommend a 10 to 15% increase above stock settings for the "sweet spot" for power and fuel economy. Much more than that and you start getting into exhaust gas temps that could melt your turbo or blow a head gasket. I've seen a lot of guys also use a trick of blocking the waste gate on the turbo for more power. However this almost always ends with a blown head gasket and in a TEOTWAWKI situation this would be detrimental.
Regarding bio-diesel: From what I've seen, bio-diesel is better than petroleum-based diesel in both lubrication of fuel systems and horsepower and fuel economy. But it is slightly acidic. It is murder on rubber, I've talked to several people who've replaced fuel lines because it "ate" the rubber lining and continually clogs up the fuel filter. I would recommend solid steel lines for all diesel engines whether you are running petroleum based fuel or french fry grease.
Things to look for when buying a truck with a 5.9 12 valve Cummins engine: These little engines are notorious for leaking oil. Most diesel engines with miles on them will. But don't worry about that, it is a diamond in the rough. 12-valves have a knack for vibrating the bolts on the front gear cover and oil pan loose. I've had guys bring them to me, thinking that their front main seal was leaking, and all we had to do was re-torque the front cover and oil pan to stop the leak. Sometimes however, new gaskets are needed. That can get quite expensive, because you have to remove almost the entire front of the engine to do it. Also, look for a pinhole to a 1/4-inch hole in the front cover, just to the right of the oil filler tube. Some of the engines have a pin in the camshaft that works loose and will wear a hole in the front cover, causing an oil leak. Eventually, the pin can fall into the gears behind the cover, and really mess things up. I believe this was re-called by the factory, so many have been corrected. If not, make sure you get this fixed, leaking oil or not. Also, with it running, inspect all 6 injectors. If any are leaking fuel replace them! This can cause your cylinder to "wash out" and will cause a blown head gasket along with scoring of the cylinder walls, meaning an overhaul! If you catch it in time, this is not a big deal at all, just don't let it go for an extended period.
Another item to look for is the fuel pump. The older VE pump is round and is located on the driver's side of the engine, just above the power steering pump. It can be identified by the fuel lines running out the back of it to the injectors. (The proper term is spray nozzles but I call them injectors). The newer Bosch style pumps are approx. 12 to 14 inches long and are about 8 inches tall. They are located in the same place as the VE pump and have 6 fuel lines running out of the top of the pump going to each injector.
Another point I'd like to make is about black smoke. I know that some think black smoke is cool. But in fact, the smoke is black because the engine is exhausting un-burnt fuel when the valve opens. This is a result of turning up the pump or reprogramming your CPU, but not attending to anything else. Everyone knows that to have fire, you need fuel, oxygen, and spark. Diesels get their spark from the compression of atomized fuel and air, too much fuel (and not enough air) can result in an incomplete burn. If you feed it more, it has to breathe better, by both intake and exhaust, to maximize your efforts. Otherwise you are just losing fuel and money out the exhaust pipe. That is why I only recommend a 10 to 15% increase. That's the happy place, without having to worry about opening up the lungs.
For all you who have other makes of trucks, there is hope. Whether you have gas or diesel engines now, there is a place that sells installation kits to put a 5.9 Cummins into your truck. I have no affiliation with these guys, and there are other kits available, but I like the one sold at FordCummins.com. They will even sell you an engine, but I think they are a bit pricey on them. But, I can do the rebuild myself so I am partial.
These Cummins engines can be found all over, in school buses, medium sized delivery and dump trucks, generators (mostly the trailer-mounted ones that the highway department uses), sandblasters (same as the generators), and I believe that all manufacturers used this engine in their larger trucks, but only Dodge used them in pickups.
It's an amazing little engine and has a long life if maintained properly, I personally own one with just under 700,000 miles on it! I did have to rebuild it at 475,000 because of the "washed out" cylinder that I told you about earlier. Had I caught that in time, I may not have even have had to rebuild it.
I'm no expert, and just thought I'd add my two cents. I'm certain that I've missed a few things and may not be 100% correct on some, but I know that the pool of SurvivalBlog readers could add to where I've fallen short.
God Bless, - Gary in Kentucky