:: Detailed G60 Engine Guide ::
[Note, this is the first part of a detailed guide which should be easily printable]
There are a lot of horror stories kicking around about G-laders going pop at vast expense but in our experience the charger is a strong unit that just requires regular servicing. The snag is that VW never specified any service requirements for the unit so however diligent you are in maintaining your car, unless you move in VW circles you may not know what needs doing. On the plus side, the engine is pretty much bullet-proof, and produces bucket loads of torque as well as being easily tuneable with some simple bolt on mods yielding some reliable bhp hikes. It is also a relatively simple four cylinder which means that most home mechanics should be able to do most jobs themselves.
Air Filter & Intake
The air filter determines what gets into your charger and what doesn't. Ideally lots of air gets in and dirt stays out. It is essential that you never run a G60 with any kind of foam air filter. These are fine for normally aspirated engines but they do not filter as well as a paper or cotton gauze filter does. They allow grit into the charger that mixes with the oil in the charger to form a grinding paste that accelerates charger wear. The standard paper filters are fine but if you want a bit more grunt then use a cotton gauze filter (£30) in the standard airbox and remove the front intake trumpet from the airbox as well as drilling it out (see our airbox modding guide). This will allow more air into the charger and give a slightly louder induction roar.
If you want to go one stage further then a cotton gauze cone style induction kit will help but these are a bit more pricey (£150). These replace the airbox with a large cone shaped filter and improve breathing as well as giving a wicked induction roar. Ensure that you get one with a heat-shield to prevent the filter sucking hot air from the engine bay. Some people find the induction kits a bit loud so opt for retaining the stock airbox. You are unlikely to notice any performance difference between the cone filter and an aftermarket filter in a modded airbox.
Carbon canister removal
Underneath the airbox is the activated charcoal filter (or carbon canister). This neutralises petrol vapour from the fuel tank and feeds it into the engine under load. The charcoal is then regenerated by passing fresh air over it. After 100k or so the CC does very little and can be removed. This leaves a nice big hole under the airbox/induction kit and you can then run a bit of cold air ducting up through the hole to feed the intake system. If you retain the std airbox you need to cut a hole out of the bottom of it that matches the hole where the carbon canister used to sit. On the Corrado the cold air ducting can be run down to the off side brake cooling duct. You will find the external air temp sender attached to this brake cooling duct (on a Corrado) and a few people have been known to move this up to the intake area to monitor intake temperature.
The G-Charger runs with very tight tolerances and the bearings, oil seals and apex seals only have a finite life.
As a result the chargers need rebuilding on a regular basis depending on the state of tune they are in. As a rough guide the following intervals should be adhered to:
In addition to regular rebuilds the small drive belt that links the main shaft to the auxiliary shaft should be changed annually. As std these are 6mm wide but should be replaced with an 11mm one (£8.50) as available from suppliers such as G-Werks.
Check out our G60 rebuild guide to get an idea of what is involved. A standard rebuild is about £400 rising to £500 if you have some mods done at the same time.
Whilst the charger is apart it is worth considering having the upper chambers and exhaust ports flowed and enlarged to help the charger flow more air. You should check your charger on a regular basis to determine how healthy it is. As the unit wears the apex seals start to leak and so the charger produces less boost. The oil seals also start to go and the charger then begins to leak oil both externally and into the intake pipework.
On a regular basis you should remove the intake pipe and check the inside of the charger top chamber for oil as well as the soft rubber boost pipe between the charger and the intercooler.
You can also remove the intake air temp sensor from the plastic pipe between the throttle body and intercooler and check this for oil. A fine misting of oil is acceptable but a large quantity
of oil indicates that the charger needs attention. The boost levels can also be checked using a boost gauge function on the MFA (Corrado only). Use the following procedure:
Running a standard 78mm pulley you should see 11psi if the charger is in good nick but a charger with a smaller pulley should make more than 11.6
Any more than this and you must ensure that the fuelling is seriously up to scratch At this point you are into the realms of different injectors, aftermarket engine management and so forth.
If you suspect a boost leak then examine all the intake pipe work very closely for damage. The soft rubber hoses leading to and from the intercooler are prone to splitting and the join
between the two halves of the charger baffle box is also a problem area (silicon sealant or an RSR outlet should sort this out!).
Oil selection and condition is very important to the G60 engine, particularly to the charger. The G-Lader bearings are lubricated by engine oil fed in along a braided line and fed back to the sump via another line. Due to the tight tolerances within the charger the oil needs to be as thin as possible, for this reason the engine should not be driven hard until the oil is up to temperature and thus at the correct viscosity.
