Munk's Motors - Master Cylinder Tech Tips!

Q - I have a 1987 Cabriolet. I put the top down, left it parked, and a cloud burst flooded the car! What should I do? Is it OK to just start it up?

A - First, smack yourself in the forehead and resolve to never do it again. Next, disconnect the battery, remove the driver seat, remove the DME computer and carefully remove the circuit board inside. Check for moisture and corrosion. After letting it dry, put it all together reconnect the battery, and pray.
MC

Q - When if first start my 1990 Carrera 4 I hear a funny noise like a high speed zipper back in the engine compartment. By the time I open it up to look, the noise goes away. When the car is warm, I never hear the noise.

A - On Carreras with two belts, one for the fan and another for the alternator, Porsche needed a warning light to alert you if the fan belt broke. That noise you hear is the tiny little idler wheel that is keeping tabs on the fan belt. It's a little roller attached to a bracket with an arm on it. Temporarily, you can put a little spot of oil on the bearing to make the annoying sound go away but you better order another of those sensors. I have seen the little device without the idler even on, ty-wrapped in place so the light would NEVER go on. This is a recipe for disaster since you could burn up your engine without even knowing.
MC

Q - I notice that when I try to raise the top on my Cabriolet, it tends to "stick" on one side and the motor makes a groaning sound unless I lift it up a little. How come?

A - There are a few reasons for this. On the Cabs, the top tends to loosen up as a normal process of wear and tear. In a nutshell, the screws that hold it together, the locating pins, and the bolts that secure the gearboxes to the car simply vibrate loose. The gearboxes are only held in by three long 6mm bolts! (that is pretty small considering the load) There was also a technical service bulletin that applies to mid 95 and earlier cars which suggests replacing the top pins with Targa locating pins which are shorter. The part number for the shorter pins is 911 565 074 40 and they are only about $15.00 per pin
If you hear that groaning sound or if the top bangs hard as it is coming down, you could facing a major expense if you ignore it. Then best case scenario is that tightening and adjusting the top will restore perfect function. In the worst case, you can break the top parts or even rip the top…at huge expense. With the top part way up (or down), try rocking it back and forth and see what is loose. You might be surprised. And if it sticks or binds avoid using it until you get it fixed.
Recently I inspected four Cabriolet top mechanisms and ALL FOUR had loose parts. One of them came in with the top literally ripped off when it opened (by itself) on the freeway. It pays to have good insurance and a well adjusted top.
MC

Q - When I hit the brakes on my 1991 Carrera, I feel a shaking in the steering wheel. The wheel kind of twitters back and forth. I had the brake pads and rotors replaced two years ago because I was getting the same symptom and after that, it went away. Now that bad old feeling has returned even though I was told that my brakes looked fine last time the car was inspected. This is very frustrating.

A - Frustrating is only the half of it, expensive is the other half. When your brakes were done last, the original cause of the symptom wasn't figured out and that's why they are doing it again. Porsche has an elegant way of engineering their parts and on your car, the pads slide on stainless steel spring plates that are screwed into the calipers. Corrosion sets in under those plates causing the pads to "stick". The brakes functioned safely, but the pads simply did not fully release. The excess heat build up in turn warps the rotors.
Removing those plates it important to get a long lasting job but it is not easy. Those little screws usually do not come out without a fight and if you are in a hurry, they can break right off.
The other issue with brake shake that you can feel in the steering wheel has to do with all the wear and tear on your steering system. If you ignore the shake, the tie rod ends, inner sockets, steering rack, ball joints, and steering shaft all have to soak up that annoying vibe before it even reaches your nervous palms. Now that can make it a lot worse.
MC

Q - I had the brakes replaced on my 993 at an independent shop and now six months later, there is rust on the inside of the brake rotors when you look through the spokes of the wheels. Did they put cheap parts on my car? Why are they rusty? The original rotors never were.

A It is unlikely that the rotors were cheap but that rust issue is annoying and it makes the job look cheap. Fact is, Porsche uses a protective gray coating on their rotor "hats" and only their rotors come with that coating. That does not make them work better, it just keeps corrosion from forming on the exposed (non working) surfaces. When I install rotors, I use a Zinc Cold Galvanized coating on the rotor hats. On my own car, I even sprayed it into the cooling vanes and the drilled holes (yeah, I am a bit picky). That rust does not hurt anything, it just looks tacky.
MC

Q - I have a 1987 Carrera and when I turn on the heater, I hear a squealing sound coming from the heater fans. After it is on for a while, the noise goes away but I am afraid that something is not right.

