Last month a frustrated 928 owner was considering selling his Porsche since he could not count on it. Here is the rest of the story: After repeated test drives (over 400 miles) a pattern failure of starting and dying become more consistent. A dip in fuel pressure was noted during hot cranking and attempted starts and a subtle “chattering” sound was heard under the hood. With the sage advise of “Dave K” (a 928 guru) this led to the suspicion of a failing component in the Motronic computer. We sent the computer to a respected vendor for Porsche ECUs for evaluation. Their testing revealed NO PROBLEM FOUND with function. They did note that the circuit boards inside the metal box were not for the vehicle and therefore on-board diagnostics would not work, which we confirmed. With this information, and with a correct circuit board installed, our diagnostic computer would “talk “and the car performed perfectly. To quote the owner, “in the three years I have owned the car, it never ran better and the symptom is completely gone”. To hear that the computer repair shop could not duplicate the problem did not surprise me since the car had to be driven many miles before it happened. The ability to scan the car for trouble codes and install the correct computer was a viable risk to take and it paid off. He is no longer selling it and the car is now getting a new interior. MC
Q – The brakes on my Cayman S are testing my resolve. I admit that I use them hard. I do not abuse them, well OK, I did once, but it seems like no matter what I try, they fade after a few hot laps. Driving this car is the joy of my life, it is a fabulous car but I have tried everything. I roasted my red calipers until the red turned “burnt umber” (from my Crayola days). The caliper seals were shredded and I had them replaced, I installed titanium heat shields, GT3 air ducts, flushed out the brakes after every event and I use the best fluid I can get. Most recently my master cylinder began to cause a soft pedal and I replaced that too. Still my brakes are fading! Tim
A – It sounds like you have suffered. Your frustration is very clear. After a test ride with you on the track, I don’t think it is how you’re driving. My opinion is that you have made all the right choices but one. It is time to try another composition brake pad. When you build up so much heat that you red calipers turn brown and you can only get six laps in, you need new pads. While I do not claim to be a brake system engineer, it stands to reason that the heat which shreds rubber and boils brake fluid will also affect the brake pads coefficient of friction. To stop you have to have both pressure and friction to get the job done. If that fixes it, remember which pad works and which one didn’t and let me know. The best advice I can give often results from feedback I get from club members like you. MC
Q—I am thinking or selling my 944 and moving up to a 928. I wonder which one I should choose and what I should be looking for before I take the plunge. –Emil
A—Taking a plunge into the Shark Tank can be a scary and exhilarating process. My thumbnail analysis is to budget two times the purchase price to do needed maintenance and repair inevitable problems that these older classics are prone to. I suggest that any one considering a specific model should join the local Club that is most associated with that model. Join the model-specific community of motorheads who live, breathe, and sleep in that world. One group recommend is the 928 Owners Club. Attending an event geared toward making an informed decision is also a wise move. The local 928 geeks meet once a month at a local watering hole and they are a great group of guys and gals. Yes, wives and girlfriends are welcome.
Q—Should I start my car up when it is stored in the winter time? If so, how long should I let it run? –Chuck
A—I do not endorse starting the car routinely in the wintertime unless you can drive it. Starting it up without a full warm up creates more problems that it solves. During warm up, that metal parts get coated with corrosive chemicals that are eliminated when the system gets up to operating temperature. If you decide to drive it, I would recommend a 10- to 20-minute run to get everything up to temp with a few high rpm romps and some hard stops thrown in to clean the flash rust off your brake rotors. Even if it does not help your car, you will feel better; that is what it is all about anyway. –MC
Q—I am getting ready to put my car up for the winter, just after the color tour. What do you recommend? –Pete
A—This simple check list is all it takes:
1) Wash the car a week or two before you cover it up, allow all the water to evaporate.
2) Clean the wheels to remove all the brake dust before you store the car. Your best bet is to remove them first. When you do, you can clean your beautiful brake calipers with the wheels off. Brake dust contains corrosive elements. You do not want that on your wheels and calipers all winter.
3) Clean the interior, under the seats, in the map pockets, check the glove box for missing receipts and don’t forget any other compartments as well as the trunk(s).
4) Wax the car. If it needs a good buffing, do that before you wax it. Now that your wheels are clean, wax them too.
5) Use a protectant on the vinyl trim and rubber. Use a leather treatment on the seats.
