Timing belt replacement – Lotus Excel SE (1986 with round tooth belt and eccentric tensioner)

I have updated this after changing my cambelt. So you know it can be done!
Click on the pictures to get a bigger version.
If anyone has any comments/suggestions  please email me: steve at benani dot com

1.   Disconnect battery - just for safety.  Remove bonnet – undo & remove bonnet earth strap, windscreen washer pipe, disconnect gas strut, undo locknuts (10mm), withdraw (using M4 Allen) M8 x 50 pins.

        * On my car the 'bolts' are 8mm and need a 13mm spanner to undo the lock nut and a 4mm allen key to remove.
            I would recommend a 1/4 drive ratchet as they are quite long!
  Bonnet off viewbonnet%20off%20side%20view.jpg
Now you can get at everything  so much easier.

    *Cover wings and front panel with cloths to protect paintwork.  I  always put a good coating of  polish and don't wipe it off  then cover with old towls.

2.    Remove air inlet trunk (flat screw on jubilee clip and cut securing cable ties).

3.    Remove upper and lower timing belt covers – undo twist lock fittings 90° and withdraw carefully. Remove belt cover supports where fitted. Turn the engine by hand in neutral so that you have a ‘feel’ for resistance. If needed, slacken / remove spark plugs for easier turning.

        * Top belt cover has throttle cable held to it by a clip, just pull the cable out. I would recommend removing the spark plugs it make it so much easier to turn the engine over by hand.

4.    Align timing marks – Cam pulleys, crank pulley (TDC), auxiliary pulley for ignition timing and highlight with Tippex / white paint. Count and record numbers of belt teeth between marks – e.g. crank pulley mark to auxiliary pulley mark (preferably between all marks for completeness). Note – additional reference marks can be painted on as required. Fit a double cam pulley holding tool to lock the cams in place or make sure you have clear alignment marks for the cams.

Cam pulley marks
tdc marksign pulley mark
     Cam pulley marks                             TDC marks                   
Ignition pulley mark*

4a.     Another suggestion for aligning the timing marks.  Paint a sort of wide stripe across the edge of the belt to include two adjacent teeth. Now, here's the important part; continue the paint across the edge of the cam pulley as well. The inlet pulley is probably easiest.
For the other reference marks, paint a single stripe across all other pulleys AND belt.

This method establishes the all important relationship between belt and pulleys. It eliminates the need to count teeth, and you don't need to bring the engine to TDC.
With the old belt removed, transfer all markings to the new belt and install.

4b.    Another method that has been suggested is to cut the old belt to leave about a 1/4 inch of belt on the car then fit the new belt. When you have the new belt 3/4 way on cut and remove the old belt. Using this method I would suggest that you are very, very careful how much you slacken off the tensioner, to much and the ignition pulley will be able to 'slip' a tooth on the old belt.

    * As you can see from the above picture on my car the ignition pulley mark was not in the position that many websites say it should be. This does not matter. The only thing that matters is that you do not move the pulley.
        CAUTION: The ignition pulley will move very easily. Take a picture, as above, before you remove the old belt.

5.    Remove lower coolant hose and drain 1-2 litres of coolant. NB ensure that heater flap is fully open inside car (HOT setting). Collect coolant for re-use if required.

6.    Check the installed tension of the v-drive belts for reference when installing new items. Slacken the adjuster and remove the v-belt from the alternator. Slacken the bolts and remove v-belt from power steering pump.

            * PAS pump is slackened by the 2 allen bolts (8mm allen key).

7.    With engine in gear (e.g. 4th) slacken retaining bolt on crankshaft v-pulley in preparation for later removal (access to cam belt tensioner). If the bolt is done up tight, use a large screwdriver inserted through hole in transmission casing at lower driver’s side (RH drive) of engine into starter ring gear to lock up the engine while the pulley bolt is unfastened – don’t forget to remove this afterwards!

