Diamond in the Rough: 2003 Jetta Upgrade

Readying an ’03 Jetta for the Next 100,000 Miles

We all love our trucks here at Diesel World, but there is something about having a vehicle capable of knocking down 50-plus mpg that is undeniably empowering. Enter our latest find: an ’03 Volkswagen Jetta TDI GLS model. While not perfect, the MK4 sedans (built from ’99.5-‘03) are great on fuel, simplistic in nature, are reasonably comfortable, and respond well to power adders—making them highly sought after. The ALH 1.9L sports a Bosch VE rotary style injection pump and is known to last well beyond 400,000 miles if properly cared for.

The Right Choice

With the current price of fuel so low ($1.89/gallon as of May, 2016 in central Illinois) the demand for the MK4 Jettas has come down, which means prices aren’t quite as high as they used to be. However, finding a rust-free, well-maintained unit with a five-speed manual transmission can be exhausting. Upper Midwest and Northeast versions are usually riddled with rust (particularly the front fenders), and frankly a lot of the interiors are destroyed. If you’re in the market for one, you have to remember that most of these cars are bought solely to be commuters, so it’s natural for them to have a few miles racked up (especially now that they’re more than a decade removed from production).

It should come as no surprise that our 200,000-mile candidate was a commuter. But, it was lady-driven, came with a stack of service records, and has an interior that is in what we’d call immaculate condition. With doors still completely intact, a glove box latch and hood latch that work, and a center console hinge in good working order, we’ve found a true diamond in the rough. And, for $4,000, we simply couldn’t say no.

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To make sure the little V-dub was as mechanically sound as possible, we reached out to a company that arguably knows more about these cars than anyone else: Kerma TDI. They advised us to change the timing belt, water pump, and tensioner as soon as possible (as the 1.9L is an interference engine) and to give their Q-loader programmer a try for a little more oomph. Read on to see the ins and outs of a timing belt change, as well as the other items we tackled this month to keep this TDI a reliable fuel-sipper.

Parts List:

High Mileage Timing Belt Kit                                                                                $399
Motor Mounts (Street Density line)                                                                   $327
Beru Glow Plug set                                                                                                   $65
Total                                                                                                                     $791

The high-mileage timing belt kit offered by Kerma TDI comes with everything you need to perform the second belt change on your ’99.5-‘03 Jetta TDI. Along with a quality Gates cog-style timing belt, serpentine belt, tensioner, water pump, and a 1.5L container of Rowe HighTec G13 coolant, the kit also includes a new serpentine belt tensioner, crankshaft bolt (and seal), EGR seal, and roller studs. Anytime you’re dealing with an interference engine such as the ALH 1.9L, it’s good practice to replace everything in the timing belt’s path (not just the belt), and this all-inclusive kit allows you to do exactly that.

Performing all of the work on our Jetta was Flynn’s Shop in Alexander, Illinois. With an in-house Volkswagen expert under their roof, we had tremendous peace of mind knowing that Flynn’s had an experienced TDI wrench on the case. Technician Jake Bosie got started by draining all coolant and then removed the serpentine belt and serpentine belt tensioner.

Surprisingly, the Jetta’s timing belt wasn’t terribly inaccessible once a few items were removed. Both the hot side (bottom) and cold side (top) intercooler tubes were pulled, followed by the degas bottle. Then the power steering reservoir was disconnected and tilted up and out of the way to better gain access to the front of the engine (and so no fluid would be lost).

The old timing belt actually appeared to be in pretty good shape with no visible cracks present after 84,000 miles of service. One thing we really like about the ’99.5-’03 Jettas is the ease at which you can unclip the timing belt cover and inspect the belt. It’s a quick, convenient way to keep tabs on (arguably) the most important component on the engine.

