1.6D CS engine to 1.9D AEF SWAP

I wanted to swap the 1.6D CS engine in my T3 Autohomes Kamper for a 1.9D, because the 1.6, although it was a full recon with 10k miles only, would not keep 90kph up motorway inclines in UK and more particularly Europe. It's important for safety to stay ahead of the trucks, and we have come across some seriously steep inclines on two lane motorways in Germany and Spain where trucks aren't permitted to overtake. They get very irritated when baulked by a campervan, and in one case a Portuguese trucker tried to physically sweep us off the road. We don't need more speed on the flat as we're quite happy to cruise at 62MPH (100kph). Our journey times seem to be more about keeping going and avoiding jams than about top speed. The aim was to end up with a van that would be as reliable as it was before, with no compromises on engineering integrity. So every aspect of the swap was investigated with reliability and simplicity (and possible improvement) in mind.

I had been pleasantly surprised at the 15% estimated improvement we got by reducing weight and air resistance by replacing the old Autohomes Kamper pop-top with a sleeker, lighter version. The 1.9 engine would give a further 24% increase in torque as standard, and with improved breathing could probably be upfuelled by another 5-10% without too much smoke. Altogether that's a 50% improvement on the original spec. I was aware that the van would probably feel undergeared if I kept the original transmission, but didn't want to trade off hill climbing ability for top speed. I could always decide later whether to trade some of the torque for top speed by longer gearing or taller tyres.

Which engine to choose? Either a 1Y or an AEF are normally aspirated 1.9 diesels built on similar block and cylinder head to the CS. Either would give 64bhp against the 54bhp of the CS, and the increased torque would be in a similar rev range to the old engine. 1Ys and AEFs have a throttle cable so will operate without electronics. A turbo would give more power, but at lower revs, necessitating a change of gearbox, and the engineering complexities and reliability issues of cooling oil, water and intake air. All that ruled a turbo engine right out for me. Other issues might be engine mounts, and interference with the engine bay cover. Also I'd want whatever I ended up with to be understood by Pierre, Fritz, Paulo, Dave, or whichever mechanic was called upon to repair it in my absence.

So I looked for 1Y and AEF engines at car breakers, and on a well-known internet auction site. Breakers had no 1Ys, but all had AEFs, already removed from donor vehicles. I found an AEF locally on ebay, and was able to see it running in the donor Polo. Cost me less than £200 for an 80k engine. The reconditioned CS engine that was in my van cost me £1200. To me that's a bit of a no-brainer, if you're prepared to take the risk of a used engine, it has to be better value.

I'm going to describe all the issues I came across, one by one, with the solutions I came up with, and the thinking behind the decisions. My apologies if I'm teaching some of you stuff you already know, and much of the knowledge has been gained from too many other people to acknowledge here. I wanted to gather ALL the information for this particular swap together in one place. This is not a set of instructions. Information and opinions are provided in the spirit of being helpful, everyone should interpret and use the information carefully and safely according to their own circumstances. I have assumed that you have suitable skills to do a like-for-like engine replacement. Some minor welding and simple metal fabrication skills are required, as is the ability to do some reliable electrical wiring. All the information provided relates to the differences between the two engines.

I don't claim to know all the answers either. Please, if any of this is wrong, or can be improved, then add your bit. Where I know my knowledge is skinny, I've asked for more info. If I'm talking b*ll*cks please tell me, I won't be offended.

BUYING THE NEW ENGINE

Try and see it running in the donor vehicle. Polo cars are likely to have been more gently treated and have lower mileage than vans or pickups.

The new engine needs to be complete with diesel injection equipment. Most that I have seen being sold by scrappers are sold without the pump. You can't easily use your old Bosch injection pump on these engines.

Try to get the engine with all ancillaries and bits and pieces that connect to it. As`well as all the diesel injection gear, you will need the alternator (plus connectors and a few inches of cables), water pump housing and pump, power steering pump with connections (even if you don't have power steering), belt tensioner, fuel pipes, cam cover breather, cam belt covers, crank damper/pulley, oil filter housing.

