Case Studies - Our Service Solutions

Originally intended as a showcase to potential customers of our workshop and staff's abilities, this page has evolved in an interesting and informative teaching tool, and one of the most popular pages on our site!
A Collection of the Odd, Unusual and Interesting Found While Servicing our Client Vehicles.

Each photo can be enlarged by clicking on it.
 

2004 Mercedes C-Class - Air Flap Lever Fracture "Snapping" Noise
Hiding in the dash of that nice C-Class is a small plastic lever, which, given time and use, may fracture, resulting in a noise from the dash area. The noise is noted as a "snapping" or "popping" sound in or near the center vents, and the customer may also have a concern about incorrect temp or air flow from the vents. The problem, a small plastic lever which operates the foot well flaps via a servo motor.
 
Running a diagnostic with the Mercedes SDS computer should confirm the fault, before the teardown and visual inspection. The plastic lever in question has been redesigned to be more robust, and the update kit is available from Mercedes. The service correction is quite involved, requiring removal of the center console upper panel, radio, climate control head, and lover dash with the glove box. Once the arm is located and replaced, the SDS should be used to run a "normalization" routine on the flap system.

1999 BMW Z3 M Convert - Evaporative Emission System Fault
Most late model cars are equipped with a system to both capture and recover vapors from the fuel system. In the past these vapors were often vented to the atmosphere, not exactly an environmentally friendly approach. The evaporative emission recovery systems are usually reliable, but from time to time, as cars age, problems do occur. In our workshop we've chosen to efficiently diagnose these problems through the use of a machine that creates a low pressure smoke containing a UV dye. By the use of this system, even leaks as small as a pinhole can be located.

We've all seen the ubiquitous P0455 - Large Evap Leak or BMW Fault Code 251 - Minor Leakage, pop up on the diagnostic computer. Often it is a loose fuel tank cap, or a deteriorated evap hose, both common for the age and mileage of most of these cars. But how many times have you found the photos below? One of our skilled techs, in process of diagnosing the leakage in the system, noted diagnostic smoke coming from the fuel tank area. On the Z3 this is no small challenge, as the entire rear suspension must be dropped to remove the fuel tank, not an easy task. But as you can see from the photos below, our techs observations were right on! A large rodent nest was found on top of the tank, and the rodents had gnawed through the evap and fuel recovery lines.

2001 Audi AllRoad - Camshaft Tensioner Seal Oil Leakage
We saved this customer from what could be a very expensive repair, a broken timing belt. Like most cars now on the road, the Audi 2.7 and 2.8 engines use a rubber timing belt. Located in a plastic housing on the front of the engine, the timing belt keeps the valve opening in sequence with the rotation of the engine pistons. A failure of the timing will allow the valves to contact the pistons, resulting in major engine damage.

The Audi and VW 1.8, 2.7 and 2.8 liter engines also use a timing chain to drive the secondary camshafts. This chain is kept in proper tension by tensioners fed from the engine oil. Over time, many tens of thousands of miles, the seals which serve to seal the tensioners to the cylinder head start to leak, note the image below. As a rule we always replace then when serving the timing belt, but sometimes they don't make it that far. Our goal, when doing a timing belt service, is make the work last another 100,000 miles.

The oil resulting from these seal leaks can find its way into the front engine timing cover, and onto the timing belt. The timing belt, being made of rubber, deteriorates with time and can fail without warning, resulting in catastrophic engine damage. Thankfully this was caught by one of our observant techs before failure occurred.

2004 VW Passat TDI - Engine Damage From Incorrect Oil
But why do I need to use "expensive" Synthetic oil the customer may ask. To which just one of these photos should be worth a thousand words...or a couple of thousand in engine damage. The sad thing, is that this could have been avoided, with a little care, and the proper synthetic engine oil.

This Passat has a very unique engine, one of the early VW ""Pumpe Düse" design. Developed by Volkswagen in conjunction with Bosch, Pumpe Düse means "pump injectors" (though "pump dooz" is more fun to say aloud). The electronically-controlled injectors are located at each cylinder where they create a very high pressure to better atomize and more precisely meter the fuel flow. The result is increased power, improved fuel economy and – most important for sensitive North American ears – quieter engine operation.

