Technical Service Bulletins



Updating of radiator fan fuses

To protect the radiator fan circuits against the effects of water deluge.

It has been found that under certain exceptional conditions, including driving through deep puddles, water inundation into the radiator area can be sufficient to impede radiator fan rotation, stall the motors, and blow the 1.0 A fuses. Any resultant high coolant temp. would be indicated to the driver via the temp. gauge and overheard tell tale.

The fuse for each of the three radiator fans (on the relay bracket in the front luggage compartment) has now been uprated from 10A to 15A. This specification can be used on any Esprit since the introduction of the "revised wiring harness" in Dec 93, but NOT on earlier cars with the radiator fan fuses in the main fusebox, due to the design capacity of the wiring harness.

Introduction of 'revised wiring harness' on Esprit S4 and Sport 300:

      R 1242 (LHD S4)
      R 1250 (RHD S4) Dec 93
      R 8030 (Sport 300)

Back to top of document



Corrosion protection of clutch slave cylinder.

To ensure reliable operation of the clutch release mechanism.  In wet storage or extreme weather driving conditions, it has been found  that corrosion of the clutch slave cylinder bore can become sufficient to inhibit proper operation of the clutch release mechanism.

At the next opportunity, on all '92 M.Y. onwards Esprit models in the ff. VIN range;

        N 0001 to P 1089

carry out the ff. check and precautionary maintenance:

  1. Pull back the rubber boot from the clutch slave cylinder, and inspect the condition of the end of the cylinder. if necessary. push back the piston, remove  the pushrod, and clean the cylinder bore thoroughly using a recommended brake fluid. do not use any substances or methods w/c may contaminate the hydraulic fluid or damage the bore surface. 
  2. Use Girling red rubber grease to protect the cylinder end. Refit the pushrod  and use the grease to seal the rubber boot to the cylinder and pushrod.
  3. Test clutch operation.

0.2 hr/car. Warranty claims marked S/B 1993/13 Class 2 should be submitted.

Back to top of document



Start up idle speed on electronic injection Esprits.

To clarify specification and allay customer's concerns.

Some customers have expressed concern at the high idle speed  ff. start-up, under certain conditions, of an Esprit Turbo w/ Elect. inj. The following information should clarify the situation:

  1. At low engine coolant temperatures, the engine mgmt. system, primarily via the idle air control valve, raises idle speed to between 1000- 1500rpm dependent on temperature.
  2. At engine start up coolant temperatures between 17-31C, the back pressure valve and throttle jack will operate to provide an idle speed of approx.2,400 RPM for about 2 minutes, in order to improve catalyst efficiency.
  3. On chargecooler SE models, the system can, if necessary, be switched out by 'stabbing' the throttle pedal to more than 50% travel quickly enough not to allow high RPM to build.
  4. For operational details of the back pressure valve and throttle jack, see Service Notes manual Section 'EMG' or 'EMH' Sub-section EMG/EMH. 2-W, and for adjustment see EMG/EMH. 3-T.
  5. For emissions reasons, hot engine re-starts will be followed by a raised idle of approx. 1200 rpm, which will gradually return to normal.

Back to top of document



Fitment of latest type radiator to earlier Esprits.

Non-availability of early type radiator. The IMI radiator (#082K4101) fitted to all Esprit Turbo models prior to N.A. Esprit models from S3 'HC' May 90 is no longer available, necessitating that the latest type NRF radiator (A082K4237) may be fitted as service replacement. The radiators may be identified by their thickness, measured across the frame:
   Early type IMI  #082K4101  -approx. 54mm
   Latest type NRF A082K4237  -approx. 68mm

Fitting rad A082K4237 in place of #082K4101, requires the ff modifications to be made:

  • Remove the end flanges from the plastic fan cowling, which formerly wrapped around the ends of the radiator . If necessary, enlarge the cut out in the cowling for the top hose connection. Secure the cowling to the radiator . using 6 screws along the top edge, and four along the lower edge.
  • If necessary, enlarge or slot the radiator fixing holes in the sides of the duct, and on air con cars, slot the condenser mounting holes in the underside of the duct.

  Note: that the radiator duct part # changes from A082B4906K to B082B4906K for the new type radiator.

Back to top of document



Revision to headlamp main beam relay on non-USA cars.