You will not require the flywheel, dipstick, or sump, except that the dipstick and sump will protect the engine against dirt, till it is installed. You also won't need the electronic controller, or the key and transponder.

INLET TRACT

The air inlet system is important for noise reduction, and for providing the maximum quantity of cool air for combustion. It is situated in the left hand duct rising at the side of the engine compartment. The original is quite well designed in that it takes air from a high pressure point in an air scoop generated by vehicle forward motion, just behind the grille, but on mine, the corrugated tube leading down to the plastic bend was broken and appeared woefully inadequate in cross section for even the 1.6, let alone a 1.9. Intake breathing is very important for minimising smoke and maximising power in a NA diesel.

I re-used the original plastic top terminal, used a bit of wood to wedge the intakes open a bit and used a heat gun to reset the plastic. I threw away the corrugated tube and replaced it with a 600mm long piece of 90mm builders PVC duct (bummed from a contractor burying telephone cable ducts) which I reshaped to an oval section and bent slightly with the heat gun, so that it fitted in the void without touching the sides. A bit fiddly to install over the bottom bend and the air scoop, and seal with silicone, but it gave a slight increase in speed at the top of my test hill, even with the old 1.6 engine.

I used the intake manifold, air box, and filter from the CS, as it was all easy to fit, cleared the chassis, (just) and was easy to make air and noise tight with the original intake air tract. The oval ports on the CS manifold didn't match exactly with the D shaped ports on the AEF engine, so I made a token attempt at matching them (and the manifold gasket) using a round file. On the left is the modified port, the original on the right. 

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There is not enough metal on the inlet manifold to do full accurate port matching, but every little helps on the inlet side. I also cleaned the engine of all the crud deposited in the inlet ports by the EGR valve, making sure the valves were closed before cleaning the ports. I used the CS inlet manifold gasket as it fitted much better than the new 1.9 gasket.

Important that the whole inlet system is leakproof to prevent noise breakout. The new setup gave a very slight increase in noise inside the van as the old corrugated tube had a built-in noise attenuator, and my PVC pipe did not, but I sorted that by fitting soundproofing to the inside of the vertical air duct. The noise outside the van was noticeably more, but I'm not so fussed about that.

The air filter box is 12mm further to the left and slightly higher due to the slightly taller engine block. So I had to fabricate a couple of wiring clips to raise the wiring harness a couple of inches to clear. I slightly modified the profile of the inner skin of the wheel arch at the front of the air filter box with a lump of wood and a big hammer, and used any tolerance in the engine mounts to move it as far to the right as possible. The aim was to have about 15mm clearance round the air box.

The choice was between the original CS exhaust manifold and system complete, or I could have used the AEF manifold and fabricated a pipe using the AEF flange, with larger diameter tube coupled to an Early 1.6TD silencer, which would mount on the original points. Of course I would have to blank off the old EGR valve flange on the manifold too. Seemed like a lot of work for not much gain.

Although the larger diameter system would present less resistance to exhaust gases, and hence promise slightly better performance, I reckoned the difference would be minimal. I opted for the original CS system complete, as I couldn't be bothered to do the fabrication, and if a special broke, no-one would be able to supply a new one off the shelf.

So I fettled the manifold to improve the gas flow a little, and left it at that. Oh, and one other thing while we're on the exhaust system.....because of the taller engine the exhaust needs adjusting (pulling out by 12mm) at the joint between the downpipe and the silencer. If this joint is rusted solid a complete new exhaust will be required, cos it won't fit!

Perhaps when this exhaust eventually needs replacing, I'll have a go at evaluating a custom system.

DIP STICK

The AEF dipstick is on the wrong side of the engine, so I blanked off the old hole by tapping it 12mm and inserting an Allen headed bolt with loctite 271 sealant on the thread, and for good measure a fibre washer under the head.

The new dipstick hole was drilled through the thoughtfully provided boss on the other side of the engine with an ordinary electric drill, while the injection pump was off the engine. I drilled a 12mm hole to a depth of 17.5mm to the shoulder, then changed to a 10mm drill to go right through. I snapped the drill because I didn't use a backing block to ease the breakthrough.

