HOW TO: REPLACE 997 TURBO BOOST ACTUATOR RODS
Urban dwelling 911 Turbo with seized turbo actuator rods
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