Tech Tips & Info (Boxer) A-Z

AFM- The Air Flow Meter- The 33 16v uses Bosch Ml4.1 Motronic Fuel injection. The first part of the system is the AFM, which is just after the air filter, and this sends signal relating to the air flow rate and temp to the ECU, to determine the amount of fuel injected. A faulty AFM can give rough running and flatpsots. A common fault is that the connections on the potentiometer track can become impaired. It is easy to prise of the top cap, and put a little electrical conduction fluid or even 'wd40' on the tracks.

Alfasud- The car the Alfa boxer engine was designed for. Produced from 1972-1984. Alfas first front wheel drive car, and renowned for its excellent handling, but also its unfortunate proneness to corrosion. The first cars were four door with a boot, two door cars followed, and finally three and five door hatchbacks.

Arna-1983-1986 The result of a collaboration between Alfa Romeo and Nissan. It was essentially a Nissan Cherry with much of the Alfasud's running gear, including it's boxer engine. Nissan also sold 'their' version of the car, badged the Cherry Europe.

Brakes- All Alfasud and early Sprint models used inboard front disc brakes, with outboard rear discs. The inboard brakes give improved handling, and less torque steer, due to a lower unsprung weight. To replace the brake pads on inbord front calipers it is necessary to wind back the pistons. The inner piston is actuated by a 7mm bolt on the top, and the outer by an allen bolt on the side with a 17mm locknut. Because of their location, it is a fairly awkward job, and 'hamfisted' attempts have damaged piston seals etc.

Later Sprints and most Alfa 33 models used outboard front disc brakes, and drums at the rear, with ATE and Bendix components being used. 1700cc models used vented front discs, and the Alfa 33 16v Permanent 4 (4wd), and ABS 33s sold in some countries used rear discs.

Cam Belt Replacement-All the boxer engines need to have their cambelts changed every 48,000 miles to prevent a breakage, and subsequent engine damage. It is necessary to remove the grille and the radiator to carry out replacement. For 8v engines the Haynes Alfasud/Sprint manual gives the replacement details. Most specialists recommend the replacement of the pulley wheels at the same time as the cambelts. For 16v engines CLICK HERE FOR BREIF GUIDE

Catalytic Converter-On the later injection 33 models the first exhaust silencer was replaced with a catalytic converter/silencer to meet emissions regulations. These are very expensive to replace, but they can sometimes be renovated. It is also very common on all cars that when the rear silencer is replaced the 'cat' tailpipe is also very corroded. On pre-cat cars the centre box would often be replaced too, but as this is unecconomical with a cat, it is often necessary to make up a sleeve or weld on a new bespoke tail section.

Alfa Romeo and the replacement exhaust system manufacturers do not make replacement cat tail sections for the Alfa 33 models, and the 1500, 1700 8v, and 1700 16v all use different cats.

Clutch- It is possible to change the clutch by removing the gearbox alone, but it is generally accepted that the 'best' method is to remove the engine and gearbox as a whole from under the car, and then split them. Original equipment clutches were made by Valeo.  See Engine Removal

The clutch slave cylinders are prone to leaking, and can give the problem of difficulty in engaging gears etc. They are held in by a large circlip which can be awkward to access with the eng/gbox in situe. They are however quite easy to bleed, especially once the airbox/ intake manifold has been removed.

Engine Number Identification-. 301.02 - Single carb Sud 1.2 63hp
301.04 - Sud 1.2 ti 68hp
301.02/S - Sud 1.2 60hp
301.84 - Sud 1.3 74hp
301.60 - Sud Super 1.35 70hp
301.64 - Sud 1.35 75hp
301.68 - Sud 1.35/Sprint 63hp
301.24 - Sud 1.5 ti/Sprint 83hp
301.28 - Sud 1.5 ti/Sprint 95hp
301.46 - Sud 1.5 ti/Sprint/33 105hp
310.00/305.00 - Arna 1.2 60hp
310.10/301.68 - Arna 1350 Gti 85hp
310.16/305.20 - Arna 1500 Gti 95hp
305.00 - 33 1.2 68hp
305.02 - 33 1.3 75hp
305.04 33 1.5 ti 84hp
305.20 33 1.5 ti 90hp
305.50 33/Sprint 1.7 114hp
305.58A - 33 1.7 ie Kat 105hp
307.43 33 1.2 78hp
307.32 33 1.3 86hp
307.34 33 1.5 105hp
307.50 33 1.5ie 96hp
307.51 33 1.5ie Kat 95hp
307.46 33 1.7 16v 137hp
307.36 33 1.7 ie 110hp
307.37 33 1.7 ie Kat 110hp
307.47 33 1.7 16v Kat 132hp
307.55 - 33 1.3/1.4 IE specific to Greece and runs the Bosch L-Jetronic 3.2
335.01 145/146 1.3i Kat 90hp
332.01 145/146 1.6i Kat 103hp
334.01 145/146 1.7i 16v Kat 129hp

Engine Removal- The engine and gearbox are removed as one from under the car. Once everything including exhaust and driveshafts are disconnected, the front crossmember is removed, the top engine bulkhead mount and rear gbox mount are undone and the supported engine/gbox can be lowered to the floor. The Haynes Alfasud manual method can be used on all 2wd models, but injection models have many extra connections for sensors etc etc. Four-wheel drive models need special care with the propshaft connection, and some specialists remove the engine alone to avoid disturbing the 4wd coupling/ connections etc.

Exhaust Systems- Alfa Boxer engines can be impaired by the fitment of some 'cheapo' exhaust boxes. The original equipment was generally Descam. Exhaust centres could cause problems, especially if the manifold section is changed, as some may fit a 1200cc sized pattern part to all models!