This car, with about 90,000 miles on the odometer, has led a hard life. See those small circular "cups" in the second row of photos? They are called "Camshaft Followers", and open and close the engine valves when compressed by the camshaft. You'll note that two of them have actual holes worn through on the top, this is not good. You'll also note that the camshaft, whose lobes are supposed to have a tear dropped shape, has severe wear, and many of the lobes are now close to round! This is also not good, as the engine valves are not opening fully. But even worse, is the wear on the lobes used to drive the rocker arms, which cause the injection valves to operate. The roller arm wear surfaces are also galled and damaged, such wear should not be seen at 100, or even 200K miles in a properly lubricated engine. In addition the camshaft, cam follower and rocker arm wear, one of the very expensive "Pump Düse" injection valves has been damaged. Even the camshaft bearings, normally lasting the life of the engine, are scored from inadequate lubrication. In short, the upper engine on this car needs a complete rebuild, a very pricey proposition.

Remember, cheap oil changes are the most expensive thing you can buy for your car!

2001 Audi AllRoad and 2000 Volvo V40 - Rodent Damage
A mouse in the house, or in this case in the engine air box and under the intake manifold. A real problem in Maine, we've heard tales of using moth balls, dryer sheets, even pepper spray to repel the little critters. I'm not sure any of these really work, but I guess its better than traveling with some extra friends on board, worse yet, suffering wiring harness or engine damage from their "creations". Make certain your service facility checks for this when they are caring for your car, forewarned is indeed forearmed. Or to quote that tried but true old bromide, "An ounce of prevention is worth a pound of cure."

2000 Volvo S70 - Defective O-Ring Seals on Oil Pump Pick Up
Car presented with engine making a moderately loud tapping noise, and via OBD-II a fault code was found to be stored for the variable engine valve timing solenoid. Upon inspection the technician noted that engine oil pressure warning light wire was disconnected. We connected wire and engine oil pressure warning light came on. A check of engine oil pressure with mechanical gauge showed pressure to be very low at idle, about 5 PSI, gauge is unsteady and flutters. During extended idle the reading will nearly drop to nearly zero at times. The low and unsteady gauge reading indicates possible cavitations in oil pressure.

Volvo has a somewhat common problem of defective oil pump pick up seals. These small rubber sealing rings serve to connect the engine oil pickup, located in the oil pan, to the engine block where the actual oil pump is located. After several years and thousands miles of engine heat, these seals become hardened and allow air to enter into the oil pickup system, preventing the oil pump from drawing the proper amount of oil. Early symptoms are a oil pressure light on at idle, or an engine that sounds unusually loud, often a tapping noise, at idle.

The correction for this involves removing the engine oil pan, cleaning and inspecting the pan sump and pick up tubes. The small rubber o-ring seals are then replaced on both the oil pick up and engine oil cooler. It is important to inspect the sump, and clean any oil sludge or debris from the oil pan area. As the 850 and S/V70 series engines use a two piece crankcase, you can not easily remove the main bearing caps for inspection, nor are the rod bearings readily accessible. The best test of the engine condition after this service is to use the mechanical gage again to verify pressure readings. On the car in question the engine oil pressure went from nearly zero at idle, to 35 PSI warm, and nearly 75 PSI at speed. This pressure in indicative of a engine in good condition, not having experience any wear in the bearing surfaces. Given the exceptionally low oil pressure, it is a testament to the robust design of the Volvo engine that no damage seems to have occurred.

2003 VW Diesel TDI - Clogged Intake Port
Low power, loss of acceleration on hills and under loads...all of these are symptoms of a clogged intake port on the VW 1.9 liter TDI engine. If you have 70K or more miles, and have not had a intake cleaning, chances are your intake port looks something like the one below. All the air for the engine must pass through this port, and as the port becomes clogged, airflow is reduced, the engine loses efficiency, and power output drops off. Imagine trying to breathe through a straw, and you have a good idea of how your engine feels. Since this is a gradual process, often taking years and tens of thousands of miles to occur, most owners do not notice the gradual loss of power. But they notice the difference after a proper cleaning has been carried out!

