In a recent Mercedes Sprinter engine replacement (Used engine fitment) it was noticed at the time of purchase that there was an issue with No.2 Injector seal leaking. Obviously this needed attention and there was more chance of being able to remove the stuck injector once the engine was fitted, than try to do the work on the engine prior, as it would simply move around the floor with the physical effort involved!

What I did do before fitting the engine was to get rid of all the carbon ‘Black-Death’ build-up due to the leaking injector. This involved careful chipping and clearing the cables, connectors and pipes that were buried beneath the charcoal coating. If you want a really clean and sparking job, I can recommend a none-acidic oven cleaner for a final dressing, but in this case it was cleaned to a ‘practical degree’ that fitted with the age and condition of the vehicle.

Without a doubt, if you are able to start the engine and get it warm, even loosen the clamp bolts five or so millimetres above the shoe clamp then rev the engine, what often happens is the injector gets ‘blown out’ a little under engine compression and once the carbon seal is initially broken, it can make subsequent extraction a great deal easier.  Sometimes it works – sometimes not!

In my case I knew that the engine would probably not start as the seals were in such bad condition. As I turned the engine over clockwise using a 27mm socket/breaker-bar on the crank nut, you could hear the escape of air past the injector seal on each rotation. This was confirmed by localised spraying of WD-40 onto the suspect injector and watching it bubble/vaporise as air from the combustion chamber was forced by the injector during a manual rotation of the engine. I had to proceed without heat or hot engine – always makes for interesting removal!

Obviously you will have to remove the inlet manifold upper half and also the engine cover if fitted before you can gain access to the injectors. It is important to plug all the intake tracts to prevent items such as the bleed off pipe spring clips finding their way down there etc…

Once the engine was fully installed, the injector power plug was removed, the bleed off return pipe unclipped and moved well out of the way. The steel diesel supply pipe and the injector union connection were removed with a 14mm spanner and 13mm socket respectively. As soon as the union was removed the hole was plugged with a small section of kitchen towel pushed into the tapped hole. This simply prevents any bits getting into the open hole while working to extract the injector.

Rarely it is possible to clamp a pair of good mole grips to the injector solenoid fixing nut and rotate the injector ten or twenty degrees back and forth to loosen it in its bore, more often it takes a great deal more work!  Using a searching penetrant or diesel itself is a good aid to getting things moving. This twisting method can be successful, though what usually happens once you start to get going is that the fixing nut undoes slightly and puts a stop to using that method of extraction, as it simply rotates upon the head of the injector body.

What you have to do in this eventuality is grip the injector just below the solenoid nut and attempt to move the cast head part – rotationally back and forth. As the diesel supply union is completely removed, you will get the maximum chance of realising this important few degrees of movement, that will in time result in the total removal of the injector body.

If you have a 24mm open end spanner or its imperial equivalent this is your key tool. If your area of work is the rear three injectors there is a little technique that may work for you. If you lay a 19mm combination spanner along the top of the duct that carries the injector wiring, interlocking the open end into the rear intake manifold support bracket, this will provide a sturdy supporting surface on which to lay the ‘operating’ slightly slack fitting, 24mm spanner onto whilst moving it back and forth. As you will probably only be able to shift the injector a few degrees back and forth at first, it is important to keep the area well irrigated with penetrant. As your movements get more dynamic, begin to press the back of the operating spanner down onto the 19mm rider. Keep pushing as you rotate back and forth. This induces a small lifting force under the solenoid nut from the 24mm spanner and as you move it, it will in time begin to raise the injector out from its bore. If your injector is at the forward end of the engine you will have to locate the 19mm ‘rider’ spanner’s open end somewhere up-front to fully enable this method, but it is not impossible!

Mercedes CDI Diesel Injector

Eventually you will extract the injector – a feeling of achievement will appear as you take an inspection mirror and torch to peer into the blackness from where it came. If you were lucky then the copper washer/seal will have accompanied the injector out of the hole.  If not, a ‘rat-tail’ round file of suitable size, pushed into the hole will retrieve the seal without issue.

