Restarting an Old Engine

As Cougars become more popular, more and more of them are being pulled out from under oak trees, out of sheds, and even out of junkyards to be restored and/or put back on the road.  In some cases these cars have been reasonably well stored, but for the most part they have just been neglected or worse.  And when a car has been stored for a long time, condensation and rust can seize or eat away parts of the brake system and seals, and bearings can dry out.  Hoses and belts get dry rot, wiring and insulation can be attacked by mice, heat, and other natural hazards, and a whole host of other things can go bad on the car.  Before the car can go back on the road, most or all of these problems have to be addressed. Of course, one of the biggest obstacles besides moving the car out of the shed and into a garage is getting the engine running again.  No matter how good or bad the car looks, a running engine is an important milestone in the process of bringing a car back to life.  For some cars, this means installing a new engine because the old one is missing or beyond repair.  For other cars, it means the engine has to be pulled and rebuilt.  But for some cars, there is another option.  With some work, it may be possible to get the current engine in the vehicle running.

This process is not for every engine.  Each case has to be reviewed to see if the risks outweigh the benefits.  The only sure way to restart an old engine and not damage it further is to tear it down and check it out.  But for some cars, the risk of trying to start the old engine may be worth it.  For example, if the engine is the base model engine, it's not going to cost that much more to rebuild/replace the engine if this process does damage something.  But for a less common engine like the 427s, 428s, or Boss 302s, the risks are rarely worth it.

The guide detailed here is best for an engine that was known to be running when the car was parked/stored.  Hopefully, the exhaust system and air filter remained on the engine, and the hood has been down to minimize rainwater in the engine bay.  These items reduce the chances of large amounts of water/condensation from entering the cylinders through open valves and allowing the pistons to seize.

If everything goes according to plan, there is only one special tool needed for this project.  That tool is an oil pump primer, which can be rented or a temporary one can be fabricated out of an old distributor shaft or even some old tools.  Besides those listed here, there are other tools that could come in handy once the engine is running or for troubleshooting electrical problems, but these should be sufficient to get the engine running.


    Regular (slot) screwdriver 

   Oil pump primer tool


   Oil squirter (nasal aspirator)


   8” vacuum hose

   Spark plug socket

   Battery charger/jumper cables

   15/16” socket (for crankshaft bolt)


   1/2” wrench or socket w/extension

   Damp towels

  15/16” wrench (for fuel filter)

   Drip pans

   Wrench for oil plug

   Shop towels

   Breaker bar

   Dry sweep/kitty litter

   Oil filter wrench

   Gas can

   Spark plug gap tool

   Bottle cap

   Points file/emery board

   Carburetor cleaner

   Timing light

   Fire extinguisher

   Multimeter/test light

   Safety glasses



The cost for this project isn't much, either, assuming that nothing is missing from the engine.  Although not part of the engine, the biggest cost is typically a battery, which is almost always missing or dead. Besides the battery, expect to spend about $20 for new oil and oil filters, around $5 for a new fuel filter, about $5 for fresh coolant/antifreeze, and a couple of bucks for some fresh gas.  At this point, it's a good idea to chip in another $10 for a new air filter too, but it can wait if the budget is tight.  The cost goes up about $15 more if the valve covers are pulled, which is a good idea, but is usually not required.

Although it can be done in less time, the process here takes about two days to prep and restart the engine.  It isn't a matter of labor, though.  Most of the time on the first day is to give the oil a chance to penetrate the piston rings, which reduces the chances of damaging the cylinders.  The intent of this process is to start the engine without damaging it and to minimize any changes to the current tune-up settings.  Minimizing changes to the existing tune-up settings increases the chances that the motor will restart, assuming that the settings haven't been modified since the engine was last running.