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That's Mrs CtF putting in an appearance by the way.

I chamfered the top edge so the dipstick O ring would slip in easily, then installed the dipstick and tube and measured the distance below the sump flange, and compared it with the old engine. Depth of the hole was spot on. The tube had to be bent away from the block slightly to clear the bypass hose. With hindsight I realise I could have drilled the hole at a slight angle to save having to bend the tube. The original tube fixing bracket was ground off and a new one welded on nearer the top of the tube, using the bolt where the water pump bracket fixes to the injection pump bracket.

FLYWHEEL/CLUTCH

I used the original CS flywheel, with new bolts of course. Very important to install and grease a new spigot bearing in the end of the crank, as the AEF doesn't have one in the Polo application. The CS clutch should easily be able to cope with the extra torque, and had only done 10k so I re-used it. Normally I would put a new clutch in as a matter of course.

Oh, and I fitted a new input shaft oil seal in the gearbox.

SUMP etc

Because the engine will lean over at a greater angle than in the Polo, the CS cast sump, and the oil pump pick up pipe must be used, with a thin sump gasket. I used the rubber gasket from Brickwerks, which is a bit thicker than the standard version, but just fits. The AEF windage tray (that's the steel pressing with the rubber sump gasket) is too thick and cannot be used, as the bellhousing bolt holes into the end of the sump won't line up with this fitted. This sump gasket is below the oil level so must be a good seal.

CAM COVER

The AEF cam cover must be used, complete with the filler cap, and this will have to be used for oil fill due to the oil fill pipe being fouled by one of the auxiliary belt pulleys. I removed the whole oil filler pipe and fitted a fabricated blanking plate using the original gasket.

WATER PUMP AND ALTERNATOR ETC

I would have liked to use the original vee belt setup with the T3 water pump and alternator etc for the sake of originality, but although it looked like it would all fit, the mounting bosses on the AEF block make this quite impossible, so I had to use to use the AEF water pump/alternator/flat ribbed belt setup complete. This setup needs an idler pulley at the power steering pump position, or the belt rubs against itself at the tensioner position, so I removed the vanes and stator from the PAS pump, filled it with oil and blanked off the connections. The auxiliaries belt is a 5PK1220. This is quite a neat setup and all fits snugly and well below the engine hatch lid, but the PAS pulley fouls the oil filler tube, so the tube has to be removed, and the hole in the sump blanked off. I used a piece of scrap, cut and drilled to the shape of the original flange, with the original gasket.

The much improved grip of the ribbed flat belts on the pulleys together with the angular momentum of the rapidly rotating alternator has introduced problems, resulting in auxiliary belt, tensioner and crank nose failures for many engine makers, and not just VW. All beyond the scope of this thread, but you can search the internet for "overunning alternator pulley" to find out more about this problem. I managed to find an alternator with a clutched pulley, so shouldn't have this problem, I hope. It is important to make sure the crank bolt is tight, and new if it has been removed.

INJECTION PUMP

The AEF engine uses the Lucas injection pump, whereas the CS and most of the others use the Bosch. This Lucas pump has been given a pretty bad press in these kinds of forums, but my diesel specialist says that although he prefers the Bosch (he's a Bosch agent after all), the Lucas does the job perfectly OK. That's as long as you stick to standard diesel, and don't use Bio, or try and wind up the pump to deliver loads more fuel (ie turbo etc). After all there's plenty of French filth out there running around on Lucas pumps and doing high mileages. Can't be that bad then.

It is necessary to remove the immobiliser from the injection pump, and to do this the pump has to be removed from the engine. Before doing this components must be accurately marked for replacement positions. I used a Stanley knife to make accurate scribe marks on pump flange/bracket, and on the pump boss/sprocket. Although the pump mounting holes are not design to be adjustable, there is enough play to make a difference, so I marked the flange to bracket position. I made TDC marks with tippex on pump sprocket/bracket, on crank sprocket/engine and on cam sprocket/engine. Then the tensioner and timing belt were removed followed by the three bolts holding the pump sprocket to the boss. Don't under any circumstances loosen the centre nut, or the basic timing setting of the pump will be lost, and you'll have to take it to a diesel injection specialist to get it reset. Remove the four steel injection pipes as two pairs. The injection pump can then be taken off for modification.