As most G60's are cracking on for 100k we would not recommend using something as thin as Mobil 1 as this is likely weep out of every single gasket. A good compromise is a 10W40 oil, and ideally a fully synthetic one. Bearing in mind that oil changes are cheap and easy we would recommend an oil and filter change every 6,000miles or 12 months whichever is sooner. Obviously if you have had the engine rebuilt recently then go with fully synthetic 0/5W40 BUT remember that you must NOT run a rebuilt/new engine on thin fully synthetic oil until it has done a good 10k otherwise the oil is thin enough to get forced past the rings thus glazing the bores up (rebuild time!)..
Another oil related weak-point of the G60 engine is the oil feed line for the charger. Although braided, the core is just a small diameter rubber pipe which perishes with age and ultimately blocks. This obviously starves the charger of oil and kills it. If you still have the original feed line on your car then it is likely to be tired and should be replaced. G-Werks and Pitstop Developments can sell you a vastly improved line with a Teflon composite core and more durable over-braid as well as high quality ends. These are about £20 but are 'fit and forget' items. The oil return line rarely needs attention as it is a larger diameter, but it is still worth checking it for signs of damage.
Superchargers generate a lot of heat and if you own a std Corrado G60 then you are likely to see oil temperatures up to 130 degrees. This increases under-bonnet temperatures which does nothing for the ancillaries as well as increasing charge temperature. For every 10 degrees that you can reduce the charge temp by you will see approx 3% increase in power. It is therefore well worth fitting an aftermarket oil cooler (£120).
These fit very neatly below the charger and could knock as much as 30 degrees off the oil temp. They fit via a thermostatically controlled sandwich plate that sits between the stock water/oil heat exchanger and the oil filter. These heat exchangers are prone to leaks (leading to water in your oil) and so people often remove them when fitting a stand alone cooler. If you do not remove them then you will need to use Mk2 GTi oil filters as opposed to G60 ones in future as the G60 ones have a nut on them that fouls the front cross-member when a sandwich plate is in place. Internally there is no difference between the filters.
The ECU takes information from a number of sensors in order to apply the fuel and timing settings to the engine. If any of these sensors are not working properly then the ECU will get an
incorrect signal and the engine will not run properly. It is possible to check a number of these sensors and connections to help diagnose any running problems you may be experiencing.
The ECU relays on these cars are notorious for failing and although not an expensive failure it is one that will leave you stranded. It is prudent to obtain a brand new replacement relay from VW (approx £10) and to keep it in your glovebox. You want VW part number 165906381 and it lives in position No. 3 on the relay board (assuming No. 1 is top left). It will have a No. 30 or 32 on top of it. If it is black and made in Malaysia or the Philippines then it falls into the unreliable category. VW uprated these and new ones come in a light grey case.
The ECU contains a MAP sensor (Manifold Absolute Pressure), which it uses to determine engine load. This is fed by a black vacuum hose running from the manifold to the ECU. It is essential that this hose is in good shape, a lot of G60 running issues are down to this hose. Examine it for wear and if in doubt replace it as it is a cheap part. Be warned however, that it must be exactly 1m long so don't go trimming the end off and reattaching it to the ECU!
Water Temp Sensor
There are two water temp sensors that sit on top of the casting that joins the rad top hose to the front of the block. The blue one provides a signal to the ECU whilst the black one is the sender for the dashboard gauge. With the engine at operating temperature disconnect the plug to the blue one. You should hear the engine note change, this indicates that the sensor is working. If it does not change, then the sensor needs replacing (about £5 from VW).
The ECU must detect 12v across the fuel rail for it to operate properly. If the voltage drops below this then the ECU dumps extra fuel at the top of the rev range to prevent the engine from running lean. This will not affect performance in a massive way but won't do your fuel economy any favours. With the engine running check the voltage using a multimeter. If it is above 12v switch all the electrics on (lights, fan, indicators, demister, stereo) and check again. If the voltage has now dropped below 12v then the alternator may well be getting a bit tired. VW charge about £100 for alternator (exchange), which, is cheaper that we could find them elsewhere, although if you can live without the car for a few days most auto electricians can overhaul them for a lot less.
This is basically a microphone that bolts to the block and detects pinking by listening for sounds waves of a specific frequency. When the knock sensor detects pinking the ECU is then able to retard the ignition timing accordingly. The signal is passed from the sensor to the loom via a shielded cable. It is essential that this cable is in excellent condition, if there are any nicks or tears in the cable then the knock sensor should be replaced (£45, VW only part). It is simple to replace and merely plugs into the loom at one end (the plug can be found near the fan and distributor) and bolts onto the block at the other. It must be torqued up to 15ft/lbs, any more or less and it will be under or over sensitive.