The 1700cc 8v manifold can be fitted to 1500cc suds/sprints and 33s, and gives a little improvement in breathing. The 16v heads have the ports in different positions to the 8v, and so manifolds are not interchangable with the 8v.

Late 16v 33s and the 145 16v use crossover manifolds which join the front cylinders, and the back cylinders, however they are different between the two cars.

See Catalytic Converter

Filters- Original Alfa Romeo oil filters should be used on the boxer engines, as they contain a non-return valve. Original euipment air filters are generally made by Fispa, and fuel filters by Corrello or Uni.

Many owners have installed 'performance' air filters to their cars, either as 'pancake' type filters directly to the carburettors/ air flow meter or as a relpacement element inside the airbox. K&N produce both pancake filters for the Weber/Dellorto carbs, and performance high-flow elements for most of the air boxes.

Firing Order- 1324 all models, with 1 being the furthest forward cylinder, 3 behind it, and 2 the other front.

Gearbox- See Engine Removal

Handbrake- The Alfasuds and Sprints with inboard front disc brakes have the handbrake working on the front wheels, where as the other models have 'conventional' rear opperating handbrakes.

There were some problems with the strength of the 'sud handbrakes, and a recall was carried out on many series 3 hatchback cars, to replace the calipers.

HT- The Alfa boxer engine loves and needs good quality HT components and leads. If your Distributor is a Bosch or Marrelli, use a Bosch or Marrelli cap and rotor arm. Use the original equipment Ht leads, Bosch or Brecav.

See Spark Plugs.

Injection- The series 3 Alfa 33s and the 145 Boxer were all fuel injected. Different systems were used between the models, with the most 'complicated/sophisticated' system being used on the 33 16v. This model used the Bosch Motronic ML4.1 system, which has the ECU fed information by an Air flow Meter, sensors for air temp, eng temp, rpm and timing, and throttle min and max opening. Later 'cat' models also had a Lambda Probe added to the system.

It is possible to self test the ML4.1 system using 'blink codes'. Check out pages at for more information on making a DIY tester, the 'T2' connections, and the table of fault codes. It is possible to also connect a simple switch and a multimeter to read the fault codes.

Lambda Probe- Later Alfa 33s and the 145 were fitted with an oxygen sensor or 'Lambda Probe'. This device is fitted upstream of the catalytic converter and sends information about the emissions to the ECU so that it can alter the mixture.
Lambda probes should last between 60-80,000 miles, but engine problems can damage them. If they are faulty or become disconnected the ECU may go into a very rich 'limp home' default mode which will be noticed by rough running and excessive fuel consumption. Sometimes there may be no apparent fault, until the car fails an MOT on high emissions!

A company called 'Lemark' manufacture pattern Lambda Probes which are sold through large Automotive retailers. They cost substancially less than original equipment items.

Power Assisted Steering- Most Series 3 Alfa 33s were fitted with a ZF power steering rack.

If the gaiters are split or the rack is leaking oil, it will be neccessary to remove the rack. Its location is the same as a non-power rack, but because of its extra size, can be very difficult to remove, especially with 16v heads. It may be neccessary to lower the engine/gbox to allow clearance, and removing the front suspension strut on the drivers side, will certainly help (also on non power racks!).

PAS racks are very expensive but can be overhauled by specialists. It is worth noting that many Alfa Romeo garages never changed the gaiters on these racks, but insisted on a new/reconditioned rack. It is very easy to damage the internal valves etc!
Click here for breif PAS rack removal guide.

Production figures- Alfasud(1972-1983)
approx 894,000, Sprint(1976-1988) approx 121,000, Alfa 33(1983-1994) approx 989,000 Arna- Few, but too many!


Radiators- All models use Valeo radiators of various size. They are easy to change, but remember to remove and replace the cylinder head drain plugs to fully drain the system, and to put the heater on full when refilling and purging the system of air. 16 valve 33s will really need the bonnet removing, but this is very straight forward, and helps with many major under bonnet jobs!

Spark Plugs- Alfa Romeo recommended that the spark plugs be changed at 24,000miles on all 8v models and the non-cat 16v. However many owners change them at 12,000miles.

All Sud/Sprint/33 models use the multi electrode Golden Lodge 25HL spark plug except the late 16v 33 with a catalytic converter. This model uses platinum NGKPFR6B plugs due to its hotter running. These plugs are very expensive, but do last 60,000 miles, which is an advantage as 16v plugs are notoriously difficult to change (especially cylinder 4!)

Sprint- The Gorgeous 2 door coupe designed by Giugiaro, based on the Alfasud. Originally with chrome bumpers, but gradualy clad with more and more plastic with the final versions dressed in a Zender bodykit which arguably spoilt the clean lines of the original car.

Strut Pan Bearings-These bearings at the pan base of the front struts seem to be a weak point on many Alfa 33s. However they are not very expensive, but will require specialist fitting.

Tappet Adjustment- All early (up to 95bhp aprox 1982) engines had easy to adjust tappets via holes in the camshafts. The later engines use shims and require a special tool to insert/remove them.

Water pump- The water pump is located in front of no2 cylinder behind the cambelt on all models. Pump failure is a common fault, and many specialists recommend it to be changed if there are any signs of bearing noise, whilst the cambelts are being changed. Similarly if the water pump does fail, it is a good opportunity to change the cambelts.

The water pump has a very tight fit, and can be very awkward to remove. It may be neccessary to split the pump with a drift, but take great care not to damage the engine casing. provides this information in good faith, but does not assume any responsibility or legal liability whatsoever, for the accuracy, usefulness or completeness of any of the information.

Copyright 2002