Case Studies

A Collection of the Odd, Unusual and Interesting Found While Servicing Our Client Vehicles.

Originally intended as a showcase for 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!

By nature, these are rather extreme examples of failures, and not what we typically find during service. Our goal at Atlantic Motorcar is to prevent these from happening to you and your car. But rest assured, if we can fix these challenges, regular maintenance is breeze!

We like to call this our “YES WE CAN!” page. You can also view many of these concerns on our Facebook page. Each photo can be enlarged by clicking on it.

Mercedes C-Class – Air Flap Lever Fracture “Snapping” Noise

Case Studies

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.

Read More

BMW Z3 M Convert – Evaporative Emission System Fault

Case Studies

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.

Read More

Audi AllRoad – Camshaft Tensioner Seal Oil Leakage

Case Studies

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.

Read More

VW Passat TDI – Engine Damage From Incorrect Oil

Case Studies

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!


Read More

Audi AllRoad and 2000 Volvo V40 – Rodent Damage

Case Studies

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.”



Read More

Volvo S70 – Defective O-Ring Seals on Oil Pump Pick Up

Case Studies

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.

Read More

VW Diesel TDI – Clogged Intake Port

Case Studies

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.

Read More

Volvo V70 – Power Steering Rack Failure – Water Entry

Case Studies

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.


Read More

Audi A6 – Constant Velocity Joint (CV) Boot Cracking

Case Studies

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.


Read More

VW Jetta Diesel TDI – Dual Mass Flywheel Failure

Case Studies

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.

Read More

Accessibility Toolbar