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How To Revive A Hibernating Engine - 4-Wheel & Off-Road Magazine

There it is! There you stand in somebody's backyard or garage, your eyes a little bit wide and your pulse taching up. It's a dirt-cheap, no-way-to-say-no deal on exactly the older precomputer 4x4 you've dreamed of fixing up.

You barely hear the seller saying, "Well, the engine hasn't been started in a little while, but it ran fine before I parked it." You know you have to own this truck and that's it. We've all been there (or certainly will be, sooner or later).

131 9802 Ran Fine When Parked engine Photo 30848479

And pretty soon, it's time to try to wake up the sleeping engine. If the mill really has only been idle for a few months, the restart may not be a big deal. But let's take a look at a more extreme example that involves most of the problems you might encounter.

Our sleeping beauty was a '50s-vintage Dodge flathead six-cylinder engine in a pickup that the seller guessed had been parked for four or five years. Here's how we managed to revive the engine, using a low-buck, do-it-yourself approach.

PhotosView Slideshow Fuel, spark, and a relatively sealed place for combustion to happen are the three basic necessities for running any engine. You'll also want oil and coolant to keep the thing running. The water pump and radiator were loose in the pickup bed, the thermostat was missing, and mud-wasp nests completely clogged the water pump in our truck. Fearing the block's water passages might also be obstructed, we stopped at a car wash as we hauled the Dodge home. We blew high-pressure water through the water passages of the block, alternating it through the intake and outlet holes until only clear water flowed out. Beware of any and all holes, passages, and crevices in a hibernating 4x4. It's not just dirt that gets in. We should've gone straight to a radiator shop when we found the first traces of a rat's nest (in hand) in the top tank. But misers that we are, we fished out as much nest as we could with our fingers and coat-hanger wire, then flushed the radiator with water. We hoped any leftover lint would help plug pinholes but wouldn't clog the main passages. The engine runs cool; guess we got lucky. No local parts store stocked a new or rebuilt water pump for the old Dodge. It has to be ordered and is expensive. Luckily, the old pump was easy to disassemble. Water soaking and screwdriver prying loosened the wasps' mud nests. The pump worked fine after reassembly. Try to consider parts availability when you get bit by the gotta-have-it bug over a classic 4x4.
The longer an engine sits, the more the oil settles in the pan, taking lubrication with it. After as little as a year, the engine's friction surfaces may be left practically unprotected, and such a dry start-up can ruin an engine in seconds. An oil and filter change should be mandatory whether the mill has been untouched for six months or 20 years. If you can, prelube the engine using a special tool to spin the oil pump with an electric drill motor before starting the engine.
We pulled the plugs and squirted a small quantity of motor oil into each cylinder. On a flathead, this oil reaches both the cylinders and valves. On engines with overhead valves, engine-machinist Bob Cherveny of B.C. Engineering recommends popping the valve covers and using carb cleaner to zap any sludge from the rockers and valve guides. Then he says to apply Marvel Mystery Oil to the moving parts (and down the plug holes, too) and let it soak in to loosen sludge, rust, and ring corrosion. Don't get in a hurry to fire the mill, he cautions.
On a more valuable or desirable engine, a pressure oiler such as Pre-Luber could be used to circulate the oil and bring up the pressure before fire-up. We skipped this. With the plugs out and new oil in the pan and cylinders, we first turned the engine by hand to make sure everything was free. This is very important in an engine you've never actually heard run. Then we turned the engine with the starter (which, luckily, worked fine). With no load or cylinder pressure, the starter easily turned the mill. We scribed a mark on the pulley to help count crankshaft rotations.
We kept the removed plugs in order. They were in such good shape that we decided to reuse them. Indeed, they supported the seller's claim that the engine ran fine when parked. Of course, a truly savvy shopper would've checked the plugs (and lots more) before buying the truck.

The distributor cap, rotor, and coil appeared to be in good condition. There was no evidence of cracks, burned contacts, or other problems. The plug wires were surprisingly pliable and supple, with no obvious splits or flaws to cause crossfiring or misfiring. And since the plugs looked as though they were all firing, we (being cheapskates, remember) left the original cap, rotor, coil, plugs, and wires in place. We also confirmed that all vacuum lines and connections were in place and in good shape.
Like the water pump, the old generator was packed with wasps' nests. But after chipping out the mud with a screwdriver and turning the generator by hand until all the chunks and dust quit falling out, we took the unit to be tested. At first, it didn't charge, but then the tech polarized the generator by momentarily connecting the unit's two terminals with a jumper wire while it was running on his tester. Surprise: It worked perfectly.
With spark, oil, and coolant taken care of, the last hurdle was fuel. Heeding Cherveny's advice once more (and noting that still more insects were holed up in the severed fuel line shown here), we bypassed the entire old fuel delivery system (except the carb itself). Cherveny warns that even year-old gas starts to break down, leaving a varnish-type sludge that sticks to intake valve guides and causes the valves to stick open. The results can ruin an engine in a hurry.
Another great thing about simple old mills: Loosen a few screws and the whole top of the Carter single-barrel carb lifts away to reveal all the inner workings. In ours, everything was squeaky clean and free of dirt and sludge. As is common in such cases, the float's fuel-intake needle and seat required a bit of cleaning to keep the needle from sticking closed and preventing fuel from entering the carb.
Be careful when disassembling components you're not very familiar with. For example, our Carter carb's fuel-intake needle seat appears more like a fitting for the fuel filter than a part of the carb. The needle is small and can be lost easily (we spent a frustrating hour or so finding ours) when you think all you're doing is removing the old fuel filter to change to a modern one.
To bypass the stock fuel system, we rigged a gravity/siphon setup using a jerrycan, fuel line, and a marine-type squeeze bulb. This is the same emergency system four-wheelers often use when their fuel pumps fail in the field (assuming the jerrycan is secured a bit better). The squeeze bulb primes the carb to start, then siphon action and gravity usually keep a mill limping along. A proper marine fuel tank is preferable for fire safety. Either way, keep a fire extinguisher close by.
If you plan to actually drive the rig after the engine start-up (sans the emergency system), don't forget to check all fluids (including tranny, transfer case, and differentials) and make sure you've got brakes and steering. Don't laugh; we've seen some pretty old hands get excited and space out. Also remember that the engine has to turn clutch parts or a torque converter. Make sure nothing is hung up, missing, or binding between the engine and the tranny-broken or frozen linkages, dirt, forgotten tools, animal nests, and so on-that could create havoc at fire-up.
Finally, ready to fire. To prevent a fire or fuel spray, make sure a bypassed fuel pump is empty and disconnected from the fuel tank. We crossed our fingers and turned the key. Nothing but starter grind. Then we thought to clean out the rats'-nest-clogged exhaust pipe. Yes! The mill blew white smoke for a minute or two, burning off the cylinder oil we added. Then the exhaust cleared up and the mill chugged happily along. Now it needs a good tune-up and a cleaned-out fuel tank, but maybe we'll rethink our plans to swap out the torquey old six-banger.