928 starter motor repair.

[geedee]

I have done a couple of jobs on a pals 928 some years back and thought to share my experience in the off chance it might help others... but I profess NO specialist knowledge.
Being a regularly used 928 it developed starter issues, and being a manual at least he could depend upon willing man power for a push start if it failed at club get togethers... (-: When he finaly decided push had come to shove... I volunteered to pull the starter out of it. The problem seemed to be within the solenoid, it would click strongly enough but was intermittent on switching the power through to the starter motor section. I tested the motor section by supplying it with power directly and it spun strongly.
The starter solenoid performs two functions when it`s coil is energised. When energised the magnetic effect generated causes a rod to move internally. One end of the rod attaches to a lever which acts on a lever and engages the starters motors movable gear with the teeth in the flywheel.... and the other end of the solenoid rod at the same time forces a copper disc across the two heavy bolts to which are connected the heavy power lead from the battery, and the equally heavy lead to the starter motor it`s self. Thus with everything working well the instant the starter gear is fully engaged with the flywheel the starter motor section has power applied to it via the heavy copper switch closing.
Yeah somebody has no doubt done a You Tube vid on the starter operation but this was a time long before YT or the general public had access to the www.
It was a simple matter to unscrew the solenoid section off the starter motor, and unhook the rod from the lever to remove the solenoid, though to access the contacts held within which switch the power through to the motor, I required to unsolder the two connections which supply power to one end of the solenoid`s internal coil and the other which gives it an earth, l in order to remove the plastic cover.
With the cover removed the copper disc was exposed to view, as above the disc makes contact with the two threaded bolts in effect shorting/switching across both of them. Both the copper disc and the areas of the bolts were the disc contacted them were badly burned, the disc surface being hollowed/pitted to the extent that cleaning it and the contact areas of the bolts may just allow it to operate more regularly but definately not to be depended upon.. I cleaned up the bolt heads to reveal clean metal and reversed the disc on the rod to present it`s unmarked face to the bolts when called to do so. The 928 like many old Porsches has been rarely used since I performed the repair but to the best of my knowledge it is still operating fine some 20 years later... A relatively cheap fix and simple fix, even better if/when starters may be difficult to source..?

 

[Waylander]

A new solenoid is about £14, and readily available from Woodauto services,
Much easier just to fit a new one

 

[geedee]

More fool me then eh..(-:
Being an old dude I grew up as the offspring of the make do and mend generation thus we learned how things worked and also how to repair them, look upon it as a challenge which provided a sense of satisfaction when it worked.
For sure times have changed and for some time now we have been in the throw away society, wither that is better or not.. Shrug..?

 

[Waylander]

Oh don’t get me wrong, I rebuild starters and alternators for 968’s, and wiper motors

at the cost they are, the wiper and starter are over £500 new

 

[geedee]

Many thanks for taking time to reply and for providing a heads up on the cheap and faster fix, and a sourse of supply. The world has certainly moved on since I carried out that repair, for at the time there was no www, Amazon did not exist and a Bosch parts department was not just round the corner, thus it was handy to have been brought up with a degree of self reliance built in..?
I note that some parts are seemingly becoming scarce, thinking K-Jetronic kit. When I was younger old cars were very simple machines compared to the..err..sophistication built into modern ICE driven vehicles, thus home repair was possible without the need for specialist tools or equipment. The guys running old machinery were reliant on scrap yards to find parts and at reasonable cost as there was perhaps little chance of finding new spares at a dealership, either that or the cost was prohibitive, if they were available.
I think for some time now old Porsches have been very well catered for by comparison with earlier times, more so since the creation of Porsche Classic set up to provide limited spares for older cars AT A PRICE.. I suspect the 928 not being the most popular Porsche (?) and with somewhat complex on board electric/electronic systems compared to it`s air cooled bretheren, thus may well become a tad more difficult to keep going with the passage of time.. if not already...?
I was only passing time typing in the hope of providing info that might help someone somewhere, sometime.

 

[Waylander]

Any help we can provide for anyone keeping these wonderful cars on the road at less than extortion prices is a good thing,
the big thing to remember is a lot of these parts are not Porsche’s they are made by third party and used on a bunch of other makes, the trick is figuring out what and when, and then where

 

[geedee]

T`was in the 70`s that Lotus that taught me the games played to make profit by rebranding parts, having bought a track rod end from an O.E. supplier to later find out it was a Triumph Spitfire part which could be sourced from Triumph for a lot less, and even cheaper if bought through motor factors as an after-market item. At least in those days it was made in the UK, whereas cheap parts these days could be of very suspect quality and made who knows where, you pays your money you takes your risks..?

 

[Waylander]

this is very true indeed, if it has made in china on the box its sent back,
but a lot of german made parts are available if you know what your looking for,

All the cam belt rollers and tensioners are made by INA and popped in a P box for 3 times the money