Next, the passenger side motor mount had to be unbolted and removed. With a hydraulic floor jack and 4×4 block of wood lifting up slightly on the edge of the oil pan (to take the weight of the engine off of the mount) the motor mount itself was reasonable enough to remove, but it took a little more finesse to retrieve the bracket beneath it. And because the engine had to be tilted slightly to fish the mounts out, the air intake tube was disconnected from the airbox (to rule out the possibility of the plastic connection point breaking).

To lock the camshaft in place for the timing belt change, the vacuum pump had to be removed from the valve cover. However, once Bosie removed the vacuum pump, we found a corroded O-ring seal—the possible culprit behind the engine’s small oil leak. Luckily for us, Kerma TDI supplied us with a new replacement seal.

Because Bosie didn’t pull the valve cover and inspect the positioning of the number one cylinder cam lobes in order to put the engine at top dead center (TDC), he used this long reach camshaft locking plate to find TDC. The locking plate will only install one way (with the engine positioned at TDC), so the crankshaft was rotated using a 12-point, 19mm socket until the plate fit perfectly in place. This tool is usually only used by experienced Volkswagen techs in order to speed up the timing belt process (by not having to remove and later reinstall the valve cover).

Other key tools used during the job were an injection pump locking pin and a 2-pin tensioner spanner wrench. Here you can see the injection pump locking pin being utilized. It’s important to note that this pin only locks the pump in place so the engine will start and run once the new timing belt is installed. Final timing has to be checked and possibly adjusted via Vag-Com (VCDS) or OE diagnostic software, which we tackle later on.

From there, the crankshaft pulley was removed, along with the remaining timing belt cover bolts. Note that a two-piece timing cover came on the ALH engine: an upper and a lower.

Prior to pulling the old timing belt off, Bosie marked the cam gear, injection pump gear, and crankshaft gear in order to match the new belt up perfectly. Marks were also made on the old belt so that the teeth between each mark could be counted and matched up identically with the new belt.

Notice that Bosie even labeled which marks related to which gear (“pump” written near the injection pump gear marks). Once the old timing belt was off via employing the 2-pin tensioner spanner wrench to release the belt tensioner, Bosie made quick work of removing the tensioner and idler.

Next, the old water pump was removed. We’re not sure if this was the original water pump or if it had been replaced at the first interval, but it had something we didn’t like: a plastic impeller. We’ve heard plenty of horror stories where the plastic impeller spins on the shaft causing overheating issues. When this happens, the car’s coolant temp is fine at idle, but way too hot cruising down the road—which unfortunately can go unnoticed by the average commuter until it’s too late.

After hearing (and seeing) so many plastic impeller-related water pump failures, we were happy to find a metal impeller water pump included in our timing belt kit. Made in Germany by HEPU, the impeller features a sealed bearing assembly and is known for being a high-quality brand made of stamped metal.

Before installing the new water pump, Bosie cleaned up its sealing surface in the block. Then the water pump’s O-ring was coated with assembly oil to ensure a trouble free install and a proper seal. Once flush with the block, the new water pump mounting bolts were torqued to the required 15 Nm specification from Volkswagen.

With the supplied timing belt idler rollers installed (complete with new bolts), Bosie turned his attention to marking up the new Gates timing belt (PN 038109119M) the same we he’d marked the old one. The amount of teeth between each mark was counted twice before his final marks were made.

From there, the new timing belt was loosely installed around the cam, injection pump, water pump, and crank gears. Then the new timing belt idler was bolted on.

Once the new timing belt tensioner was in place (not to mention the alignment prong resting in its designated spot in the head), Bosie set the belt’s tension using the 2-pin tensioner spanner wrench and checked his work with a mirror. After the tensioner was set, the center nut was fully tightened using a 13mm socket. Then the cam locking plate and injection pump locks were removed, the engine was rotated twice by hand, and the tensioner was re-checked.

There is definitely room for improvement when it comes to the factory motor mounts on MK4 Jettas, and at 13 years of age and 201,000 miles, it was time for some replacements. These Street Density 034 Motorsports mounts, offered through Kerma TDI, feature a 50 durometer rubber hardness for a 25-percent stiffness improvement over stock, are void and fluid-free, and reduce drivetrain slop without increasing noise, vibration or harshness (NVH) inside the car. The engine mount is pictured on the bottom left; the transmission mount on the top left, and the dogbone mount (also known as the pendulum) is on the right.