Now you can begin to inspect the seal itself, giving up many clues to the demise of its capability to hold pressure. Clean it with a rag and take a close look at its copper surfaces. If there are any scored lines, cuts or deep marking, this is the route the escaping combustion gasses have taken to ‘carbon-up’ your engine with ‘Black-Death’. Indeed any gas-cut passages in the sealing surfaces will have most certainly also cut into the aluminium injector seat and in severe cases damaged the steel injector face that mates with the copper seal.

I would recommend always at least cleaning the recessed seat of any removed injector with a special tool made for the job. This special tool is a flat face end-mill or reamer with the correct diameter sleeve to cut or reface the base surface with some precision. These tools are available from Laser for under £60 from most motor factors and are essential to DIY replacement and the successful re-sealing of injectors – experience has found in every case, if you don’t at the very least ‘lightly face’ and prepare the injector seat before reinstallation, you are not giving yourself the best chance of success, therefore I would get the proper tool for the job, period!

Escaping combustion gasses often cut the aluminium seat and this needs to be re-faced so that a perfectly gas tight seal can be maintained

One or two rotations with the seating tool will be sufficient to enable you see if the seat is damaged in any way, using your inspection mirror and light. If there are any black marks on the seat (rather like worms!) as the drawings below show, then continue to use the seating tool, checking and wiping aluminium shavings as you progress to remove material. Eventually the tool will re-face the damaged seat to show a clean, uninterrupted ring of aluminium. It is possible if you do not fully rotate the tool when using it, mistakenly rotating the tool left to right rotationally, may cause the finished surface to have ‘chatter’ marks on it. This is surface unevenness that must be removed and is only achieved by turning the tool lightly and continually in one direction, stopping movement only as you simultainiously relieve pressure from the cutter. Inspect and clean often, to obtain the best surface finish possible.

Improper use of the seating tool sometimes causes chattering on the surface of the seat. This needs to be smooth and not disrupted with tool marking

Now turn your attention to the face of the injector body that compresses against the copper seal. This must be free of any carbon build-up and ‘shiny clean’. You can take some fine emery paper and lightly work this surface until it is bright and continuously clean around its circumference. Now you are almost ready to reassemble!

The injector hold down bolts are a one-time-use, stretch to yield fastening, that must be new and unused on each replacement. Cut a short groove with a saw file to make a thread cleaner out of the old bolt and use this to freshen up the tapped hole for the clamp bolt. Use a thin screwdriver to clear the oily debris from the bottom of the hole as it often builds up here and can if not removed, be forcefully compressed into a plug, causing it to burst through into the cylinder head water jacket – take special care to clean this hole out!  If the thread is damaged in this deep tapped hole you have a number of repair options, these are covered briefly in this post.

Now you can use ceramic grease to coat the outside of the injector body (not the tip or any mating/sealing surfaces) place a new preferred Honda Accord Diesel Seal onto the injector tip and carefully lower it into the clean and prepared hole. Do be sure to have one final check with torch and mirror to make doubly sure there is no debris left on the sealing surface before final assembly. Once the injector is fully inserted, with the fuel connection pointing to the fuel rail, add the clamp and loose-fit the clamp bolt to hold things in place. Now refit the fuel union to the injector, removing the tissue plug that has prevented dirt getting inside, then refit the steel fuel line from the injector union to the fuel rail, finger tightening the union nuts. Now torque the clamp hold down bolt to 7Nm plus 90 degrees (MB Specs say 90 plus 90 degrees after 7Nm, but actually the yield has occurred after the first 90 degrees and clamping force reached, so I see little point in risking further stressing an otherwise ‘spindly’ and fragile fixing). You may now refit the fuel bleed off pipework, electrical connector and tighten off the steel fuel line unions. Rebuilding your engine is now a reversal of dismantling. (remember to remove the manifold intake plug of rags or paper before fitting the upper section!)