The AEF engine was designed to be managed from an electronic controller, which controls five items:-

• The solenoid for the exhaust gas recirculation valve. This won't normally be fitted in a van.
• The solenoid valve for the high idle vacuum actuator. This won't be fitted either.
• The "full throttle stop solenoid". This isn't vital, but should reduce smoke from a cold engine. This will remain, but won't be connected.
• The "commencement of injection solenoid". This advances the injection timing, and is needed for clean starting from cold.
• The glow plugs. Vans have their own control relay, and we can use this, with modifications.

My experience with the transplanted engine has revealed that the commencement of injection valve (grey/yellow wire) needs to be operational for about 10-20 seconds after starting from cold, to avoid spluttering and white smoke on startup. This can be achieved either with a delay-off timer which is triggered by the starter motor signal, or by a manual switch in the cab.

The standard glow plug relay works well for cold starts, but the AEF needs a short glow even with the engine warm. This can be achieved by adding a resistor to the glow plug sensor wiring. First I tried 470ohm but this wasn't quite enough. Two of these (940ohm) seemed a bit too much, but I haven't tried any values in between yet. I reckon about 600ohm would be about right.

These are the various parts of the injection pump:-

A is the immobilser which can be removed once the pump has been taken off the engine. For security it is designed not to come off unless the pump is removed. You will need to connect the stop solenoid B, so disconnect the wires at the immobilser at C. D is the anti-theft bracket and can be removed from the pump bracket E by removing the security bolt F. This allows you to get at the wiring to connect it after you've put it all back on the engine.

L is the throttle lever, and must be retained.

M is the throttle position sensor for the electronics, and is discarded, along with the bracket.

N is the high idle lever. Can be left in place but disconnected from the vacuum actuator. By default, the spring pushes this lever towards the "High Idle" position, so it should be tied against the spring pressure with wire.

P is the high idle vacuum activator, for boosting the idle speed against loads such as air conditioning. As we don't have aircon this can be discarded. The bracket would interfere with the engine hatch cover anyway, so should be cut off, as in the after photo.

Q is the idle adjustment screw

R is the max revs adjustment screw (only for the brave!)

S Supply fuel pipe

T Return fuel pipe

U Nipple for sucking fuel up to the pump.

V Air bleed screw

W Max fuel adjustment is inside this plastic cap

For timing of the belt, see other threads on this forum, or a Haynes manual for VW Polo (Haynes manual No. 3500). The only special thing about the Lucas pump is the use of a 6mm dowel to set it at TDC, otherwise setting the crank and cam at TDC is exactly as for all the other VW diesels. This is a photo of the finished pump as installed.

DIESEL PIPES

I kept the two rubber elbows complete, which connect to the injection pump, but rotated to face to the back of the engine, and with new fuel hose clips. The fat one is the supply, and the thin one the return. I had to slacken the banjo on top of the fuel filter, and swivel it round a bit. The clear pipe from the filter connects to the supply, and the black one to the return. Both need metal inserts. I cut the intake rubber elbow down for a neater job. These pipes must be adequately supported with zip ties to stop them vibrating, and anywhere they pass near other pipes they should be sleeved with short lengths of suitable rubber tube.

The steel injector pipes MUST be refitted with the plastic anti vibration clips, or they will quickly fracture.

THROTTLE CABLE

The CS throttle cable is used, with slight modification. I drilled right through the plastic blob at the end, and used a spring clip to hold it on the pin. This increased the clearance from the hatch cover, which is pretty minimal at this point. The bracket for the grommet has to be modified by cutting and shutting to provide clearance from the hatch cover. This bracket should be 125mm from the throttle lever pin at mid adjustment, then the cable doesn't need adjusting under the cab floor at the front of the van. Once I had this set up, I modified a spare cable to match so I won't get caught out if it breaks. To further increase clearance from the hatch cover, I bent both the throttle lever and the bracket for the grommet downwards a bit. Even then, when I ran the engine these bits rubbed slightly on the foam under the hatch cover, so I removed a small amount of sound insulation from it at this position.

