Page 1 By P.B. Gill

Diesel tips for light trucks with diesel engines.

Diesel tips for cars with diesel engines

Proper maintenance, Good clean fuel and keeping records are the main steps to success with a car or light truck with a diesel engine and the same would apply to any vehicle ,and these are also good practices for any vehicle for the most economical operation .

Clean fuel is very important in any engine , and even more so for a diesel engine .

For example, Water in the fuel will turn to steam , in the heat of combustion . Steam expansion pressure is much higher than the normal air fuel expansion. Due to the very high compression of a diesel engine to start with, steam pressure can cause connecting rods to bend or pistons to crack or other internal engine problems. Also water or other contaminants can damage fuel injectors , fuel pumps (and injector pumps if used) and cause driving problems .

To insure clean fuel I recommend buying fuel from brand name stations. In most cases the big fuel companies maintain their tanks better than most independent stations . This is not to say that all independent stations are bad . Some independent station operators my maintain their tanks and fuel properly . If you know the station and you know their fuel is good , that’s ok . If you buy fuel at stations were a large volume of big trucks go , you can normally count on clean fresh fuel as these stations pump a very high volume of fuel , so it is always fresh . This is something to keep in mind when on trips or when you need fuel in an area you don’t know . Stick to the same brand of station as much as possible as this give you a proof advantage , should you have fuel problems .

Stick to the same station as much as possible. This is in your best interest.

If you know the stations fuel is good, stick with that station.

If you know the people at the station were you deal , it can be to your advantage if a fuel problem should occur.

As I stated above , a station that sells lots of diesel fuel is the best

to deal with as their fuel is always fresh and up to date for the

season. (winter fuel uses anti gel agents , that are not in summer fuel). If summer fuel gels in cold weather it will not flow , and the engine will not run .

If you have these problems due to bad fuel , Do Not continue to run the engine until the problem is corrected , as serious engine damage could occur . Don’t let this scare you off diesel , as bad fuel is very rare to occur . Similar problems could occur with bad gasoline in those vehicles . The objective of this chapter is mainly to help you avoid problems . In the rare event that you should have a problem , it will help you to know the proper thing to do .

If you have all receipts for fuel purchases for a long period of time and you deal with the same company most or all of the time (and the last fuel purchased is from that company), it is most likely the fuel company will pay the repair bill for any problems caused by by their fuel . (or they can be made to pay)

This is why I recommend the Brand Name fuel company stations , getting receipts and writing the mileage of your vehicle on the receipt before you leave the station .

In 40 years I have repaired about 10 contaminated fuel problems,(non in the past 9 years and 1 in 12 years) so as you see , it is not a large concern. But if it does happen to you, it is inconvenient and very expensive .

In all occasions were the fuel was purchased from Brand name fuel companies, the big companies paid the bill for the repairs.

Some companies even sent their representatives into the dealer where ,I worked , to pre approve the repairs and sign the bill.

The one small independent station, were bad fuel was purchased , refused to pay for the repairs , and the customer had to sue the owner of that station to get his money back . The customer did get his money back because he had fuel receipts that proved (to the court) that he bought the bad fuel at that station .

So clean fuel , brand name stations , the busier the better , and get receipts, write the mileage of your vehicle on the receipt and keep them a year or so.

One good way to help you to buy good fuel , specially when traveling is to look for a station were a lot of big trucks are fueling . Truckers know were to and were “not” to buy fuel . If there are big trucks fueling the station will likely have good and very fresh fuel .

Maintenance for you diesel is critical for long engine life an lowest operating cost overall .

Changing the engine oil and filter and lube the chassis as specified by the vehicle manufacturer is best for longest engine and vehicle life .

Today’s diesel engines use hydraulically operated , electrically activated and controlled fuel injectors. The wrong oil can cause drivability problems , internal engine damage , and power loss. Aeration is one problem the can occur with wrong or inferior engine oils. Aeration is foaming oil . Oil must maintain pressure . Foam will not maintain pressure . Too low viscosity oil will not cushion and lubricate engine parts properly , which could result in premature engine failure , or shorter engine life . Too thick oil will not flow properly to lubricate internal engine parts , which could result in engine failure .