There are a few tips here that hopefully will help you achieve this sometimes daunting job, but with care, patience, the right tools and a little effort this can easily be done by a DIY mechanic.

Some time back the brake caliper on the drivers side of the Mercedes Vito (W639) was giving trouble. It was sticking badly and as a result stuck on one day to the extent that generated hear melted the brake pad warning sensor.  Obviously I dealt with the sticking caliper but at the time I did not have a replacement sensor to hand so I joined the two ends of the remaining wires just to extinguish the warning lamp on the dash.  To read how the sticking brake caliper was repaired read here.

It was a nice afternoon and I had little else to do, so I decided to fit the sensor that I had purchased from the Motor factors as a replacement for the ‘work-round’ but so far had not had the chance to fit it – Ideal play day job!  The part was just under £4.00 from the motor factors, with an OEM part number of 906 540 15 17 or  a VTECH aftermarket part code of  649ME0130 – should you wish to order one.  Interestingly, you often get a pair of sensors with a new set of brake pads but if you choose Mercedes parts you have to additionally purchase the sensors individually. 🙂

I must point out that if you do get a light on the dash, warning you of low brake pad thickness, please investigate it, as its probably warning you of the actual wear condition and not a faulty sensor like in the case investigated here. (I knew it was a faulty sensor, so ignored the light for a few weeks!)

The warning light on the dash does extinguish automatically once the faulty sensor is replaced, simply by cycling the ignition.  In the video I use the Autel Maxidiag code reading diagnostic tool to investigate if the fault is stored at ECU level and how the effects of clearing the logged fault with the diagnostic tool resets the dash warning lamp.  Interestingly even once the fault code is cleared (Key in – engine on), the dash lamp remains illuminated until the ignition is cycled, unlike the majority of cleared engine fault codes that immediately extinguish the warning lamp when actioned by the diagnostic tool, either engine running or static with ignition on.  Watch the video, its simple stuff but there is some interesting commentary if the job is new to you.

Replacement of this sensor is quite simple, all you have to do is remove the road wheel and remove the brake caliper as if changing the pads.  Once the caliper is removed, slip out the outboard pad and install the sensor in the provided cut out on the steel backing of the brake pad lining.  Thread the sensor connector through the access hole in the caliper as you reassemble it. When the slide bolts are in position and tightened, plug in the pad sensor to the mating part that is bolted to the brake carrier assembly.  Replace the road wheel and cycle the ignition.  I hope you find this of some use.

For whatever reason you may be looking to purchase a used replacement engine, there are quite a lot of pitfalls that you may fall foul of if unaware. I hope to highlight some of the things to look for and be aware of when searching for that ‘mechanical bargain’ in the small ads or breakers yard.  Indeed this guide could be used to assist you if you were about to purchase a used van and needed to know/check a few things out indicating the condition of the engine before you buy.

Probably the most obvious thing is, ‘can you hear the engine start and run’?  Without doubt this is the best way to buy a used engine. Quite often engines may be removed from a scrap vehicle and sold on this basis.  They will frequently be strapped to a pallet or resting on an old tyre waiting for sale and although there is little you can do about that, there is a few things you can check to be more positive about your potential purchase – especially as you will not be able to hear it run!  Don’t forget to take along your torch on any reccy’ as you will need this for most of your checks.

If you do get chance to inspect an engine while it is still in the vehicle, make a mental note of the mileage and ask questions of the seller – even before you lift the hood/bonnet or turn the key. It goes without saying the reason for the sale should be credible, if the rest of the van looks good, one would ask why the engine was being sold – is it stolen and being parted-out?  Just be aware.

Always better to hear a used engine running if possible

If the registration plate is still there make a note of this too, along with any vin number.  The purpose of this is to have all the information to hand if you need to later double check if the engine is compatible with your vehicle, these are the details that a dealer or independent will need to cross check the parts on his system to confirm compatibility with your own vehicle if you are in any way uncertain.