Port cleaning is not a simple procedure, but it is a necessary one. To do a through and professional job, one must remove the intake air inlet, often mistakenly called a "throttle body", intake manifold, attendant hoses, electrical and vacuum lines. Properly done, it takes from 3-5 hours, depending on the degree of coking found. The cost for labor, chemicals and the required parts, is approximately $300-500, but the returns in both power and efficiency make it well worth the expense.

2001 Volvo V70 - Power Steering Rack Failure - Water Entry
A simple repair, costing less than $75, could have saved this owner from a nearly $1,900 repair bill, and potential accident. A protective rubber boot, one is located on each side of the steering rack, had split, and over several months, had allowed water to enter into the sealed and lubricated surfaces of the power steering assembly. The water quickly did its damaged on the polished and machined surfaces of the steering rack and pinion gears, as well as contaminating the power steering fluid system. The resulting damage caused in rapid wear to the steering rack assembly, excessive play in the steering, and a very hazardous driving condition.

To complicate matters, Volvo has updated the design of the steering rack, so the correction consists of replacing not only the defective steering rack, but also the pressure and return hoses, and the steering coupler. Prevention is always less costly than correction. Be sure that your steering rack boots, along with the boots used on the Constant Velocity (CV) joints, are inspected every service.

2001 Audi A6 - Constant Velocity Joint (CV) Boot Cracking
I should first mention that this is not an Audi problem, but is a concern on any front wheel drive vehicle, as well as some cars, Mercedes and BMW, which use CV joints on the rear axles.

Just in the nick of time, one of our techs noted the deep cracking on the constant velocity (CV) joint boots during a scheduled service of this car. The axleshaft is used to transmit force from the transmission to the wheel. The CV Joints allow the axle to pivot when the wheels are turned, and rotate at the speed of the front/rear wheels.

The CV Joints are covered with a protective rubber boot which keeps out dirt, and keeps the lubrication inside the joint. When the protective rubber boot splits or tears, this allows the lubrication to be thrown out of the joint, and dirt and debris to enter. A damaged CV Boot will lead to a rapid failure of the CV Joint itself, complete failure of the joint will prevent the car from moving. Often, but not always, a pronounced clicking noise can be heard from damaged joints. To minimize expense and CV joint replacement, these rubber boots should always be inspected each service for splits or tears, and replaced BEFORE failure occurs.

2003 VW Jetta Diesel TDI - Dual Mass Flywheel Failure
Great idea, poor implementation. Sometime back in the early 1990s Porsche tried this in the 911 series, it did not work out well then, and it seems not to have worked well now. The dual mass flywheel is composed of two parts, damaged with silicone to soften engine noise and impact shock during clutch engagement. Often, with older and high mileage cars, the silicone and damping material fail on the dual mass flywheel, resulting in engine noise, vibration, and excessive lash in the driveline when engaging the clutch. This vehicle experienced the failure at about 50K miles, really quite low as far as clutch life normally goes, but apparently quite common with the dual mass design.

The repair can be approached two different ways, taken from either a cost or durability standpoint. The costly method, and one which we feel not to be durable, is the installation of the same expensive dual mass flywheel unit, with the attendant failure problems down the road. We suggest the replacement and update of the complete clutch assembly to a solid flywheel design. The proper solid flywheel replacement has the approximately the same mass as the dual mass set up, so the exchange is all but transparent to the driver. Aside from the cost benefits, durability is of course improved with the solid design, as there is no longer any damping material to leak out, or become damaged. The photos below show the original dual mass set up, and the replacement, solid flywheel kit. Note the use of multiple discreet damping springs in the clutch disc on the solid flywheel unit, this takes the place of the damping material in the dual mass flywheel.

2001 Audi AllRoad - Heated Steering Wheel Problem
After no less than 5 trips to a local Audi dealer, and over $1,100 in repair bills, this car landed on our doorstep. Now, as a former AllRoad owner, I have soft spot in my heart for these wonderful cars, complex as they may be, so I viewed this as an enjoyable challenge!  The problem, the heated steering wheel did not work. Yes, you read that right, some of the Audis do have a heated steering wheel, and as a Audi owner I can testify that its might nice to have on those cold Maine winter mornings.

