How to buy a used car engine
Your engine has packed in. A brand-new one will cost a fortune or you can't even get hold of one. No problem, you can buy a second-hand one; but is this your best policy? There are a few questions you need to ask yourself before going ahead and starting what could be a major project, that may just go terribly wrong.
Do you actually need a full engine?
Many engine parts can be swopped without changing the whole one. Cylinder heads, valves, pistons, con rods, crankshafts can fail but in many cases they can be replaced individually. Unless the engine itself is highly suspect you may find that repair is a more economic option. It may be worthwhile getting expert opinion on this before proceeding further.
Is the engine you are thinking of buying really the right one for your car?
Manufacturers often use the same engine for numerous car models, but specifications can change in subtle ways that you may not be aware of. Mountings may be different, parts such as pumps and alternators may differ or the specifications for the mating of the engine to the transmission may be slightly different.
Just which parts are you buying?
Many people who are not mechanically minded are unaware of the difference between a long and a short block engine. If you are an experienced engineer please excuse me for explaining something you may feel is nursery school level. However, for the rest of us:
A short engine is just the stripped down heart of the engine; with all removable parts taken off. These are much cheaper to buy than what we can term a 'full' or long block engine; but the drawback is that it costs more to fit it and you would be relying not only upon the fact that none of the parts of your existing engine are defective, but that they will fit the 'new' engine satisfactorily.
A long block engine on the other hand has a cylinder head already fitted as well as the valves, guides, camshafts, and sometimes alternator and pumps as well. Provided that it is a good match for your existing engine it should be fairly easy to fit.
How good an engine is it?
lthough a second-hand engine is usually a lot cheaper than a new or reconditioned one, by the time it has been fitted it still represents a considerable expenditure and if it proves defective it could cost a great deal of money to rectify. Unfortunately it is extremely unlikely that you would be able to hear it run before buying it and so you would have to rely upon the reputation of the person selling it.
As an absolute minimum you would want to know why the car it came from was scrapped. Engine problems are one of the major reasons why people dispose of their cars, but if it was dismantled because of accident damage then provided that the engine itself did not suffer any mechanical damage there would be a reasonable chance that it would at least run satisfactorily.
You would however want to know what mileage it had covered, and whether or not the previous owner had had problems with it. Ideally you would want to have an expert check it over. Signs of excessive oil leaks or dirty oil in the sump would throw out warning signals, and any froth on the dipstick could indicate major issues.
You would want to have a guarantee of your money back if any problems were to arise within at least a month.
Is it an engine from a scrapped car, or a 'reconditioned' one?
Some stockists will provide you with an engine, which they believed to be in a reusable condition, from a scrap car.
Others however will provide you with an engine which has probably been damaged in some way in the past, but which they have repaired. They will insist on getting your old engine in part exchange and they will repair that, as well.
Some of these engineers will produce a superb engine by replacing bearings, valves and springs, and sometimes pistons as well, re-boring the cylinders in the process. Others however will merely take out the broken parts and replace them. There may be other badly worn components in the engine that you are not aware of which could cause premature failure.
It is important therefore to find out just what it is you are buying and what has been done to it. Again a guarantee should be expected and you should be sure that you are dealing with an established and reputable company.
An engine replacement can be very expensive but using second-hand parts could cut the cost considerably. It is vital however to make sure that you get the right engine, and that you know where it came from.
It is far better if the company that you bought the engine from fits it, rather than have someone else carry out this work; that way if things prove difficult there is only one person to blame, and you would not find yourself in the middle of a dispute between the provider and the person fitting the engine.