Buying Re-conditioned / Exchange Engines

Re-conditioned / Exchange Engines

The industry of re-conditioned and exchange engines is probably smaller than it used to be say 15 or so years ago.  This is probably in part due to the reliability and improved performance of the modern motor and its manufacturing standards.

Let’s consider duty cycle in relation to this category. Of course it is hard to generalise, but an engine that may have been reconditioned is likely to fit into one of the two stages of its life.

  1. Catastrophic failure
  2. End of duty cycle


Let’s take a exchange engine that has been rebuilt after a catastrophic failure.  Lets say that the engine that was rebuilt originally overheated and dropped a valve through a piston and seized. It is highly likely there may have been multiple places within the engine that have been stressed or damaged which are hard to detect. This is due to and engine being a complex assembly with many moving components.  Not to mention many special metals that can easily be damaged permanently due to the heat stresses at failure point.  It is conceivable that even an extensive re-conditioning of a motor such as this can miss critical components that may have been heat stressed and suffering from almost invisible damage and distortions.  This is why an exchange engine can possibly bring with it a inherent risk.  The person who exchanged their failed motor did so for a reason.  Of course there is many cases where the engine is basically good and a genuinely good re-build candidate.  But it will pay to be sure to only deal with reputable re-builders to be sure that they choose from only the best candidates.

Getting your own engine rebuilt is an option.  The good thing here is that it is the “devil you know”.  In other words you know exactly why it failed and how badly it failed.  But for logistical reasons it rarely works out.  This is due to the time it will take to have the rebuild done.  Unless you can wait until the re-build is done and have your vehicle off the road this is a high time cost option. The advantage is that at least you know why your engine failed in the first place.  Of course if you are able to find another vehicle in the mean time it is a very strong option and has many risk benefits if your engine did not fail catastrophically.

Price comparisons. It is also important to make price comparisons between part types. It is highly likely that you may be able to purchase a re-useable engine that has travelled kilometres that are well within its duty cycle. Or in other words it has a lot of life left to go. Comparing this to the re-conditioned motor on a dollar for mile expected life and you may find that the re-useable motor stacks up as a good option. The other factor that is worth considering is the cost of parts that you may need to replace. These can be as simple as plugs that help you attach the wiring of the motor to your car or the distributor in the engine. Often with a re-useable motor you will get many of those parts that you don’t get with a ‘short’ motor.

Short or long. Make sure you know what you are getting. A short motor is really just the basic motor. So here is a general definition of the two:

A short engine is one that has only been fitted with pistons, rods, camshaft and associated bearing etc. It does not include the heads, oil pan or any other attaching parts. The main issue this can cause is that the engine with new rings and a re-bore will hopefully have more compression. With this improved compression the head/s will be under more pressure also. This often results in leakage or bypass on things like valve stems. So a short block can often result in other parts being unable to handle the new found power of the bottom end.

A long engine includes many of the engines attaching parts such as, heads, oil pan, valve covers. But be careful. It often does not have things like the distributor or exhaust manifold. Of course depending on the state of your old engine these can have issues too that can cause the replacement motor to have issues. For example it is possible to get caught with a distributor that has unacceptable run out. (This is to do with how far off centre the shaft can run as it spins.) This can cause things like the hall affect device on the distributor to give unreliable performance.) An overheated engine being replaced will often have cracks in its exhaust manifold. It is often possible to negotiate a re-useable motor that is a drop in replacement with electrical plugs, distributor and exhaust manifold in place.  So you need to make sure to make that comparison and use that information when completing the final negotiation with a re-conditioner.

Another challenge is will there be a re-conditioned engine the same as yours on the shelf. This can be a big issue and mean that you end up having to get your engine re-built loosing a lot of valuable time.  It is a big cost for a re-conditioner to have a lot of stock on the shelf of these big ticket items.

An important consideration is that over the year’s re-conditioned engines have not all been the same. With some re-conditioners doing the minimum internal re-building to get the motor back on the road. Whereas others have focused on an extensive rebuild every time. In general you will get what you pay for. Re-building engines extensively and to specification is not a simple exercise and is a lot of exacting work. So remember not all re-conditioners are the same. The important thing to consider with a replacement engine is the cost of failure and who will bear that cost. For example let’s say the worst happens and your newly fitted engine does not start up well. Who will replace that engine and who will pay for fitting the next one?  These questions are critical ones to ask prior to the engine being fitted. If it is your re-conditioner that supplied and fitted the engine they may be happy to refit the engine for you, but you may be stuck with an engine that needs more work done. For example if you paid for a short re-build, but it is now apparent that you have an issue with your head/s you may be up for more money and more waiting.

Of course the other factor to consider is if this is a commercial vehicle or one that is critical for your work; you need to factor the time you may be down if the project goes badly, as a part of the costing exercise. If your commercial vehicle is out of action for a week and you need to hire one, what will that cost? If your workhorse is down for a day or two unexpectedly how will you respond to work you have lined up? Murphy’s law will generally rule here. Take short cuts and the chances are that there will be problems; along will come the added costs of the error off judgement.

Once again the best thing to do is stick with only the most reputable re-builders and make sure of the work done.  Check with other people that have been supplied rebuilds.  The important points are to ask what if something goes wrong.

*Much of the information here is written from the author’s own experience with re-conditioned engines. Having purchased or inherited many engines over the years, often with very pretty stickers on them and lovely paint jobs. Only to find that many of these engines failed in months or in a one to two year period of normal use. Due mainly to the issues that are covered in the text above.  There are highly reputable engine re-conditioners and when done well the engines can be good for many, many years.  But it is important to check carefully exactly what you are getting.


*The information on this site is based on the personal views and experiences of the author and are in no way an endorsement or critical appraisal of any particular supplier, product brand  or service provider.  The individual may experience quite different results in any of these areas than that of the author. Both paid and unpaid advertisements may appear on this site.  The author takes no responsibility for the performance of products and service provided by paid or unpaid advertisers or posters on this site.  Any person that uses information on this site uses this information at their own risk.