Service Hints
Heater cores:
Use the right ant-freeze. READ THE LABEL. Use only anti-freezes that are free of silicates (sand), phosphates, borates, amines, and nitrates. These chemicals can become electrically charged and cause electrolysis. ECD or electro-chemical degradation destroys hoses as well as the metals in the system. Industry trends include using de-ionized water rather than even sterilized water. Tap water now –a- days is a big NO. You should ALWAYS test the anti freeze for a balanced PH. You want about 7.2. Anti-freeze and additives with silicates (sand) DO NOT go in aluminum cores. Anti-freeze recyclers often contain some quantities of other antifreezes like propylene glycols, ethylene glycols, and their additives. The correct answer is to thoroughly flush the system including using pure water as a rinse.
Fuel Tank Sending Units:
General Motors recent use of modular fuel pumps in place of pump and hangers is
relatively new. It comes with a new set of issues that must be checked to
eliminate "comebacks". There are 2 basic reasons for premature failure. The #1
issue fuel contamination, either from water, ethanol, chemical additives or
particulate matter. The # 2 reason is severe voltage drop caused by wiring
harness connector failures. Whereas you never had to check fuel quality before,
now its a necessity. When diagnosing a potential fuel pump failure, look
for melted plastic at connection points, The connectors location makes it
impossible to diagnose the problem with a voltage drop test. In most cases, a
new harness section or pigtail will fix the problem. Not another fuel pump!
Courtesy of Carter Fuel Systems, Federal-Mogul Call our counter for a copy
of the article.
Due to the options of newer cars and trucks, there is no longer a specific listing for tank units. You MUST refer to the “broadcast” number on the top of the old one. Look for a tag, a molded in alpha or alpha-numeric code or in older systems, an ink stamp.
Electric Fuel Pumps:
These pumps run continuously. They are designed to be cooled by the gasoline. If the customer runs it dry or extremely low all the time, the pump will fail. They are also prone to increased heat from poor connection or corroded connection on the pigtails. If the terminals are loose, broken or corroded, the pigtail MUST be replaced. As gas is becoming more expensive, people will look to cheaper fuel. Traditionally, cheaper fuels are that way because they are not filtered as well. Water kills these pumps. Please see the attached explanation from ACDelco Service...
A/C Compressors:
Compressors have changed enormously in recent years….and so
have the problems. Because of the costs involved in servicing A/C (especially
R-12 vehicles) is so expensive, the customers are “re-using” as much as
possible. Filtering becomes critical. Basic A/C 101. Always replace the orifice
tube and receiver dryer with each compressor you change. If the compressor does
not have a filter screen on the suction side, PUT ONE IN. You need a line screen
as well as the orifice screen. Never flush with anything other than the
specified refrigerant. Solvents void all manufacturer warranties. Too much dye
is a bad thing. Dye washes the oil off the moving parts. Don’t use solvent
flushes or solvent based dyes. Check with the manufacturer when determining
which type of flushing materials should be used. Mark the system with the date
you added dye for the next guy. Noisy compressors are usually caused by lack of
lubrication or the wrong oil being added. Almost ALL GM COMPRESSORS ARE SHIPPED
DRY. Add oil to the system by following factory recommendations. Often, a/c
recyclers have a micrometer cup that captures the oil and that amount at least
should be replaced. As a rule, most systems need 8 oz. of oil. 1 oz. in the
dryer and 7 oz. in the compressor. PAG oil is the ONLY oil that can be put in
most newer systems. Never use Ester Oil unless the manufacturer recommends it.
Ester oil should only be used on retro-fit vehicles. Be sure of what refrigerant
was in the system before. There are many blends on the market as well as
conversions. You MUST be sure to flush the entire system. PAG oil comes in 4
different viscosities. Ford uses 68 viscosity. Delphi systems use 100 or 150.
Denso systems use 46. Sandon systems use either 46 or 100 viscosity oil. The
wrong oil will prematurely kill that compressor. If you pull out the orifice
tube and it’s black, flush the system.
**Suburbans with rear air (C61) really need the condenser and rear expansion
valve changed with a compressor replacement.
**Fords should always have the liquid line replaced with a compressor change. (YF2491)
** ACDelco 15-21184 Suction screen kit (color coded)
** ACDelco 15-10413 Universal In-line filter kit
** NW Air K10-1150 Orifice screen kit (color coded)
Brakes:
Doing a brake job 15 years ago is far from what is expected today. ABS has added the complication of bleeding sequences and additional diagnostics. Industry statistics suggest that about half of all ABS systems are not functioning correctly. Remember that in the more sophisticated ABS units, to accomplish a panic stop at 60 MPH, the fluid is reversed in direction up to 60 times per second. Dirt, gummy valves, using the wrong brake fluid and the fact that no-one ever checks the functionality of these systems means that when the customer really needs that system to work to its peak performance, it probably won’t. A brake job should really include flushing the system on a REGULAR basis. Use the correct brake fluid. And don’t substitute the type or quality of the pads on a vehicle. Ceramics, semi-metallic and organic should only be put on where they were stock. Modifications to pad material changes the heat co-efficient and thereby the ABS system's ability to stop the car. Washing rotors with soap and water is becoming the cure for noise. Next time you turn two rotors, wash one with soap and water and use brake clean on the other. Then wipe them both down with a white towel. You will see why that customer might come back next week with the brakes squeaking. All that greasy residue left behind gets imbedded in the pad material and your customer's new brakes are squeaking.