Replace the fuel filter regularly . Every second oil change in sever service use . Or every third or forth oil change for normal or all highway use.

Check the air filter every oil change and replace it when it is dirty. Many vehicles now have a filter minder (gauge) on the air cleaner , which will tell you when the filter is restricting , and needs replacement. Normally the air filter will need to be replaced at the same mileage each time.

For normal use vehicles spring and fall will often be enough.

Air filter replacement is often recommended when it is not really needed . If you are in question about being told you need an air filter , ask to see the old one . If it is full of dirt you will see the dirt . If it is deteriorated (furry looking )or water damaged you can see it . These are the three reasons to replace it.

Replace the Fuel filter regularly . It is a good idea to replace the fuel filter at regular intervals , like every third oil change or so .

Interval the same as the air filter replacement works well for the fuel filter replacement . If the air filter is dirty , and the fuel filter has the same mileage its likely due .

Cold starting is said to be a problem with diesel engines . It should not be any problem on a well maintained vehicle.

The battery is normally serviced during a tune up on gasoline powered vehicles . On a diesel you don’t do regular tune ups so

battery service is often overlooked . Cable connections at the battery should be cleaned at least once a year(most light trucks with diesels have two batteries) Starter connection should also be inspected .(they can shake loss at times, due to normal engine vibration).

Batteries must be kept in good condition , as they must turn over a very high compression (17 to 1 and higher)engine and operate the glow plug system at the same time . This is no problem if every thing is working right and the vehicle has good batteries and the right batteries.

Alternator and charging system tests and inspections on older trucks is a good idea. Once a year , on the fall service is a good idea . Servicing and making sure all systems are in good condition just before the cold weather comes , can prevent problems on any vehicle !

Keep the glow plug system working properly. As well as helping on cold starts , they also preheat cylinder walls and pistons before starting, all year around, which increases engine life.

Glow plug systems normally work on a total resistance , timed system strategy . If one glow plug burns out the total resistance of

the system changes and the ,“on time“, of the glow plugs will be less . If two glow plugs burn out , the “on time” will be even

shorter and so on. If you notice the on time of the glow plug light or , the wait to start light is shorter and the engine is harder to start, it is likely you have glow plugs out. White smoke from the tail pipe when starting (or turning the engine over to start)is also a sign or glow plugs not working properly .

In most normal usage cases the vehicle will be 2 or 3 years old or more , before new glow plugs are needed. If a glow plug burns out due to age , it would be best to replace them all if they are all the same age. This will save down time and money in the long run. If the glow plugs are under the valve covers , and one is out due to age , at least replace all (4) under that cover (on V8 diesels) . This will save money as the main labor cost is to R&R the valve cover for the glow plug replacement .

Cold Start . In very cold conditions , it is some times best to let the glow plugs stay on for a longer period of time before starting the engine .

Some glow plug systems will stay on much longer after the indicator (wait to start light) goes out. Some times up to 2 min.

If you turn the key to the on position you may hear a click under the hood as the glow plug relay turns on. If so you will also hear it click off after a time . In hard start conditions , if you start the engine right after the glow plug relay turns off , it will start easier , as the batteries are only turning the starter and the glow plugs have heated the cylinders and turned off. Only the starter is drawing power from the batteries at this time .

If the vehicle has a battery meter (voltage or amp meter) , turn the key on and watch the gauge . When the glow plugs have turned off the gauge will read higher (go up). Start the engine as soon as the gauge goes higher , when the glow plugs have just turned off .

A third way to help on cold start is to cycle the glow plugs 2 or 3 times or even more before turning the engine over to start.

This is done as follows. Turn the key to the on position and leave it on until the wait to start light goes out. Do not turn the engine over yet. Turn the key to the off position . Now turn the key to the on position again and wait until the light goes out again.(this step can be repeated as many times as you think necessary (3, 4 ,5) . Now start the engine as soon as you have completed these cycle steps .

These starting procedures can also be use as a temporary measure for starting, in the event of a hard start condition due to some glow

plugs being inoperative .