The first step is to check the oil.  If the oil appears to be gummy or unusually thick, drain about half of it out and add new oil.  Use a multi-viscosity oil for this, even if you don't normally use that type oil.  If the oil appears unusually thin, examine it closely to see if it appears that the oil has been thinned out by gas.  If it has, drain all the oil, install a new filter, fill with new oil, and install a new fuel pump. Otherwise, just drain out about half and top off with new oil.  If the oil seems to be separated, or has white clumps in it, or otherwise has signs of water/coolant contamination, completely replace the oil and filter now also.  If the oil appears to be normal, just bring it up to the proper level.  If you know the engine has sat for several years, go ahead and change the oil and filter now.

Some folks recommend adding transmission fluid to the oil, which is supposed to help free sticky lifters and valves.  While the actual benefits have not been proven, it is ok to replace one or two quarts of oil with transmission fluid when topping off the oil.  Anything more than two quarts risks thinning out the oil to the point where it will not leave enough lubricant on the cylinder walls to prevent them from being scratched.

After the oil has been checked, remove the plugs.  Examine the plugs and compare them against the photos in the repair manual.  Make a note of which plugs appear to have problems with oil or carbon fouling.  This check has to be done now, as future steps will eliminate this evidence.  Squirt about 30 cc of oil (about one tablespoon) into every cylinder with a nasal aspirator or similar device.  Reinstall the spark plug immediately after the oil is squirted in.  Let the oil sit over night. This allows the oil to soak back around the rings, which is especially important for those cylinders that have had open valves where the oil has evaporated.  It won't get all the contact area of the rings, but it will get a fair amount.


A length of rubber vacuum tubing attached to

the nasal aspirator ensures that the entire

30 cc of oil is forced into the cylinder and on the

inner cylinder wall where it can drain down to the

piston, completely soaking the oil rings. 

Fill the aspirator, insert the hose in the

cylinder, then turn the aspirator over and blow

the oil into the inner wall of the cylinder.


The next step is to get rid of the old gas.  Gas deteriorates over time and any gas more than six to eight months old is not good for an engine.  The engine may run on it, but not well.  To remove the old gas, put a catch pan just behind the driver side torque box and remove the rubber section of fuel line between the two metal lines.  For cars with a one-piece line, put the pan under the fuel pump and disconnect the hose there.  This allows the gas in the tank to run through the lines and at flush out at least some of the crud in the lines.  Have a couple of catch pans ready, there's no telling how much old gas and water is trapped in the tank.


That red tint in the gas sample on the left is not a

lighting trick.  This is what happens to gas when

it sits around too long.  Compare the old gas on

the left, which is probably at least 10 years old,

to the fresh gas on the right.  Although the old

gas may burn, it will not burn cleanly or evenly. 

It also stinks.  If your nose protests when you

remove the gas cap, the gas is probably bad.


If you have access to compressed air, disconnect the fuel line at the tank and blow air through the lines to get rid of the old fuel trapped in the line.  If you don't have access to compressed air, pour some fresh gas in the tank and let it run though the lines.  Reinstall the rubber connecting hoses.  If a lot of rust and/or trash came out of the line, consider installing another fuel filter between the gas line and the fuel pump.  A second fuel filter installed here will catch debris as it is flushed out of the tank and before it can damage the fuel pump.  This isn't required, but should be considered even if the old gas looked relatively clean, as there is probably some sediment on the bottom of the tank that is going to shake loose over time.  Dispose of the old gas at a recycling center, as it is not fit to even run a lawnmower at this point. Remove the wing nut on the air filter lid and remove the entire air filter assembly.  Put a rag under the fuel filter to catch any gas that leaks out when the filter is removed.  For original Autolite 2100 and 4100 carburetors, remove the fuel filter with a 15/16" wrench and a pair of pliers.  For other carburetors that have a filter in the line, instead of screwed into the carburetor, remove the clamps and pull out the old filter.  While this doesn't drain out the gas remaining in the carburetor float bowls like it does on the 2100/4100 Autolites, it is usually better to fight through the any remaining bad gas in the fuel bowl, than to pull the carburetor and rebuild it.  It doesn't hurt to spray the inside with carburetor cleaner, but use it sparingly for now.  Washing all that accumulated crud into your intake will not help the engine start.  Install the new fuel filter once the lines have drained.

