From Austin.... to Austin

When the time came to leave Austin we headed west on the 290, loosely following a scenic drive recommended in a book we’d been given as a gift before we left, passing through some of the Texas Hill Country. I’m not exaggerating when I say that the biggest inclines and the greatest rises in altitude that we’ve encountered so far on our 3000 mile drive through Georgia, Florida, Alabama, Mississippi, Louisiana and Texas, have all been on bridges crossing the many rivers and lakes we’ve passed by. The coastal areas of the US deep south are beautiful in many ways, but they are no blessed with exciting topography. This quickly changed as we left Austin, as the swamps and beaches of Georgia and Florida, and the river delta of Mississippi and Louisiana make way for the hilly scrub and woodland of the Hill Country.


The scenery changes gradually as you leave Austin, but by the time we had reached our first stop at Pedernales Falls State Park, the hills are gentle but continuous and Jim had probably spent more time out of 6^th gear than in all the miles completed so far. The scenery on the whole is not dramatic in the sense of the Rockies or Appalachians, but is beautiful in the same way that encourages so many Europeans to holiday in Tuscany and Umbria in preference to the Alps and Dolomites. Pedernales Fall are pretty beautiful by any benchmark, and Austinites are blessed to have such a park so close to their city. The waterfalls drop a considerable distance, however they don’t do it in a single dramatic freefall, rather they drop over a series of steps in the tilted layers of hard rock. The falls themselves are the highlight of the park, although there are some decent hikes to be had in the surrounding area.

For $26 we got two days in the park, and an overnight parking spot with water, electric and a waste water dump station, and got to give Boris a proper run around after a few weeks of gentle city walks. The sun came out long enough for us to enjoy dining al fresco after a period of unusually cold weather for this part of Texas.

From Pedernales we continued west to Fredericksburg, a historic town worth a visit for anyone travelling through Texas. It has a large war museum, but for those not terribly interested in the glorification of organised killing, there remains plenty to do. The town has a German heritage, and for a state that is so unwaveringly patriotic, I was surprised at how much the town embraces its Germanic past. There are wineries producing Rieslings and Gewürztraminers, microbreweries making Pilsners and Weis beers, and restaurants selling wiener schnitzels and sauerkraut. We spent a great night in Hondo’s listening to swing and country played by Harry and the Hightones, and drinking a local bourbon. The next morning we made an early start for the Enchanted Rock State Park, a park surrounding a huge lump of granite rising out of the countryside, joined by two smaller siblings.

We visited on a sunny Saturday, and the park’s proximity to Austin and San Antonio meant that by lunchtime the park was at capacity. The car park was full, the adjacent campsites were full, and the short amble from the car parks to the top of the rock had a solid stream of people; however all of the trails longer than a half a mile, and all of the campsites which required a walk from the car park were almost entirely empty. We walked up the biggest of the batholiths at about 8.30am and ate breakfast in complete solitude at the top, if we’d done it a few hours later we would have undoubtedly shared the vista with a throng of wheezing visitors. We spent the rest of the day walking the various trails around and between the rocks, and using the offices’ excellent Wi-Fi connection.

 

We left the park in the afternoon and spent the next 18 miles educating some other visitors to the park on the differences in power and speed between an 18 tonne European truck and the light domestic vehicles they were driving; the lesson became quite frustrating for some as we dropped down to 25mph on some of the bigger hills.

At Fredericksburg we took the 16 south west; the hills slowly fade out, giving way to flatter, fertile farmland in the floodplain on the Guadalupe river. Despite its picturesque location on the banks of the Guadalupe, Kerrville is not a picturesque town, and its historic centre is lost in the sprawl of superstores and strip malls leading away from it in all directions. Thankfully we were not in town for sightseeing, the Sunday was the Superbowl and we were in town to learn something about American football in a traditional sports bar. We struck gold with the eight ball bar on Junction Highway, Sunday is happy hour all day ($1.50 pints!), the draft beer was great (Brooklyn lager, Shiner Bock, Blue Moon, etc), free pizza was available all evening, and we met a friendly local car salesman who insisted on buying us a whiskey. We drank  five pints and two whiskeys, ate half a pizza, played pool for a couple of hours, and met some great locals, spending only $14, if only all nights out were that cheap.

Our winning streak ended as we went to leave Kerrville, we were looking forward to the most dramatic part of the drive we’d planned through the Hill Country when the parking brake problem which had started in Florida, reared its head again.

The symptoms were the same, in that on releasing the parking brake, the parking brake light stayed on and the calliper on the right of the rear axle failed to release. This time however I realised there was a problem and got out of the truck to investigate; I quickly realised that with the parking brake released in the cab, the contents of the pressurised air system was rapidly discharging through the load compensation valve on the back axle. The valve is mounted to the chassis and has a linkage to the rear axle, which senses the load on the rear axle based on how much the suspension is compressed; it then automatically adjusts the power of the rear brakes accordingly. I’m no expert on air brakes but I couldn’t see why this valve should be applied the parking brake system, I would have presumed that the parking brake should apply full power to the brake callipers regardless of the load.