EEC lighting regulations.

On '88 M.Y. onwards non-USA Esprit models, the outboard headlamps are fitted w/ twin filament (dip/main beam) bulbs. On cars built prior to Dec 90, all four headlamps are used for main beam. however, in order to comply w/ EEC directive no. 84/8/EEC, w/c limits the lighting output on main beam, it  has been necessary to change the double contact main relay (A082M6182F) for a single contact relay (A089M6058f) so that only the inboard headlamps light on main beam. Cars have been built to this later spec. since Dec 90. Owners of later spec. cars within EEC countries should be advised that substitution of the single contact relay for double contact relay A082M6182F, may result in lighting regulations being contravened.

Back to top of document



Instrumentation Illumination

A running change has been made to various aspects of the instruments and their bulbs in order to upgrade and better balance the instrument illumination. these changes have implications for service replacement of individual gauges.

The revised instrument illumination parts have been introduced at the ff. change point:

              (approx) S4:      S 2034 (mph)      S 2038 (kmh)
              non-USA S4S:  S 4059 (mph)      S 4118 (kmh)
              USA S4S:         S 3097
              Sport 300:         S 8061

Speedometer A/B082N4030 (mph) & A/B082N4031 (kmh) 
Revised internal lighting diffusers have resulted in a change to 'B' prefix part numbers. 'B' type instruments may be used as direct replacements for 'A' type speedometers. For identification, note that the 'A' version has a plain trip reset button, and the 'B', a fluted button.

Tachometer A/B082N4032 
The case of the new 'B' level tachometer has been revised to accept more secure type bulb holder. This instrument can be used to replace an 'A' type if the tachometer bulb holders are also replaced w/ A082M6618 (2 off). In order to match the lighting level of an 'A' type speedo, fit 24V 3W bulbs (A082M6311).

Time Clock A/B082N4037
The graphics of the 'B' level clock have been revised to improve illumination. The later instrument is a direct replacement for the earlier unit.

Minor Gauges
These instruments are unchanged, but the bulbs have been changed from 24V 3W to 12V 1.2W

Back to top of document



Weather sealing of rear luggage compartment.


a). The source of an occasional concern with water ingress into the rear luggage compartment has been found to be the fixing holes for the body rear lip spoiler.

b). On a small number of Esprit S4S models fitted with the body mounted rear aerofoil, water ingress into the rear luggage compartment has been found to emanate from a hole in the RH rear body designed to accommodate the wiring loom for the high mounted stop lamp used in some territories.


a). To seal the rear spoiler lip fixing holes, peel back the rear transom carpet, remove one fixing at a time, and seal the washer and bolt head using a suitable mastic sealant (e.g. Siiastic}.

b). On S4S models equipped with a centre high mounted stop lamp (CHMSL) on the underside of the rear aerofoil, the wiring harness for the lamp is routed through the RH plinth, and a hole in the body within the confines of the aerofoil to body mating surface. The hole is sealed by the aerofoil to body gasket, in conjunction with a ring of Silastic around the hole. On cars without a CHMSL, the hole for the harness may still be present and if this is found to be the source of water ingress, the aerofoil should be removed, the hole blanked off with suitable tape, and a ring of mastic sealant used to fully seal the aperture.

Back to top of document



Introduction of gear linkage ball joint boots.

To prevent stiff gearchange operation caused by weather corrosion of gear linkage ball joints.

Rubber boots have recently been introduced for the ball joints at the rear ends of the 2 gearchange cables, and on both ends of the translator tie rod. If any of these components are disconnected for any reason, the opportunity should be taken to fit the protective boots to the benefit of durability.

Parts Required
Boot, gear linkage ball joint    A082F4149F      4 off per car.

Back to top of document



Modifications to improve stop lamp switching.

It has been found that the brake pedal on some Esprit models can become, due to a variety of factors, reluctant or lazy in returning fully to its' off position. In such cases, the stop lamp switch may remain closed (brake lights on), and an ABS fault code A034 may be set.

In order to improve the consistency and reliability of stop lamp switch operation on such cars, the spring pressure of the stop switch plunger can be reduced, and a brake pedal return spring added. These revisions may be incorporated on any Esprit model with anti-lock brakes where such symptoms are experienced.

