0311344 JOHNSON BOLT,Double end

Owner/Operator Input
The following are some of the questions which should be asked before beginning any diagnosis or repair for an engine performance complaint. There Are No Hard And Fast Answers For These Questions. There are many factors that can cause poor fuel mileage or make users believe they are getting fuel-poor-mileage.There are also a variety of customer expectations which are acceptable. The answers to these questions will give you a better understanding and perspective on the complaint and may identify characteristics which will help pinpoint the cause of the complaint quickly. 1. Are miles measured accurately?A most common problem in determining mpg is errors in recording the number of miles traveled. A. Is this vehicle hub or cab odometer accurate?The easiest way to check an odometer is to install a hub odometer known to be accurate and for the tire size on the truck. Run the truck over several hundred miles and compare the reading with the original odometer.Odometers may also be checked by comparing them to interstate mile posts or by running over a course of known length - a 50-mile run is required to get a good check. B. Are "book miles" or "driver-paid miles" correct?Another way in which miles for mpg calculations are obtained by a fleet is the use of "book miles" or "driver-paid miles". The use of this system can short mileage accumulation by 10 to 15%; thus, mpg is low by 10 to 15%. C. Is the vehicle used for pick-up and delivery operation?Another problem affecting mileage accumulation in many fleets is the use of linehaul equipment for pickup and delivery operations. In the "book mile" system, the truck rarely gets credit for any miles run in pick-up and delivery. 2. Is fuel measurement accurate?There are a number of ways in which fuel measurement can be the source of mpg problems. A. Are fuel pumps calibrated?If fuel tickets come from company-owned fuel pumps, there can be errors because nonrevenue fuel pumps do not have calibration requirements in many states. B. Are road fuel tickets accurate?The only way to verify fuel additions when road fuel tickets are used is a laborious ticket-by-ticket audit ensuring that the correct amount of fuel has been entered for the vehicles in question and that there are no indications of incorrect entries. C. Are tank-full mileage checks correctly done?The big problem in "tank-full" checks is getting the tank filled to the same level before and after the user "checked the mileage". With two 100 gallon tanks, errors of 5 to 10 gallons are very common in topping off tanks because of the way truck tanks crossfeed with a relatively small common line and the sensitivity to the truck being level. 3. Does the Caterpillar Engine have the comparable rating - hp and rpm?Obviously, if a competitive engine is rated at 1800 rpm and the Caterpillar engine is rated at 1900 rpm, the Caterpillar engine is at a disadvantage. If a competitive engine is rated at 300 hp and the Caterpillar engine is rated at 350 hp, the Caterpillar engine is again at a disadvantage. A. Is the wheel horsepower comparable?When checking wheel horsepower using PAR Level II, to compare Caterpillar and competitive engines, if the Caterpillar Engine has more wheel horsepower or power at higher rpm, the competitive engine has an advantage. B. Is the maximum vehicle speed comparable?When you give the driver of the vehicle higher rpm and more power, it gives the vehicle the potential to go faster. The faster the truck goes, the more fuel it will burn. C. Is wheel horsepower and vehicle speed higher than unit with better mpg?If the Caterpillar Engine is set to specifications and this does not equalize the wheel horsepower and vehicle speed, the use of an alternate lower horsepower rating - when available for the Caterpillar Engine should be considered. 4. Are the tractor specifications comparable?Often, a general discussion or questioning of a tractor's specifications will uncover a significant difference which leads to differences in mpg results. A. Tires?The difference in fuel efficiency between radial and bias-ply tires is well known. A vehicle or a fleet of vehicles that are on bias-ply tires will have worse fuel consumption than those on radial tires. Also, tire size changes have the same effect as rear end ratio changes. B. Rear end ratio?One objective in choosing a rear end ratio for optimum fuel consumption is to limit the engine rpm at the user's desired road speed. Normally, a higher ratio (lower numerical number) will yield better fuel consumption at a given speed. However in some situations, the higher ratio can give additional vehicle speed which will hurt the fuel consumption if the higher potential vehicle speed is used. C. Transmission ratios?The transmission ratio difference which has the greatest effect is an overdrive transmission versus a direct transmission with the same rear end ratio. Obviously, the overdrive ratio allows the vehicle to go faster which can hurt mpg; but overdrives can be used to reduce average engine rpm at a low vehicle speed which helps mpg. Therefore, the same situation exists as with rear end ratios. What can be good in one application can be bad in another.The number of gears in the transmissions can also be significant. The effect of the number of gears depends on the skill and motivation of the driver. Again, general rules do not always apply but, it would be expected that less skillful drivers would get better mpg results with 7 - or 9-speed transmissions than with 13-speeds. However, a very skillful driver may be able to get better mpg with a 13-speed. D. Temperature-controlled fan?A malfunctioning or poorly engineered temperature-controlled fan can be a very significant contributor to an mpg complaint. An appropriate question for all mpg complaints is "does the temperature controlled fan run often"? If the answer to that question is "yes", normally there is something wrong with the way the temperature-controlled fan is installed or engineered or there has been a system