TECH SESSION – Not so obvious

By Pedro P. Bonilla, GCR-PCA (from Provinz June 2014, page 12)

Most Porsche owners regularly check tire tread wear, tire pressures, oil level, oil change interval, brake pad and brake rotor wear, brake fluid flush and service schedule intervals. In other words, the obvious stuff. And that’s great, but there are several other wear items that are not so obvious that many times get overlooked by DIY’ers and even by some shops:

The least obvious is the Front Engine Mount (in the Boxsters and Caymans) or the Transmission Mount in the Carreras. This mount, which is made of rubber and supports half the weight of the engine/transmission while it dampens engine vibrations.

MountAlthough the new mounts from 2008 are much better than the old ones from 1997, they still crack and wear out and should be replaced regularly. If allowed to wear down, they will affect shifting, could cause damage to the transmission mounts in the Boxster/Cayman or the Rear Motor Mounts in the Carrera, as well as quick deterioration of the Continuous Velocity Joints (CVJ) and half-axles.

These mounts can only be properly inspected when removed, so many people tend to forget about them until too late. As a rule of thumb, after 72,000 km they should be inspected because most likely they have already cracked. The cost is around $150 plus a couple of hours labour to replace. There are remanufactured mounts available at considerable savings, since what wears is just the rubber centre, not the structure.

Another wear item is the Air/Oil Separator found in all of the water cooled boxer engines.AOS1

 

The function of this particular piece of equipment is to distill any oil out of the crankcase. Using vacuum from the intake, crankcase gasses are pulled up and through a diaphragm which doesn’t allow droplets of oil to go through. Any drops are redirected back to the main oil supply while the “dirty air” that makes it through the diaphragm is mixed with the intake air and gasoline to be burnt up in the combustion cycle.

Generally, when this piece deteriorates, a BIG, no, a HUMONGOUS cloud of white smoke is produced at startup. In some cases a loud screeching (almost metallic) noise or whistle is produced by a tear in the diaphragm. AOS2When any of these symptoms appear, quickly replace the air/oil separator. Failure to do so may cause the engine to hydrolock from liquid oil in the cylinders, which could get very expensive to repair once damaged. The life of the air/oil separator varies from a low of 64,000 km to well over 160,000 km. It is not terribly expensive. Somewhere around $100 for the part and a few hours labour to install.

Although this next piece of equipment can last a bit longer than the two above, if and when it fails it will leave you stranded. I’m referring to the water pump.

Water pumps generally last well over 160,000 km but I have seen them fail at just about any mileage. People who constantly open the coolant reservoir, generally have the highest failure rates. PumpOpening the coolant cap, especially when hot, allows air into the closed-loop cooling system. When air circulates through the system and passes through the water pump it will cavitate and may break one or more of its impeller vanes.

When this happens the pump is no longer balanced and starts to destroy its seal and bearing. When the pump fails, all coolant will be lost, rendering the car un-drivable. The water pump is more expensive than the previous wear items, costing around $300 for the part, three to four hours labour plus materials, such as gaskets, coolant concentrate, distilled water, etc.

Finally, suspension components are also wear items that should be routinely inspected, especially if the car is auto-crossed or tracked.

Pieces such as lower control arms, trailing arms, wishbone, connecting rods and sway-bar drop-links have ball joints that will wear with mileage.

The first to go are usually the drop-links which canDroplink cause quite a rattle when driving over pavers or irregular pavement. Most of these parts are difficult to diagnose because they cannot be inspected with the car loading the suspension, and even with the suspension unloaded it may still be difficult to obtain movement when the part is just slightly worn.

Shocks and struts tend to last a long time and when they fail the usual telltale sign is an oily seepage on the strut or shock.

ControlThe springs, on the other hand tend to settle a bit initially and then very slowly but continuously with time. If your car is approaching or has passed the 160,000 km mark, I urge you to inspect these not-so-obvious pieces and have them replaced when necessary. You will enjoy your Porsche much more if you do.Trailing

Many of these parts can be replaced as a DIY project. To learn more about wear items and parts in general, and for detailed DIY Instructions on these and other projects, please visit my website at: wwwPedrosGarage.com.

Happy Porsche’ing,

Pedro Bonilla

george oneillTech Editor’s Note: Spring is finally here, so go drive your car. But before you do, read the above article from our friend Pedro Bonilla who outlines typical wear items on Porsche sports cars that can get overlooked. Whether you tackle any needed repairs yourself, or take your car to your favourite shop, spending time to get more informed about these items will better equip you.

Remember as always, submit your ideas for future tech articles to me at George@ONeillAdvisors.ca and even better, consider writing your own article for us to publish. Your feedback is always welcome.

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