After the factory (passenger side) motor mount bracket had been wrestled back into place and bolted up, Bosie installed the new Street Density mount. The transmission mount installs on the driver side of the car.

While the passenger side motor mount attempts to control the engine’s side to side movement, the dogbone mount keeps the engine from rocking front to back. Replacing this mount was a piece of cake, given it’s easy to access and we had the car up on a lift at Flynn’s. While comparing the OE unit to the new dogbone we could definitely feel a difference in rubber stiffness between the two.

Turning his attention back to the engine, Bosie reinstalled the vacuum pump (utilizing the aforementioned new O-ring seal), the new serpentine belt tensioner and belt, along with everything else removed during the teardown process. Then it was time to make a 50/50 mix using the supplied Rowe HighTec G13 container of coolant and top off the Jetta’s cooling system.

With maintenance items fresh on our minds, we decided to go ahead and replace the glow plugs as well. The four Beru glow plugs we installed came from Kerma TDI, which are said to have quality that is on par with the Bosch units also offered.

To be fair, the glow plugs we replaced came out easy (indicating they’d been done before), but we wanted to make sure we started with fresh units, and not have to wonder about their health once winter hits. After tightening each glow plug to 15 Nm, the engine was started, warmed up, and taken for a trouble-free test drive.

The final step was making sure the injection pump’s physical timing was within spec. It was, although it was on the higher side in terms of timing advance (note that over time, timing can be thrown off slightly by a stretched belt). There are no shortages on theories as to which amount of timing advancement yields the best overall mileage, performance, and drivability on these cars, but since we’re already seeing 50-mpg, we decided to leave our timing slightly aggressive for now—to see if any performance is gained. Most ALH enthusiasts use the aftermarket diagnostic software VCDS created by Ross-Tech (also known as VAG-COM) to check timing. The OE software we’ve seen is coined VAS 5150B. If we would’ve needed to alter the car’s timing to get it into spec, it would’ve required us to loosen the 13mm bolts on the injection pump sprocket and use a 22mm wrench to turn the pump’s input shaft (toward the grille advances timing, while turning toward the firewall retards timing).

As you can imagine, at 90 flywheel horsepower from the factory, there is much left to be desired in the “go” department on the ’99.5-’03 Jettas. For an extra kick, Kerma TDI sent us one of its Q-Loader programmers, which can add up to 25 hp and 60 lb-ft. at the front wheels on stock injector Jettas like ours, as well as add 1-2 mpg. It’s said to be some of the most refined tuning on the market, and we can’t wait to interface this thing with our ECU. In addition, the Q-Loader will allow us to update tunes via email later on (should we decide to upgrade injectors) and it can also read and clear DTC’s. With our road-ready maintenance work out of the way now, we’ll get the car tuned and report back with our power and mileage gains in the coming months.

Sources:
Flynn’s Shop
217.478.3811

Kerma TDI
877.537.6283
Kermatdi.com

FREQUENTLY ASKED QUESTIONS.

Why are ALH-powered Jettas still popular despite the Dieselgate scandal?

Why ALH-Powered Jettas Remain Popular Post-Dieselgate

Despite the cloud of controversy cast by the Dieselgate scandal, ALH-powered Jettas have managed to sustain their popularity and here’s why:

Untainted Reputation: Unlike their counterparts caught in the emissions debacle, these ’99-’03 models were not involved, maintaining a cleaner image among diesel enthusiasts.
Loyal Following: A dedicated community continues to support these vehicles, celebrating them at annual events and showcases. This vibrant subculture has kept the excitement alive, drawing in fans of both modified and stock versions.
Practical Attributes:
- Reliability: Known for their durability, these Jettas often cover impressive mileage with minimal issues.
- Simplicity: Their straightforward engineering makes them easier to maintain, appealing to DIY mechanics and car enthusiasts.
- Fuel Efficiency: With rising fuel costs, their excellent fuel economy is a significant selling point for budget-conscious commuters.
Collectibility: As more consumers seek out vehicles with unique histories or cult status, these Jettas are increasingly viewed as collectibles. Enthusiasts and collectors value their unique place in automotive history.