To finish off the fuel system, pour some fresh gas into the gas tank, preferably two or more gallons.  This much should dilute any remaining old gas in the tank and ensure that primarily fresh gas gets to the engine.  If the gas tank or fuel lines are damaged, or you are not sure that they are clean enough, another option is to place a gas can on a short table by the driver side tire, and run a line from the fuel pump into the gas can.  Make sure the end of the hose is in the gas and not just in the can.  This technique is significantly more dangerous than putting gas in the tank, but is an acceptable alternative to get the engine running, as long as you always keep in the back of your head that you have a highly combustible material at your feet, especially when cranking the engine over.  When using a gas can to provide fuel to the engine, attach the gas can to the vehicle last to avoid knocking the gas can over and spilling gas and to prevent fumes from building up in the garage and causing a fire hazard.


The temporary gas tank needs to be placed at

roughly the same height or slightly higher than

the original tank.  In addition, the fuel line should

be held upwards and filled with gas before being

inserted into the tank.  The age and condition of

the pump may prevent it from being able to suck

fuel up from the ground and/or get the air out of

the hose; these precautions will overcome those obstacles.


Next up is the coolant system.  Examine the radiator and heater hoses closely.  If the hoses are unusually hard or soft, dry rotted, or oil soaked, go ahead and replace then now.  The last thing you need to deal with is a hose exploding just after the engine has reached operating temperature. Being splashed with hot antifreeze will earn you a trip to the emergency room for chemical burns and take all the fun out of this endeavor. If the heater core is suspect, bypass the heater core by connecting the inlet hose to the return fitting.  Once any questionable hoses have been replaced, top off the coolant system. After the coolant system, check the accessory belts.  If the belts appear severely dry rotted or separated, they should be replaced.  Otherwise just make sure the belts are tight.  If the car has air conditioning, remove the A/C belt for now.  At this point it is just extra load for the starter to pull.  Smog pumps and PS belts can also be removed on some, but not all, engines.  If removing belts, three items must remain connected: the water pump, the crankshaft, and the alternator.

The vacuum system comes next.  Examine the vacuum ports on the engine and manifold.  Cap off any open ports and replace any old caps that no longer fit snugly or are cracked.  Check all of the vacuum lines for signs of dry rot.  As the headlight door system has a lot of vacuum lines and, thus, many places for possible leaks, the simplest solution is to disconnect the vacuum line going to the headlight doors and install a vacuum cap on that port.  For that matter, for now, it is a good idea to disconnect every vacuum line except for the ones going to the vacuum advance, the transmission, and the PCV valve.

After the vacuum system comes a whole host of electrical checks.  Clean the battery terminal and cable ends.  Remove and clean the electrical connectors at the starter solenoid and at the voltage regulator.  Install a new battery, put a battery charger on the old battery or install jumper cables from a good battery.  Turn the key to ACCY and check for power (check the lights and gauges).  If power is present, move the key to the RUN position and check for voltage at the + terminal of the coil.  The reading should be around 6 volts.  If power is not present at the ACCY position or the coil doesn't have about 6 volts in the RUN position, dig out the electrical diagrams for the car and troubleshoot until the problem is found and fixed.

Note: Do not leave the key in the RUN position for long periods of time.  If the key is left in the RUN position for an extended period of time, it can damage the coil. Check the wiring system with the key in the ACCY position only.  Once power is restored to the car, then and only then, turn the key to the RUN to check the coil circuit.

The last electrical checks deals with the distributor.  Remove the cap and examine the inside.  Check for signs of arcing between contacts, rust or corrosion on the contacts, and for signs of water in the cap.  If the contacts appear to be in good shape, clean them and the rotor, then reinstall them.  If there are signs of heavy rust, corrosion, pitting, or other damage to the contacts, replace the rotor and cap with new ones.  Transfer the plug wires one at a time to ensure the firing order isn't changed.  Open the points with a screwdriver and examine the contacts.  Insert a points file or a finger nail file between the contacts to clean them without having to remove them and, thus, disturbing the dwell setting.

