PORSCHE TECH­NI­CAL TOP­ICS

Tech­ni­cal prob­lems solved

911 Porsche World - - Contents - For more in­for­ma­tion about MCE’S ser­vices and spe­cial­i­ties go to mce­porsche.com, or call 07796 372239. The com­pany is just off the A422 be­tween Ban­bury and Brack­ley, and lit­tle more than a mile from Junc­tion 11 of the M40 mo­tor­way. For more about Millers

I re­cently spent a fas­ci­nat­ing af­ter­noon at MCE Porsche in Ox­ford­shire. Pro­pri­etor Mike Cham­pion is an en­thu­si­ast of many years’ stand­ing, and also a time-served and highly qual­i­fied en­gi­neer with a long ca­reer in the au­to­mo­tive in­dus­try be­hind him. And you have to ad­mire a man who, while work­ing on clas­sic 911s, lis­tens to clas­sic vinyl al­bums of the same pe­riod. Ready to go on his bench-top turntable were, among many oth­ers, The Doors, The Beach Boys, Aretha Franklin, Jimi Hen­drix and Led Zep­pelin.

My visit, hav­ing first met Mike at a Porsche event just a few weeks pre­vi­ously, was pri­mar­ily to have a longer dis­cus­sion and a look around his com­pact but very welle­quipped premises, but also to work out what sto­ries we might col­lab­o­rate on in fu­ture edi­tions of the mag­a­zine. And, as luck would have it, there was an ideal can­di­date ve­hi­cle on the two-post lift even as I ar­rived.

A man­ual-trans­mis­sion 987 Cay­man ‘S’; 2005 model, around 70,000 miles on the clock. Ob­vi­ously owned by a fas­tid­i­ous in­di­vid­ual – an­other en­gi­neer – and equipped with at least two mods that mark him out as a knowl­edge­able and far-sighted en­thu­si­ast: a beau­ti­fully made stain­lesssteel ex­haust, and pro­tec­tive grilles for the front air in­takes. Here’s some­one who knows all about rot­ting ra­di­a­tors and the po­ten­tially dis­as­trous consequences thereof.

His un­der­stand­able worry on this oc­ca­sion, how­ever, was the engine’s seem­ingly high oil con­sump­tion. The car had been ser­viced – else­where – in the fairly re­cent past, but now, af­ter just 1000 miles, the bar-type dis­play in the in­stru­ment panel was sug­gest­ing that the level in the sump was down to the bare min­i­mum. An engine of this type and mileage should con­sume no more than around half a litre of oil in that dis­tance. Three times that amount was sug­gest­ing that some­thing was clearly amiss.

Mike’s mis­sion, then, was to es­tab­lish whether this was due to ei­ther a faulty gauge or sender – by no means un­known – or per­haps to some other me­chan­i­cal mal­ady. (Fa­mously, and for rea­sons best known to it­self, Porsche aban­doned the good, old-fash­ioned and in prin­ci­ple fail­safe me­chan­i­cal dip­stick with the ces­sa­tion of 986/996 pro­duc­tion.)

Rather than wade in with di­ag­nos­tic kit or an in­ter­nal ex­am­i­na­tion, how­ever, Mike was sen­si­bly start­ing with the most ba­sic and eas­ily mea­sur­able pa­ram­e­ters. ‘I am al­ways care­ful not to jump to con­clu­sions about these en­gines,’ he says, ‘and pre­fer in­stead to take an ob­jec­tive, re­sults-led view. Ob­tain the en­gi­neer­ing facts, present them to the cus­tomer, and de­cide how to pro­ceed from there.’ Armed, then, with Porsche’s pub­lished fig­ures for the fill vol­ume for the car (7.75 litres with a fil­ter change; 7.5 litres if you leave the el­e­ment undis­turbed, and thus with around 250ml in­side the hous­ing), the first job was to drain and then ac­cu­rately to mea­sure what was in the engine to start with.

Re­sult, af­ter about 20 min­utes, and when there were no more than a few drips ooz­ing from the ori­fice: al­most ex­actly 6.0 litres in the plas­tic con­tainer which, with his ob­vi­ously cus­tom­ary pre­ci­sion, Mike had pre­vi­ously grad­u­ated with a ruler and per­ma­nent marker. Given the typ­i­cally 1.0–1.5-litre dif­fer­ence you can ex­pect be­tween ‘max’ and ‘min’ on the av­er­age con­ven­tional dip­stick, this sug­gested that the gauge was, in­deed, giv­ing a re­al­is­tic view of the sit­u­a­tion – and might even have been very slightly op­ti­mistic.

But even now Mike wasn’t con­vinced. ‘I have no rea­son to doubt who­ever car­ried out the last ser­vice,’ he con­ceded, ‘but I have no way of know­ing for sure that the sump was filled to the cor­rect level 1000 miles ago. What I shall do, then, is first re­fill it with the same quan­tity of new oil as the amount I have just drained out, to see if that gives the same read­ing on the gauge. If so, I shall add more fresh oil – in known in­cre­ments, check­ing the gauge as I go – un­til it’s up to the max­i­mum. If the vol­ume added matches what I would ex­pect, then I can have con­fi­dence in the ac­cu­racy of the gauge. I will then let the cus­tomer drive the car nor­mally for the next 1000 miles, know­ing that we have both a con­trolled start­ing vol­ume and a re­li­able means of mea­sure­ment.

‘If, as I sus­pect it will, the gauge sub­se­quently shows only the usual mod­est re­duc­tion in level that you might ex­pect, then all will be well, and we can put it down to op­er­a­tor er­ror. If within that dis­tance, on the other hand, the level gen­uinely falls back to the same as it was to­day, then clearly there is a deeper prob­lem that will have to be in­ves­ti­gated.

‘In an­tic­i­pa­tion of fur­ther in­ves­ti­ga­tion be­ing re­quired, I shall also take the pre­cau­tion of col­lect­ing a sam­ple of the old oil, and send­ing that to Millers Oils in Hud­der­s­field. As I’m sure you know, they of­fer a highly in­for­ma­tive spec­tro­graphic anal­y­sis ser­vice, which for around £50 a time gives you a very de­tailed view of any con­tam­i­nants and par­tic­u­late mat­ter. That should give me an ac­cu­rate pic­ture of not just the cylin­der con­di­tion, but also of the pis­ton rings and skirts, the crankshaft bear­ings, and even the val­ve­train. And at this stage it’s far less costly than hav­ing me re­move all six coil packs and spark plugs, and then start car­ry­ing out cylin­der leak­age tests, and so on – es­pe­cially if the mea­sure­ments re­veal that it re­ally was just a fill­ing er­ror dur­ing the pre­vi­ous ser­vice.’

Cay­man owner was con­cerned that af­ter only 1000 miles since last oil and fil­ter change, lu­bri­cant level in sump had dropped to min­i­mum mark. But was that be­cause the engine was burn­ing it, or be­cause the gauge was faulty? Or even be­cause the level wasn’t cor­rect to start with? Only way to be sure is the ap­pli­ca­tion of some ba­sic sci­ence, by pre­cisely mea­sur­ing the quan­tity of oil that comes out, and then re­fill­ing to the cor­rect level and ob­serv­ing what hap­pens over the next 1000 miles. Spec­tro­graphic anal­y­sis of the oil would be a good in­di­ca­tor of prob­lems, too – or hope­fully the ab­sence of them – and af­ter-market mag­netic drain plug was en­cour­ag­ingly free from tell-tale swarf

With 911 & Porsche World’s con­sul­tant editor, Chris Hor­ton

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