Overall, the ALH-powered Jettas combine reliability, community support, and practical benefits, ensuring their continued popularity even in the wake of industry scandals.

How has the Dieselgate scandal impacted the perception and modification of Jetta TDI vehicles?

The Impact of Dieselgate on Jetta TDI Vehicles

The Dieselgate scandal undeniably cast a long shadow over diesel vehicles, but the Jetta TDI models, particularly those powered by the ALH engine, have managed to retain a dedicated fanbase. These models were not implicated in the emissions scandal and have thus maintained a more positive reputation compared to other diesel vehicles.

A Loyal Enthusiast Community

Despite the overall downturn in diesel enthusiasm post-scandal, the Jetta TDI community remains vibrant. Until recently, gatherings like annual TDI Fests would showcase numerous customized Jettas, highlighting the ongoing passion for these vehicles. Owners seem undeterred by the controversy that surrounded other diesel models and continue to modify their cars with enthusiasm.

Reliability and Appeal

The ’99-’03 Jettas are celebrated for their reliability, straightforward engineering, and impressive fuel efficiency. These traits make them especially attractive to a diverse group: daily commuters appreciate their cost-effectiveness, car enthusiasts enjoy their modifiability, and collectors seek their enduring value. The scandal, while damaging to diesel as a whole, seems to have had a muted impact on these particular models.

In summary, while Dieselgate dampened the overall popularity of diesel vehicles, the ALH-powered Jettas have largely escaped the fallout, continuing to be cherished by their community for their unique qualities.

What are the benefits of upgrading injector nozzles on a Jetta TDI?

Unlocking Performance: The Benefits of Upgrading Injector Nozzles on a Jetta TDI

Upgrading the injector nozzles on your Jetta TDI can transform your driving experience. Let’s dive into the key benefits:

Increased Horsepower and Torque

Swapping out the stock nozzles for larger ones can significantly boost your engine’s output. For instance, you could see gains upwards of 15-20 horsepower. Opting for more advanced upgrades can push the performance boundaries even further, potentially adding up to 60 additional horsepower at the wheels and an impressive 110 lb-ft of torque.

Improved Fuel Efficiency

Not only do upgraded nozzles enhance power, but they can also help refine fuel efficiency. The precision of enhanced nozzles leads to a cleaner and more efficient burn, maximizing each drop of fuel.

Cost-Effective Enhancement

In the world of modifications, upgrading your nozzles offers one of the best returns on investment. With relatively low costs compared to other performance upgrades, this modification provides substantial enhancement in power and efficiency, making it a smart choice for those seeking noticeable improvements without breaking the bank.

Compatibility with Stock Components

The beauty of nozzle upgrades lies in their compatibility. Many options work seamlessly with the factory turbo, allowing you to enjoy the performance boost without the need for extensive additional modifications.

These upgrades cater to both performance enthusiasts and practical drivers, making them a versatile choice for anyone looking to enhance their Jetta TDI.

Do modifications affect the fuel efficiency of a Jetta TDI?

As you can imagine, at 90 flywheel horsepower from the factory, there is much left to be desired in the “go” department on the ’99.5-’03 Jettas. For an extra kick, Kerma TDI sent us one of its Q-Loader programmers, which can add up to 25 hp and 60 lb-ft. At the front wheels on stock injector Jettas like ours, as well as add 1-2 mpg. It’s said to be some of the most refined tuning on the market, and we can’t wait to interface this thing with our ECU. In addition, the Q-Loader will allow us to update tunes via email later on (should we decide to upgrade injectors) and it can also read and clear DTC’s.