Most diesel engines come equipped with an engine heater (block heater). In cold weather if this heater is plugged in , the engine will start after 1 to 2 hours (even if the glow plug system is not working )

If you turn all electrical accessories off (lights ,A/C, heater, radio ,etc) before you turn the engine off and leave them off until after the engine is started again ,it help to keep the battery voltage higher in any vehicle . This will often help greatly for much better starting, any time of year and specially in colder weather. This would also apply to any vehicle , no mater what it powered by , cars , trucks suvs , rtvs sleds , or any thing started by batteries .

Fuel additives are recommended from time to time . They help to keep the injectors clean and lubricated . Be sure any additive you use , meets with manufactures specs. before you buy it . Most are good but there are a few that are ok for older diesels that can do harm to the newer electronic injectors . Be sure its compatible with your vehicle before you use it .

Diagnostic tips

Some tips to assist you to determine and diagnosing problems (on higher mileage or older vehicles) are as follows .

“Loss of power”

Restricted or plugged air filter can cause power loss . Any restriction in air intake system will lower power.

Bent pinched or damaged fuel lines or fuel leaks , can cause power loss, and other drivability problems.(stalling , hesitation , poor fuel mileage , etc)

Restricted or plugged exhaust system ,or bent or damaged exhaust parts will cause power loss . Tail pipes that have hit something , when the vehicle was backed up , is a common example of this . If the pipe is bent to a partly closed position it will restrict the exhaust flow and cause a power loss.

Wrong exhaust parts,(pipe too small etc) will cause power loss. Improper tire inflation can cause high road resistance ,which can result in , lower power and poorer fuel mileage.

Sticking brakes are some times over looked and engine is thought to have a power loss and lower fuel mileage. This could apply to any vehicle .

Sticking brakes can be checked by , raising the wheels of the vehicle , off the ground and then try to turn the wheels by hand . If you can not turn them easily , the brakes are likely sticking . If you try the above procedure , be sure the vehicle is properly and safely supported . Use safety stands ! Also make sure the engine is turned off . The transmission lever must be in neutral to check rear wheels .

Slipping transmission is some times mistaken for power loss and poor fuel mileage . If the transmission slips engine will rev higher than normal on acceleration .

White smoke from tail pipe is an indication of unburned fuel , which indicates an engine performance deficiency . (Normal cause of white smoke from the tail pipe when starting ‘only’ would be inoperative glow plug(s).) Most likely cause of white smoke from the tail pipe while the engine is running or when the vehicle is being driven , would be an open leak through a fuel injector.(s).

Black smoke from the tail pipe is over fueling, most likely from fuel injectors (or injector pump if equipped ) fueling to rich. Too much fuel is being fed into the engine .

“Hard Start or No Start” the most common causes are ,

- Glow plugs not operating properly.

- Low battery voltage (to low to operate fuel solenoids etc and starter at the same time?)

- High starter draw (same as above)

- Summer fuel will gel in cold weather and will not flow to run the

engine. This is rare to occur as the fuel companies are very good to ensure the proper fuel for summer and specially winter . The most common place to run into this would be if fuel were purchased from a station that sold a very small amount of diesel fuel . In such places the fuel sits in their tank for longer periods of time . This would mean that these low volume stations could possibly still have summer fuel in their tanks when the weather gets cold enough that winter fuel is needed .

If it were to occur the only fix is , to move the vehicle into a warm garage until the fuel liquefies and then add the proper winter fuel anti gel additive. Note that the anti gel additive is special and would only be needed in the event of gelled summer fuel . In this rare case though , do not expect normal diesel fuel additives to cure to problem of gelled fuel . You must use an anti gel additive ! The normal fuel additives are to help clean and lubricate fuel system parts and do that job well .

The advantages of diesel are;

Much more power at lower engine speeds. Better fuel mileage when compared similar gasoline powered vehicles , and long engine life .

For example , I have a 1 ton single rear wheel van ,with a 7.3 direct injected turbocharged diesel engine . It weighs 5800 pounds empty.