The next step is to get the oil back into the game.  Because the engine has sat for a long time, virtually all of the oil has drained into the oil pan.  The way to get the oil back onto the cam, rocker arms, lifters, and other required places without taking the engine apart is to run the oil pump.  The oil pump is driven off the bottom of the distributor, which is turned by the cam, which is driven by the crankshaft.  Since most of the engine parts currently do not have enough oil on them, the way to put the oil back is to run the oil pump without moving the rest of the engine parts.  This means pulling the distributor.

Clean the area where the distributor goes into the block thoroughly, removing all the dirt and rust that could fall into the engine when the distributor is removed.  Spray penetrating oil around the base of the distributor.  This will help loosen the distributor from the block.  Also clean the sides of the distributor.  Reference marks will go on the block and the distributor housing, which means that they need to be clean to ensure the marks cannot be wiped away.


Once the oil has a chance to soak through overnight, pull the spark plugs and squirt an additional 30 cc of oil into every cylinder, reinstalling the plugs immediately after the oil is squirted in.  When that is done, pull the distributor cap.  Take a look at the rotor and place a mark on the side of the distributor at the point the rotor is facing (point A in the illustration below).  Next, clean the base of the distributor and the area of the block where the distributor goes into the block.  Draw a line starting on the distributor base and ending on the engine block.


These marks are essential to pulling and reinstalling

a distributor without changing the timing. 

Mark “A” indicates where the rotor is pointing in

reference to the distributor housing.  The line drawn

from the base to the block, marks B and C, align the

housing to the engine block.  It is essential not to

erase these marks.  Use a scribe if you plan on additional

cleaning of the housing and engine block to ensure that

these marks are not erased.



Remove the 1/2" bolt and the distributor retaining clamp.  Clean away any dirt that was trapped under the clamp.  Spray more penetrating oil on the base of the distributor and let it soak in for a while.  Make sure the penetrating oil has not removed the alignment marks, then gently twist the distributor housing back and forth until it can move somewhat freely.  This may take a while, but do not succumb to the temptation to beat or pry on the distributor.  Pull upwards on the distributor housing while keeping the line from the base to the block lined up.  Mark the point (point D in the illustration below) where the rotor is pointing on the housing when the distributor clears the cam.  The distributor shaft will quit turning when it clears the cam gear.


This last mark, D, is used to when reinstalling the distributor. 

Before marking the housing, make sure marks B and C are

still lined up.  When reinstalling the distributor, the rotor is

pointed at D and then the housing is turned to line up B and C. 

As the housing is slid into completely back in place, the rotor will

turn back to point at A.  When this happens, the distributor has

been properly reinstalled without changing the timing.



With the distributor out of the engine, carefully wipe away any remaining dirt around the edges before it can fall into the opening.  Next, take the flashlight and look inside the opening.  Inside the opening is a hexagonal shaped shaft.  Note the orientation of the shaft.  The oil pump primer tool rotates this shaft, which then runs the pump and pushes oil through the engine.  This shaft has to end up back in the same position it started in or the opening in the end of the distributor shaft will not line up with the pump shaft, which will prevent the distributor from being reinstalled. Do NOT rotate the engine until the distributor is back in the engine.  If the crank is moved while the distributor is out, the reference marks are rendered invalid and the engine timing has to be manually reset.


This is what happens when you pry on a distributor. 

The distributor housing is made out of cast aluminum

and is easily cracked.  If the distributor is stuck and cannot

be moved by hand, remove the vacuum advance and use a

strap wrench around the housing.  A pair of vice grips around

the base may work also, but will scar the base and could

damage the bearing if too much pressure is applied.