6) Fill your tires to the maximum pressure allowed and for added benefit, consider tire cradles to keep them from flat spotting. Don’t worry too much about that however, my tires flat spot over the winter and when I get the car out in the spring, it takes a week or two and the problem goes away. It is important to remember to adjust the pressures back to their proper spec when getting the car OUT of storage. I will often write myself a note to that effect and tuck it in front of the steering wheel, so I’m sure to see it when I get in the car in the Spring.
7) Consider a battery cut off switch. If you do not have one, disconnect the negative terminal from the battery until you are ready to fire it up. If you have an electrically operated front hood latch, I suggest that you place something to obstruct the latch. If you don’t, and it shuts, you will have to jump power to get it open in the springtime.
8) Use a modern high quality battery tender, not a trickle charger, to keep the battery up to snuff. If the unit you have in your car was installed by the dealer when you bought it, go online and investigate the wisdom of replacing it with a newer version. Ask me why later.
9) Fill the tank with gas. When the tank is full, there is no air space in the tank which can contain moisture. Put some Sta-Bil in the tank and one can of premium gas line treatment containing isopropyl alcohol.
10) If your car is due for an oil change, change it before you store it. If not, don’t worry about it.
11) Have you had your annual brake fluid flush? Better to do it more frequently than less. Brake fluid absorbs water from the air and letting it sit in the brake system all winter is not a good idea.
12) Purchase a carpet remnant for your garage’s cement floor. This will keep condensation down. –MC
Q–. I plan to have a direct oil feed installed in my Boxster, but I am confused.
Do I still need the LN Engineering bearing? Can I keep my existing bearing? Do you recommend a ceramic bearing? –Pete
A—With the direct oil feed, you may be able to use your existing bearing if it is in good condition. You can also purchase a new standard bearing if your original bearing feels rough or if you want to put a new one in for insurance. I would vote for the new one regardless since the cost is low and you cannot be sure of the lifespan of the original bearing. As far as the ceramic bearing, it is a fine idea and for even MORE insurance, go for it. Is the ceramic bearing actually necessary? I do not think so. The load factor on the original bearing is relatively light and simply supplying oil should make it last the life of the engine.
Q – The wipers on my 1990 C4 just stopped working. I have to drive the car so I am afraid to get stuck in the rain. I checked the fuse and it is fine. Gary
A – The most common problem that I have seen is dirty contacts in the switch itself. I have had some success by removing and cleaning the contacts but first things first. To make sure that the problem is not the motor, remove the intermittent wiper relay in the fuse box. If the wipers work, you can then drive the car until you can have the problem fixed. You will notice however, that they no longer park.
So assuming your wipers now work, you could have a bad switch or failed relay. My vote is to replace the relay first with a known good one and see if everything goes back to normal. The relay is located in the fuse box under the hood and identifying it is easy. The number is 928 615 101 01. If the wipers still don’t work with a good relay plugged in, you may need actual diagnosis and on your car, with the air bag and all, I would leave it to a professional.
On my car, (older Carrera) my intermittent wipers quit working and the park function failed at the same time. My cheesy solution is to park them wherever I want. For me, being vertically challenged, I like them to park on the right side of the windshield rather than the left anyway. On my personal to do list, intermittent wipers are a relatively low priority. – MC
Q – My 944 climate control doesn’t work and I am planning to drive it this winter so it has to keep me warm. When I rotate the fan control knob, nothing happens, it just spins. When I rotate the temperature control, I get no heat. Got any hints? This is going to be my daily driver and I’ve got plans for it but I need to keep the bill at a minimum right now. Calvin
A – It is a rare individual who plans to drive a Porsche in the winter, and I salute you, sir. I have driven my 944 in the winter too and it is an excellent car with all season tires and about 300 pounds of sand in the rear hatch area. No problem, except for the salt! Wash the underchassis regularly. But I digress…
The problems you are having could turn out to be quite expensive. For now, I will just focus on getting heat. First of all, the climate control should fail safe in defrost mode, full heat and yours does not. Have you had any cooling system work done on it? Sometimes an air bubble will keep the coolant from flowing through the heater core. Assuming there are no bubbles and that warm coolant is reaching the valve, to see if the heater could work, disconnect the vacuum hose to the control valve, in the engine bay at the center of the firewall. You should now get heat. The heater control valve is the same part as used on older Audi 5000’s and when vacuum is absent, it goes full open, full heat. If you still get no heat, remove and inspect the valve. I have seen some where the lever moves but it is not connected to the flap inside the valve.