8.    Re-position engine if necessary to ensure cam pulleys, crank pulley and aux pulley are at timing marks. Ensure the engine is in gear/transmission locked and lock the cam pulleys in place using clamps if you can (or borrow a friend to help keep their alignment). CARE – engine must not rotate from this point on in order to avoid bent valves!!

9.    Remove top radiator hose and any other pipework needed to access the cam belt /tensioner, etcetera.

10.    Remove the crank v-pulley to access the eccentric tensioner. This can be difficult and may require a pulling tool – there is not much room between the pulley and oil cooler. Slacken the cam belt tensioner bolt and note the orientation of the tensioner for re-installation (it can be adjusted eccentrically in two directions and only one is correct – with the eccentric hole towards the top). Remove the tensioner and install a new bearing, pressing off the old one in a vice.

crank pulley off       tensione slack.jpg
        Crank pulley off                                Tensioner loose

11.    Remove the cam belt and carefully replace with a new item, checking for correct orientation, exact match (size, tooth profile and number of teeth) and ensuring same relative position – i.e. same number of teeth between key marks (crank pulley/aux pulley, exhaust pulley/crank, etc) as originally.

12.    Re-install the tensioner and adjust it to tension the new cam belt. Note that the eccentric adjuster can swing against the belt in two different directions and should be installed so that tension tightens the bolt, i.e. by swinging anticlockwise as viewed from engine front. Tension is correct when there is nominally 85-90° of finger twist about a vertical axis between the aux and inlet cam pulleys. Check that all the timing marks still align – ESPECIALLY ignition timing - and correct any if needed.

How the tensioner should be.
I found the above picture on the internet,  can't remember, where so if the owner would contact me I will credit them or remove it.

13.    If timing marks are correctly aligned, remove the cam pulley clamps and place the transmission in neutral (or remove screwdriver). Replace the crank v-pulley if needed for the alignment check and tighten its bolt firmly. Turn the engine clockwise by hand gently and check the belt tension at 1/3 turn intervals for at least 2 full revolutions. If excess resistance is encountered return the engine in the reverse direction to TDC and re-check timing mark alignments. Check for mis-alignment of the belt on the pulleys. ENSURE that the tensioner is correctly tightened – if this slips, the damage caused can be considerable.

14.    If alignments are correct and the tension acceptable, replace the crank v-pulley (if not done already) and re-install or replace v-belts. Ensure that V belts are correctly tensioned (i.e. pretty tight). While you are down there, check that the bolts holding the PAS pump are secure – if not, remedy this promptly as it can cause expensive problems later.

        * My PAS pump bracket was loose and one bolt was missing. They are very difficult to get at but it is a must do job. Two allen bolts at the front which  you can't see use 6mm allen key, the two nuts at the back are 13mm  spanner size.

15.    Replace the coolant hoses, check that they seal well and replenish the coolant. If using new coolant, check that the anti-freeze is alloy compatible and dilute (1:1) with de-ionised water. Re-install / tighten spark plugs if they were loosened or removed.

16.    Replace the lower and then upper timing belt guards. Ensure that the timing belt passes them freely when turned by hand (i.e. no fouling or abrasion).

17.    Start the engine (carefully) and listen to the cam belt. If there is excessive noise the belt tension is a probable cause and will need to be re-checked. Basically an over-tight belt will whine and a slack belt will flap or flutter on over-run. Let the engine run for ~ 2 mins. Stop the engine and re-check belt tension. Also check for minor coolant leaks from the hose unions and tighten them if needed. If all is OK, replace the other components – air inlet hose (cable tie this in place in its brackets), bonnet and so forth.

18.    Check for missing / loose components, stray tools and top up the coolant. Tidy away other materials. Job done.

Original written by  chrisw2811 with additions by GavinTaylor & myself.
Find us and a lot more very helpfull folk at the excellent  Lotus Excel forum 

NB. The usual disclaimers apply - ie if it goes wrong you can't blame anyone but yourself.