Once the distributor is out, an oil pump priming tool is put on the oil pump drive shaft and turned counterclockwise with a ratchet or a drill to pump oil through the engine.  Continue rotating at a moderate speed until noticeable resistance develops.  If the local tool rental store doesn't have an oil pump primer, there are a couple of other ways to accomplish the same task.  The easiest alternative is an old distributor shaft that has the cam gear removed.  Another option is to make an oil pump primer.


An old distributor shaft and an Allen wrench work almost

as well as the actual tool.  Another option is to piece

together a primer out of old tools.  The one shown here is

made of a nut driver, a 1 1/16” socket, an extension, and

some tape.  The tape is important to ensure all the parts come

back out when the job is done.  A socket welded to a long extension

will also work.  The 351W and 351C have a 5/16” shaft, while the

rest of the Cougar engines have a 1/4” shaft.


After running the oil pump, turn the oil pump shaft until it is back in the same position it was in when the distributor was first removed.  Reinstall the original distributor by lining the distributor housing mark B up with mark C on the engine, then turning the rotor to line up with the last mark (D) you made.  Lower the distributor back into the engine.  When the housing is completely seated, marks B and C will line up, and the rotor will point to the first mark (A) you made.  When this happens, the distributor is back in place exactly as before. At this point, it is a good idea to pull the valve covers and expose the drive train.  This allows all of the valves to be visually checked for proper operation when the engine is rotated in a few minutes.  Removing the valve covers adds some time to the project because it can take a while to remove the old, dried out valve cover gaskets.  Although removing the valve covers is not necessary, it is an extremely good idea.  Consider it $15 worth of preventive medicine.  And, if any of the valves turn out to be stuck, the valve train needs repairs and continuing here could damage some parts (valves, push rods, and pistons) that could otherwise be saved.

Rotate the crankshaft drive pulley by hand for at least one rotation.  If the engine rotates by hand it is a good sign that none of the rings have stuck to the cylinder walls.  The first move will be the hardest.  If necessary, use a breaker bar on the crank bolt, but only if you can't move it by hand first.  You want that first move to be gentle.  But, if the engine will not move by hand or it feels like the breaker bar may snap the crankshaft bolt, use the starter to turn the motor over.  Unplug the power wire to the coil wire before cranking the engine to prevent damaging the coil during the next steps.

Once the engine will rotate, turn the motor over several times with the starter.  Besides pumping more oil through the engine, this pumps fresh fuel into the carburetor.  Rotate the engine to bring the number one piston to about 10-15 degrees BTDC on the compression stroke.  Remove the spark plug and put a clean rag under the spark plug hole.  Rotate the engine to TDC and then wipe up any excess oil that drains out.  Install a new, properly gapped plug back into the engine.  The old plugs can be cleaned and re-gapped, but new plugs are preferred.  Follow the firing order to drain out the excess oil from the engine and to install the remaining new plugs.  Another option is to pull all the plugs at once and install rags under all of the holes, then rotate the engine to push out the excess oil.  While easier than doing one plug at a time, this option is almost always messier.  Use new valve cover gaskets to reinstall the valve covers if they were removed.

Reinstall the distributor cap and reattach the coil wire.  If the car is inside, it may be best to move the car outside as the engine will smoke heavily when it starts and may continue to smoke when running.  Also, if the starter seemed weak when turning the engine over or if the battery is suspect, attach a set of jumper cables or a battery charger.  Attach the timing light, then prime the carburetor with two or three soda bottle caps full of gas.  Turn the key on and attempt to start the engine.  If the engine doesn't start after three or four tries, re-prime the carburetor with one or two bottle caps of gas.

If the engine doesn't start after ten tries, pull the plugs and check for oil and or gas fouling.  Clean as necessary.  Before installing the last plug, attach the plug wire and while holding the plug against the block with insulated pliers, crank the engine to make sure the ignition circuit is working.  Check the carburetor for fuel by moving the throttle and seeing if fuel squirts into the bowls.  Fix any problems with the ignition and fuel systems before continuing.  If the engine seems to try to start, but tends to backfire and blow large blue sheets of flame out of the carburetor, the distributor is most likely off by one tooth, and you are probably using too much gas to prime the engine to boot.  Using the method discussed later in this article to check and or correct the timing.

