Case Studies

Porsche 911 (Type 991) – Engine Cover Latch Release Problem, and Correction

The Vehicle
The Porsche 911, type 991, is prone to a common problem relating to the remote release of the engine deck lid from the passenger compartment. We recently saw this at Atlantic Motorcar Center with a new client car and thought it would make an excellent case study.

How This Happens
It is not uncommon when service is being carried out on the car for the actuator, the electromechanical device that pulls on the cable, to become disconnected from the rear deck lid latch or to be moved out of the bracket on the actuator itself. This prevents the rear engine deck lid from opening. The actuator and cable are located on the passenger side of the engine bay, very close to the engine oil filter, and with the tight space, it is easy to knock the cable loose. This might not even be discovered until the next time service is done and the rear engine compartment can not be opened. Porsche has an emergency release cable in place in the event of an actuator failure, but this is only useful in the event that that cable is still attached to the latch.

Generally, there are three failures if you have a problem with the rear engine lid not opening. This tech tip will give you information on how to diagnose the nature of each failure and then how to gain access and correct it without damaging the car.

The first failure would be a failure of the latch actuator itself. The lock actuator is like an electric motor that pulls on the cable attached to the latch. Should the lock actuator fail, this is easily overcome by the emergency release located under the rear spoiler. That releases a cable that is attached to the end of the lock, actuator latch, and actuator, which allows you to remotely unlock the rear engine cover in the event of an actuator failure.

Trust But Verify
If you have access to an engine borescope, you can likely sneak that under the rear spoiler when it’s raised and over or under the plastic engine fan housing to get a view of the latch. You’ll note on the picture here that we could verify that the latch cable had popped out before disassembly. This can save considerable time and effort to understand if it is simply an electrical fault that can be reversed easily or a cable or latch issue, necessitating a more complex solution.

Failure Mode One – Actuator Or Controls
It’s easy to diagnose a failure of the actuator if, when operating the rear deck lid switch in the passenger compartment, you don’t hear the actuator motor run, which sounds like a whirling noise that lasts for about 2-3 seconds, then chances, are you have a failure of the actuator, the switch or the wiring and voltage supply. You still should be able to access the emergency cable and open the deck lid so you can diagnose and correct the problem.

Failure Mode Two – Cable To Bracket
The next cause is a failure of the cable which retains which connects the actuator to the latch itself. The cable itself is quite robust and unlikely to break on its own accord. However, because of its proximity to the engine oil filter, which is commonly accessed during service, it’s easy to knock the latch actuator cable out of the metal bracket on the actuator side. If this occurs, even the emergency cable will not allow access to the engine compartment, as the latch actuator cable is no longer properly connected, and the sheath will move back and forth. We’ll talk about how to overcome this failure mode shortly.

Failure Mode Three – Cable To Latch
The final cause of failure, and perhaps the most common, is when the latch actuator cable becomes disconnected from the latch itself. In this case, the plastic retaining clip that holds the cable onto the latch becomes displaced, which often occurs during service or changing the engine oil filter due to its proximity. If this occurs, even the emergency cable will not allow access to the engine compartment, as the latch actuator cable is no longer properly connected.

Why This Happens
Porsche has made no provision for positively anchoring the cable line into the latch; rather, it is not retained by a screw or bracket and only requires a small bump to become disconnected and misplaced from the latch. When this occurs, and it is not noticed before the engine cover is closed. Access to the engine cover is impossible, either through the emergency cable or the latch actuator. The cable will still move, but because it is no longer attached to the latch release arm, it does not operate the latch.

Photo Gallery – Visual Of Our Process

Correction – First, Do No Harm
The important thing is to protect the car from any damage; the correction, though it takes time, it’s not exceptionally difficult, especially with an automotive lift and the assistance of a teammate. We suggest using blue painter’s tape on any sharp edges, corners, or exposed areas of the paint to protect the finish.

Step One
The next step is to remove the rear, bumper, and carrier from the vehicle; this does take some time and will require the assistance of a teammate to ensure the damage does not occur, either to the car or to the bumper cover. Once the bumper cover is removed, it can be placed on top of large trash, container, or workbench to protect the finish from damage.