COLD START BOWDEN CABLE

This is not needed, so can be removed. I tied it out of the way in the space over the transmission, as it looked difficult to remove completely. This has also removed an annoying engine related ticking noise in the cab, incidentally.

COOLING SYSTEM

Cooling system is absolutely as standard, but will have to be in top condition to cope with the extra load imposed by the larger engine.

I used the cast alloy hose flanges from the CS cylinder head, because they have the temperature senders built in. All hoses can be reused from the CS without modification, apart from the bypass hose, which needs trimming at the bottom to provide better clearance from the dipstick tube, and because the AEF water pump outlets are a bit further back than the CS ones.

On my engine there was a 8mm steel vent pipe sticking out of the rear of the cylinder head, and this isn't needed, but it wasn't easily removed, so I made a cap out of a length of 8mm tube, with a plug in the end and two jubilee clips.

I used the oil filter housing and oil cooler off the AEF, as the CS one is different. These housings never seem to have a flat face to seal against the block, so I lapped it flat with fine emery paper on a sheet of glass, before bolting it up.

Thermostat should be installed with the arms top and bottom, to get the best coolant flow horizontally past the sensing element. I should have known better than to reuse the old one....it was letting by, and I had to drain down to fit a new one.

Thermostat cover needs to have an angled outlet to clear the engine mount. Either the CS or AEF one will work.

I have left the original radiator for now, to see if it is adequate for the new engine on long summer climbs. We'll see. Most important to check the operation of the fan thermoswitch to avoid overheating problems. Before removing the old engine, I got the engine nice and hot, and left it idling to ensure that I could hear the fan cutting in and out.

VACUUM PUMP

The vacuum pump has to be from the AEF, because it's a different fitting to the CS one. The non return valve on my vacuum pump was broken, and because I was too tight to buy a new one, I punched out the broken NRV and welded a 12mm pipe stub on to the vacuum pump lid. Then I used a generic NRV (from a type 2 van) with a couple of lengths of vacuum tube and jubilee clips. Works great!

ELECTRICAL ITEMS

All unwanted wiring was removed from the AEF engine as discussed above. The only wires remaining should be those from the three injection pump solenoids.

Label all the wires connecting to the old CS engine so you can replace them all in exactly the same place on the new engine. Reuse all the various sensors in the same places. In particular, the oil pressure switches, which look very much the same, should be replaced in their original positions. The 0.3 bar oil pressure switch goes in the blanked off hole at the back of the cylinder head. There are two pressure switches in the oil filter housing, the one with two connections is removed and the blank previously removed from the cylinder head I used to blank off the outlet. The "buzzer of doom" 0.9 bar pressure switch goes in the other boss in place of the existing one. Confused? I was. I got it wrong initially, and had the BoD frightening me on starting the new engine.

The alternator has to be from the AEF, preferably with a clutched pulley. I fitted a new regulator as a precaution. I had to join the connectors on the alternator to the wiring on the van, by soldering the wires together, then shrink sleeving overall. (that's why you need the cable ends with your alternator)

I scraped a clean surface on the water pump housing mounting to connect the engine earthing strap.

Important to replace the zip tie securing the two wires to the starter solenoid, to prevent the connections failing.

Coolant temperature sensors are transferred with the cast alloy hose flanges off the CS. I scraped the surface of the water flanges under the bolt heads, as I couldn't get earth continuity (weird).

INJECTION PUMP ELECTRICS.

The short wire which used to go to the immobiliser from the fuel stop solenoid connects to the black wire on the van. The other side of the solenoid goes to ground at one of the fuel pump cover screws.