A - Trust your intuition. The bearings in those fans are knows for drying out and if you run it that way, you will burn them out. My car does this too and I will get back to you with a solution (short of outright fan replacement) after I experiment with my own car (and my own time)
MC

Q - I have a 993with a full shield under the engine. My tech said to remove it with the benefit being a cooler running engine. Since Porsche put it their, I am not sure if I should take his advice or not. What is it there for if it is not important?

A - Darn good question Cliff. I thought that it was an aerodynamic aid that helped streamline the car and I further thought that, where in America can you drive fast enough to reap the benefit of it. Now I know that we can blame it on the Swiss. Noise regulations in Switzerland are so strict that this under tray is there to keep sound at bay. If you leave it on, your Porsche will not only be quieter, it will also run a little hotter! Who needs it? My suggestion: Take it off and hang it in your garage for posterity and for the next owner of your car.
MC

Q - On my 1996 993, I just paid a lot of money to have the oil changed. What makes it so hard to change oil on these cars?

A - 1) They hold a lot of oil, 2) The more oil they hold, the longer it takes to drain and fill, and 3) To drain the oil and change the filters, you have to remove panels that are in the way.
It was suggested to me that certified technicians did not have to add the oil, that apprentices could do it and do it cheaper too. I am not sure I like that idea on my Porsche but as a cost saving measure, you could offer to add the oil next time you have it changed. That usually takes about 20 minutes and at Porsche labor rates, it might save you over 20 bucks. The other cost saving idea would be to see if the facility offers you a "quantity discount" since they are selling you almost two cases of that expensive synthetic oil. I am not saying that you will get any takers, but you can always ask. As far as doing the oil change yourself, that is always an option but a messy one.
MC

Q - When I first started my 911 up in the morning, the oil level gauge was all the way into the red. It really worried me so I added oil until it was full. Now my car smokes like crazy and oil is dripping from the right rear fender. Did I ruin my car?

A - Chuck, my student, you have committed the first travesty of the 911 world by believing your oil level gauge in the morning. Your car holds 11 quarts wet and about 13 quarts dry! Don't feel bad about it though, I have done the very same thing. Maybe you have to do it once to become initiated into the Porsche fraternity.
In the morning, you may be able to find oil at the bottom of the dipstick but never fill it up until you have met the criteria in the owners manual regarding temperature. I know, it is not mainly to read the manual but in this instance, you must. As far as the mess, your right frame rail will never rust since it is now internally coated with oil. Drain a couple quarts and check it again when it is hot.
As far as ruining your car, that is unlikely but it may take a while for the smoke to go away. Anyone you know planning a picnic? Got a mosquito problem?
MC

Q - I have a 1968 911. When I took the car in to have the chain tensioners replaced with the pressure fed, upgraded variety, none of the parts fit! It apparently has a 1967 engine in it even though the numbers match. How can this be? Is there a way to retrofit the later tensioners to my engine?

A - No problem, John. Porsche was not too strict regarding the exact engine they installed in a certain year car. Sometimes they used up the engines they had left over from the prior year. In addition, cars built the year before are often titled as the year they are sold. What you have is a 1968 with a 1967 engine in it. That is where it gets interesting.

The tricky part is retrofitting the later tensioners. It can be done but it requires block modifications to do it since the studs do not line up. Then you would also have to buy new chain boxes. Unless you are planning to overhaul the motor, it would be cost prohibitive. Considering how many miles you intend to drive the car, I suggest using the original style but updated design tensioners along with the "stops" to keep them from fully collapsing. In addition, the pivots should be replaced with the updated design at the same time. The original design should work fine for about 40,000 miles between rebuilds, perhaps more with modern oil technology.
MC

Q - My 99 Carrera four eats tires!! I have only been able to drive about 10 to 15 thousand miles before the inside of the rear tires are bald. I didn't even notice it since the outside tread, the part I could see, looked fine. The last time I had the car serviced, the tech advised me that with Porsche alignment specs, that was normal. Normal for who, I am not Donald Trump! I do not track the car and only occasionally drive it hard. What do you suggest? (I know I shouldn't complain, it is a Porsche after all and I can afford it, but damn! Those tires cost about $400 bucks each!) Help!