If any ABS equipped Esprit model is found to exhibit symptoms of the brake lights staying on, or if an ABS fault code A034 is set, refer first to Service Notes section JF.l7 (Date 1995/ 0l) to check the brake pedal height and stop switch adjustment. If the symptoms are still apparent, carry out the following modification:

Parts Required
Brake Light Switch (modified) A082M50115  1 off
Brake Pedal Return Spring A082J43975  1 off

  1. Disconnect and remove (twist 1/4 turn counterclockwise) the stop switch.
  2. From the stop switch mounting bracket on the pedal box, press out the plastic stop switch bush. Using a small round file, make a shallow groove in the top notch in the bracket, of sufficient depth to anchor the new return spring. Refit the bush.
  3. Hook the round loop of the new brake pedal return spring into the bracket groove, and hook the other end around the front of the brake pedal.
  4. Fit the modified stop switch into the bracket and adjust as detailed in Service Notes section JF.l7.

Note that in order to prevent over stretching, the spring should be disconnected before a brake bleeding operation.

For cars in Warranty, claims should be submitted quoting S/B 1995/21 Class 3. time allowance 0.4 hr.

Back to top of document



Sealing of transmission output shafts.

A small number of cars have been found to suffer slight oil leaks from the transmission output shafts via the roll pins securing the inboard C.V. joints. The splined transmission output shafts carry the driveshaft inboard C.V. joints, which are secured by a pair of concentric roll pins passing diametrically through the C.V. joint spigot and outboard driveshaft. An 'O' ring fitted onto the transmission output shaft is designed to seal between the shaft splines and C.V. joint, and a double lip oil seal fitted into the transmission case seals against a polished sleeve pressed onto the outside of the C.V. joint spigot. In isolated cases, transmission oil has been found to seep down the splines and out via the roll pin drillings.

If oil is found to leak from around the driveshaft roll pins, or if a driveshaft is to be refitted, carry out the following procedure to seal the area.

  1. Before fitting the inboard C.V. joint to the transmission, clean the roll pin bore in the joint spigot and output shaft.
  2. Fill the roll pin bore in the C.V. joint and output shaft with Silastic RTV 732(A075U6044V) silicone rubber sealant.
  3. Lubricate the lips of the seal and the 'O' ring with transmission oil, and fit the C.V. joint onto the splines with the roll pin holes aligned.
  4. Use the tapered tool in set TOOOTO67B to fully align the roll pin holes, and insert the two NEW concentric roll pins with their slots diametrically opposed and at 900 to the shaft axis.
  5. Progressively knock in each of the pins

Back to top of document



Revised clutch pedal adjustment setting.

Increase clutch plate release clearance, and reduce drag.

The clutch pedal and master cylinder pushrod adjustment procedure is detailed in Service Notes section QC (see manual B082T0327J and also Service Bulletin 1993/17. Ongoing data analysis has resulted in the setting being revised as follows:

Esprit S4 models:
Set the clutch pedal upstop to achieve a dimension of 170 -175 mm between the back of the pedal pad to the bulkhead. This setting should result in a slave cylinder pushrod movement of 17 -18.5 mm.

Esprit S4S/Sport 300 model:
Set the clutch pedal upstop to achieve a dimension of I75 -180 mm between the back of the pedal pad to the bulkhead. This setting should result in a slave cylinder pushrod movement of 18.5 -19.5mm.

Note that the whole of the master cylinder stroke is not used, and that any further clutch fork travel may result in damage to the clutch assembly from over travel. The slave cylinder pushrod movement quoted in the Service Notes (29.5 mm) is incorrect.

Please ensure that your manuals are updated accordingly, prior to the issuing of an update to Section QC.

Back to top of document



Replacement tyres for pre '89 Esprit models

Non availability of original equipment Goodyear tyres.

The original equipment tyre fitment on 15 inch wheel Esprit models from 1980 to 1989(pre 'Eagle chassis') was:
Type Size Lotus Part No.  Pressure
Front: Goodyear NCT or Eagle NCT 195160 VR15 A082G4060H  21 lb/in2
Front: Goodyear NCT or Eagle NCT 235/60 VR15 A082G4062H 25 lb/in2

These tyres are no longer manufactured by Goodyear.

