Trailer Life: Troubleshooting starter systems

Find problems fast with thlese helpful tips

The three most important steps in solving automotive electrical problems are diagnosis, diagnosis and (did I mention?) diagnosis. One such problem is poor cranking performance, and if you don't take the time to troubleshoot properly, you can waste a lot of time and money. Weak or undercharged batteries, undersize or faulty battery cables, a defective starter relay, motor or solenoid, neutral safety switch (automatic transmissions only), clutch switch (manual transmissions only) or poor connections can all keep you from getting started. Here are some cool tips on curing summertime starting problems.

GETTinG STARTED

First, check the basics. Carefully inspect the battery terminals for corrosion. Side-terminal batteries, especially, can look OK but hide corrosion under the terminals and covers. Remove both terminals and clean them thoroughly. There are special tools available in autoparts stores for cleaning conventional and GM-style side-terminal battery connections. The reason for the small hex head bolts is to prevent people from over-tightening and breaking the terminals loose in the battery case. So, resist the temptation to tighten them with a Vise Grip or a similar tool.

CABLES AND CONNECTIONS

Inspect the battery cables for cuts, abrasion, burned insulation, breaks and corrosion. Ground or negative (-) connections are just as vital as the positive (+) side. Check for ground straps between engine and frame and battery. Sometimes they may be left off following a repair, or the ends will become frayed, loose or corroded. Remove each end and clean away any paint, oil residue or corrosion. Install clean bolts and/or nuts securely, and use star-type washers between the terminal and the ground contact point for a better connection.

CRANKING VOLTAGE

Battery voltage will drop significantly during cranking, and this is normal. A fully-charged 12-volt battery without a load should read about 12.6 volts (if it reads 12.0 volts, it's almost fully discharged). With the starter operating, voltage (in warm weather) should not drop below about 9.6 volts. If it drops much lower than this, it could indicate a faulty or discharged battery, a defective starter, high resistance in the switches, wiring, relays, solenoids or, in rare cases, a "tight" engine.

CHARGING SYSTEM

If the battery is not charging properly, it will not have enough stored energy to maintain voltage during cranking. A quick test requires the use of only a voltmeter. Connect the meter to the positive and negative posts of the battery and use the 20-volt DC range. Start the engine and watch the voltage. It should start to rise and top out at about 13.5 to 14.5 volts. If the voltage doesn't rise, look for an alternator or voltage regulator problem. If the voltage goes much above 14.5, you probably have a defective voltage regulator that's overcharging and "cooking" your battery. In that case, you may have to replace both the faulty regulator and the damaged battery.

BATTERY

Batteries should last several years, but they can fail at any time. If jumpstarting or using the battery-booster switch (on multi-battery systems) gets the starter going, suspect the battery. Starting batteries that don't have sufficient capacity can cause a slow-cranking problem. As a rule of thumb, the engine-starting battery should have a cold-cranking amp (CCA) rating more than 1.5 times the cubic-inch displacement, so they have some reserve capacity. In all cases, use a replacement battery rated at least as high as original equipment.

Parasitic draws that slowly discharge the battery should be a factor only when the coach has been sitting for a while, not on a hot restart. If the charging system checks out OK and the connections and cables are good, have the battery charged and then load tested. If replacement is necessary, select a quality battery that has at least as much rated capacity as the original equipment.

NEUTRAL SAFETY SWITCH

All vehicles equipped with automatic transmissions have some type of neutral safety switch. Usually the neutral safety switch is located on the steering column adjacent to the brake pedal or on the side of the transmission where the shift linkage connects to the transmission. This switch prevents the driver from starting the engine when the transmission is not in park or neutral, preventing the vehicle from suddenly moving when the engine starts.

Sometimes these switches are out of adjustment. You can test this by setting the parking brake, stepping on the foot brake and moving the shift lever slowly through all positions while you try to operate the starter. If it suddenly starts to work in a gear position other than neutral or park, you've found a problem. The switches can be adjusted so the engine will only crank in neutral and park. If the switch is completely "dead," the two wires going to it can be connected together in an emergency to get the vehicle to a repair shop, as long as you make sure to start the engine in park and hold the brake on as a precaution.

CLUTCH SAFETY SWITCH

A lot of manual-transmissionequipped vehicles have a switch connected to the clutch pedal that requires the driver to depress the dutch before the starter will operate. If this switch breaks or goes out of adjustment or its wiring is faulty, the starter cannot be activated. Check the switch (usually located near the top of the pedal arm) and wiring. If necessary, connect the two wires that go to the switch to bypass the system. When this is done, be sure to start the engine with the clutch depressed or the gearbox in neutral.

IGNITION SWITCH

Ignition switch failures are less common than problems with dirty terminals, etc., but they do happen. Usually you can wiggle the switch back and forth with the key and get it to work enough to "limp" in for repairs.

SOLENOIDS

A solenoid relay is basically a remotecontrol switch that allows a small current to control a large current. They allow lightduty switches to control heavy current and also reduce voltage drop in circuits.

