Whether you just bought a lawn-ornament Jeep that hasn't run in years or you've neglected one of your own projects, your motor will need a little CPR and mouth-to-mouth to bring it back to life without damage.
Engines are complicated assemblies with many precisely-machined parts that require proper lubrication. But they are also extremely easy to make run. Get fuel and spark to happen at the right time and you've got a running engine.
However, an engine that sits for more than six months can be a problem. Fluids separate, metal oxidizes, and seals dry up. There are a few steps required to provide spark and clean fuel, and also some work to make sure that no problems have developed during hibernation.
Almost no one, including us, plans on their Jeep sitting ignored for years. So usually the engine isn't prepped to avoid damage and problems during storage. Here's what you should do before starting an engine that has been sitting for awhile, as well as some troubleshooting help in case it doesn't fire right up.
It's Alive!
Hopefully, you followed the steps outlined here and were rewarded with an engine that fired up and is now running. Do yourself a favor, and don't close the hood and hit the highway just yet. Give the entire vehicle a thorough inspection while the engine is running to check for leaks and problems. Here are a few often overlooked things to check:
•Look for coolant leaks from hoses
•Check cooling hoses for spongyness
•Inspect the weep holes on the water pump and engine-mounted fuel pump; replace the parts if they are weeping
•Check the sides and front of the engine to see if any of the freeze plugs are seeping
•Look under the Jeep at the bellhousing - there are freeze plugs at the rear of the block, and oil may leak from the rear-main seal
•Check for fuel leaks along the entire path of fuel system
•Is it overheating because of a clogged radiator?
•Look for oil leaks from gaskets and oil fittings
•Make sure the electric fan comes on when it should or is the mechanical fan and clutch operational?
•Is there plenty of power steering, tranny, and transfer case fluid?
The first step is to change...
The first step is to change the engine oil and filter. Oil breaks down and moisture accumulates in an engine when it sits. Even if the oil was brand new when you parked the Jeep, give it some fresh lube. If you have a spendy engine, pre-lube the engine before you fire it. If you don't have a tool to do this, then you probably don't have an engine that needs this kind of attention.
Engine coolant breaks down...
Engine coolant breaks down over time. It usually lasts two to three years, but beyond that you should change it. Our radiator was nearly empty, which would have caused problems after a few minutes. If your engine hasn't been started for a long time, you may want to flush the coolant system to remove all the rust that will most likely come out of the block and clog your radiator.
Fuel is another chemical that...
Fuel is another chemical that breaks down with time. See a trend here? There are a couple of products you can buy that convert gasoline back into gasoline after it has been sitting, but your best bet is to drain it and put in fresh stuff. Next time, use a fuel stabilizer if you think the Jeep might sit for a few months.
If you have an inexpensive...
If you have an inexpensive fuel filter that has been marinating in old fuel for years, the paper-style element will probably come apart and travel directly to your carburetor or fuel injection. Replace the fuel filter before starting the engine. If it's a serviceable filter like this one, clean it and inspect the filter element. If you have a metal gas tank, expect that it has rusted during years of sitting. The rust will break loose from sloshing fuel and then clog the fuel filter. Check your filter regularly for awhile once you start driving the Jeep again.
Clean the rat's nest out of...
Clean the rat's nest out of the air cleaner and do your best to remove the leaves and other flammable garbage from the top of the engine. Most stock carburetors have a metal filter at the fuel inlet. If your engine runs for a bit and then dies, pull this out and clean it. Check rubber hoses for cracks. These can cause vacuum leaks which may make the engine too lean to start or run correctly.
If you have fuel injection,...
If you have fuel injection, the injectors may be gummed up after sitting. It can cost a couple of hundred dollars to have them cleaned, but if the engine runs poorly once it is started, this may be the problem. You can check the fuel pressure at the rail on most systems to troubleshoot a possible weak fuel pump if it's suspect.
It's very likely you're going...
It's very likely you're going to need a new battery. The old Optima Yellow Top in this Jeep worked for four years and then sat for six, so it had a full life. Low voltage can be a problem in getting a fuel-injected engine to start. Rather than trying to charge or jump start a battery that's more than a few years old, put in a fresh battery to save yourself extra troubleshooting.
Let's say you have fresh fuel,...
Let's say you have fresh fuel, oil, engine coolant, battery, and the fuel filter is clean. You turn the key and-nothing. Check your battery cables at both ends. Corrosion can rob enough amperage to keep the engine from cranking, and a corroded ground strap at the engine or chassis can often be the culprit. If everything is clean or new, get out your test light and check for power at the starter solenoid terminals.
If the engine has been sitting...
If the engine has been sitting for a long, long time, you're very likely going to need plug wires soon after restart. There are two schools of thought: don't touch them and replace them if needed, or go ahead and replace them before trying to start the engine. If you need to check the spark plugs, grip the boot around the plug and twist to break the seal without destroying the boot.
If the engine cranks but won't...
If the engine cranks but won't start, you can tell a lot by pulling a couple of spark plugs. If the plugs are nasty and corroded, that's probably your problem. Put in new plugs. If the electrode and tip are clean, smell them. If there's no gasoline smell, you have a fuel-delivery problem. If they are dripping with fuel, you have a spark problem.
A spark problem could be corrosion...
A spark problem could be corrosion inside the distributor cap. These contact points need to be clean, as well as the metal on the rotor. If these check out fine and you've already replaced the ignition wires and spark plugs, check that you're getting power to the distributor when the key is in the On position. In some cases, the coil or ignition module (or points) might be toast.