Once the engine starts, let it run for about 10 to 20 minutes.  At this point, the engine only needs to come up to temp and stabilize.  Listen closely for any unusual sounds.  Some tapping is to be expected, but if there is any heavy knocking, rattling, or misfiring, shut the engine down immediately.  Once the engine is running, use the timing light to confirm that the timing is roughly correct.  The vacuum advance is still connected and the RPM will be higher than proper to accurately set the timing.  Just make sure it is in the ballpark for now.  While the engine is warming up, do not rev the engine except as necessary to keep it running. Do not rev the engine hard for any reason.

Watch the engine temperature closely.  As the original coolant is probably too old to be of any use, the engine could start to overheat.  If the temperature goes past midpoint, use a water hose sprayed on the radiator to cool the engine down or shut the engine off until the coolant system can be fixed.

Once the engine temp has stabilized, check the transmission fluid and top off as necessary (automatics only), then turn the engine off and change the oil and oil filter.  Examine the oil closely for signs of fuel or coolant contamination or signs of metal.  Flush the coolant system as soon as practicable.


If you have access to a torque wrench, a better way to start an engine that has sat for a long while is to pull the heads and examine the pistons and valves directly.  Pulling the heads is quite a bit more ambitious than just starting the engine, but if you plan on keeping this engine, it's the only way—short of rebuilding the engine—to check the internals and ensure you will not damage the engine.  Once the intake and heads are removed, pour the oil directly into the gap around the edge of the piston and the cylinder wall.  Pour oil directly on and into the lifters.  Also pour a little into the holes above the cam.  Once the oil has soaked in, turn the engine with a breaker bar.  Do not use the starter as this can launch the lifters out of their bores.

Rotate the engine through a couple of rotations and inspect each bore for rust and scarring.  Either of these conditions is a good indicator that the cylinder in question needs machine work.  If the pistons rotate and none of the cylinders appear damaged, reinstall the heads.  Rotate the engine through one complete cycle while watching the valves.  Make sure all of the valves open and close.  If not, pour some oil on the valve and let it soak in.  This may free the valve, but most likely the valve will have to be removed and replaced by a machine shop.

If all of the valves operate properly, install the intake and carburetor. Once that is done the timing can be set. Rotate the engine while watching the #1 intake valve. When the #1 intake valve closes, continue to turn the engine until the #1 piston is between six degrees BTDC and TDC. Install the distributor, making sure that the rotor ends up pointing at or just past the #1 spark plug wire and that the vacuum advance is centered in the open space between the radiator hose/thermostat housing and the AC compressor. Now that the timing is roughly correct, reconnect the fuel lines, throttle cable, and other disconnected items, then attempt to start the engine using the other steps noted earlier. 


If the engine was running when the car was parked, the processes we've described here should get the engine back up and running without having to take it apart, but that is all that will do.  The engine will not run any better than it did when it was parked.  In addition, as the engine has sat for a while, some or all of the engine and transmission seals may have dried out and, now that the engine is running again, these seals may start to leak. For this reason, watch the front and rear main seals, the water pump, the valve cover gaskets, the oil and transmission pans, and the radiator closely for the first few months.


The techniques described in this article are, to the best of our knowledge, effective and safe when performed as described.  However, if you use them, you do so at your own risk.  this web site assume no liability for damages resulting from the use of the procedures and products described in this article.

  • Use caution whenever working with chemicals.  Always test chemical products on a small area before proceeding with the job.
  • Avoid the danger of shock when working around electrical components.
  • When raising a car or any of its major components, be sure your jack and/or jack stands are used properly and that they are adequate for the weights and stresses involved.
  • Never weld on or near any part of your car's fuel system.
  • Carefully read and follow the manufacturer's instructions when using or installing any product.