It must be bewildering for someone buying car parts on ebay. Especially an expensive item like a turbocharger. I want to explain the differences, what to look out for.
You have been told that your turbo has failed, car smoking, noisy or totally dead. That'll be expensive. Well maybe not too bad actually. First of all, turbos don't usually fail of their own accord, lots of the time it is oil starvation, poor oil change schedule, overfilled, underfilled, wrong grade etc etc. So find out why.
OK so you need a turbo. If you are on a really tight budget, or will be selling the car on again quickly you might look at a secondhand one, but this has not been checked or tested. What is the labour charge? can you afford to pay it twice? because fitting a 2nd hand unit is really hit and miss. sometimes you can be lucky, sometimes not, are you a gambler?
New turbos, well they are obviously the best are they not? More and more turbos we are seeing on ebay are not original items, they are copies, usually originating from China, they won't have any manufacturers markings on them and in our experience are not made to the same standard, tolerances and sizes might be different, wastgate settings will be "generic". If you are considering one of these, find out more about it and what warranty you are getting.
Reconditioned/Remanufactured - well first of all let me tell you what we at The Turbo Guy, call reconditioned. Every reconditioned turbo will be completely stripped down and cleaned, all external corrosion will be stripped back, all wastegate or variable vane parts will be cleaned in an ultrasonic cleaner, and prescision checked for wear and damage. Central housing or core, will be opened up and thoroughly checked and measured and ALL bearings and oil seals will be replaced and the whole assembly will be balanced to higher that manufacturers specifications. If the inernal core is worn we will replace the core or CHRA with a brand new core at a considerable expense to us, often eliminating any margin from the repair. Lots of turbos don't make the grade with to much wear and will be off to the scrap bin!! This process takes alot of time and investment in expensive equipment.
Unfortunately we have seen lots of turbos described as reconditioned which have not been through any kind of reconditioning process, lots which have just been plastered in spray paint to look like new, or worse have been "reconditioned using 2nd rate components and not balanced properly. An unbalanced turbo will not last long, bearing wear will be accelerated by shaft vibration and these turbos tend to be noisy or whistly. Find out from your turbo reconditioner what process they use and what warranty they are putting on the repair. A correctly repaired turbo from an experienced repairer should probably be of better quality than a new one, because they have a reputation to look after!
Only turbos balanced in a VSR or vibration sorting rig balancer will last as long as an original unit. Not all turbo repairers have a VSR balancer due to their considerable cost, for any variable vane turbo charger or VNT turbo, which is most of the current turbo diesels, MUST be balanced in a VSR balancer.
Oh and don't even get me started on repair kits, without being balanced, that is a really short term answer!