A - "Your Porsche is a finely tuned machine" and yes it DOES eat tires. It also handles like an overgrown go kart and yes, of course, you can afford it, you lucky dog. The question is one of compromise. Many folks that I advise want decent tire wear and are willing to sacrifice ultimate handling to get it. The local Porsche dealer and the tire store may not like it, but with a less aggressive rear toe setting, your car will no longer chew on that expensive rubber and it will still out-grip, and out-handle, 99.8 percent of the other cars on the road.
Will it affect handling adversely? No, not unless you are driving your car at it's limits. Will the purists lament? Don't tell them…but when they complain about how many rear tires they have gone through, just smugly say, "Yes, I had that problem once", and leave it at that.
MC

Q - I have a 96 Targa and my check engine light keeps coming on. It has been shut off numerous times but in a few weeks, it comes back on. The diagnostic codes that set don’t make sense to me but my mechanic says that the secondary air system has failed. He wanted 4 grand to pull the motor and correct the problem. To me this is absurd and besides, the car runs great. Can I get a reality check on this?

A - Be aware that the check engine light can set for numerous reasons and that computer is still not smart enough to diagnose the problem. It only gives you clues. I know a number of clients who have fired the “parts cannon” at their cars only to discover that the computer lied.

Your mechanic is correct on one point. Odds are, the secondary air system is the source of the problem but pulling the engine to fix it IS absurd. The likely culprits are clogged holes in the cylinder head exhaust ports near the exhaust valves.

Fortunately, the holes can be accessed from under the car by removing the exhaust and heater boxes. On an older car, this might be easier said than done. The nuts securing the exhaust are usually rusty so finesse is required to remove the exhaust. If you do not have a source of heat to warm them up, don’t try it, the penalty for breaking a stud is pretty stiff. We have had more than one car towed in after the owner tried to do it himself.

Once the system is off, you probably will not be able to see the holes since they are packed with carbon deposits and somewhat hidden behind the valves. I fabricated a “port cleaning reamer” out of an old accelerator cable chucked into my trusty Makita cordless drill.

Once you clean the deposits off the exhaust port surface with carburetor cleaner, you can find the holes and start feeding the cable into the holes to break through the clogs. Work at it gradually and let the carburetor cleaner do the work for you since you do not want to push the carbon up into the ports.

Once you get the ports nice and clean, reinstall the exhaust and you are on your way. The total cost; about $800.00 dollars or so, plus gaskets and hardware. This is not a guaranteed fix, but for the money it is a good option and every car I have inspected for this has had clogged secondary air holes.

By the way, while the exhaust is off, you can clean all that stainless steel with Scrubbing Bubbles and Scotchbrite (if you are as anal as I am). This is a great way to clean around the exhaust cutouts on the rear valance and to get the tail pipes back to new as well.

MC

Q - I have a 1984 Targa and my windows go up too high. It makes it hard to shut the door unless I lower the window a little. The window hits side of the weather-stripping and then the window sticks out. It also leaks! I removed the door panel and I could see a stop for the window with a chunk of plastic. It looks bent. What do you suggest?

A - Porsche offers a repair part for the window regulator that can be installed once the regulator is removed. It is stronger than the original and will probably last another twenty years or so. The other option is a new, improved window regulator. It is a more robust design and a permanent cure but it requires slight modifications to fit. The part costs about two hundred dollars but if you enjoy tinkering, for about 20 bucks, you can save the extra cash and take your wife out for a really nice dinner in your Porsche.

MC

Q - I have a 1985 Carrera and since it is my first Porsche, I probably got in a little over my head but here goes. It has an oil leak at the pipe connecting the engine to the oil thermostat (it’s the one with two solid steel ends and some braided hose in the middle). I was thinking of changing it myself but I discovered that it takes special tools to get it off the thermostat and what’s worse, the hose costs $284.00! Help, I didn’t realize that this car would be so expensive.

A - First, Chuck, I share your pain. These cars can suck your wallet dry faster than a 6 hp. shop vac. But I have found a simple and cheesy solution to your dilemma. You can rest assured; it is not endorsed by Porsche nor is it a guaranteed fix. The flexible part of the hose is probably leaking and it is secured by crimped-on clamps called ferrules. When the hose is new, these make a fine seal but when the hose ages and shrinks, the fit loosens and the leak begins. If the ends of the hose are leaking, replacing the ferrules with clamps might help. Incidentally, on the race engines built by Jerry Woods, he also feels that clamps are more reliable and he ought to know.

To remove the ferrules, you need to cut them through and break them off the hose. The easiest method for this is a cutting disc on a high speed die grinder. You will have to make three or four cuts to weaken them sufficiently but do not cut into braiding of the hose or the game is over.

Once they are cut, squash them with Channel Lock pliers and remove the chunks. Replace the ferrules with two hose clamps per end. Clean up the mess with Gunk Engine Brite and a power wash to see if the cure worked. If that is where the leak was happening, you have solved it for 10 dollars and about two hours of your time.

