Tech tips designed to make your life easier and your shop more efficient
FURNACE FILTER FIX
Just a quick tip here to keep the shop floor cleaner. We put cheap furnace filters in our drain dollys. This prevents splashing when draining oil.
We just tear off the cardboard borders and put them in the pans. This really works and keep us cleaner, too.
Naturally, you need to dispose of these filters properly.
Thanks and keep up the good work.
Jeff Wilman, ASE CMAT L1
Firestone Complete Auto Care
GROOVED NISSAN ROTORS
Improperly installed rear caliper bracket bolts on some 2002-2012 Nissan Altimas may cause the rotor to groove and fail. This will cause the bolt to make contact with the inside of the rotor surface, creating a groove just above the center of the rotor and will cause extreme overheating, with the potential for rotor hat separation.
On this application, take note on how the caliper bracket bolts are removed. One bolt (bottom) features a washer and one bolt (top) does not feature a washer. The top bolt without the washer uses the ABS sensor bracket as its washer. If the bolts are installed incorrectly, the bolt without the washer will contact the rotor. If this occurs, replace the rotor and pads and inspect calipers and brake fluid, due to the overheating issue.
Courtesy Raybestos/Brake Parts Inc.
Whenever installing new brake pads or shoes, a break-in (burnishing) procedure should be performed.
After confirming that the brake system features a good pedal (by stroking the pedal to move the wheel cylinders and caliper pistons back out to their normal position), perform the following burnish procedures during the test drive.
The 30/30/30 Burnish Procedure
• Perform 30 stops, from 30 mph, with a 30-second cooling interval between stops. These stops will be performed at a decelerating rate of 12 feet-per-second or less. This means that it should be a gentle, easy stop.
• The 30/30/30 burnish procedure beds the pads into the rotors and shoes to drums. The bedding procedure also deposits the necessary friction transfer to the rotors and drums for optimum braking performance.
• Following this procedure also assures that your customer will have excellent braking performance from the first time that he/she drives the vehicle after brake service has been performed.
• Perform the bedding procedure before the customer takes delivery of the vehicle. You should never depend on the customer to handle this task.
Courtesy Bendix/Honeywell Intl. Inc.
CRUDE, BUT EFFECTIVE
To remove wheels that are stuck to brake drums, instead of using hammers or pullers that can damage alloy or steel wheels, just loosen the lug nuts and drive the vehicle in your parking lot, hitting a few bumps.
This will usually break them loose.
Smitty’s Body & Glass Shop
Please tell your readers about this little tip that can save time and make things a little easier and more efficient.
For the longest time I’ve wanted to have a test light that I could use as a back-probe. Today I made that dream a reality. I took one of my back-probe pins, removed the yellow thing, and re-bent it to fit tightly on my test light. Just bend the circle end into a piggy tail slightly smaller than the test light probe and slide it on. This tip really works!
Finally, one handed back-probing is here. Thanks again for the great mag and keep your sockets spinnin’.
Jeff Wilman, ASE CMAT L1
Firestone Complete Auto Care
VINTAGE DATSUN WOES
A common brake system problem can occur when servicing the brake master cylinder on a 1971–1978 Datsun Z (240/260/280 Z) equipped with power assist.
The customer may complain of a low, hard pedal without power assist (difficult to stop and can’t lock the brakes). The problem may be traced to a loose/misplaced “reaction disc” inside the power booster. This is a hard (composite) disc between the input pedal rod and the output rod that engages to the master cylinder.
When the master cylinder is removed, this pad may fall out of position, into the bottom of the booster tank. If this occurs, remove the master cylinder, remove the exposed rod retaining clip from the front of the booster, and remove the master cylinder actuator rod assembly. If the black disc is not attached to the rear of the rod face, it has fallen out.
Use patience and long needle-nose pliers to retrieve the disc from inside the booster. Clean the disc and the rod’s rear face and epoxy the disc onto the rod’s rear face. Reinstall the rod (with disc), secure the rod retaining clip, reinstall the master cylinder and re-bleed the system.
Larry Ritz, Technician
BMW FUEL LEVEL RESET
A 2003 BMW 325xi came into our shop, with the owner complaining about an inaccurate fuel gauge.
One of my techs performed all the right tests in the attempt to fix the problem, including replacing one of the sending units. However, he was not aware that many 1996 and later BMWs also require the instrument cluster reset procedure to be performed after replacing the fuel level sensor. Once he was aware of this, the problem was solved and the customer was happy. By the way, this BMW features a saddle tank with two sending units, with one showing less than 5 ohm resistance with a full tank of fuel.
When testing the sending units, each features two wires. One wire is black with a color trace and the other wire is brown with a trace. The black wire with a trace should have a 5V reference from the instrument cluster. The brown wire with a trace should be ground, going back to the instrument cluster. The resistance of each sending unit should be about 10 ohm with a full tank to around 250 ohm with an empty tank.
