HOW TO: RE­PLACE 997 TURBO BOOST ACTUATOR RODS

Ur­ban dwelling 911 Turbo with seized turbo actuator rods

911 Porsche World - - This month -

There can surely be few bet­ter ex­am­ples of un­ex­ploited per­for­mance, and the re­sult­ing ar­guably un­nec­es­sary com­plex­ity – and ex­pense – than this 2008-model 997 Turbo Cabri­o­let. It’s a lovely car by any­one’s stan­dards, and brand-new, fresh out of the box, its 3.6-litre flat-six would have been good for 480bhp and a stag­ger­ing 620Nm. Top speed: 193mph. Stand­still to 62mph? Around four sec­onds. As it was, with one and pos­si­bly both tur­bocharg­ers fail­ing to boost, it was now lit­tle or no quicker than a con­tem­po­rary stan­dard Car­rera – and per­haps not even as fast as that. And in truth its ur­ban- dwelling owner hadn’t re­ally no­ticed.

The Porsche PIWIS sys­tem tells no lies, though, and the mes­sage it dis­played on the screen was un­equiv­o­cal: ‘Boost­pres­sure actuator adap­tion not pos­si­ble’. (Or mes­sages, ac­tu­ally. There are two ac­tu­a­tors, and at that point nei­ther was op­er­at­ing, so two iden­ti­cal faults were

flagged up.) But Porsche-torque pro­pri­etor Sid Ma­lik, to whom had been en­trusted the task of restor­ing the car to full health, af­ter he had spot­ted the prob­lem dur­ing a rou­tine ser­vice, wasn’t too wor­ried. (He never is. Un­flap­pable to the last, that’s Sid.) ‘There is a short, socket-ended rod be­tween each actuator and its turbo,’ he told me. ‘But the sock­ets of­ten par­tially seize on the balls, thanks to cor­ro­sion, and that re­stricts the free move­ment of the en­tire mech­a­nism. Re­sult? Lit­tle or even no boost.

‘It’s not a guar­an­teed cure, be­cause there may be a fault within the actuator(s) them­selves, but the first thing to do is take off the rods, and see if the arms on the tur­bos and on the ac­tu­a­tors above them are free to move. If they are, you can ei­ther clean and grease the four ball-and-socket joints and re­fit the old rods, and see if that makes any dif­fer­ence, or fit two brand-new rods – af­ter equally care­fully greas­ing those, of course. No point hav­ing to take them off in a year or so’s time to do the job

again. The only prob­lem is that ev­ery­thing is very awk­ward to get at, tucked away be­tween the tur­bos and the ex­haust man­i­folds. But at only around £11 each for the parts, it’s worth a lit­tle bit of ef­fort to have a go. Ideal for one of your how-to sto­ries in 911 & Porsche World, per­haps?’ Ab­so­lutely, Sid. You must have read my mind. I shall see you to­mor­row…

‘To­mor­row’, for var­i­ous rea­sons, turned out to be a week later, but the re­sult was the same. Re­mov­ing the two rods proved, as Sid had sug­gested, that the four balls and their sock­ets were cor­roded. (And that this is not a job for those with large hands and lit­tle pa­tience.) But it also showed that, with all four of the mech­a­nisms they linked seem­ingly free-run­ning, it war­ranted fit­ting the two rods he had or­dered in, and check­ing if the faults could be cleared. In the event – and not sur­pris­ingly – that was only par­tially suc­cess­ful. The left-hand actuator was now work­ing, PIWIS told us, but the unit on the right, pos­si­bly dam­aged by push­ing against that seized link­age, was dead. Noth­ing for it, then, but a re­turn match, to see how to fit a new one.

This would re­quire re­mov­ing the rear bumper, Sid told me, and even then each actuator’s three M6 se­cur­ing screws would be quite awk­ward to reach. But per­haps iron­i­cally in a ve­hi­cle of this na­ture it would place the job within the scope of a com­mit­ted DIYER – and in truth re­mov­ing the apron, which is not dif­fi­cult, would make it a lot eas­ier to get at the rods alone in the first place, es­pe­cially for those with­out the ben­e­fit of a wheel-free lift. You will still need a di­ag­nos­tic ma­chine to ‘adapt’ (ie to re­set) ei­ther an orig­i­nal, work­ing actuator, and cer­tainly any new one(s), but there would be noth­ing to stop you do­ing the span­ner­ing your­self, and then driv­ing the car to a spe­cial­ist for that to be car­ried out. An ideal how-to story? Al­most per­fect, ac­tu­ally!

