Hard to Start Your Old Chevy?
Here are a few things you might check!
Old Chevys can sometimes develop a hard starting problem. When this occurs there are several things you should check to keep your engine running properly.
Spark plugs, ignition points, 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.
- 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 an HEI (High Energy Ignition) ignition and SHOULD NOT have the newer type HEI suppression (carbon) spark plug wire. 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 metallic solid core spark plug wires. Check yours to make sure they are the proper type. Replace if necessary.
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.
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.
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 when driving at a constant speed. In early cars with vacuum wiper motors you may also notice reduced performance of the windshield wipers. To test the vacuum advance for a bad diaphragm, remove the advance and push in on the vacuum advance lever. After 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.