Step Two
With a bumper cover removed, you’ll need to remove the air intake boot from the engine and throttle body to access the area directly under the engine cover latch. If you’re very lucky, you may be able to snap the cable back into the latch and then use the remote control inside the car to operate the cover.

Step Three
If you find that difficult, the next best solution is to simply fabricate out of a stiff wire at a 90° angle pic, with a gentle bend to get around the engine. Using a mirror and a flashlight, place the end of that pic inside the area of the rear deck lid latch, where the cable normally goes, and operate the latch to the passenger side of the car until the rear deck lid opens. It will take firm and steady pressure rather than a fast pull.

It may take several tries with this method before you have success. Take your time, and ensure that no damage occurs to you or the car. If the latch still does not release, it is possible that you have a mechanical problem with the latch itself. You can still access the latch retaining bolts, two 10 mm bolts, from underneath, and once unbolted, raise the deckled to remove the failed latch.

Step Four
Once you have the rear engine cover open, you’ll need to remove the plastic cover that retains the two cooling fans on top of the engine. Be careful of the two wires that are used to power the fans; the connectors are small and can be fragile from the heat of the engine bay. Once you have that fan cover removed, you should be able to look in the center back portion of the engine bay and locate the release latch in the center back of the opening.

Step Five
We suggest removing the latch from the body of the vehicle. You’ll find it retained by two 10 mm bolts about an inch or so long. Removing those is easy, and you’ll probably find factory marks already described on the latch to show you its installed location; if not sharpie or grease pencil can be used to create your own witness marks so that the latch may be reinstalled in the correct position.

Step Six
Once you have removed the latch, you can install the cable carefully, snapping the retaining clip on the passenger side of the latch in place. You’ll note that that is not a very secure connection, and although it may work, it would be easy to displace again. May be a good idea to clean and lubricate the latch with some silicone spray.

Before testing the latch in the actuator, make sure the cable end closest to the actuator is actually snapped into the black metal bracket. If this is not snapped into the bracket, the cable will not operate correctly, as the sheath will move back and forth.

Final Step
With a cable verified to be correctly installed on both ends, we suggest operating the actuator a few times to verify the latch is working correctly before remounting it onto the body. Once the latch is installed back onto the car and lined up with your witness marks, close the rear engine lid and verify latch operation and release. Do it several times just to be sure that it is reliable.

The Fix
While the actuator cable is retained with the plastic positive clip, we’re a big fan of the belt and suspenders approach and suggest fabricating a small metal bracket that can be placed under the passenger side latch retaining bolt removed earlier.

If you look at our picture, you can see that the short bracket, less than 2 inches long, covers and positively retains the actuator cable into the latch body. The cable can only be removed in the future by loosening one of the 10 mm bolts and rotating the bracket out of the way.

Check Both Ends
While this is an elegant solution to the problem on the latch end, one must still be cognizant of the potential ease of knocking the actuator and the cable out of the bracket there. Consider a carefully placed back nylon wire tie, or perhaps, just a check process to make certain on service that the lock actuator works before closing the engine cover. And then retest after the service is complete.

Reassemble In Reverse Order
At this point, with the latch reinstalled, the small bracket fabricated, and the operation of the latch thoroughly tested, simply reverse the process, reinstalling the air, boot air boxes, and rear engine cover, carefully lining everything up. Remove the blue painter’s tape placed for protection, and you should be ready.

Watch The Video
You can review a narrated short video of this tech tip on the Atlantic Motorcar YouTube page; see below.

How We Can Help You
The Service Team here at Atlantic Motorcar is well experienced in this issue, and others, with over 35 years of European auto specialization, serving clients from the areas of New England, we are familiar with the needs of the special service of your auto.

As Maine’s leading European auto specialists, we provide expert-quality services at a fair rate than nearby dealerships and specialty shops. If you’re experiencing any of the above-mentioned symptoms in your auto, please call us immediately; we can usually see your car the same day! At Atlantic Motorcar, we’ve developed some very specific procedures and tooling, combined with our expert technicians, to make this otherwise onerous repair a snap.

Questions, or if we can help with service on your Audi, BMW, Mercedes, Sprinter, Honda, Infiniti, Lexus, Mini Cooper, Porsche, Volvo, and VW, please contact us. Our team of Service Specialists is here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing,” that’s the Atlantic Motorcar Center way.

The Atlantic Motorcar Center Service Team


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