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Changing the starter motor solenoid
Richard Martin (Teal Blue 0704) from Hertfordshire had been experiencing slow cranking with his starter motor and finally had to sort out the problem! (Jun 06)

I have noted with interest the recent discussions on the V8BB and V8NOTES mentioned on the V8 Website on the starter motor and heat shield for the MGBGTV8. As I have replaced both of these items on my V8 in the last few months, I hope my experience may be of some interest to members facing similar difficulties.

I own a largely original Factory MGBGTV8 which has covered 95,000 miles and is used mainly for summer motoring and garaged all year round. Over the last few years starting the engine has increasingly become more difficult. I found that unless I kept the batteries fully charged, then cranking speed of the engine would drop significantly in a few seconds until the inevitable "clicking" sound could be heard as the starter failed to engage to turn the engine over. In my case new batteries and a reconditioned alternator only improved the situation marginally. The last straw resulted in my only being able to start the engine by using additional power from a high amperage mains battery charger or jump-starting from another battery in another vehicle. At this point I decided to fit one of Clive Wheatley's reconditioned original Lucas starter motors and replace the heat shield which has virtually disintegrated. I had earlier purchased a remanufactured heat shield from the same source.

I was aware that lighter more powerful starter motors could be fitted to the V8 engine but wished to retain the original spec starter motor. I wished to keep the car original out of a sense of loyalty as a production engineer who had previously trained with a Lucas subsidiary. On investigation with a number of sources it then seemed unlikely that removal of the starter motor was possible without an engine removal unless some or all of the following were dismantled or removed - the steering rack and/or column, the offside exhaust manifold and down pipe and the offside engine mounting brackets.In view of the amount of work involved in removing these items and the fact I still retained the original cast iron exhaust manifolds (which seem to strip their downpipe stud threads at the earliest opportunity), investigation of an alternative was called for. So I therefore decided to attempt a replacement of the solenoid which is carried "piggy-back" style on the body of the starter motor. This unit carried internal copper switch contacts which can burn and degrade with age and use. Removal of the solenoid would also allow corrosion to be cleaned from the brass terminal which is mounted on a
Nylon moulding and steel bracket on the offside chassis leg near the clutch slave cylinder.

The terminal acts as a joint between the main positive battery feed and the power offtake to the starter and ignition. In order to unbolt the solenoid from the starter, I needed access to the small mounting bolts on the solenoid to permit the use of a small box spanner which would normally be obstructed by the heat shield. The decayed insulating material of the old heat shield was easily removed which then left the remains of the steel mounting bracket bolted to the side of the engine block. However even though I had soaked the mounting bolt over several days with release oil, it still failed to undo - even when a long ring spanner was used. As I did not want to wreck the head of the mounting bolt or shear the thread, another method was called for.

After a bit of lateral thinking I realised that probably the bolt could be jammed due to corrosion or the pressure of the wide and thick washer under the bolt head which clamps the steel mounting bracket in place. After a few hours careful work with a Dremel type mini drill fitted with a small diameter milling cutter, I was able to cut through most of the washer. This then allowed another application of release oil to soak behind the bolt head and luckily this time the bolt was undone with some ease when a ring spanner was used.

The mounting bolt, spring washer and thick clamping washer were all replaced with stainless steel items bought or turned on a lathe to match the items I had removed. These were then loosely fitted to the engine block before the solenoid and heatshield. All this extra work meant the solenoid could finally be fitted together with its associated copper connections ands terminals. The heatshield was then finally twisted round and the slotted mounting bracket fitted under the previously placed stainless steel bolt and washers. Care needs to be taken on the final tightening of this bolt to ensure there is clearance between the starter/solenoid electrical terminals and the heatshield.

The final job was to clean the brass terminals and the connections to the chassis leg mounting bracket. Obviously all these operations need to be carried out with the batteries disconnected.

Since the completion of this work, starting has improved significantly and I have not needed to remove the engine. However if a future clutch or gearbox change is required, then I will fit the reconditioned Lucas starter motor which I have in stock.