 Lotus recommend the following alternatives in complete car sets- mixed tyres, including axle sets, produce unacceptable vehicle handling characteristics:
Type Size Lotus Part No.  Pressure
Front: Pirelli P600 195/60 R15 88V A082G6102S 25 lb/in2
Rear: Pirelli P600 235/60 VR15 A082G6103S 30 lb/in2

Alternatively, by fitting the 16 inch rear wheels {A082G6053F} from the Chargecooler type 'Eagle' Chassis, complete car sets of Goodyear Eagle ZR5O tyres can be fitted - mixed tyres, including axle sets, produce unacceptable vehicle handling characteristics:
Type Size Lotus Part No. Pressure
Front: Goodyear Eagle ZR5O 215/50 ZRl5 A082G6055F 26 lb/in2
Rear:  Goodyear Eagle ZR50 245/50 ZR16 A082G6054F 26 lb/in2

Note: For sustained speeds over 120 mph, tyre pressures should be increased to 34 lb/in2.

Back to top of document



Wiring harness connector block checks.

To help diagnose intermittent electrical problems.

If an electrical problem is encountered on any car, especially of an intermittent nature, diagnostic checking procedures should always include a rigorous verification of any connector blocks in the circuit. It is possible for a poor or intermittent contact of an individual terminal within a multi-terminal connector block to occur w/out its being visually
apparent. A terminal can also `back out' of a connector block if misaligned in some way, or if withdrawn and reinserted incorrectly. An accurate assessment of connector integrity can be made using a spare male spade terminal to probe each of the female terminals with a connector block. A sample male spade from a 'Mini TTS' type of connector block, commonly used on all current Lotus models, is provided herewith:

  • Unplug the suspect connector block., and carefully examine the security of each of the terminals, both male and female parts.
  • Using a spare male terminal, probe each of the female terminals, and check that each push fit provides a consistent dragging feel, with no looseness. If necessary, withdraw the female terminal from the connector block to rectify a fit problem.
  • To withdraw a terminal, release the keeper bar, and using a suitable probing tool (e.g. T000T0905} depress the retaining barb and pull the terminal from the connector block. If necessary, use pliers to close up the lips of the female terminal, and adjust the leaf blade to provide the required contact.
  • Before re-inserting a terminal, ensure the retaining barb is suitably angled, before pushing into its housing, the correct way round, until fully secured. Refit the keeper bar.

Back to top of document



Specification check of a.c. high pressure switch.

Possible fitment of incorrect switch on' R-12 ' cars. Service Bulletin 1995/06 advised the introduction of 'CFC free' refrigerant R134a. On page 2 of the bulletin, reference is made to the binary switch fitted to the receiver-drier; in particular to a new higher pressure 32 kgflcm2 switch which may be fitted to Rl34a equipped cars. It is possible that
some R-12 filled cars may have been incorrectly fitted with this higher pressure switch instead of the correct 26.5 or 27 kgf/cm2 switch.

At the next opportunity, on all R-12 type Ears in the VIN range identified below, check the switch specification, and if necessary replace with the correct type.
          S4:                 R 1453 to S 2016
          USA S4s:       S 3000 to S 3011
          Sport 300:      R 8047 to S 8057 excl. 8042, 8043, 8051

Parts Required
Binary Switch, R-12 refrigerant AO82P6053F       1 off

  • Open the front bonnet, and insert the label on the binary switch fitted in the top of the receiver-drier unit mounted behind the RH headlamp pod.
  • If the switch is found to be O.K. as detailed above, take no further action.
  • If an R134a switch is found to be fitted, change the switch for an R-12 type (A082P6053F) as follows:
    • Using a refrigerant gas recovery plant, de-pressurize the a.c. system.
    • Apply some R-12 compatible refrigerant oil to the thread and 'O' ring of the new switch, unscrew the old switch and fit the new.
    • Recharge the system with the R-12 refrigerant (refer to Service Notes Sub-Section PD .6).

l .8 hr/car. Warranty claims marked SB 1995/07 Class 2 should be submitted.

Back to top of document



Addition of Betaseal to removable roof panel sockets.

Closer fit of retaining tongues and suppression of roof rattles.