Have a quick look at the engine in situ, dip the oil and look into the coolant expansion tank – it is that the vehicle was front ended, the radiator will likley be broken and there will be nothing to look for in here, but have a look anyway.  It should be clean inside with no frothy oily mess and should not be coated with thick brown rusty sludge.

As with any other vehicle purchase if you can, you will want to hear it run from cold. It should start without hesitation and soon settle into an even idle.  Try and gauge if it is as quiet as your own engine was when it was working properly.  If there is no coolant, you will not be able to run it for long so quickly pull of the breather hose from the oil separator or turbo intake pipe and look for smoke and pressure here, if either is excessive walk away.  This is an indication of worn bores and/or piston rings and really not what you want to be buying into.  You can look for fumes and blow-by pressure at the dipstick tube also, but this is not always as conclusive as what can be seen at the breather pipe.

Can you here the turbo spool up?  If you are in doubt remove the air cleaner cover or intake hose to the turbo body and dab the throttle.  You should hear a healthy howl if everything is working correctly.  Glance back to rear of the vehicle as you rev the engine and make sure you can still see the sky!

Below is a checklist to help you assess your potential ‘running’ or ‘palletised’ engine purchase, some items in this list may/may not apply:

Coolant Expansion Tank (Front right hand side slam panel area)

Should be clean inside, no brown sludge, no oily mayonnaise. With the engine cold and running, carefully remove the filler cap and place your hand over the coolant reserve neck, get an assistant to blip the throttle, there should be no pressure to lift your palm off the lip.  Have a quick glance inside – no bubbles is good.  Problems here could indicate a potential head gasket issue.

Oil Separator (Top of engine behind oil filler cap)

While it is normal for a high miles engine to be a little ‘wet’ with oil around this area, any white smoke or fumes beyond the ‘barely visible’ from the vent pipe that runs to the turbo inlet could signify worn bores and/or piston rings.  Pull the pipe from either end and observe to be sure. Do not be too concerned by traces of oil here and also if the pipe is gummed with a little mayonnaise as in many cases this is normal.

Check for excess crank case pressure – inspect the oil separator pipework

Water vapour, moisture and condensation escape from the crank case and exit here to the turbo inlet.  The device that is present on the lower pipe is not a sensor it is a small heater! This actually stops moisture and crank case water vapour freezing in the vent pipe in colder climates, blocking it.

Oil Dip-Stick

Pull this and check the oil level, there is not much to be told from the black oil that will be on the end but caution must be observed if there is any water droplets, froth or whitish deposits on the stick. As with the coolant tank inspection any issue here could mean that the head gasket may be suspected as leaking.  Any obvious quantity of water in here could also mean that the oil cooler fixed to the side of the oil filter housing is passing pressurised water into the engine – not good. There should be little or no pressure, or smoking from the open dip stick tube.

Oil Filler Cap

Pretty much the same visual inspection applies as above. Do not remove the oil filler cap with the engine running – you will have an ‘oil-shower’, as the duplex timing chain runs directly beneath the cap.  If there is a lot of oil around the filler cap it is not unusual for the cap-lip to be slightly split, allowing oil to pass out onto the rocker cover and run down the left of the engine finding its way onto and into the alternator!

If there is oil around the filler look for a split plastic filler cap on the lip – Simple fix

Leaks – Visual Inspection

Start from underneath with your torch, you will not need to jack the vehicle, just slide under and look under the front bumper.  Places with oil staining and dripping will be very easy to spot. While most oil leaks can be fixed, there are some cost implications to be considered depending on what and where the leak is.  A leak around the crank pulley for example will mean it will have to be removed and a new seal fitted, often if this has been leaking for a while the harmonic  damper pulley (if fitted) may have suffered deterioration due to the oil. (See Harmonic Damper Pulley in the check list)  Oil may be leaking from the rocker cover, do not assume this will be a simple fix, if it is going to be a problem all the injectors have to be extracted to remove the cover and replace this gasket, doing so can sometimes open a whole can of worms (Injector removal and so on). Lots of oil around the turbo body is not a good sign, it should be reasonably dry and in most cases the iron casting should remain red rusty.  Look beneath the turbo and seek out where the turbo oil return pipe enters on the sump line.  This could be oily, contaminating the surrounding area, indicating the oil return pipe seal requires replacement.  (two gallons a min. circulate through here!) The turbo/manifold has to be removed to replace this commonly failing seal.