MC

Q - On my 1992 Carrera, the sun visors are very stiff. I am afraid they are going to break unless I use both hands. How do you oil them? - Greg

A - If you have to use both hands, you will definitely going to break them and it’s not wise to oil them. Porsche provided an adjustment screw near the pivot to regulate the amount of friction (tightness) in the hinge. If you have too much friction, a simple adjustment or service will fix it.

To adjust the friction, simply loosen the screw a little and see how it works. If you are not happy with the way it feels, the moving parts are not hard to service. To make them move nice and smooth, remove the visor assembly and loosen the adjustment screw (don’t remove it). Rotate the “stem” of the visor bracket while pulling it out of the visor. Clean the stem, spray some silicone into the hole, and reinstall the stem into the visor. Install the assembly then tighten the adjustment screw until it operates smoothly.

MC

Q - After 89k miles, my 1991 Carrera is feeling a bit arthritic and loose over bumps. I am considering Bilstein coilover struts. I also want to lower it about an inch and a half but I am afraid that the ride might be rough. What do you think? - Fred

A - I like that combo. Even without adjustable damping, the Bilsteins work great. They are biased more toward crispness than comfort but on a Porsche…Perfect. On the other hand, if you simply install the kit without considering other components, you might be disappointed and blame it on the shocks. Often, poor ride characteristics are caused by the rear upper strut mounts, front control arm bushings, and stabilizer bushings.

You can’t see the rear upper mounts when they are on the car. But when you do a side by side comparison of old mounts to new, you will see the difference. Since most of the cars weight rests on just two rubber donuts, after 17 years, the mounts are well done. Over time, rubber hardens and settles into a fully compressed shape. The front mounts on these cars seem more durable and they are expensive. I have not seen the need to recommend them even on higher mileage cars. Rubber deterioration also affects the front control arm bushings and stabilizer bushings. The bushings get twisted every time you hit a bump or bend your toy around a corner. And you thought you just needed shocks.

My rule of thumb for rubber suspension parts is: With a useful life of 10 to 20 years, when the struts and shocks are being replaced, replace the mounts and take advantage of the labor overlap.
MC

Q - I have a strange problem with my 1986 Carrera. After I turn a corner, I notice that my brake pedal drops very low. This is very disconcerting. As soon as I straighten the wheel and apply the brakes, the pedal feels normal again. I have flushed the brake fluid and taken it all apart twice! I rechecked everything I replaced: the front wheel bearings, rotors, and brake pads. I am tearing my hair out. - Heavy

A - Strange is an excellent word for this. My guess is that turning and loading the front wheel bearings pushes the brake pads away from the rotor. I have run into this and been annoyed by it myself. You can actually install incorrect wheel bearings if you don’t compare them. Bearing sets can have the correct outside diameter but a larger inside diameter. Even though bearing preload is correctly adjusted, the bearing can “act” loose when turning. Cornering forces generate strong side loads. This allows the inner bearings to “walk” out of place, and rotor deflection pushes the brake pads away from the rotor. During straight line driving and braking, the wheel hub will stay centered since there are no “side loads” (and the brake pads stay close to the rotors”). Crazy.

A 1967 Beetle schooled me on this topic. The lesson: compare parts. A late night Detroit DJ used to sign off at night with: “Remember, trust everyone…but always cut the cards”. I considered my experience just another tuition payment. Good luck
MC

Q - I have been considering a muffler bypass on my 1997 Carrera. I think it might be too loud. Have you heard one? What about an aftermarket exhaust? - Chuck

A - I really like the way those cars sound without a muffler. In the best of all worlds, you could have a switch that would allow you to select “muffler” when you pass the cops or cruise steady and then select “bypass” when you want your Porsche to sound like one. If I had to live with only the bypass pipe, I might drive my car less and I couldn’t hear my stereo on the highway, but oh, what a glorious sound. For most folks, it might be a little too loud.

I would recommend a abspeed exhaust based on the cars I have heard and driven. They fit well, do not drone excessively, and sound mellow. The best way to decide what you want is to attend an event, listen to everyone leave, then find out which brand he/she chose.
MC

Q - Help! My 96 Turbo is making me crazy. I love the car but I can’t stand it any more. It smokes so badly that I could fog for mosquitoes and charge for it. The final straw was when I started it last week and my neighbor came over and asked if he should call the fire department. I am serious! I even made a video of it. And to make matters worse, now it acts like I am losing power and I feel a hesitation.