If I drive 50 to 55mph (80 to 90 km ph) I get 25 miles per imperial gallon. This would be 20 mpg in US gallons . If I drive 60 to 70 mph (100 to 115 km ph) empty I get 23 mpg. (about 19 mpg US)

If I pull my dump trailer (2900 lb) with my bobcat (5900 lb ) on

the trailer (total weight 14,600 lb) I get 15 to 16 mpg (12 to 13 mpg US). A gasoline powered vehicle (if I could find one of similar power) would probably get 6 or 7 mpg (4to5 mpg US), if it would even pull that weight at all

The truck ,while pulling all that weight will easily maintain 55 mph even up all but the very steepest hills and slows only slightly

on them .

Turbochargers

All most all the newer diesel engines now use a turbocharger , to increase the power . With the use of the turbocharger , the base compression can be much lower . And example of this would be ,a non turbocharged diesel engine would normally have a compression ratio of 21to 1 or higher . The same size diesel engine but with a turbocharge , could have a compression ratio or 17 to 1 or in that area . This will make the engine turn over more easily for starting as well as other advantages . Exhaust from the engine is routed through the turbocharger and it is the pressure of the exhaust that operates the turbocharger . The turbocharger forces more air into the cylinder which increase the volume of air to be compressed in the cylinder and more power is produced by the engine . The first turbochargers were used mostly on smaller engines to boost power only during heavy acceleration . They weren’t very efficient and required a lot of maintainance to keep them operating properly .

Todays turbochargers are very efficient and durable and require no regular maintenance . Keep the air filter clean and securely in place and keep the engine oil clean and the turbocharger will work and late for a long time .

Most of todays turbochargers are fully functional . This means they are supplying boosted air pressure to the engine at all times except at idle and on decelerating . As soon as you push the accelerator down , more fuel is fed to the engine . The exhaust pressure increases and the turbocharges turns faster , to force more air into the engine , which in turn increases the power output of the engine . Turbochargers may use a butterfly valve or a waste gate to control the amount of boost pressure and to protect against over boost . Fuel feed is controlled by your foot on the accelerator pedal and by the power train control module . Fuel feed contols exhaust pressure . Exhaust pressure controls the turbocharger speed and boost , so you control it all with your foot. Normal turbocharger boost will range from 1 to 3 pounds at light acceleration and at cruising speeds . The harder you accelerate the higher the boost , during that acceleration . It may go to as high as 13 to 18 pounds during maximum acceleration , depending on the vehicle . Turbochargers only boost what is needed , when it is needed . This helps eliminate unneeded pressure on the turbocharger and on the engine , which helps to increase the lives of both .

Diesel engines are an engine of the future as diesel fuel can be manufactured from materials other than crude oil .

Racing diesels

Diesel engines are now being used for racing . And are giving gasoline engines serious competition , as they go just as fast and still get much better fuel mileage that the gasoline powered cars . The better mileage means the diesel will complete a long race with less fuel stops than a gasoline powered car . Diesels are also more durable then gasoline engines for racing , as the diesel will push the car fast , while turing at a lower RPM.

Racing leagues are already looking in to special regulations for diesel powered race cars to keep gasoline powered car competitive . Smaller fuel tanks on diesel powered cars is one thing I heard was considered , to compensate for the better mileage .

Diesels are great ! Most people who buy them don’t want to drive anything else !

Composer

And who wrote this you wonder ?

I started at mechanics about 1955 , at 12 years old changing tire and such after school . I started at it full time in 1963. I wrote for and got my mechanics license in 1967 . I worked at dealerships of one North American manufacture for 35 years of my 40 years + In automotive the trade . I worked at all areas of automotive , diagnosis and repair including engine repairs ,and overhauls, tune up , transmission, diff. , steering brakes. Etc.

I also am certified for auto propane and natural gas.

Since 1983 my specialty has been light trucks and light truck diesel engine diagnosis and repair.

These pages are intended to give some pointers to light truck and car owners (and buyers) and to answer some of the questions of those who are thinking of trying a light diesel truck.

This website is also intended assist all readers to operate and maintain their vehicles safely and economically, and to help the reader to make decision related to their vehicle .

P B Gill

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