As far as the fan, sometimes the knob simply breaks free from the shaft. Pull the knob off and see if you can rotate the inner part of the fan switch shaft. If you can turn the fan on…simple, a new knob fixes it. If you only get high speed, the fan resistor might have failed. The resistor fits onto the blower box, driver’s side top and it is one of the easiest fixes for missing fan speeds.
This should get you heat and hopefully by next spring, you can take the diagnosis to the next point and get the temperature control functioning again. – MC
Q – My ‘88 Carrera was driving great until I let my son borrow the car for the Woodward Cruise. I never had a bit of trouble with my transmission but when he brought it back it wouldn’t go into third gear without loud gnashing sounds. It doesn’t matter how easy I shift or at what speed either. All the other gears including reverse, work normally. The other thing that is different is that the clutch pedal is about a half inch lower than it used to be. I am hoping it just needs a clutch adjustment. I was told by my mechanic that these gearboxes are bullet proof so I wonder. How good are they? The car only has 41,000 miles on it! – Denny
A –The G-50 transmission is generally bulletproof. They are hard to break but even the best sometimes fail depending on what mayhem is committed. The Woodward Cruise has caused some normally sane people to get a little crazy. Have you been down to the loop in Pontiac? Yeah baby!!
I have some bad news for you Denny. When I have seen this symptom, it is usually due to a broken synchronizer ring or damaged gear set. “Internal transmission damage” is how I describe it. Any way you slice it the repair will not be cheap or easy. The first step is to perform a basic “eyeball” inspection of the clutch pedal, hydraulics and lever at the transmission…but that probably won’t turn up anything. The next step is to pull the powertrain out, separate the transaxle from the engine and find out what broke and how painful this is going to be.
The low clutch pedal on this car is another issue that may have contributed to the transmission failure. On this model, although the pedal linkage is adjustable, it rarely if ever needs to be adjusted. What does happen is that the rubber center of the clutch can fail and over a period of twenty years or so, it starts throwing chunks of rubber into the pressure plate. These chunks get lodged in the pressure plate, some of the clutch spring fingers warp, and this changes the release bearing height. Now I have a question for you (and your son): What happened just before third gear started grinding?
“Well, he shifted fast from second and got the shifter part way into third and let the clutch out. The shift lever kicked back at him into neutral, and then it would not go back into third without grinding”
At least you know when and how it happened but now to find out how bad it is. With the powertrain removed, things to consider at this age and mileage include rubber and plastic parts. On this list I include: the rubber center clutch, release bearing, input shaft seal, crankshaft seal, engine compartment insulation, oil thermostat O-ring, breather gasket, and possibly the oil light switch. Whenever the powertrain needs to be removed, overlap between related operations can benefit you by easier access. For my money, if I have the budget for it, I want to do it once and do it right. MC
Q – The starter on my Carrera is making unhealthy sounds and I would like to get your opinion on my choices. I see some aftermarket gear reduction starters available, some rebuilt Bosch starters and Bosch Reman starters. What’s the difference? Jeff
A – Your car was built with a Bosch starter and they work for decades, not years. The aftermarket gear reduction starter is lighter, and in some cases cheaper than the original. The benefit of that starter is weight and power. For racers, they are an excellent choice. The warranty is not as good however and it is a fabricated part meaning that if a component fails, you might just need to buy another one.
The rebuilt Bosch starter can confuse things because all original starters were Bosch and anyone can rebuild one. That’s the problem. Who rebuilt that starter? Who knows? Generally the warranty on rebuilt or reman Bosch starters covers the part itself but no labor. Another issue is terminology. What constitutes a rebuilt starter anyway? I have seen (and been victimized) by supposed rebuilt parts that simply did not work well and sometimes not at all.
A Bosch Reman starter comes right from the source, Bosch. When Bosch remanufactures a starter, ALL the working parts are replaced…not just “the bad ones!” Bosch also supplies Porsche with their “Factory Rebuilt” starters…the Factory in question is the Bosch facility in Broadview, Illinois. The quality is unsurpassed and the warranty on them is rock solid. If you take your Porsche to the dealer for a starter, you get a top quality part and a warranty on labor as well. Any Porsche dealer can correct the problem at no charge for parts or labor. If you buy a Bosch Reman, the same parts and labor warranty applies. Anywhere in the U.S. or Canada, you can get the Bosch part warranted and if it was installed by a Bosch affiliate, the labor as well.
Naturally, although the warranty is a factor, having the peace of mind knowing that you will probably never need to take advantage of the warranty is even better. My vote, saving money by choosing a “no brand” is not worth it. MC