It only has 20K on the odometer. I have religiously followed the dealer’s recommendation about oil and filters and it has never been anywhere BUT the dealer. Last visit, my service advisor said that the smoke was normal and that I should change to a heavier grade of oil. What could have gone wrong with it?br> Dave

A - Dave, I emphasize with you. I had to quit driving my turbo when it had the same problem. I couldn’t take it to parties any more, it was embarrassing! Fortunately your turbo can’t have the same problem as mine. From repeated flogging, I roasted the oil seals in mine. At 20k, I am certain that is NOT your problem.

It is an easily corrected design flaw. When Porsche redesigned the turbo for the early 90’s, they mounted two turbos, down low in the chassis for faster acceleration and packaging. They also provided an oil reservoir for fresh oil at each turbo. The problem is, when you turn the engine off, residual oil, under pressure…fills the turbos and causes the smoke on start up. I would bet that this IS your problem.

The cure consists of two new oil lines with check valves to shut off oil flow after the engine is shut down. Unfortunately, many of these cars were diagnosed with “bad turbos” which of course did not cure the problem. For a time, while the cars were under warranty, Porsche would fix them free with updated lines. Although it is expensive, once you have the kit installed and clean up the mess, there is no permanent damage. It is a lot less expensive than replacing the turbos.

Even so, for a while the car will still smoke. I prescribe a fast drive on an unobstructed stretch of road to literally “blow out the pipes” This will clean some of the oil residue out of the turbos, pipes, intercooler and the intake. The oxygen sensors (a vital fuel trim component) are certainly coated with oil residue and it takes heat and time before the car will regain full power.

As far as the advice you received, service campaigns, updates, and recalls are the tools that an advisor should utilize when giving advice. You would be doing him a service to let him know about the cure if he ever runs into this again. As many professionals will tell you, free advice is usually worth what you pay for it and he simply did not do the research.

And although this might cure the smoking problem, what about your mental health? The answer for you may be “auto therapy”. Auto therapy requires discipline and repeated test drives. After a dozen or so smokeless start ups, you should start feeling better. Meditation in your car will also help with your therapy. My personal motorhead mantra is “c….h….r….o….m….e”. Take a deep breath and try to say it very slowly so the sound creates a resonance in your head. I also recommend auto yoga which involves various postures and movements which will improve concentration and promote a feeling of deep peace and contentment. Some hacks have called this “detailing” but they miss the point. It works for me. Try it.

As far as the neighbor, next time you see him, ask that smart aleck if he would care for a ride. Then slip it into first, smoke all four tires, snatch a few gears, and then tell him to hold on while you do a “brake test”. It may not change his mind, but for a few seconds, he will be speechless. And Porsche glory is restored.
MC

Q: I just bought a 2007 Carrera 4 and I plan to take it to Drivers Ed this year. I wondered what I could do to get more power. Is it possible to install a turbo or a supercharger? - Jim

A: The quick answer is: sell it and buy a turbo. But I understand, this is the car you have and you want to have as much fun as you can. I feel the same way about my car, and I want more power too. For more power, very little is available that does not involve a huge outlay of cash. For my money, I would start with a sport exhaust, computer reflash, and a cold air intake. You can expect modest gains in power but more importantly, your car will feel faster.

For the turbo or supercharger option, there are companies that develop kits for newer cars but it is getting difficult to improve on Porsche engineering. Another factor on a new car is warranty. Porsche backs their products with an excellent warranty as long as the car is maintained and operated in accordance with their standards. If you modify a car under warranty, they can always tell you to “take a long walk on a short pier” if something breaks.

For Drivers Ed, find out how much fun your car can be with only a few only minor mods and next fall, after a season of fun, pose that question again. Some summertime seat time may change your perspective. - MC

Q: I have been considering a muffler bypass on my 1997 Carrera but wondered if it would be too loud. Have you heard one?
Chuckk

A: I really love the way Porsche’s sound without a muffler. I wish there was a switch that would allow you to select “muffler” when you need to be discrete and “bypass” when you want your Porsche to sound like one. Until then, if I had to live with the bypass pipe, I might drive my car less and I would be nervous about getting caught. Consider one of the sport mufflers instead. Most of them fit well and sound mellow compared to the muffler bypass.

Next time you are at an event, listen to some of the cars that have a sport exhaust or muffler bypass. Ask if you can go for a ride in the car to see how it sounds. If you hear an exhaust that you particularly dislike, politely inquire as to the brand and eliminate that one from your list.

The price of experimentation is not too great when you consider the residual value of your first choice. If you buy something that doesn’t suit you, you can sell it in the newsletter. Many gently used parts are purchased at fair prices. Don’t be afraid of making a bad choice. It’s your car and your privilege to change your mind.
MC