5 minute DIY - Installing a boost gauge in 300SD

Really, this install could not be easier.  I picked up a cheapo boost/vacuum gauge from Harbor Freight for about $20, came with about 3-4 feet of vacuum tube, a plastic tee connection, and some crappy bracketry.  Not only was it cheap, but it is extremely cheesy as well, allowing the user to select any number of colors to look super cool!  Being that my SD is already cool and particularly riced-out on the inside, this fit perfectly within the decor.  The easiest place to tap into the boost is with the overboost protection line running from a banjo bolt on the intake manifold over the top of the valve cover into a little cylindrical gizmo on the driver's side fender.  What this does is it monitors the boost and sends a signal to the ALDA which eventually regulates the amount of fuel going into the injector pump, thus limiting boost.  However, most turbos 30 years old are not putting out a whole lot of boost - thus the case for a boost gauge.  While you're working on the boost line, it is a good idea to unscrew the banjo bolt (don't lose it like I did last year...) and give it a really good cleaning.  They can get clogged up with soot and stuff over the years which will limit the performance of your car as well as render the boost gauge inaccurate.  Furthermore, it only takes 30 seconds of your time and is a good practice every couple years.
Anyways, regarding the gauge - I tapped in right before the overboost protection solenoid in order to give me as much vacuum hose as possible going into the cabin.  Unfortunately, being a piece of crap, the tee that came with the gauge broke almost immediately.  Luckily I had another tee on hand that fit a little better, and used that to tap into the line.  A boost gauge such as this requires the vacuum/boost hose to go through the firewall into the passenger compartment, and there are a few ways to do this.  The tubing that came with the crappy gauge was very thick and I didn't have any spare hard tubing available.  Therefore I chose  to route it in the same grommet as the hood  release cable, between the fuse box and fender.  There was a plugged space available (not sure why...), all you need to do is unplug it and route the hose through. A good trick is to stick an unbent coathanger in the tubing to stiffen it, then route it into the cabin.  That way, the flexible tubing won't bunch up and you won't have to crawl uncomfortably around the pedal area. 
You can mount the gauge wherever you please, but the most logical for me was right under the ignition tumbler, since it was out of the way yet still visible.  There is a trim piece that uses a screw along with a trim clip to secure against the top dash.  This was solid enough to mount the gauge.  I had some 90* steel brackets left over from an electronic drum kit I made, so I bent one to shape and screwed it in.  Attach the boost line to the back of the gauge and you've got a working gauge.  As far as wiring, I installed a radio at the same time, so I decided to use the 12V+ and illumination wires from that to also power the gauge LED.  The ground just went to a chassis spot.  In all, it took me longer to write this than it did to  install the gauge in the car.  Any questions just comment and I'll be happy to answer.

Pics are still coming.  I had written this a while ago, never got around to posting it, but unfortunately my camera is MIA :( 

Boxy Brown

Being an auto blog I obviously need to introduce my awesome rides.  Boxy would be the first of the Mercedes that really got me into these old heaps of metal.  It all began one day back in December 2008....

I was visiting my family in New England as I usually do for the holidays and was simply driving a nice scenic road in my Dodge Stealth (RIP!).  At this point, I was putting on about 15,000 miles a year on my car and hauling lots of stuff back and forth being in school.  The Stealth was just not a practical car though I loved it much and it was a lot of fun.  On this cold winter day, parked outside of a  very old (1700-1800s) antique and crafts store was a lonely looking turd of a 300SD.  It had massively faded paint, a bit of rust behind one of the rear wheels, and used to be dark brown with palomino interior.  The very next day I gave the guy a call and he met me outside the store, putting on the sales pitch.  He started the car and as soon as I heard the diesel clacking away in 15 degrees, I knew this car was for me.  I bought it the very next day for less than $1000.
   Driving home was an extremely scary adventure.  Since the DMV did not require inspections, I literally walked in the DMV with nothing and walked out with plates and an empty wallet.  My father drove with me to pick up the car and unfortunately by the time I got the plates on, it was rush hour.  It took me all of about 100 feet to realize only one front caliper was working.  I DID make it home about an hour later and after numerous angry rush hour motorists expressed their distaste for my slow, smoking brown slug.  The transmission flared VERY badly in the 1-2 shift and 3-4 shifts, and slipped pretty badly as well. 
   It sat in the driveway for a couple months while I was in school, since I didn't have a chance to work on it while living 250 miles away.  I saved up and bought all the parts I needed, most notably an entire braking system from the booster to the tires.  Early in the summer I put it all together, cleaned out the ALDA line, replaced the B2 piston/bushing in the trans, cleaned the valvebody, cleaned the fuel tank, replaced normal stuff like glow plugs, filters, etc.  By July I had a daily driver!  Not too bad for a diesel noob like me, I learned a LOT from Boxy. 
   Boxy had some other "mods" too, obviously the EGR valve was immediately blocked off, I switched to LED lighting on the inside, and put in a kickin' stereo system.  To accomodate 6x9's in the back, I fabricated a new rear deck and upholstered it in matching vinyl (well, the best I could to a fading pinkamino interior). 
  I should explain the name...Boxy brown is a character from Aqua Teen Hunger Force (yeah yeah, I know...)

I see the resemblance quite clearly myself.....


Anyways, Boxy served me well for over a year and only failed to start once outside the office in -6*F because the battery couldn't put out enough juice to crank it.  I put on about 15,000 boomin' miles until rust got the best of him.  When I bought the car I didn't realize the rust was that bad....turns out there was a ton of hidden rot at all of the jack points and the salt ate away at the trunk floor to the point where you could see straight through it!  Despite having a healthy engine and transmission, Boxy was dying quickly and succumbing to the rust.

So come almost exactly a year later, a fellow on one of the forums I frequent offers a Texas 300SD shell (no trans/engine, no interior) for next to nothing.  The saga continues....