O ring seals are simple to replace to cure oil leaks on the HP Diesel and Vac pump bodies

Oil leaking from the area behind the vac pump (or diesel HP pump for that matter) and running down the face of the engine block are usually a simple fix. In each case this is a large diameter ‘O ring’ that seals against the block and is simple to rectify.  Any diesel leaks should be investigated carefully and if found to be from the high pressure diesel pump (triangular shaped pump block on the front of the engine) head casting seams could indicate new seals or pump are required – not a cheap fix for a replacement pump. (It is worth noting to make sure the viscous fan central hex bolt is free and not seized before any engine installation, as this could hamper future diesel pump work)

Look also at the joint between the gearbox bell housing and the rear of the engine, any serious black engine oil presence here could indicate a crankshaft rear seal that is weeping.  Not a huge job to do when the engine is out but best avoided if at all possible, certainly another tick or cross when you are debating your offer price.

Water leaks should be easy to spot, especially if antifreeze is present in the system.  It will leave tell-tale staining in the form of a coloured salty scale.  Look at the water pump behind and up from the crank pulley there is a tiny hole in the pump casting nose, any staining or wetness here could mean the pump seal is failing and will be due for unit replacement.  Obviously hoses are an easy fix if leaking and should be all checked before putting the engine into service in your own vehicle.  Importantly include the small bypass hose at the rear of the block RHS above the starter motor area, this is a nightmare to replace once the engine is in situ due to poor access.

Noted leaks from any diesel related item or component must be investigated as these could be costly to rectify. (See Injectors Injector Cover in the checklist)

Harmonic Damper Pulley – Crank Pulley

While not a major issue to rectify if found to be suspect, it is worth checking the harmonic damper/crankshaft pulley that lives at the bottom front of the engine – it drives all the belts and is the main pulley from the motor crankshaft.  This is made in two mating parts, bonded together with a rubber metalastic material that is designed to absorb crankshaft borne detonation pulses, reducing noise and vibration of the running engine.

Pulley and idlers are worth a look

What happens over time is the rubber sandwich deteriorates (often through oil contamination) and the two pieces begin to part company.  When things have got quite bad, the pulley begins to make a ‘clacking’ sound as it rotates (usually people tend to think its a far greater internal engine problem, as it can get very loud indeed) It is actually the pulley edge catching on the crankcase as it revolves. Its presence can sometimes occur only under load as the pulley flexes it can be hard to spot.  Look at the pulley with your torch and identify the rubber seam circumference, if it looks tired and cracked then budget to replace this before you refit the engine as failure can result in expensive engine damage. In itself not a full diagnosis, but you can also try to gently pry bar the edge of the pulley away from the block to get an indication of any detrimental flexing that may be present.

Injector Cover – Injectors

This is probably the most important check that you will do and will be the most awkward, both from the point of view of asking the seller if you can take a few parts off to inspect it and also from the point of view it will take you about 20 mins to complete.  What I would do is leave this as the final ‘deal breaker’.  If you are happy with what you see, agree with the vendor a price on the proviso the injector inspection proves satisfactory and explain that without this inspection you are not interested, whatsoever – This is actually very true, as if overlooked and bought blind, the engine could land you with a bill approaching and exceeding what you have just paid for the complete engine!  Of course if the injector cover is not fitted or missing further inspection is easy and far less of an issue for all.