External starter solenoid relays, like those on Fords, are easy to test. If you turn the ignition switch to the "start" position, the relay should click. If it doesn't click, check for voltage at the small ignition switch terminal when the key is turned to the "start" position. You can bypass a faulty external relay temporarily with a jumper cable or heavy pliers.

ENGINE PRoBLEMs

Although rare, engine problems can masquerade as starter problems. For example, the pistons in an overheated engine can expand enough to drag on the cylinder walls, causing slow (or no) cranking. You can check this by removing the key from the ignition (for safety) and trying to turn the crankshaft using a socket and breaker bar on the large bolt in the center of the vibration damper on the front of the engine. Turn the crankshaft clockwise (as viewed from the front, facing aft) through two complete revolutions (720 degrees). Compare the force required to turn the crankshaft hot and cold. If the engine seems much "tighter" when warm, there may be an internal problem.

Centrifugal advance mechanisms in the distributor that are stuck in the advanced position can also cause the starter to crank slowly. This can be checked with a timing light. See if the timing is close to the idle-speed specification during cranking. If the timing appears to be advanced too far, check the distributor. Computer-controlled timing has eliminated this gremlin on latemodel engines.

RING GEAR/STARTER DRIVE

If you can hear the starter spinning freely and the engine isn't turning, the starter drive (also known as a Bendix drive) isn't engaging the ring gear teeth on the engine's flex plate (flywheel). Starter drives are inside the starter housing and can be replaced separately. If the starter drive is replaced right away, the teeth on the ring gear may not be ruined.

If the starter operates, but it sounds like it's chewing up gears, the starter drive is probably partially engaging and/or "skipping" when it hits damaged or missing teeth on the ring gear. In this case, the starter drive should be replaced and the transmission must be removed to replace a flex plate (flywheel) with damaged ring gear teeth.

STARTER ASSEMBLY

If the starter is properly grounded and has sufficient voltage and amperage available to it, and the solenoid is receiving enough voltage from the ignition switch circuit, it should work. Check for voltage at the large terminal where the battery cable goes to the starter. On starters with separate solenoids (like Fords), there shouldn't be any voltage until the solenoid is activated. On GMtype starters with built-in solenoids, voltage should be present at the upper terminal all the time. If you're having a hot-restart problem, plan ahead and connect an extension wire for your voltmeter with an alligator clip when the engine is cold. This should prevent you from getting burned trying to access it when the engine is hot. Again, look for about 9.6 volts or more during cranking.

Sometimes the starter's internal windings short together. A cranking amps test will detect this problem. Use an inexpensive inductive ammeter that can be purchased in most auto-parts stores. Although these aren't precision instruments, they will allow you to do a satisfactory job of testing the current draw of the starter. If the windings are shorted, current draw could become very high. Look for a normal maximum of about 250 amps (diesels are higher; check shop manual). Current draw during cranking can be checked along any readily accessible section of positive or negative battery cable. Temporarily disconnect a primary (low-voltage) wire on the ignition coil to prevent the engine from starting during the cranking amps test.

When replacing starters or any vital components, don't take the cheap way out. A "budget-priced" rebuilt starter may have just been cleaned up and only the pieces that completely failed replaced. Often, these "cheapo" rebuilts are put together with low-quality parts and are not up to OEM standards. Quality, brand-name remanufactured or new starters with good warranty coverage are the only way to go. The cost and inconvenience of having a "dead" motorhome or tow vehicle are just too great to play roulette with questionable parts.

GM STARTERS

With the introduction of the Vortec engine, GM has changed its starter design. Previous V-8 engines, especially the 454, had a tendency to not crank, or crank slowly, when hot. If there's not even a click when it's hot, but it starts after about a 20-minute cool-down, check for low voltage at the small "S" terminal on the solenoid mounted on the starter. Plan ahead and install an extension wire with an alligator clip for testing, as described above. Voltage at the solenoid "S" terminal must be a minimum of 7 volts. If voltage is too low, a relay (GM part no. 1114537 or 1115616) can be added (see diagram).

Make sure there's a heat shield in place between the starter solenoid and the exhaust header/pipe. Use heat shield GM part no.10068600 or 361443 or the equivalent.

There's also a special heat-resistant solenoid kit, GM part no. 10457024, that includes a shorter solenoid return spring (no. 1958679). Both of these parts should be used to improve hot restarts.

Compare replacement starters with the original part. There are standard and high-torque GM starters. The hightorque version is longer, which is what you want, and is about 11.5 inches long overall (tip to tip). Whenever a GM starter is replaced, be sure to reinstall any shims that were used between the starter and engine. Also make sure that the bracket on the forward-facing end of the starter is bolted to the block to prevent a broken starter "snout."

There are several companies that make special high-torque, gear-reduction starters designed for high-compression engines and other "problematic" applications. These are usually lighter and more compact than stock units, and they usually claim to have substantially more power than the original starters.

Two of these companies are: Hensley Battery and Electrical Supply, 2031 Bryant Street, Denver, Colorado 80211; (800) 88&8009.

CIRCLE 225 ON READER SERVICE PAGE. MG Industries, 4939 Buttermilk Road, Suite 300, West Misslin, Pennsylvania 15122; (412) 466-4009.

CIRCLE 226 ON READER SERVICE PAGE.