If a customer should express concern about roof generated rattles or creaks, the following action may be taken to suppress noise in this area:

The principle employed in this modification is the addition of Betaseal polyurethane sealant to the roof tongue sockets to ensure an individually molded fit of each tongue in its recess. In order to ensure thorough bonding of the sealant in uncontaminated sockets, a pair of new sockets and gaskets should be used.

Parts Required
Slot Recess (socket), LH       A082U6097F     1 off
Slot Recess (socket), RH       AU82U6098F     1 off

  1. Remove the four screws securing the windscreen header rail trim panel, and drop the front edge of the panel to gain access to the roof tongue sockets.
  2. Remove both tongue sockets from the body, and thoroughly clean the mounting flanges on the body.
  3. Use Betaseal primer from a windscreen fitting kit (A075B6158J) and a suitable brush or piece of flexible card to coat the whole of the inside surface of two new sockets (A082U6097/8F). Allow to dry before fitting.
  4. The socket clamping plates which preload the upper fingers of the sockets should be modified either by cutting or bending the finger loading tabs, to render this function ineffective. The plates are retained only as finishers.
  5. Fit the sockets with their integral gaskets dry, to the body and secure with the modified clamping plates. Take care to align the sockets as follows:
    • The lower edge of each socket mouth should be parallel with, and 9mm from, the surface of the roof gutter.
  6. Trial fit the roof panel, and check shut lines and heights. Adjust if necessary. Refit the header rail trim panel.
  7. Mask off the visible surfaces of the sockets as shown in the diagram. Apply a bead of Betaseal into the mouth of each socket, but do not attempt to completely fill the recesses.
  8. Coat each roof tongue w/ a release agent such as mirror Glaze Wax polish, and fit the roof into position, forcing the Betaseal into the sockets.
  9. Allow several hours for the Betaseal to fully cure before disturbing the roof. If necessary, cut away any extruded Betaseal, and remove the masking tape.
Back to top of document



Replacement of header tank 'T'- piece.

Improved durability.  Since introduction of the 'revised wiring harness' and associated changes to the cooling system in December '93, a small number of failures of a coolant 'T'- piece have occurred The 'T`- piece is located beneath the white plastic header tank (right hand rear corner of engine bay}, and connects the chargecooler air bleed hose into the header tanks main hose. Failure of this part (breakage of the small bore take-off results in loss of coolant, and illumination of the low coolant tell tale, but prompt action is required by the driver to switch off the engine before overheating damage occurs.

Due to the high potential inconvenience to the owner, and any consequent loss of confidence in the product, dealers are requested to contact all known customers with 'revised harness' years in the following VIN range, and arrange an early appointment for rectification work to be carried out.

RHD S4:          R 1250 to R 1451
LHD S4:          R 1242 to R 1449
USA S4:          R 1248 to S 1469
Sport 300:       R 8030 to R 8050

EXCEPT the following VIN serial numbers which cars have been updated at the factory:

Parts should be ordered as soon as requirements have been established.

Rectification Procedure
Parts Required
'T'- Piece Kit       A082K6069S 1 off comprising:
   'T'- Piece (15,8,15 black) B910E7006F 1 off'
   Oetiker Clip, 25.5 mm      B082K6059F 2 off
   Oetiker Clip, 16.5 mm      B082K6060F 1 off

  1. Disconnect the two cables from the header tank low level sensor, and the three hoses from the top of the tank (turbocharger return, engine bleed, expansion tank).
  2. Release the two fixings securing the tank to the rear wall mounting bracket, and raise the tank sufficiently to provide access to the 'T'- piece and hoses.
  3. To avoid draining the system and minimize loss of coolant, clamp off the header tank feed hose (from bottom of' 'T'- piece) and the small bore bleed hose from the chargecooler. Siphon out the contents of the tank.
  4. Release the hose clip securing the connector hose to the bottom of the tank, and remove the header tank.
  5. Cut off the Oetiker clips and remove the three hoses from the 'T'- piece Discard the white 'T'- piece.
  6. Fit the new black 'T'- piece B910E7006F into the main feed hose and secure with new Oetiker clip B082K6059F using Oetiker pliers;
    • Fit and secure the chargecooler bleed hose with new Oetiker clip B082K60fi0F;
    • Fit and secure the header tank connector hose with new Oetiker clip B082K6059F.
  7. Fit the header tank to the connector hose and secure with the worm drive clip. Remove both hose clamps.
  8. Refit the header tank to the rear wall, and the three hoses and level sensor leads to the top of the tank.
  9. Refill the header tank with a 30% anti-freeze concentration (Castrol Antifreeze mono-ethylene glycol blend), and check that the expansion tank behind the left hand rear wheel arch contains a small amount of coolant.
  10. Mark the top surface of the header tank with red paint to indicate completion of this bulletin.