Following the instructions in the workshop manual, I tried to manually wind off the brake on the problematic side of the axle. The instructions were essentially to just wind back the bolt on the back of the air chamber to manually compress the spring which pulls the linkage clamping the brake pads on. I’m not sure whether this succeeded in freeing off the brake, but regardless I could not drive the truck with the air chamber in this configuration, as the more I wound back the bolt, the faster the air leaked out of the load compensating valve. The air leaked so quickly with the bolt wound fully out that at cruising revs (1700rpm) the air compressor was not generating air fast enough to offset the leakage and after a short while the brakes on all four wheels would have locked on. Not wanting to investigate any longer than necessary on the cold, wet tarmac in a Walmart car park, I decided to head back to Austin to find a suitable garage to repair the brakes. We could have driven the shorter distance onwards to San Antonio, but realising that the repair was likely to take some time, we decided that Austin was the preferable city to be stuck in. I returned the bolt on the brake chamber to its operational position and gently drove off.

Thankfully after a mile or so of driving, the parking brake light went off. After a mile or so more, I would have had to pull over and call for a tow truck, so I was grateful to be spared this ordeal. To confirm what the dash light was telling me, I jacked up the problematic wheel and spun it by hand. The brake disc had heated up in the mile or so before the parking brake released, but after confirming that it had released, we drove back to Austin. It had been five days since we left Austin, but without the sightseeing, the drive back took less than three hours. We headed straight for Austin brake and clutch, who recommended a local garage who could carry out the repairs; sadly the garage did not feel confident carrying out the work due to a lack of experience with air powered disc brakes but recommended another garage who agreed to look at the truck. I had called more than ten garages who did not want to take the job before finding American Equipment in Pflugerville who were happy to take a look.

Air operated discs are pretty new to domestic American trucks, and the systems that they use here are different to those fitted by Mercedes, Man, Scania, DAF, Volvo and Iveco in Europe. Almost the entire brake system fitted to Jim is comprised of Knorr and Wabco components, and despite components of both of these companies being used on American vehicles, the systems seem to be completely different. Stephen, the mechanic at American Equipment who investigated the problem on Jim, could recognise most of the components of the system but said that everything from the compressed air connectors up to the larger components was different to anything he had worked on before. Since getting back to Austin the parking brake had freed off, and so identifying the faulty components was difficult. Stephen slowly applied air pressure to the air chamber on both the service brake and parking brake ports and couldn’t recreate the problem; the actuating rod operated smoothly throughout the travel range and there was no leakage. Stephen then spent a while tracing the air lines through the system and identified that the only way for air from the parking brake circuit to get to the load compensating valve, was via a leaking seal between the two portions of the air chamber. With the service brake not being used, the valve is essentially closed and so air from the parking braking circuit discharges here. I later confirmed this diagnosis when the problem reappeared; I applied the footbrake fully, essentially closing the valve off, this stopped the leakage and forced the seal in the air chamber closed. In the subsequent times that the problem reoccurred, I could always force the parking brake to release by pushing the foot brake to the floor. If only I’d tried this in Florida

Confident that Stephen had identified the problem, I left American Equipment to source a replacement air chamber, and brake pads to replace the pads left toasted and crumbly by the heat generated when I drove 15 miles with the calliper locked on in the Everglades. With the wheels removed I had a chance to inspect the brake disc properly; the surface was in surprisingly good condition despite the heat. The Mercedes workshop manual has a page dedicated to assessing damage to brake rotors, and the affected disc passed on all measures (cracks, discolouration, scratches, wear, etc). The disc has warped slightly from the heat, but the deformation is not sufficient to cause any binding under standard calliper clearance adjustment, and so I decided to leave repairing the disc until we return to England; the brake still operates well and there is no judder under heavy braking. Remachining the disc here would require removal of the calliper and dismantling of the wheel hub, something which would be a learning curve for any mechanic. In the UK, Mercedes have a machine for resurfacing the disc whilst it is still attached to the vehicle, and even a local garage would be able to remove and replace the disc with only a couple of hours labour.

A couple of days after I left the garage, I got a call from American Equipment, saying that their parts supplier had been quoted 12 weeks to supply the air chamber, 6 weeks to manufacture it, and a further 6 weeks for it to arrive in the US! Genuine Mercedes service centres in the UK are not allowed to supply parts overseas, even if the vehicle in question is British, as Mercedes UK, a separate entity, have the sole overseas distribution rights for parts supply from the UK. In theory I should have made contacted with them to discuss sending the parts out to us, however the last time I had an air chamber replaced on Jim, the garage doing the work was able to order the part and collect it the same day from their Mercedes service centre. Knowing that this would be the simplest way to proceed I ordered and paid for the parts over the phone at a Mercedes service centre in the UK. The next morning my fantastic father in law had collected the parts and had dropped them at a DHL depot for rapid airmail dispatch to Texas. How it can take 12 weeks to supply a part which can be purchased over the counter at any UK Mercedes parts desk is a mystery to me. I had called Mercedes on Tuesday afternoon, and today, three days later, the parts have arrived in Austin awaiting dispatch to American Equipment. With a little luck the problem will be repaired and we’ll be on the road again next week.