This looks a great clean engine…

Having agreed your ‘investigation’, you will need four tools. A flat blade screwdriver, reverse torx socket wrench or a 10mm/8mm ring spanner and a 5mm hexagon key. Undo the turbo inlet hose from the inlet manifold and tuck it out of the way.  Undo the 8x torx pins holding the top of the inlet manifold to its lower section, remove the single pin at the front near the fuel filter and the rear fixing pin behind the plastic manifold, on the top left looking in, just sneaking under the bulkhead. (This one is often not fitted/missing as it is a PITA to get at – again a measure of lesser quality servicing maybe!) Lift off the upper inlet manifold section. This will reveal the 6x injector cover hex cap-screw fixings.  Once these are removed, lift up-and-off the injector cover.  If it makes a ‘crispy crunchy’ noise as you begin to lift it away, you could almost refit it at this point and just walk away!  Once you have the cover removed all should look fairly clean and oil free under there.  Be aware the oil separator may have deposited a little oil around the adjacent area but the overall appearance should be clean and dry. Any black carbonous coal like substance and you will have some work to do.  This condition signifies the injector seals have failed on one or more injectors and will need to be replaced, as combustion gasses are blowing-by the injector seats/seals and depositing carbon waste on the engine surface.  The common name given in the trade to this condition is: ‘Black-Death’.

Mmmmm maybe its worth less than I first thought! A bad case of Black-Death… It should look like the first image at the top of this post.

The presence of any Black-Death around the injectors will and should drastically effect your offer price downward. This job is known to be very difficult to price, as issues encountered along the way could range from injectors that cannot be removed, stripped hold down clamp bolts and deep cut sealing seats in the head pockets due to passing exhaust gasses. Each extra issue encountered, over and above normal labour cost, will soon double or treble the overall cost of repair and caution should be heeded when making your offer.  Be sure to make your bid based on a worst case scenario.  There is plenty to read on this subject both here on Gen-In and on the web, just Google it and learn what you need to know.

If the vendor does not understand the issue you have uncovered, then simply look elsewhere, at least safe in the knowledge your decision was made wisely and with due diligence.  Overlooking to check here can cost you dearly! Look at the engine above that otherwise looked a very good buy indeed.  You have been warned.

Sound and Vision

Satisfy yourself that the engine sounds good (if you get chance to run it) and that there is no knocking or tapping noises over and above the normal engine song.  Any metallic ‘Brrrrap’ possibly from a little end heard under a throttle blip, or heavy knocking noticed under load or overrun, then leave well alone and look else where.

Place your hand over the exhaust at idle and feel the regular pulses from the exhaust, if irregular there is a chance you have a slight misfire at idle and this may need work in the future.  Poke your fingers up the exhaust pipe and wipe around, hopefully this is dry sooty-black.  If its ‘sticky’ or ‘oily’ this is probably an indication of water or oil passing through the exhaust and in my view  would be best avoided.  Look at the emitted gasses from the exhaust – all but for a slight whiff of black soot, visible on a sharp jab of the throttle is good.

You don’t want oily smoke like this… Blown turbo in this case.

Any white smoke, as severely shown above indicates oil presence – worn engine or turbo.  White smoke that ‘magically disappears’ or dissipates quickly is likely water from a suspect head gasket.  Listen to the auxiliary belt as the engine idles, is it flapping around? Look at how it runs over the pulleys, is it straight or canted over? If not running true or overly noisy this could signify worn idlers or failing belt tension device. Check to see all the pulleys on the drive belt route are true and not wobbling, indicating worn bearings that will soon need replacement.

Check belts for flapping, running true especially round the harmonic damper/ crank pulley – this could indicate de-lamination

When you turn off the engine it should stop without fuss, any clicking or snapping, cracking noise could indicate that the ‘sprag-clutch’ on the alternator pulley is failing.  Turn the serpentine auxiliary belt over with your fingers, if its cracked or worn it is usually a good indication the van has not been regularly serviced as this would have been changed under the maintenance regime.

