Picking junkyard engines

Buddhist monks need engines too!

When a cheap engine replacement is needed, one can always take a trip to a local self service junkyard. A self service junkyard will generally charge far less than a full service junkyard. This is due to the cost of extra labor involved in pulling and testing the engine on behalf of the junkyard. Engines generally cost $ 100-300 in a self service junkyard.

The two major downsides that result in this price is the effort required in determining if an engine good and retrieving it. Even though most junkyards provide a warranty, nobody wants to lose time picking a bad engine. Every car that does end up in the junkyard made it there either due to fire, bad transmission, bad engine, collision, or a combination of. With the following list of areas to check, one can increase the chances of choosing a good engine.

• Mileage: If the vehicle has had it’s instrument cluster ripped out chances are it is lower in miles than other vehicles at the junkyard, and someone bought it to commit fraud by switching odometers to lower mileage. This happens more frequently than generally thought. If the odometer is digital, and the car has it’s keys present,the car can be started with a battery to get an odometer readout. Most junkyards will not have any issues with allowing batteries to be brought inside, so long as they are marked during entrance.
  • If you see a vehicle that has been wrecked, the engine looks spotless upon taking off the oil cap, and everything is just perfect yet the odometer reads 200+ k miles, don’t be fooled. Although not too frequent, occasionally someone will try to save an engine for themselves by being wise and switching odometers from other higher mileage cars in an attempt to reserve the great find for themselves. Be highly skeptical of unusual states, if a car you found shows 200+ k miles yet it looks cleaner than any car with less than 100 k miles, pull the instrument cluster out and compare the date on the back of the printed circuit board to the date the vehicle was manufactured.
• Orange rust deposits: Covering a large portion of the engine bay, are a good indicator that the engine overheated and part of the coolant system developed a severe leak/blowout as a result.
• Coolant: If the coolant is clean and green (or orange in some cases) this is a good indication that the coolant system was functioning well. If there is no antifreeze in the coolant and it is straight water, chances are someone has overheated the engine and had to temporarily add water to get the car to it’s final destination. Straight water also corrodes all of the cooling system components thus making the idea of using them less attractive. In some junkyards the hoses will be cut and the coolant will be drained, however some can still be obtained from the bottom of the radiator for analysis.
• Body damage: A lot of cars that end up in junkyards are written off by insurance companies thanks to overpriced body work estimates. Even something as small as a slightly damaged combination of the hood, bumper, and fenders will result in the car being written off. This usually means the car will have a good engine and transmission. If the car is damaged quite badly, this is a dead giveaway. The car had to have been moving and working well in traffic in order to get into the accident to begin with.
• Transmission dipstick: Should be checked to see the color of the transmission fluid. If the color is very dark this indicates the fluid is burned and transmission failure may be the reason for the car being there, thus indicating the engine is good. On some rare occasions the transmission fluid may be milky or contain another fluid mixed in, usually the coolant. Certain vehicles have internal transmission coolers built in to the radiator. When the internal barriers separating the transmission fluid from the coolant rust, the two fluids mix, killing the transmission after a few thousand miles (depending on how badly it mixed). This means transmission fluid likely got into the engine cooling system as well, but usually this does not cause much harm and can be cleaned out by flushing the cooling system a few times.
• Oil dipstick: Due to environmental regulations junkyards have to drain the oil from all cars they receive, usually by punching a hole in the oil pan. However this is not done perfectly and you can usually still find some left in the pan after removing the oil drain plug, or a little bit deposited on the dipstick. Since the color means nothing more than how recently the oil is changed, the only thing that has to be checked is to make sure the oil appears to be normal and transparent without any milky deposits. They indicate that at one point there was a head/headgasket failure and coolant mixed with the oil.
• Oil cap: Upon removal, one can see inside the valve cover. The valve cover can also be removed for a more careful investigation, as they are usually easy to reinstall and don’t require purchasing a new gasket. If things inside appear to be clean or have a slight brown tint, this is a good indicator of a healthy engine. If everything is black and there are thick oil deposits, this indicates the engine had a lot of blowby and oil was not changed on regular intervals, resulting in sludge buildup. Though not completely gone, the engine should only be used if no other options are available, a full rebuild with lots of cleaning may be required. Also, if the valve cover was removed, and the vehicle is an overhead cam, the cam lobes should be expected to see if there is any abnormal pitting or wear, most engines will develop a small amount over time which isn’t bad.
• Spark plugs: Are excellent ways to read the engine condition. Generally though if they are fairly clean or a little oily, this is normal, and no further examination is required.
• Compression test: After removing the spark plugs, a compression test can be performed to determine if the engine is healthy. However, cranking the engine by hand will not give accurate readings because the engine has to turn over fast enough to compensate for the usual slow leakage through the rings and valves. If the key is available this is a very easy task. However usually this is not the case, or sometimes the terminals have been cut off. It is possible to activate the starer manually by following these steps:
  1. Connect a set of jumper cables to battery.
  2. Connect the other end of the negative cable to body of the starter, or if the shape does not permit, anything else on the engine (the closer the better).
  3. Connect the other end of the positive cable to the main connection on the starter.
  4. Use a wire laying around or a second set of jumper cables, anything available, to provide power to the smaller connection on the starter. This will activate the starter solenoid and turn over the engine.
  5. If the wires are still on the starter this task is much easier, especially when it comes to avoiding accidental shorts.
  6. Crank the engine a few times and check the pressure, typically used engines will probably put out about 105-120 psi. If the main desire is to simply get the car back on the road this will be suitable.
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  what water looks like when it’s in the oil pan.