On the Audi AllRoad, the steering wheel heater operates off the driver's seat heater switch. Its actually a little more complex than that, as Audi also places the horn, Audio and Telephone control buttons on the steering wheel, as well as a locating a handy  safety device, called an Airbag, there. Many of these signals run off a CAN (Controller Area Network) Bus system, to eliminate the number of wires needed. Think of the CAN Bus system much like a USB system on your home computer, a variety of different peripherals plug into a common set of wires, each addressable from the computer. Perhaps this sounds complex, but it is not easy to run a dozen or so wires to an object, the steering wheel, which is constantly rotating.

The long and short of the problem was this. Prior to the car arriving at our facility, the steering wheel had been replaced in a misguided attempt to correct a fault. After the 5 trips the dealer gave up and told the customer they did not know what was wrong with the car. Now we get stumped from time to time here, but you can be certain we never give up after charging you $1,100, we will work to a solution.

It took some time to properly diagnose, and in the case of most electronic parts, diagnostic time is always less expensive than just throwing a part at it. After removal of the radio and center console, to access the climate control unit and test the seat heater switches, our tech found the electronic "cassette" located in the steering column, to be defective. In fact, upon removal of the Airbag and steering wheel, we found a wire clearly broken away from the cassette contact, you can see this one of the photos. This is not considered a repairable fault as the Airbag safety system runs through the cassette, and the proper solution was replacement. Bottom line, its always less expensive to pay for diagnostic time than parts. Now the car is happy, and so is the customer! 

2001 Audi TT Quattro 1.8 Turbo - Defective Water Pump
This car has was diagnosed with a defective engine coolant pump. Symptoms were overheating and noise from the front timing belt area. Disassembly of the front cover and timing belt, no easy task on at Audi TT, allowed for removal and inspection of the pump. As you can see from the photos, it is a bit of a process to access the pump, so be sure to always replace the timing belt and tensioner at the same time. The timing belt, scheduled by Audi for replacement at 105K miles, has a history of failing considerably sooner, so consider timing belt service at 70 or 75,000 miles. The mode of failure with this pump appears to be a simple design flaw. The water pump impeller is made from a plastic material, the plastic becomes brittle with age and extended immersion in the hot engine coolant, and simply cracks apart. The defective pump, and pieces of the failed impeller, are on the left side of the photo, the new pump on the right. As this car is an aluminum alloy engine, Its always a good policy to flush the cooling system at least every two years, or 30,000 miles, and to use a quality antifreeze with corrosion inhibiters.

1997 Volvo V70 GLT - Defective Turbocharger
This car has was diagnosed with a defective turbocharger unit. Note the large amount of oil build up on the pressure side of the turbo, especially in comparison to the new turbo on the left. This oil is then drawn into the engine, resulting is severe smoking from the exhaust, high oil consumption, and even damage to the catalytic converter.
Note the Volvo replacement turbo box, we always use factory parts for reasons of longevity and proper fitment.
On late model car turbo failures are uncommon if the vehicle is cared for properly. Indeed, with proper care service life of 175 to 200K miles is expected. Turbo failures occur from two basic causes, lubrication failures, consisting of infrequent oil service, or incorrect grade of oil, and foreign material entering into the turbo and causing blade fracture. We strongly advise to never go more than 3-5,000 miles on conventional oil, and never more than 5-7,500 miles on a full synthetic. We recommended and use Castrol lubrication products in our workshop, either Castrol GTX, or Castrol Syntec.

