Andrea’s car
This past week, I’ve spent a lot of time researching solutions to some problems we were having with Andrea’s car. After the seller tried fixing the vacuum issues affecting the turbo, he disconnected the vacuum line to the turbo wastegate actuator, created a mini vacuum on that line, and plugged it so the turbo actuator was partially closed. He checked the max boost by flooring it in several gears, and the max boost displayed as 15psi. I guess this is at the top end of what is “safe” for the turbo.
Afterwards, everytime the car shifted, it made a loud noise (clunk) and shifted hard. Some intense reading at mercedesshop.com and a few days later, I decided to fix the shifting by diagnosing the vacuum lines going to the transmission. Using a MityVac, I found that the vacuum line going from the vacuum pump to the valves for the turbo/EGT were leaking like crazy, so little or no vacuum was reaching the transmission. I solved this by plugging the line that was leaking. Since that particular line was for the turbo/EGT and the seller plugged the line to the turbo, the line was useless anyway.
With the line plugged, the shifting got much smoother. In fact, the shifting became too soft! Whenever it shifted into higher gears, it would rev a little before dropping rpms. After some more reading, I fixed this new problem by adjusting the vacuum control valve(VCV). The MityVac showed that the transmission was getting approximately 12″ of vacuum and when I revved the engine by pulling on the throttle linkage, it would drop to 5″ or so. I untighted two 10mm bolts on the VCV, turned it clockwise, and retightened. I’m not entirely sure what the twisting of the VCV does, but I’m glad it worked.
Eventually I’ll post a pictures of what I modified and adjusted and update this post.
We filled up Andrea’s car. 391.7 miles and 14.457 gallons = 27.1 mpg. I think the next fill up should give us the true mpgs of her car; this time, I filled up the car until I could see the fuel in the filler tube. Go diesel!