Getting An Old Car Running

Article by Mark Trotta

Before attempting to start an engine that's been sitting for years, taking a few precautions will help ensure internal parts don't get needlessly damaged or broken.

* Read This Before You Start *

If you have no history on the vehicle, there's no guarantee the motor will start, but...

Remember the basics of an internal combustion engine. If there's no mechanical issues, and it's getting fuel and spark in the correct timing, the motor should start and run.

Getting an old car running that's been sitting for a long time will not only depend on your efforts, but also on the mechanical condition of the engine.

Be Patient.

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Reading Spark Plugs

To learn a little about a non-running motor, take out the spark plugs. Keep the plugs in order when you remove them. This will help you determine if only certain cylinders have issues.

Reading the firing end of the plug reveals what kind of tune the motor was in when it last ran. There's probably dozens of various plug end appearances, but here's the ones most commonly found.

Black, sooty plugs - This indicates carbon fouling, caused by a rich fuel mixture.

Oil deposits on all plugs - Worn piston rings and/or valve guides.

Oil deposits on one or several plugs - Worn or broken piston rings on those particular cylinders.

The last thing you want to see on a plug tip is a broken insulator (the white ceramic part). This indicates detonation, brought on by either a lean fuel/air mixture, engine lugging, over-advanced ignition timing, and/or incorrect engine modifications. This may well lead to broken or damaged internal parts.

Light tan to grayish color on the electrode of all plugs is normal.

Before re-installing spark plugs, pour some Marvel Mystery Oil (or similar lightweight fluid) into the spark plug holes. This will help free up the piston rings in the event they're stuck. One cap-full at a time is all that's necessary, and remember it takes time for the oil to penetrate.

BTW, don't assume that the plugs you've removed are correct for that year, make, and model car. Notice the spark plug part number and check it with a catalog or an auto parts store.

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Change Oil And Filter

Since automotive engine oil degrades with time (it can start losing its lubricating qualities in less than a year), you don't want to risk damaging internal parts once the engine starts.

While draining the old oil, take off the valve cover(s) and pour fresh oil over the valvetrain components. This will help lubricate the rocker arms, push rods, etc. Let it drain out with the old oil.

After the draining is complete, install a new filter and refill with the correct amount of fresh oil. You don't need the best quality oil here--any new oil is better than old dirty oil.

Lifters destroyed by lack of oil

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Let's break it down into four basic categories:

Ignition - is it getting spark?
Fuel - is it getting fuel?
Air - is air getting through?
Starting System - does the starter turn the motor over?

Diagnose Ignition System

Begin with a fully-charged battery.

Multimeter Tests

A multimeter is an instrument designed to measure electrical values such as voltage (volts), current (amps), and resistance (ohms). There are two main types of multimeters, analog and digital.

A Digital Multimeter is by far more common and actually easier to use. They have an easy-to-read numeric display, and one can be had for less than $20.

Check Wire Resistance

To check if a wire is good or bad, connect one test probe to one end of the wire, and the other test probe to the other end of the wire. With the multimeter on ohm setting, it should read .02 or less. Anything much higher than that, replace the wire and/or the terminals.

Check the resistance of the positive and negative battery cables with your multimeter. If bad, throw them away and replace with new ones.

Next, check the secondary ignition system, starting with the spark plug wires. These can be tested with a multimeter, or simply replaced if they feel stiff or hard to bend.

On cars with points-style distributors, take the distributor cap off. With the car ignition turned on, you should be able to 'rock' the distributor rotor back and forth and see if the points are sparking. The ignition coil can also be checked with a multimeter.

If it looks like the distributor can be removed easily, take it out to examine it closer. Inspect and/or replace the points and condenser (yes, you should change the condenser, too).

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Crank Motor Over By Hand

With the spark plugs still removed crank the motor slowly by hand, if possible. This is easier on a stick-shift car, but if yours is an automatic you can put it in neutral and it may work. Use a large wrench or 1/2" drive socket on crankshaft balancer bolt.

If the motor doesn't turn, something is preventing it from spinning freely.

Do not try starting an engine that will not turn over by hand - forcing it will very likely break something!

Once the motor turns over freely, continue on to the next step.

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Fuel System

Sitting unused for several years, gasoline will turn to varnish. That was the case with this Zenith-Stromberg carb on an old Jaguar. It had sat for nearly 20 years, and after the carburetors were disassembled, I discovered that the old gas had hardened into varnish in the float bowls (see picture below).

Carb fuel bowl, right side not yet cleaned.

Rusty Gas Tank Alternative

I am always hesitant to pour fresh gas into a 20+ year-old gas tank, so I'll substitute a plastic gas jug as a temporary gas tank.

If possible, install an inline gas filter.

Crank The Starter Motor

With the spark plugs removed and primary coil wire removed, see if the starter motor will crank. If it does, you can then check to see if the mechanical fuel pump is working.

Install new spark plugs, properly gapped, or clean and re-gap the old ones. Re-attach the primary coil wire. With good spark, fresh gas, and a fully-charged battery, you're now ready. The carburetor choke, whether it's automatic or manual, should be closed.

You are now able to safely crank the starter, but limit starter operation to a maximum of 5 to 10 seconds, and wait about a minute in-between tries.

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Don't Over-Use Starting Fluid

If it doesn't start up right away, a squirt of starting fluid into the carburetor may help.

Did You Know? Without any gasoline, engines can be kept running by repeated squirts of starting fluid into the carburetor, but that's never a good idea.

Do not over-use starting fluid, as there is the strong chance of washing the engine oil off the cylinder walls, and now metal is running against metal.

If the engine fires after starting fluid was sprayed, but doesn't continue to run, that tells you the ignition is OK and it's a fuel issue.

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Notes and Misc

If you're working on a valuable year and model with the original motor, you may consider not even trying to start it, and instead make plans for removal and overhaul.