I am fairly new to the EVT vocation, but have over 30 years of experience in the automotive repair field. While pump testing recently, I noted that the pump would not come to pressure.


I diagnosed that there was something wrong with the pressure relief valve on this Hale pump. Upon removing the relief valve from the pump body, the casting area between the pressure and suction sides of the pump was completely eroded and allows the bypassing of water from the pressure side to the suction side. What caused this erosion?

What you are witnessing is called “Electrolysis” which causes destruction of metals and usually in areas of dissimilar metals, like your issue between the brass relief valve and the cast iron pump body. The electrolysis issue within the pump is exacerbated by the upgrade of previous sacrificial items like the old steel tank, steel/galvanized plumbing, etc. With the new poly tanks and brass/bronze/stainless steel plumbing has left the only remaining sacrificial component, the pump to react to electrolysis. Unfortunately, you will have to replace the pump. With all of your pumps, you should have two to four sacrificial anodes in each pump to prevent future issues — one to two in the pressure side and one to two in the suction side. The specific anodes for each pump supplier are available through their individual accessory systems.

Recently, during a mutual aid fire, one of our apparatus had a failure of the Jake brake. Does this affect the brake system?

No, the Jake brake — actually the “Compression Brake retarder — is designed to retard motion though the use of compression restrictions to assist in slowing the vehicle. Retarders are of several types available — Compression Brake, Integral transmission hydraulic retarder, exhaust flow restrictor, or eddy current driveline retarder (Telma). The retarder is in place to take heat and wear away from the actual braking system components. Loss of retarder will add wear load and heat to the brake components, which would indicate to the operator that the apparatus be operated with caution so as to not overheat the brake components, which can result in a runaway. The indication to the operator, get the retarder repaired ASAP. NFPA Standards stipulate any apparatus of 36,000# GAWR must have an Auxiliary braking system. Ernie recommends the inclusion of an auxiliary/retarder in any emergency vehicle that can accommodate the inclusion of a retarder.

What is the proper process of using a cab “prop” or “safety bar” on my tilt cab?

Once the cab is raised to the point that the cab prop safety bar drops into place, stop! DO NOT LOWER THE CAB ONTO THE SAFETY BAR. Doing so could cause the cab to wrack due to the use of a single side application of load. The free sides of the cab can/will wrack the cab sub-frame and can result in structural failure of components due to the cumulative damage to the structure. If the cab drifts down onto the safety bar, repair the holding feature of the lift system to prevent potential wracking of the cab structure. To prevent issues with the holding feature, make the replacement of the lift system fluid part of the annual service — a service component we often overlook.

Are there any rules, laws, regulations, or standards that require that I service my vehicles within a certain time frame?

YES. There are several ways to determine the time frames. They may be as stipulated by local, state, federal, NFPA or manufacturer’s mandated schedules. Under NFPA Standards you must, at a minimum, perform annual inspection and service of every emergency apparatus.  Manufacturer mandates or local SOPs can be more restrictive. Every apparatus falls under a commercial vehicle “Class” of vehicle. Take away the pump and tank and any special body and tools/equipment and you have a commercial chassis. Consider that every apparatus is of a Class two through eight chassis, depending on the GVWR. Maintain it as such. Other local SOPs usually stipulate time, mileage, hours of operation, or specific situations to dictate service interval mandates. Within a single fleet operation, apparatus in the fleet could fall into all of the intervals.

Included in my new fire apparatus is a thing called a VDR. What is it and is it required? 

The Vehicle Data Recorder records a myriad of information while the vehicle is in operation. It records all component of operation. Some operators consider it as “Big Brother looking over my shoulder.” Some have even gone to the efforts of disabling the VDR, an action that can lead to all types of repercussions. The VDR should be considered as your best ally when bad things happen. I must consider and believe that all fire apparatus operators do their job correctly and when bad things happen with their apparatus the VDR is there to back you up 100 percent and will again be our best ally in court. Embrace it.

I hear there is a device that is needed to re-set an onboard computer for battery charge levels.  Is this correct?

YES. While Uncle Ernie did not know this until recently, it is a tool that has been in use on early 2002-year model vehicles. Most of the vehicles that use the technology are foreign vehicles. However, Ford F150-F750 Super Duty Trucks have had the onboard battery re-set computer systems in select vehicles since 2002. Here is the gist of the issue. As the battery ages in these vehicles, the on-board computer continues to analyze the need to alter and increase charge rate. The charge rate is increased as needed to get the most out of the battery system. When the battery finally gives up the ghost and is replaced, if the re-learn tool is not deployed, the old high charge rate will begin a process of overcharging the new battery, resulting in what you will determine is early battery failure. You may even come to a false conclusion that the battery manufacturer is at fault by supplying junk batteries and change your battery supplier, with the same new battery fail rate. You may even blame Ford for the issue. Their techs have had this re-set tool for years. Here is one of the battery re-set tools from a National shop tool supplier: The tool is plugged into the OBD port. I maintain that the battery supplier should have this tool for your use when they sell you replacement batteries. Who knew?

(Disclaimer:  Uncle Ernie does not sell any product and is simply the purveyor of available information.)

— Ernie questions answered by
Anthony D. (Tony) Bulygo.

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