0.5 hr/car. Warranty claims marked S/B 1994/06 Class 2 immediate should  be submitted

Back to top of document



Removal of clutch pedal assistor spring.

To better cater for specialist driving techniques: It has been found that drivers who habitually use a determinedly robust operation of the clutch and gear change controls, may enjoy enhanced clutch 'feel' and durability, if the clutch pedal assistor spring is discarded. The purpose of the spring mechanism is to reduce pedal effort, and provide an 'over-centre'
feel to the pedal operation. The associated tendency of the mechanism to slow a very rapid pedal release, may not provide the instant response sought by some drivers for the most rapid of gear changes.

Cars from the following change point (February'94) have been built without the assistor spring:

          R 1310 (S4)
          R 8032 (Sport 300)

 For the drivers of earlier '92 M.Y. onwards Esprits, who are known to employ the driving style described above, it is recommended that after consultation with the owner, the clutch pedal assistor spring is removed.

Back to top of document



Replacement of ABS hydraulic pressure switch.

To lower system pressure and reduce brake pedal stiction. The new pressure switch, fitted into the pump/accumulator housing, has-been recalibrated in order to lower system pressure, and reduce seal friction in the booster/master cylinder assembly. One effect of this change is to lessen any tendency of the brake pedal to 'stick' and not fully return to its up stop.

At the next opportunity on all ABS equipped ('91 M.Y. onwards) Esprit models prior to the following change point:

N 0236 (DomesticlExport'92 M.Y.)
- replace the ABS hydraulic pressure switch as detailed below.

Parts Required
Pressure Switch (inc. "O' ring  B082J6137S 1 off
Socket Spanner, 39mm long reach TOOOTl238F 1 off
DOT 4 Brake Fluid - as required

Note that the original switch (A082J6I37S) has a black plastic body, and the new 'B' version a grey body.

The ABS pump/accumulator assembly is mounted at the driver's side front corner of the front luggage compartment beneath a protective-plastic cover. The pressure switch is fitted into the housing beneath the accumulator.

  1. Depressurize the accumulator by turning off the ignition and FIRMLY applying the brake pedal up to 44 times. A noticeable change in pedal feel (to a hard pedal) will occur when the accumulator is completely discharged.
  2. Before unscrewing the pressure switch from the pump/accumulator endplate, have the new switch ready and prepared for fitment to avoid the necessity to bleed the hydraulic system. Lubricate the 'O' ring supplied with the new pressure switch using DOT 4 brake fluid and fit the ring onto the new switch.
  3. On LHD cars, it may be necessary to release the relay bracket fixings for sufficient access to the pressure switch in the pump/ accumulator endplate. Disconnect and unscrew the pressure switch from the endplate extension beneath the accumulator using a long reach 39mm ( 1 1/2") socket - available under TOOOTl238F. Use a shop towel to absorb any escaping fluid.
  4. Screw the new switch and 'O' ring into the endplate and torque tighten to 20 - 27 Nm (15 - 20 lb-ft). Connect the harness plug to the switch.

0.5 hr/car. Warranty claims marked S/B 1993/21 Class 2 should be submitted together with the displaced switch.

 An updated Service Notes section JF.13 (ABS Hydraulic diagnosis) will be issued in due course.

Back to top of document



Introduction of revised cylinder block, head & gasket.

Quality improvement. The cylinder block and cylinder head of the Lotus 910/920 engine have been re-cast and upgraded in respect to stiffness, lightness, cooling efficiency and dimensional control. In addition, a new type of cylinder head gasket has increased tolerance to severe thermo-cycling, and improved durability.

The new components have been introduced on engine serial number: 28096 (Last 5 digits of engine number} - January 1993.