But what about fuel efficiency? You might wonder if these performance enhancements come at the cost of your fuel economy. Our experience with a similarly modified Jetta TDI tells a promising story.

Baseline Performance:Originally, the Jetta is known for delivering around 49 mpg in its stock form.
Post-Modification:With modifications like balanced injectors and a custom ECU calibration, the car not only boosts power up to 120 hp (from a mere 72 hp) but crucially, maintains its impressive fuel efficiency. Even with added torque making highway maneuvers a breeze, the average fuel consumption remains steadfast at 49 mpg.

This means you can enjoy that extra power without sacrificing your fuel savings, making these modifications a win-win for performance and efficiency enthusiasts alike.

What tuning options are available for improving the drivability of Jetta TDI?

Beyond the raw power boost, there are several tuning options that can elevate the overall drivability and performance of your Jetta TDI:

Enhanced Drivability:Expect improvements like reduced smoke and a more linear throttle response, making everyday driving smoother and more enjoyable.
Engine Idle Adjustments:For those who’ve upgraded to stiff aftermarket motor mounts, tuning can include raising the engine idle to minimize vibrations, offering a more comfortable ride.
Winter Start Optimizations:Increase the glow plug duration through custom tuning for easier start-ups during those cold winter mornings, ensuring reliability despite the chill.
Track-Ready Performance:For enthusiasts aiming to push their Jettas to the limit, options like launch control tunes are available, perfect for automatic transmission models heading to the track.

These comprehensive tuning solutions don’t just add power; they refine the driving experience, addressing both performance and practical needs, making them an appealing choice for any Jetta TDI owner looking to optimize their ride.

How can the ECU be reprogrammed to increase horsepower in a Jetta TDI?

For an extra kick, Kerma TDI sent us one of its Q-Loader programmers, which can add up to 25 hp and 60 lb-ft. At the front wheels on stock injector Jettas like ours, as well as add 1-2 mpg. It’s said to be some of the most refined tuning on the market, and we can’t wait to interface this thing with our ECU. In addition, the Q-Loader will allow us to update tunes via email later on (should we decide to upgrade injectors) and it can also read and clear DTC’s.

Unleashing Jetta TDI Potential

Reprogramming the ECU is the quickest way to breathe new life into the ALH 1.9L TDI diesel, especially in ’99-’03 Jettas. Several tuning experts have made a name for themselves by offering cutting-edge solutions, including Malone Tuning, Rocket Chip Performance, and TD Tuning, alongside Kerma TDI. These industry leaders ensure a boost in performance, with general consensus pointing to horsepower gains between 25 and 30 hp when retaining stock injectors and turbo setups.

Real-World Results

Our own testing echoes these figures, with the Q-Loader from Kerma TDI delivering a noticeable 33 hp increase on the chassis dyno. This tangible improvement underscores why these tuners are trusted in the community. Additionally, the Q-Loader’s capability to read and clear diagnostic trouble codes (DTCs) adds a practical edge for ongoing vehicle maintenance.

Whether you’re seeking a modest power bump or planning future upgrades, these tuning solutions offer a scalable approach to enhancing your Jetta TDI’s performance.

Is there empirical evidence to support claims of increased horsepower from these tuning solutions?

Yes, there is empirical evidence supporting these claims. In one documented case, a 33 hp increase was observed using Kerma TDI’s tuning solutions, demonstrating the potential gains from such modifications.

What are the typical horsepower gains one can expect from ECU tuning with stock injectors and turbo?

The general expectation for horsepower gains from ECU tuning with the stock setup is between 25 to 30 hp. This provides a benchmark for enthusiasts considering this upgrade.

Which companies offer tuning solutions for the ALH 1.9L TDI engine in ’99-’03 Jettas?

Notable companies providing tuning solutions for these engines include Kerma TDI, Malone Tuning, Rocket Chip Performance, and TD Tuning. These names are recognized for their expertise in enhancing the performance of the Jetta TDI.