As a rule of thumb an auxiliary belt in this condition is an indicator of poor servicing.

Similarly the age and appearance of the fuel filter canister often gives away the lack of recent servicing.  Overall you should be happy that the engine appears to reflect its mileage – remember you are not buying new and its unlikely that it is going to be perfect. It is mainly all about minimising your risk and getting the best deal you can without spending a fortune on rectifying a catalogue of unknown problems even before you get to grafting the replacement engine to your own transport.

Turn It Over Beethoven…

It goes without saying if you are buying a ‘static engine’ out of the vehicle, do make sure it turns over by rotating the flywheel, a simple thing to do but often forgotten in the heat of the moment – who knows how long the unit has been standing?

Turn the engine over a couple of rotations to make sure its all free

Electrical Loom – Model Year to 2006

If the engine has had its loom cut – often the scrap dealer considers just the engine to be of value and not the ancillaries – be prepared to negotiate your price down a little as its a time consuming job to swap your existing loom over to the replacement engine.  I had a replacement engine come in that was ‘loom-cut’ about the point where it passes across the left hand engine mount.  On this occasion I chose to cut our own existing loom section and solder/heat-shrink the individual wires to the ‘new’ engine to make up a serviceable loom. There were sixty wires or more to deal with, although time consuming it is possible, noting a few important provisos I discovered along the way when carrying out this task.

-1 Wire thickness is important when choosing your colour match – there are often pairs of wires sharing the same colour code and tracers only decernable from each other by their relative thickness. Make sure you get this correct,

-2 The ‘Twisted Thicker’ pairs of cables are injector cables and share the same colours as other conductors.  Make sure you keep the twisted pairs together when joining.

-3 There are two identical ‘Black with Yellow Tracer’ wires in the loom bundle at this point. One goes to the starter motor solenoid, the other to Glow Plug No.2  Make sure you meter these wires out and ensure you have continuity to the correct points.  The Starter cable goes back to the grey ECU connector and the other glow plug supply should route to the glow plug module loom connector.  Just make doubly sure these two Black/Yellow wires that are of identical gauge are joined and routed to the correct point or the vehicle will not have a start signal to the starter.  If after the rebuild you suspect this may have been overlooked as the starter does not spin, its an easy check to test continuity between the starter solenoid cable ring tag to the glow plug module supply. If it bells out then you will have to split the loom and swap over the two black with yellow tracer cables – a good reason to double check this in the first instance!

-4 If your purchased engine has its loom in place you should at least give the ECU connector plugs a once-over, as if its been standing outside for any length of time moisture may have begun to work its evil on the fine connections to the brain of the vehicle.  If these look good thats great, but worthwhile treating them to a squirt of switch cleaner and moisture repellant before locking them home in the ECU.

And just before you hand over your cash…

Hopefully the above has given you a little insider knowledge to be able to assess wether the used engine you are considering is worth what the seller is asking and that you factor in any remedial work into your repair budget before ‘splashing the cash’.  There are undoubtably some bargains to be had out there, equally there are also rogues who know the full nature of the faults/condition of their engines, looking for a fast return.

Always try and get a written warranty of some sort for the engine where possible, at least one that covers it running without issue when fitted.  If you are buying from a local source maybe ‘in the trade’ and they are reputable, it is worth an extra few dollars/pounds over a private sale to have the security of even a one month warranty – It is worth remembering too that although your extra labour costs would be lost in any claim, removing and returning the faulty engine – often its better to secure the return (at least a large proportion) of your hard earned than not.

I am sure the opportunity to purchase from a private buyer will crop up and the normal ‘caveat emptor’ rules apply but with careful inspection and honest pricing, taking into consideration any faults noted, there are bargains to had from genuine people.  Just remember, minimise your risk as much as possible by using care and vigilance – knowledge is power!

Obviously this has not covered every single check-point or eventuality, but it at least prepares you for what you may find on your mission! I hope that it has at least helped you out a little.