Grey/yellow wire goes to the new cold start relay. I used a washer delay relay from an old Vol-vo, and modified it to give a longer delay. It activates the "commencement of injection" solenoid for 20 seconds after the starter is used. Any "delay-off" relay would be suitable, but I couldn't find one on offer, so I was forced to make my own. The solenoid could just as easily be operated by a manual switch and indicator light in the cab, but I didn't want to run the extra wire. Without this solenoid, cold starts are accompanied by spluttering, and some white smoke, and I was too late to try any well below freezing starts.

I left the green/yellow wire to the "full throttle stop solenoid" in place, but tied it out of the way in case I find a use for it any time.

OIL COOLER

The oil cooler off either engine will fit OK., making sure the coolant pipes are orientated correctly.

ENGINE MOUNTS

These are a direct swap from the CS. I had to use a tap to clean up the threads on most of the engine block mounting holes, as being unused till now, they were full of crud. Useful to do this before fitting the engine!

TIMING BELT COVERS

I used the timing belt guards from the AEF, including the cast alloy bit in the middle. Although not as neat in this application as the CS guards, the CS ones won't fit because the injection pump bracket for the Lucas pump is different (and far better).

THE COMPLETED INSTALLATION

The photo is high resolution and too big for the forum so here's a link.

After filling with coolant and oil (I have taken to pre-filling the oil filter before I screw it on), I removed the vacuum pump and wound the oil pump clockwise with a squashed piece of 15mm copper piping until I felt it really pumping oil. Then I replaced the vacuum pump.

If you just connect up and operate the starter, you will have a flat battery and burnt out motor long before the engine runs. It is absolutely vital to prime the diesel injection system properly. Here's how I did it.

I set the engine at TDC No.1 cylinder and took off the old timing belt. Here's the pump at TDC No.1 with a 6mm dowel inserted in the hole in the pump boss.

After connecting a bit of transparent tube to the nipple on the injection pump supply line, I sucked up diesel from the fuel filter to the injection pump, then closed the nipple. I did this several times till the pipe stayed full. Then I wound the pump clockwise with a stick in the pulley until I could hear and feel that the pump was full. There is a bleed screw on the side, and I loosened this one till fuel squirted out with no air. Next I made sure the injector unions were all slack, turned on the ignition and wound the pump until fuel squirted out of all the injector unions, before finally tightening the injector unions. With the ignition on, at this point it shouldn't be possible to turn the pump by hand because it is full of fuel right up to the injectors.

With the ignition off again, I positioned the pump at TDC No.1 and inserted the timing dowel. Then I fitted the new timing belt. Instructions elsewhere. You know the form by now.....Cam setting tool, clutch timing mark in the little bellhousing window, dowel in the pump. Normal timing belt fitting.

Then it was on with the belt covers, crank pulley, belts etc.

Then I disconnected the fuel cut-off solenoid and gave the starter a blast, to check it all went round OK with no funny noises. Also pressed the clutch to let it centralise.

Finally with fuel cut-off solenoid reconnected, turned the starter and it started first time. No smoke, and no issues till I revved it up and the "buzzer of Doom" kicked in. But that was just because I had the wrong switch on that circuit.

However, when it was warm, it wouldn't start because I found it needed a shot of glowplug, so I had to modify the glow plug wiring. The next day, in the cold, it spluttered and smoked, so I had to connect the "commencement of injection" solenoid via a timer all as mentioned previously. Now it starts every time, first time, so I will set about fine tuning the glowplug resistor to minimise glow time, whilst retaining reliable starting.

THE RESULTS

On driving the van, the difference was immediately apparent. Much more torque is available as expected, and I could drive the van without revving the nuts off the engine to get it into the next gear up. So generally, driving is much more civilised and quieter on normal roads. However, with the same gearing, the cruising speed is still 62mph, so on the motorway the engine is doing exactly the same revs as before. But it will climb hills generally one gear up from what it used to, and there isn't a hill on the UK motorway network that it won't tackle at more than 56MPH, and that's faster than the trucks, so never again will I have a truck right up my chuff at the start of every incline. Not sure about MPG yet, as I haven't done enough miles. I'm really pleased, and can recommend the swap to anyone needing to change a knackered CS. You might also consider it as an upgrade for a decent engine too.