1998 Volvo S70 Turbo - Electrical Fault in Dash/Alternator Failure
This car had an interesting story. The car presented with the charging light on, indicating alternator failure.
The alternator light would flicker, turning on and off rapidly. Alternator failures are somewhat uncommon on the later Volvo S70s, but a charging system analysis showed that the alternator was indeed not charging under load, even when full fielded. 12 VDC was found at the field wire during the testing. We replaced the alternator with a Bosch remanufactured unit and then road tested the car. The alternator light came back on, but was steady, not flickering as before. We checked for voltage on the field wire, no voltage. A check of the schematic showed that the field wire was powered up via the dashboard and indicator. We tried tapping on the dash and noted that the light would go out.
We removed and inspected the instrument cluster, no fault found. The tech then followed the harness down under the dash and found a poor connection at a large multi-block connector. Correction of this fault corrected the charging issue and the new alternator will not fail or become quickly damaged like the former unit.

1996 Audi S6 - Timing Belt Service w/ Water Pump
The Audi S6 timing belt service does not normally require removal of the nose of the car, but in this case the silicone filled fan clutch was seized onto the idler shaft and could not be removed with the nose in place. 10 years and more recently time in the coastal environment seemed to have done its worse. To fully access the clutch required removal of the front bumper cover, radiator support and radiator, evacuate and recharge of the A/C system. As the engine water pump is driven off the camshaft belt, it is a good idea to replace the pump at the same time as belt service.
All tensioner rollers should be inspected or replaced at the time of belt service.

1998 Audi A8 - Head Gasket Service
Timing belt replacement on the Audi A8 requires a fair amount of disassembly on the front end of the vehicle.
The Audi 4, 6 and 8 cylinder engines are high compression types, failure of the timing belt will result in major engine damage. Although scheduled by Audi for 90,000 miles, we have found loose or severely worn timing belts and tensioners at the 75K mile mark. When replacing the rubber timing belt, all belt rollers, water pump and thermostat must be replaced. This is a service you only want to do every 100,000 miles.
We have noted a number of the Audi V8s with head gasket leaks or seepage, this is a straightforward matter to correct when the car is disassembled for the timing chain.

1994 BMW 525 - Defective Heat Exchanger (Heater Core) in Dash
This car has was diagnosed with a defective heat exchanger, also know as a heater core.
The heater core as used in this BMW's climate control has hot engine coolant flowing through it during operation.
The heater core, which is comprised of a an aluminum core and nylon tank ends had developed at leak at the interface. This area is often sealed with rubber o-ring which fails after long term exposure to heat and coolant.
Once the o-ring seal fails, coolant will begin to seep out of the heater core into the heater box producing a strong burning smell from the dash vents. This can lead to long term problems if the antifreeze gets onto or into control motors, servos or air direction flaps. Like most heater cores this unit is somewhat buried in the dash, necessitating a fair amount of disassembly to remove and replace. Its always a good policy to flush the cooling system at least every two years, or 30,000 miles, and to use a quality antifreeze with corrosion inhibiters.

1986 Mercedes 300SDL - Fault In Climate Control System
Car presented with Incorrect air flow out the heat/ac vents. Upon inspection we discovered that a previous servicing facility had worked on the vehicle and left the ACC system in total disarray. Vacuum lines were disconnected, flaps were wire tied closed, actuators were disabled, vacuum manifolds were plugged, in short, the ACC air direction system was non-functional. This required removal of the dash pad and center console to fully inspect and access what was needed to make the system operational once again. Subsequently upon removal we found broken flaps, damaged cable actuators and stripped gears. This is a major undertaking, and it all has to be right before the dash is reinstalled back into the car.

2002 VW Passat V6 - Engine Oil Sludge - Incorrect Oil Grade Used
Engine oil sludge does not just affect Saabs, take at look at the oil pan and lower engine on this VW Passat. That black gooey substance is not tar, but engine oil sludge. Unfortunately the car was switched over to a full synthetic engine oil too late in its life, for the first three years it was run on a conventional oil, you can see the results. It is cheap insurance to always use a fully synthetic engine oil on all European autos newer than 1999. We use Castrol Syntec in our workshop, it is the factory fill on many of the European imports.

1993 Mercedes 300SL - Rodent Damage to ABS Wiring
With only 22,000 miles, rodent damage on the ABS rear wheel speed sensor data cables.
Somehow a mouse found its way inside the car, under the seat, under the carpet, under the foam padding, and into the rear wiring harness conduit for a quick snack.
Required extensive work to diagnose and then removal of the passenger seat and carpeting to service.

