Hard to Start Your Old Chevy?

Here are a few things you might check!

By Stephen Kassis

Our old cars & trucks can sit idle for months, even years. Sitting is one of the hardest things on old vehicles. Try to run your older vehicles on a regular basis. Maybe drive to the store or on a back roads tour. Even if you fire them up in the driveway and run around the block a few times – running them is important. Old Chevys can develop a hard starting problem, especially when sitting idle for long periods. When this occurs there are several things you should check to keep your engine running properly.

TUNE-UP

Spark plugs, ignition points, coil, condenser, rotor, distributor cap, and spark plug wires are all items that should be checked, adjusted and/or replaced.

  • Spark Plugs – Check for carbon build up and oil or fuel fouling. Clean or replace as necessary and make sure to get the proper plug gap setting before installing plugs.
  • Ignition Points – A common problem with ignition points is that the rub block wears down in normal operation and closes down the point gap. Check the specification for the point gap to make sure the gap has not closed up. Readjust as necessary. Also, check for burned or pitted point contacts. File with a point file or replace as necessary. Finally, put a light coat of distributor cam lube on the surface where the points rub.
  • Coil – This one can be hard to diagnose. If you are driving down the road and the car suddenly quits, check the coil. When a coil starts to fail, it can be intermittent. One symptom is that the coil will get very hot. When it cools down, it will start without a problem, then a short time later, quit again. If it gets extremely hot, replace it.
  • Condenser – This little guy is usually good or junk – very little in between for this part. One caution on 1929-1932 models with the original Electrolock cable…..The condenser wire fits through a slot in the end of the cable. If the eyelet connector gets pushed to one side or the other, it can short against the housing which would kill the spark. Make sure the wire is centered in the slot and not touching anything metal.
  • Rotor – Check for burned or broken contact or spring on the rotor. Replace if necessary.
  • Distributor Cap – Check for burned contacts, cracks or moisture in cap. Moisture in the cap will cause misfiring and rough idle. It can be a sign that the cap is cracked. Replace if necessary.
  • Spark Plug Wire – Early Chevrolet engines do not have HEI (High Energy Ignition) and SHOULD NOT have the newer type HEI carbon suppression spark plug wires. Running this type of plug wire will cause a loss of voltage to the spark plugs. The result of this will be hard starting, reduced gas mileage and performance, running rich, fouled plugs and a lack of power. Early Chevy engines should only be using low resistance solid core metal center spark plug wires. Check yours to make sure they are the proper type. Replace if necessary.

VACUUM LEAKS

The symptom of hard starting can be caused by a vacuum leak. Early Chevys – 1954 and earlier – have vacuum windshield wiper motors. Vacuum motors were used on some cars & trucks through 1959. If the shut off valve is leaking, loss of vacuum at this point can be a major problem. Check the vacuum lines from the manifold to the switch and back to the wiper motor to be sure there is no vacuum leak in hoses or fittings.

Another common vacuum leak area is the intake manifold. A simple test for intake manifold leaking is to run the engine until it reaches normal operating temperature. At idle, spray a small amount of WD-40 on the connection point between the intake manifold and the cylinder head. If an increase in RPM is noticed, there is an intake leak. Attempt to tighten the manifold bolts and re-check. If it is still a problem, it is time to replace the manifold gaskets. Also check that the intake and exhaust manifolds are straight and aligned so they will seat properly on the head.

A vacuum leak can be anywhere that vacuum is used in the vehicle – like the distributor vacuum advance. When the diaphragm in the vacuum advance fails, it will allow a small amount of vacuum to be lost. This will cause a gradual degrading of performance and many times will go unnoticed for a long period of time. In more advanced stages of vacuum advance failure, there will be a noticeable miss in the engine and erratic operation. Also check for loose fittings on the vacuum advance line.

To test the vacuum advance for a bad diaphragm, remove the advance and push in on the vacuum advance lever. While pushing in the lever, cover the fitting (where the vacuum line attaches) with your finger. Release the lever and it should not return to its original position until you remove your finger from the fitting. If it does not hold a vacuum, the diaphragm is leaking. Have the vacuum advance rebuilt or replace it with a new unit.

FUEL ISSUES

Today’s fuel has a lower boiling point and is prone to causing vapor lock (turning fuel into vapor before reaching the carburetor). When possible, use non-ethanol fuel to prevent vapor lock. Non-ethanol is better for operation and much better when a vehicle is not run on a regular basis. This fuel is much more stable than ethanol fuel and won’t turn to a gummy mess in just a few months.

Ethanol fuel can cause a warm carburetor to evaporate the fuel in the bowl, causing it to be hard to start on the next time it is needed. The extra expense of premium non-ethanol fuel is really worth the cost in our old cars. It will save you maintenance issues and frustration in the future. This symptom is often mistaken as a fuel pump problem. However, fuel pumps, like vacuum advances can have a failing diaphragm.

If your fuel pump has never been rebuilt or replaced, it could be the cause of hard starting. Just like a vacuum advance, fuel pump diaphragms can fail gradually. Pull the fuel pump off and check it. While you’re at it, check your fuel filter. See our tech article on Fuel Pump Overhaul.

BATTERY PROBLEMS

When vehicles sit idle, the battery used to start them will eventually get weak. The can lead to starting problems. Keep a battery maintainer hooked up when a car will be sitting for long periods. This will help battery life and also help when trying to start the engine.

Another related problem would be bad battery cables. Early 6-volt systems require heavy cables as the amperage required is much higher than 12 volt systems. If your car has 12-volt cables from your local auto parts store, these can cause the starter to struggle to turn over. Heavy gauge battery cables should always be used on 6-volt systems. Also check the starter switch and battery posts to make sure the connections are clean and tight.

These early engines are very simple and, if properly maintained, should operate smoothly and start easily.