Pos­si­ble that boost fail­ure can be fixed by new link rods be­tween ac­tu­a­tors and blow­ers (left), but also that new actuator(s) may be needed (above). Both jobs are DIY prospects

For all the com­plex­ity of its ultra-mod­ern vari­able tur­bine ge­om­e­try, the 997 Turbo re­lies on a sim­ple four-inch socket-ended metal rod to link each blower to its actuator. Each socket, with an in­ter­nal spring-clip, is a straight­for­ward push fit over the rel­e­vant ball. In­tense heat, and not least a lack of lu­bri­ca­tion, can cause the rods par­tially to seize on the balls, pre­vent­ing free move­ment of the mech­a­nism, and most likely switch­ing on the check en­gine light and/or flag­ging up a fault code in the car’s mem­ory. First step is to see if heat of­fers any im­prove­ment. If it does, it’s worth re­mov­ing the rods to check free move­ment of both the actuator and the arm on the turbo it­self and, if that’s OK, lu­bri­cat­ing the joints with an­ti­seize paste or, bet­ter still, fit­ting new rods. They cost around £11 apiece. They are not that easy to re­move – and cer­tainly to fit – but you should be able to do so given safe ac­cess to the un­der­side of the car, and a com­bi­na­tion of screw­drivers and long-nosed pli­ers. A home-made wire hook is use­ful for pulling one or other of the arms into the cor­rect po­si­tion, but you will need to thin it down with a bench grinder so that it doesn’t also pre­vent the socket push­ing fully home on its ball. On this oc­ca­sion it seemed pos­si­ble that the ac­tu­a­tors would still be ser­vice­able, but in the event the Porsche PIWIS sys­tem tester sug­gested that, even with new rods fit­ted on both sides, only the unit on the left of the car was work­ing. Noth­ing for it, then, but to or­der a new one for the right side and re­con­vene at a later date for part two...

Re­plac­ing one or other – or both – of the ac­tu­a­tors is go­ing to mean re­mov­ing the rear apron for ac­cess, and in truth you may want to do that from the be­gin­ning, for eas­ier ac­cess to the link rods alone. Start by re­mov­ing the rear lights. Plug-and­socket con­nec­tions can be awk­ward if you don’t know the knack: press down on tab (ar­rowed, above left) and care­fully pull. A screw­driver blade can be used as a lever or, bet­ter still, get hold of the spe­cial tool shown in the lower group of pho­tos – this one came from Laser, Sid Ma­lik tells us. Rear section of each whee­larch liner needs to come out, too, af­ter you’ve re­moved pan-head se­cur­ing screws. Wheels can be left in place, but prob­a­bly eas­ier to re­move them first. Undo ver­ti­cal screw se­cur­ing each corner of the apron to the wing, then the ones un­der­neath, and fi­nally the row across the top. Pull the panel gen­tly to the rear, dis­con­nect­ing the wiring to the num­ber-plate lamp as you do so. Store it some­where safe so it doesn’t get dam­aged

This type of multi-pin plug-and-socket con­nec­tion is widely used in mod­ern VAG ve­hi­cles (far left), so it’s worth spend­ing a few pounds on the spe­cial tool that helps to re­lease them – and the po­si­tion of some is such that they would oth­er­wise be al­most im­pos­si­ble to dis­con­nect. With apron re­moved, next you need to undo the Torx screws se­cur­ing the outer edges of the heat-shield (far left), and then the two big ver­ti­cal screws through the bumper proper. This re­veals the ex­haust sys­tem in all of its rusty glory...

With the in­ter­cool­ers out of the way (and the hose to the turbo it­self plugged with a piece of cloth to pre­vent for­eign ob­jects falling in) you can clearly see each turbo actuator, but in or­der to re­lease its three se­cur­ing screws you will also need to lower the en­gine a few inches. Sup­port it on a jack as you undo the se­cur­ing nuts (best to tackle one side at a time), and use the jack to push power unit back into po­si­tion, not the wind­ing ac­tion of re­plac­ing the nut. Wiring con­nec­tion to actuator is an­other of those some­times awk­ward plug-and­socket jobs. Part num­ber sug­gests actuator has been su­per­seded at least once and pos­si­bly twice – hope­fully for a longer-last­ing item

Re­plac­ing the in­ter­cool­ers is a re­ver­sal of re­moval pro­ce­dure, but note the rubber grease on the hose con­nec­tions so they slide to­gether neatly. Make sure pipes are pushed fully home, and also that the clips are seated cor­rectly. Fi­nal job, whether you use the orig­i­nal ac­tu­a­tors, two new ones or, as here, one new and one old, is to have the sys­tem ‘adapted’ such that the car’s man­age­ment sys­tem recog­nises them. Di­ag­nos­tic ma­chine is re­quired for that, but noth­ing to stop you driv­ing the car to a suit­ably equipped in­de­pen­dent

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