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2004 BMW M3 Sport Coupe - Upgrade Exhaust System
A fun and rewarding job, installing a stainless steel sport exhaust on a brand new BMW M3 coupe.
Looks pretty and sounds even better!

2000 Audi A6 Quattro 2.8 V6 - Scheduled Timing Belt Service
Audi/VW timing belt replacement is a bit of a project as it requires the removal of the front nose of car.
When replacing the timing belt it is critical to also replace the engine water pump and thermostat as they are located behind the timing belt, requiring belt removal to access. Not the most technician friendly design. It is also strongly recommended to replace the tensioner roller, serpentine belt and inspect the tensioner seals for oil leakage.

1998 Audi A4 Quattro - A/C Evaporator Core Replacement
A/C Evaporator Core Service, requires extensive dash removal.
Car suffered repeated loss of refrigerant, testing dye did not indicate external leakage but internal to dash.
Note the yellow dye stains on the removed evaporator core, lower right photo.

1998 Audi A4 Avant Quattro V6 - Engine Oil Leaks
Engine oil leakage from timing chain tensioners.
Previous service facility had replaced the timing belt but not checked/serviced the tensioners seals.
The new timing belt had been ruined by oil leakage and required replacement.
Continued use of the car with the oil leakage and damaged timing belt would have resulted in severe engine damage. The timing chain tensioner seals should always be inspected for leakage during timing belt service.

1999 VW Passat V6 Engine - Water Pump Failure
Failed engine water pump, requires removal of the front nose of car.
The engine water pump and thermostat are located behind the timing belt, requiring belt removal to access.
Not the most technician friendly design. Always replace the water pump and thermostat when servicing the timing belt.

1991 Audi 200 Turbo Quattro - Clutch Release Bearing Failure
Failure of clutch release bearing damaged TDC pin in flywheel.
Early replacement of the clutch release bearing would have avoided this expensive failure.

1997 Volvo 850 Turbo - Improper Repair HO2 Sensor Wiring
Aftermarket HO2 sensor spliced in by previous servicing facility, note nylon wire tie securing to sway bar!
Any wonder why the Check Engine light was on? That's why we use only Original Equipment parts on our client vehicles, aftermarket parts cost both the owner and workshop time and money.

1999 Saab 9-3 Turbo - Engine Oil Sludge - Incorrect Oil Grade Used
Car had 50,000 miles, all services carried out and stamped in maintenance book, yet engine was ruined by oil sludge.
Saab has been having an issue with this engine fault.
We feel it is due to extended service intervals without the use of semi or full synthetic engine oil.



 

1998 Mercedes SLK - Water Entry Into Body Computer
Water entry into trunk filled and damaged the pneumatic body control module.
Believe it or not we were able to repair this unit, saving our client hundreds of dollars.
Our service facility is equipped with a state of the art electronic service workshop.
More importantly, we were able to find and correct the water leak preventing expensive future problems.

1998 Volvo V70 - A/C Evaporator Core Replacement
Defective evaporator core requires removal of the dash and center console.
Quite a project, the dye stains on the evaporator core provide confirmation of the leakage.
Although this part often fails from age, its cheap insurance to keep the cabin air filters clean and free of dirt and water, water and debris will enter and will cause corrosion to the evaporator core. Although a V70 is pictured here, the procedure is the same on the Volvo 850 and S70 models.

 
 

1998 Jaguar XJ8 - Broken Timing Chains, Bent Valves
A very unfortunate but very common Jaguar fault, a broken secondary timing chain.
With less than 78,000 miles on the car, in this case it appears that the plastic timing chain tensioner guide had come loose. The loose tensioner guide was then caught between the chain and the sprocket, causing the chain failure.

1999 Saab 9-3 Sedan - Engine Oil Pan Damage
A very unfortunate event, this Saab 9-3 turbo oil pan struck a rock and damaged the pan allowing the engine oil to leak out. Note the broken aluminum oil pan parts and material caught in the oil sump pickup.
Metal particles may have entered the engine lubricating system.