With the exception of the block deck height and various core and blanking plugs, the new block and head share all functional dimensions with the old type, and when service stocks of the older components are exhausted, they will be replaced by the new parts. New heads may be fitted to old blocks and vice versa, but the new head gasket should be used in both cases.

The new block and head may be readily identified by cast Lotus logos on the front and rear faces of the cylinder head, and at the top right hand rear of the block.

Cylinder Head Gasket
The steel/asbestos laminated gasket, B9O7EOO26Z (Coopers - silver in colour) has been replaced by a reinforced fibre composite gasket A912E7029Z (Goetze - grey/brown colour), which uses a built-in silicone sealing bead around the periphery, and a Viton seal around the oil feed hole. The compressed thickness of the new gasket is approx. 0.5 mm (0.020") greater than the old gasket, and the deck face and liner seats of the new cylinder block have been lowered by a corresponding amount.

Service Replacement
i) New engines must be fitted only with the new type gasket. Fitment of an old type gasket to these engines may result in piston foul and/or detonation due to the raised compression.
ii) When stocks of the old gaskets are exhausted, old engines should be fitted with the new gasket, which will also replace the 'extra laminate thicker gaskets (A911E 1292, B911E 1292} used on some low compression 912 N.A. engines. Note that the extra thickness of the Goetze gasket will result in a slight reduction in compression ratio (typically about - 0.5 numerically) when used on old engine This may be advantageous to fuel octane tolerance, especially if the head face has been machined
to correct distortion or erosion.

Goetze Gasket Fitting Procedure
There are two points to note when fitting the new type gasket to new or old type engines:
a) The gasket is fitted dry.
b) The cylinder head nut tightening procedure has been amended, and requires the use of an angle gauge. A Sykes Pickavant tool under Lotus Part No. T000T1235 will be dispatched and invoiced to all dealers shortly.

  • Check that the studs (with oiled threads) are tightened into the block to 37 - 41 Nm (27 - 30 lb-ft).
  • Fit head gasket (dry) and cylinder head. Fit washers, oil head stud threads and fit nuts.
  • Using the existing tightening sequence (from the centre outwards; see Service Notes EB.7), tighten the head nuts in the following stages:
    • i)   20 Nm (15 lbf.ft).
      ii)  + 75 degrees
      iii) + 40 degrees
Cylinder Liner Adhesive
The sealant used between the base of the cylinder liners and the block (formerly Hylomar) has been changed to Loctite 572 adhesive sealant (A912E7030V) in order to: reduce fretting and noise; improve sealing durability; reduce the risk of liner disturbance with the cylinder head removed. The use of Loctite 572 has been Introduced together with the new block and head castings, but may be used on all Lotus 900 series engines. Loctite 572 Application Procedure:
  • Thoroughly clean the liner spigot and seat, and the corresponding areas in the block.
  • Dry fit the liners and check that there is a nominal clearance between the top end of the liners: Check the standout of the liners above the block deck face (liner "nip') which is unchanged at:
    • 0.03 mm to + 0.05 mm (- 0.001 to + 0.002 in); 
    • max. variation between adjacent liners: 0.03 mm (0.001 in).
  • Apply a small bead of Loctite around the seating face of the liner.
  • Apply a thin smear of Loctite around the outside of the liner spigot.
  • Apply a thin smear of Loctite around the top edge of the liner spigot bore in the block.
  • Slide the liners into the block and fit the cylinder head within 4 hours to ensure that the liners are seated correctly before the adhesive cures.
  • If this procedure is used on an 'old' type engine, apply a red paint mark for reference, to the cylinder block at the end of the engine number stamping.

Note that when assembled as above, the liners will subsequently require the use of a liner puller tool (T000T0012A - existing part of the dealer special tool kit) in order to extract a liner from the block. The improved security of the liners also means that if care is taken, there is no necessity to reseal the liners in the normal course of cylinder head removal/refit.

Description Part Number  Qty
Cylinder Head Gasket  A912E7029Z 1
Loctite 572 Adhesive/Sealant  A912E7030V A/R
Angle Gauge T000T1235 1
Plug, 1"-14 NPTF socket taper, oil gallery side face A912E7111Z 1
Adaptor, thermal switch (head A rear face - Excel) A912E2600S 1

Back to top of document