Troubleshooting with Steve Rothwell

Our helpful Q&A hotline may be able to solve your classic-related problems, so why not email us at classics.info@kelsey.co.uk and we’ll try and help

ROUGH IDLE

My 1977 BMW 523i has covered just under 110,000 miles. It has been maintained by myself for the last twenty years and the oil has been regularly replaced at intervals of around 7500 miles. The air filter is in a good clean condition and the spark plugs were replaced recently, but this has made no difference to the fault I have have.

The problem is that the engine speed at idle drops very low and occasionally when pulling up at a junction the engine will stall. I suspected an air leak in the inlet system and have listened under the bonnet for any air leaks but nothing untoward has been found.

Melvin Stuart The problem you describe is very likely connected to an air leak as you‘ve suspected. This is likely to be in the engine breather side of the inlet manifold and so the normal rushing air sound associated with an air leak may not be heard.

One very simple test to see if this is the case is to remove the oil filler cap with the engine running. If the cap is difficult to remove and being sucked back down into place as you attempt to lift it off, this will confirm the source of the failure.

The crankcase breather valve sits under the centre of the inlet manifold and can be tricky to access, but it is a common failure point. Remove the air filter housing first as this will allow more room. Also check the lower connecting hose to the engine block, as given that the valve has failed, this hose also may have perished and replacing it at the same time would be a wise move.

SOLID RIDE

I’ve owned my 1988 Citroën BX for a while now and remember being impressed by the smooth ride it gave when I first purchased it. Now a few years down the line I’m beginning to feel it is turning into a bit of a boneshaker. I know the roads are not what they used to be and that there are far more pot holes around, plus the addition of speed humps at every opportunity, but even on smooth roads (when you find one) the ride is not what it was.

I’m not sure if this is the result of the car getting older or me! Are there any adjustments I should make to try and regain that smooth suspension feeling I experienced when I first purchased my Citroën? Barry Harrison

The hydropneumatic suspension system used on Citroën vehicles does give a very smooth ride and the system has been wowing owners since its first use in the early ‘Fifties.

It is relatively maintenance free, but this does not mean that parts of the system do not wear out or need replacing. The accumulators or spheres used in the system contain valves and these in time can fail.

Replacing the spheres on your Citroën BX would in most cases restore the original feel to the suspension.

If the harshness in the ride is limited to the front suspension, then it is possible that the front struts are worn. This can be tested by running a small amount of lubricant in the small hole found in the outside of the sphere support on the front suspension. If this eases the ride it conforms that there is wear in the strut.

POINTS FAILURE

I run a 1974 Jaguar E-Type 5.3 litre V12 and the only problems I regularly have are related to the ignition system. I’ve been considering for some time now replacing the original distributor for an electronic type. Is this job very complex and will I be able to reset the ignition timing afterwards using my standard timing light? I do carry out most of the routine maintenance jobs on my E-Type and consider myself to be a competent `DIY’er

Jacob Osbourne The fitting of the electronic ignition kit such as the Lumenition Optronic Ignition kit is a straight-forward replacement and something which I’m sure as a competent DIY mechanic will be well within your scope.

I would advise that before fitting such a kit, you check that there is no undue wear within the distributor itself. The base plate and advance/ retard springs can wear and even with the electronic pick-up fitted, you may still suffer from some of the problems associated with the points type ignition system.

If there is wear in the distributor, it would be advisable to replace this at the same time. The job is not too complex and you should ensure that the position of the rotor arm is checked when removing the old distributor. When fitting the new unit, the position of the rotor is matched to the removed unit.

Modern phones with a camera facility are a good friend when carrying out any such work and help to ensure that the position is correctly recorded before the replacement is carried out. With the distributor fitted using this method, the timing should be close enough to allow the engine to start. The timing can then be set using your strobe light in the normal manner.

INTERMITTENT MISFIRE

I’m hoping that you can help with a problem I have with my 1985 Ford Fiesta 1.1 OHV. It has been regularly maintained by myself and has always proved to be reliable over the years I have owned it. However, it has now developed a fault in that it has started to misfire under certain conditions and does not run well. This is worse when the engine is cold.

When I first looked at the fault, I noted that the timing marks (2° BTDC) would not stay stationary and would move between around plus or minus the 2°mark when using my strobe light. So I replaced the spark plugs, distributor cap, rotor arm and HT leads to ensure the basics were covered before moving on to more involved procedures.

