Posts Tagged body

Transmission Fluid Exchange

Posted on July 18, 2011 | Automotive Repair.

Manufacturers have always had a suggested service interval for changing fluids and that includes the transmission whether it is an automatic or manual shift. When automatic transmissions were first introduced the suggested service interval was about every three years or 50,000 miles. The transmission service consisted of draining the fluid from the pan and maybe the torque converter and replacing the filter. This was a realistic time frame interval and service method as the vehicles were very open and did not build up much heat.

Around 1980 the US auto manufacturers downsized the cars for fuel economy and mounted the power train transverse into the area previously reserved for the engine only. As you can imagine this increased the heat retention in the engine but especially so for the transmission. The demands placed on the transmission fluid have increased exponentially as a result. The unexpected warranty costs from this required a switch to synthetic fluids that can handle the heat better. Even the synthetic fluids and their additive packages fail over time, as evidenced by the number of valve body failures that cease working properly from gum and varnish deposits.

General Motors tried an experiment of sealing the transmission and stating that “it was good for lifetime service”, however that failed miserably. What happened was the fluid and additive package failed to keep gum and varnish off critical components like the valve body and clutch packs. These gum and varnish deposits stick to the valves in the valve body and on the clutch assemblies. The valves move sluggishly or become stuck completely resulting in improper operation or a burned up transmission. Clutch packs slip, hang or grab, which burns them up after some very bad shifting problems.

These problems can appear in any transmission some with really low mileage. Most auto manufacturers realized that a transmission fluid exchange was needed so they engineered a transmission flush machine for their own vehicles and made it an essential piece of equipment for their dealer network (meaning dealers are required to own it). Most transmission fluid exchange machines use a bladder type system to hold the new fluid (usually about 16 quarts), the old fluid flowing from the pump to the transmission cooler is interrupted and the equipment inserted into the loop. The old fluid supplies the hydraulic force to exchange the old fluid for the new. Sometimes they supplement the pressure with a low pressure pump. The new fluid is returned to the pan, where it flows through the filter first, then into the pump, valve body, etc.

The response to auto manufacturers equipment from the aftermarket equipment manufacturers has been excellent, with tools like the bulky T Tech II and others like Wynns, BG, and Mighty made by White Industries.

Transmission Flush Service

Most auto manufacturers suggest 100,000 miles for transmission service but that is too long. It better to be safe than sorry so it is still a good idea to perform a transmission flush service every 3 years or 50,000 miles. This could save you a tremendous amount of money and headaches in the long run. If a valve body fails from excessive gum and varnish deposits the expected cost can easily reach $1000.00, a transmission requiring replacement can be even more.

The procedure is pretty much the same from one piece of equipment to another. A cleaner such as Wynns or Mighty that can remove gum and varnish deposits WITHOUT softening seals or friction disc materials is first added to a previously warmed transmission. The vehicle is then started and the transmission is shifted to all the different gear positions and allowed to run in each position for a time determined by the product manufacturer. Some suggest a short light duty 15 minute or under drive to clean the valve body better.

Then the equipment is inserted into the pressure line from the transmission to the cooler. The vehicle is started and the old fluid along with the transmission flush additive gets completely removed during the fluid exchange IF the mechanic does his job correctly.

This transmission fluid exchange should be interrupted part way through as the old fluid shows clearing. A new filter should be installed, then finish the flush and top up the transmission with new fluid. Follow the flush chemical manufacturers suggestions and add their required additives, but do not overfill the transmission.

Subaru Impreza WRX STI Engine

Posted on May 30, 2011 | Automotive Repair.

The introduction of the Impreza line began with Subaru in 1993. Subaru’s main goals when producing this vehicle were to help fill a gap in the small car market initially; later in its life Subaru changed its goals to become dominant in rally race scenes. The power to weight ratio of the Impreza when a combination of the fairly small, light chassis and the boxer styled four cylinder Subaru engine made it instantly successful in the rally races. Each year brought new revisions to the Subaru engines, ramping up power while still keeping the lighter chassis making it a dominating force when on the track.

The first versions of the Impreza were offered in either front wheel drive or an all wheel drive configuration. It was available in either a four door sedan or a five door station wagon/estate. Initially the Subaru engine offered was a 1.8 flat 4 cylinder known as the EJ18. This was followed quickly with the addition of the 1.6 litter version. Subaru chose to stay with the same basic design of the engine known as the flat four cylinder (or boxer) engine as they believed that by keeping the engine on a low centre of gravity, in line with the transmission, minimised body roll as compared to vehicles with offset engines. Another bonus to this design is that it also eliminated the need for a weighted counter rotating crankshaft. Since each piston is counter weighted by the opposing piston directly opposite while the engine is running. The 1.6 and 1.8 engines were dropped from production in 1996 and replaced with the now common 2.0 litre.

Subaru then introduced the STI(Subaru Technica International) version of the Impreza into the Japanese Domestic Market or JDM as it is more commonly known, in 1994. The STI was an upgraded version of the Impreza WRX models currently available. The STI came equipped with performance tuned suspensions, engines and transmissions. The STI was immediately successful in rallies and was sought after by street racers. There was even an option to order special RA (Race Altered) versions direct from the manufacturer which were modified by being lighter in weight, having reduced sound proofing, manual window mechanisms, omitting the air conditioning and coming equipped with more robust engines, shorter gearing and driver controlled center differentials.

The Impreza model received an external facelift in 1997, this was followed by an internal redesign incorporating the more advanced dashboard from the Forester in 1998. Further upgrades were found on the European models in 1999-2000. These upgrades included making parts from the STI range standard, front brake callipers were now four pot with 294mm brake discs, wheels were upgraded from 15 inch to 16 inch, they added vented rear disc brakes, a firmer suspension and bucket seats.

The beginning of 2001 saw the introduction of the second generation of the Subaru Impreza. The body style was larger, safer, more refined, the suspension was stiffer and more responsive. Many Subaru owners use nicknames for their vehicles based on the headlights they came with. In 2002-2003 the headlights became known as “bug eyes”, these were followed in the 2004-2005 “crocodile eye” versions also known as “blob eyes” and then finally in 2006-2007 the headlight configuration was to be known as “hawk eyes”.