  Oil pan: Can be removed to check for any metallic deposits or obvious damage to the rods and crank. Reasealing it with RTV is easy to do and should not increase expenses from having to get a new gasket. If there is a little bit of water deposits in the oil pan, appearing as a milky color, it does not mean the engine is bad. This is the result of a car sitting outside with it’s hood removed and often times the dipstick or oil cap, allowing rainwater to get in. As long as the amount of water is small and there is no rust damage that can be seen beneath the oil cap and on the actual crank and rods, the engine is still good. By removing as much of the water from the oil pan as possible, a quick oil change after a few miles will help clean up the rest.

• Turning over the engine: If a compression test gauge and/or battery is unavailable, the engine can be rotated by hand to feel the resistance and pressure from compression. Sounds from the compression should be heard from the exhaust manifold. It should sound like “ffoooK”. If the engine turns too easy and no compression noises are heard, or the noises are not evenly spaced and only come from certain cylinders, it is likely the engine is bad.
• Water pump: Spinning the water pump to make sure it turns freely is important. Certain engines will have a ceased water pump which may have resulted in overheating. If the water pump is powered by the timing belt this could have resulted in a timing belt failure and serious damage to any interference engine.
• Cylinder head: Can always be removed and inspected for cracks and bad valves, or damage in the cylinder walls. This procedure should only be a last resort because usually resurfacing the head, buying a new headgasket set, and buying new head bolts will cost as much as the whole engine at the junkyard. However if the head is removed, rubbing alcohol, acetone, mineral spirits, or other solvents can be poured in to the individual ports when the valves are closed to check how well they seal. Very minor leakage is to be expected from a typical used engine.

Afterwords

• Often times junkyards make the foolish decision of puncturing steel oil pans to get the oil out faster, as if turning the oil drain bolt is so hard and time consuming. Before re-using the engine, welding the oil pan may be required. Do not depend on the crappy rubber plugs they put in them and RTV. One of the simplest ways is to find a bolt laying around that is the similar width of the hole, cut it really short, put it in the hole and weld the head to the rest of the oil pan. Then grind away any excess metal. An example of this done to a Zetec oil pan can be seen below:

  

Written by Alex.