As the new parts had made no difference, I obtained a replacement distributor but after fitting it the car was still the same. There’s a nice strong spark at all of the plugs and so I’m happy that the ignition amplifier is good. The fuel supply is good and I have no problems with the VV carburettor, although I don’t believe that this would affect the timing.

I’m now wondering if the problem is with the timing chain and would like your opinion on this. Peter Wray

The usual reason for the timing to wander as you have described is because of wear in the distributor. As you have fitted a replacement and presuming this was a good unit and not subjected to the same wear as your original, then I would check the play in the distributor drive. After removing the distributor cap you should attempt to rotate the rotor arm back and forth and side to side. There should be little perceivable movement and if movement is felt it is likely that your replacement distributor is suffering from the same problems as your original.

Although a slack timing chain may give you the symptoms described, this would normally also be accompanied by a timing chain rattle.

Another possibility is that the vacuum advance and retard system is at the root of the problem and I would check the vacuum pipe to ensure that this is not intermittently loosing vacuum.

VEHICLE VIBRATION

I have a vibration in my 1986 BMW 316 which seems to shudder the whole vehicle as the speed rises. I can also feel the gear lever move as the speed increases and decreases. I have discovered that the prop-shaft rubber coupling can be a problem on these vehicles and wonder if I should replace it as a matter of course.

I have been told that the prop-shaft needs to be removed from the rear axle to allow enough room for the coupling to drop down and wondered if you think it’s a job I could do myself with the vehicle up on axle stands?

Terry Gilcrest The rubber drive coupling or Giubo to give it its correct name, can be problematic and should be checked for any cracks or damage caused by oil ingress. If the coupling does need to be replaced the prop-shaft will have to be dropped at the rear. The centre mount also will need be disconnected to allow the prop-shaft to move backwards sufficiently to be removed from the coupling.

Before replacing this joint I would first check the two rubber mounts at the rear of the gearbox. These can also cause problems such as the one you are experiencing and are much easier to replace.

Finally, you should also consider the possibility that the centre mount on the prop-shaft may be the problem or indeed a worn universal joint at the rear of the prop-shaft. With the prop-shaft removed you should ensure that the UJ moves in all directions freely.

If movement in one direction is tight or not possible, the joint should be replaced.

REMOTE FOB FAILURE

My 1997 Jaguar XK8 has been left standing for some time due to a few mechanical issues which needed dealing with (another story). These have now been rectified but after charging up the battery and restarting the vehicle neither of my remote locking fobs are working.

I’ve replaced the batteries, but the central locking will only operate if using the key in the lock.

Someone told that these fobs on ‘newer’ cars can only be reset using dealer level equipment, is this true?

Rob Taylor The official word is that the fobs can only be reset using dealer equipment, but there are a couple of methods that I’ve used, one of which does work in most cases. I would try these before resorting to paying the dealer.

If the vehicle has a valet button in the centre consul (under the arm rest) then try this method: Unlock the boot using the key and the turn the ignition on, the warning light on the dash should come on briefly and then go out. When the light goes out immediately lift the arm rest to access the valet button and press the button five times within five seconds. The Lights should flash, and the horn should sound a brief blip. Press either of the buttons on the remote control. Turn off the ignition and test the remote for operation.

If the Jaguar does not have a valet button, or if the first method doesn’t work, try this: With the key out of the ignition, hold the headlamp stalk in the flash position so that the headlamps are on. Whilst still holding the stalk in the on position, put the key into the ignition and turn it to the accessory position. Now release the stalk and flash the headlamps four times.

The vehicle should enter programming mode, which will be indicated by a flash of the lights and a plip of the horn. Now press one of the buttons on each of the fobs to be programmed. You must use five presses, so if you have two fobs, press the button three times on one and twice on the other one. After the five presses the vehicle will beep to confirm it is no longer in programming mode.

Turn off the ignition and test the fobs. It should also be noted that if the ignition lock is sticky then the fobs will not work. When checking the ignition barrel, ensure that the small silver flap which covers the barrel when the key is out, is moving freely. If this does not cover the barrel with the key removed the remote may not work. Checking this first may prevent the need to go through the programming process.