When a fuel level sensor is replaced, the instrument cluster reset procedure will need to be done, or the fuel level will still be inaccurate. This reset procedure tells the cluster that a new sensor has been installed and it will “learn” the new sensor.
DON’T LET THE LIFTERS FALL
Performing a camshaft change on a GM LS engine is fairly easy, thanks to the design of the plastic lifter guides. After removing the water pump, crank pulley and front cover, loosen all rocker arms and remove the pushrods. Rotate the crank twice (360 degrees). This will allow the cam lobes to push the roller lifters up into the lifter trays, where a slight interference fit in the lifter buckets will hold them up and away from the camshaft. This allows you to remove the cam (and install the new cam) without the need to remove the lifters from the engine. That’s the factory method.
However, here’s a tip: While the slight interference fit of the lifters in the lifter guides (trays/buckets) should be sufficient to hold the lifters up, the possibility exists for one or more lifters to accidentally drop down into the cam tunnel, which would require cylinder head removal in order to retrieve the lifter(s).
To avoid this, once the lifters have been popped up into their buckets, and before removing the camshaft, insert a pair of 1/4-inch or 5/16-inch diameter steel rods into the lifter galley oil passages at the front of the engine (off to each side of the cam). Each rod should be about 24 inches long. With these rods in place, even if a lifter tried to drop down, it can’t drop far enough to disengage from the lifter bucket guide.
Once the new cam is installed, remove the temporary steel rods. Install the pushrods, and pop the lifters down onto the cam by simply pushing on the pushrods. Complete the reassembly and you’re done.
Using these “fail-safe” rods will save you tons of extra work in case one or more lifters try to drop down.
USING A VACUUM PUMP
The purpose of a vacuum pump is to remove air and moisture from an A/C system.
Moisture in a refrigerant system, directly or indirectly, is the cause of most problems and complaints. First, moisture can freeze-up in an A/C system. Moisture is picked up by the refrigerant and transported through the refrigerant line as a fine mist with ice crystals forming at the point of expansion.
“Freeze-up” is not the only problem caused by moisture. It can also cause corrosion, the effects of which are not apparent until the real damage has occurred. Moisture alone in the form of water can cause corrosion. But when combined with refrigerants such as R-12 containing chlorine, hydrochloric acids can form which greatly increase the corrosion of metals.
Refrigeration oil has an attraction for moisture and will absorb it rapidly. Water-formed acids combine with the refrigerant, forming a closely bonded mixture of fine globules. The effect is called sludging and it greatly reduces the lubricating ability of the oil. A vacuum pump removes this troublesome moisture by lowering the pressure within the system and vaporizes it, then exhausting it along with the air.
Service Solutions LLC
CHEVY NO-GLOW PLUGS
A few of our 2009 Chevrolet Silverado 2500 fleet trucks equipped with the 6.6L V8 diesel engine have, on a few occasions, stored DTC P0674. The potential causes include glow plug(s), GPCM and/or glow plug wiring. In our experiences, it was necessary to replace the glow plugs.
We first cleared the codes (clearing all DTCs). We then command the glow plugs using a scan tool. Typically the DTC re-appears. We then use a test light at the glow plug connector to see if the GPCM (glow plug control module) is sending current to the #4 glow plug. We also compared the glow plugs to known good glow plugs.
Cam Barkley, Fleet Maintenance
OLD PONTIAC INTAKE MANIFOLD LEAKS
Vintage Pontiac 455 engines feature an intake manifold with a front water crossover passage. The water passage of the manifold is pulled forward to mate to the water pump tube. This sometimes pulls the entire intake manifold too far forward. If not sealed properly, this can result in vacuum leaks. Or if the manifold bolts are tightened before mating the front of the manifold to the water pump, coolant leaks can result.
A common cure is to simply cut the water passage section of the manifold free from the rest of the manifold. This allows you to install the intake in two separate pieces. The manifold itself can be aligned to the intake ports of the heads, and the water passage can be properly mated to the water pump. Separate the front coolant passage section by cutting between the two front manifold bolt locations on each (LH and RH) mounting deck of the manifold. Deburr the cut edges and install separately.
When changing or upgrading camshafts, always measure for correct pushrod length. Never assume that the existing pushrods will be correct. For example, when removing a lower-lift cam and installing a higher-lift cam, the base circle may be smaller on the higher-lift cam, requiring longer pushrods. By the same token, removing a high-lift cam in favor of a lower-lift/milder cam, the base circle on the new cam may be larger, requiring shorter pushrods as compared to the pushrods that were correct with the higher-lift camshaft. Use a checking (adjustable) pushrod, at least on number one cylinder’s intake and exhaust lifter locations.
Wadsworth, Ohio ●