As with most other distributor-based VW ignition systems the Hall senders are prone to failure. It lives in the distributor and uses a magnet to determine the position of the distributor before feeding a signal back to the ECU. Sadly the hall senders are not worth servicing (very fiddly and not that cheap) and so it is a new distributor job. Your dealership is usually the best source for a replacement and they even come with a new arm and cap!
The Hall sender usually announces its imminent failure with some very rough running (random misfires) interspersed with backfires and subsequently (and very soon after) the engine dies. The symptoms are usually worse when the engine is hot. VW used a number of very slightly different distributors on the same car but ultimately you want part number 037905237X which replaced 3 other similar part numbers.
The spark plugs are meant to last about 40k but it is worth checking them for condition. They should only be replaced with the appropriate platinum tipped Bosch plugs. For a standard or modestly tuned G60 you want W6DPO plugs and for a highly tuned lump use W5DPO (as fitted to the G40) as they run slightly cooler than the 6s.
As mentioned earlier any reduction in charge temperature leads to an increase in power [due to cooler air being denser and more oxygen rich]. Also, the cooler the charge the less pinking will occur allowing the ECU to run more timing advance. The G60 supercharged engine comes complete with an intercooler (i.e. an air to air heat exchanger) to cool 'charged' air but the format of this unit varies from model to model.
The Corrado intercooler is a very small unit which is of limited effectiveness. If you can't afford to upgrade, it is worth removing it and cleaning it very thoroughly as this will improve its efficiency. It draws air from behind the bumper and lives just in front of the nearside wheel arch. The internals are likely to be coated with a good misting of oil and the outside covered in road kill (bugs and grime). It should be filled with a decent detergent (Persil or de-greaser etc) and allowed to soak before being thoroughly flushed. If you have the patience it is also worth carefully straightening the cooling fins with a flat blade screwdriver as well as removing any gunk from the outside of the unit.
If you can afford it (£500) then the intercooler from a Golf G60 is a direct swap onto the Corrado. It is much bigger and sits in front of the rad. You will need all the golf pipework as well but it will make a massive difference. Stay clear of coolers from Golfs with air con as these sit on top of the engine and draw hot air from around the engine making them even more useless than the standard Corrado unit. Aftermarket companies will also be able to make bespoke coolers and supply all the relevant pipework and these are likely to be a bit cheaper but tend to require some cutting to make them fit to the car.
An alternative to a larger intercooler is to fit a charge cooler (£400-500). A charge cooler is a water to air heat exchanger and size for size is more efficient than an intercooler. The main part of a chargecooler can sit pretty much anywhere whereas an intercooler must be mounted in the air stream. This makes chargecoolers easier to package in the engine bay and popular for conversions such as Mk1 G60s. The charge cooler then requires a water resevoir and a small radiator to cool the water heated by the charged air as well as plumbing and a pump to link the two.
Although efficient, it is obviously a more complicated solution so if you have the space I would go for an intercooler. The final charge cooling option which can be run in conjunction with an IC or CC is water injection (£250 - £500). This system sprays a fine mist of water into the airstream before is goes into the engine thus cooling it. The spray obviously needs to be fitted before any inlet air temp sensors. Such a system requires a pump and reservoir but can be fitted very discretely. It usually operates from a throttle switch to only activate at full throttle otherwise the reservoir would continually need refilling. Generally such a system is used in conjunction with an IC or CC as is used on highly tuned cars to prevent pinking under full load/boost.
G60 Idle Stabilisation Valve [ISV]
Idle Valve - The G60 uses an electronically controlled idle valve that bypasses the closed throttle to feed a controlled amount of air into the engine and sustain an idle. These often become sticky and work erratically (causing a hunting idle) or cease working at all. In most cases that can be fixed with a quick clean. Remove them from the car and soak in petrol or carb/injector cleaner before rinsing, drying and refitting. Check also the pipes to and from the valve for air leaks as these can also cause idle problems.
The idle valve also acts as a boost limiting system. When boost reaches a certain level the ECU sends a signal to the valve to open a solenoid that bleeds excess boost out of the system and into the boost-return pipework. Some people have fitted check valves to prevent this excess boost being bled off. These should probably be removed as not only does the ECU open the valve to bleed the excess boost off but it stops retarding the timing. If you retain this extra boost the timing will be too far advanced as the check valve makes no adjustment to the timing for the extra boost and thus the engine is likely to pink.
Less specific to the G60 but worth highlighting nonetheless is the cam belt tensioner. These often seize up on older high-mileage cars causing premature wear and thus failure of the belt. They only cost £10 so if it looks tired or squeals then change it. It should always be changed with the cam belt as a matter of course but this does not always get done. Remember that the belt should be tensioned so that you can twist the longest unsupported run of the belt through 90 degrees…..no more….and no less!
Like what you've seen so far? - In that case click here for our G60 Tuning Guide