W124 Front end rebuild

Today I took a break from my own cars to help a friend rebuild the front end of his 1993 300D 2.5 turbo. Its a very nice car with only 140k miles, and less than half that on a Mercedes Benz crate motor. Since he plans on keeping the car and continuing to make his daily commute it in, we decided it makes sense to replace all the front suspension components at once.  The shocks were known to be weak, and the inner control arm bushings looked like this:

So, he ordered up:

  • Front struts (Bilstein comfort from http://www.buyeuroparts.com/)
  • Control arms (A 124 330 30 07 & A 124 330 31 07)
  • Upper shock mounts (A 124 320 14 44)
  • Sway bar bushings (A 124 323 49 85 & A 124 323 56 85)
  • Wheel bearing kits (A 201 330 02 51)
  • Tie rods (A 124 330 08 03 & A 124 330 09 03)
  • Center link (A 124 460 12 05)
  • Steering shock (A 124 463 04 32)
  • Idler arm bushing kit (A 124 460 01 19)
  • New hardware
This is pretty much everything in the front end that can be replaced.  While it is possible to replace the bushings and ball joints in the original control arms, its loads easier to just buy new arms with these parts installed.  Everything except the shocks came from the dealer.  The dealer is the only place you should be buying suspension components, aftermarket “OEM” stuff simply doesn’t last.
Having some special tools make this job fairly easy and straight forward.  This includes the original Mercedes Benz Klann spring compressor, and a joint popper.
I’ve tried the knock-off versions of the Klann compressor and have been very disappointed.  Its larger than the original tool, difficult to fit on the spring, and is generally poor quality.  Removing a spring with this Klann tool is simple and safe.
Everything came a part pretty easily except for one tie rod. A sawsall was used to cut off the joint so I could grab it with some large locking pliers and remove the nut.
The final result was very satisfying.  The car still needs an alignment, we simply marked everything on disassembly and installed everything the same way.  But the car drives very differently.  With an alignment and new tires, it will be like new!

Fuel tank and fuel pump

I moved onto cleaning up the fuel system this week.  I was happy to find that the fuel tank was essentially empty, reducing the risk of a environmental disaster significantly.  Removing the fuel lines from the tank and fuel pump resulted in only a few drips of foul gasoline out of each.  Dropping the fuel tank out of the car was very easy… four bolts and a little prying and it dropped out.

I pulled the fuel level sender out and could see by the stains on it that the tank was probably about half full when it was stored.  It seems that if you leave about 10 gallons of gas for about 20 years, it reduces to about 1 quart of nasty brown stuff.  With the help of a friend, we poured what we could of what remained into an appropriate container.  Getting the last bit out it nearly impossible due to the location of the drain, fuel pickups, and filler.  Inside, its definitely rusty, but I’ve seen worse.  There is a local radiator shop that can clean it up for me.

Next, we moved onto the fuel pump.  Overall, it doesn’t look that bad from the outside.  We decided it made sense to remove the bottom cover of the pump to see if what crud might have made it inside.  There was some sludge and varnish, but it wasn’t too bad.  After soaking and flushing with some acetone I had handy, it cleaned up nicely.  Here is a look inside during the cleaning process:

We then briefly connected the pump to a battery to ensure that it would run.  The pump did run, but a bit unevenly.  It didn’t seem like a good idea to run it any more than a few seconds without any fuel in it, so I concluded that it works well enough to install back in the car for now.  I’ll order up a new seal (thats A 004 997 04 45, I hope) along with new fuel lines, a fuel filter, and tank screener.



Turning the engine, and other work

I spent about two hours working on the car today, mostly taking care of little things.  I replaced the heater hose eaten by mice, changed the oil and filter, and managed to get the battery cable off the positive post of the 1983 battery finally.  The oil was quite clean, almost red in color.  The bottom of the oil filter housing had some sludge, but I couldn’t feel much of anything with my finger in the bottom of the oil pan.  I was happy to see the filter was a nice German made one:

But the most important task of today was turning the engine:

Very exciting video, I know.  But it turned very easily.  I had already changed the oil, and poured a bit in each cylinder, on each cam lobe, the rockers, and around the chain tensioner.  This is very encouraging!

I then moved onto the interior and started to repair the wiring which was chewed by mice.  It wasn’t quite a bad as I thought.  Head light switch had 4 wires with the insulation chewed a bit, and about the same with the fuse box.  The two wires running to the switch inside the air suspension height adjustment box were the worst and will need to be cut back and replaced.  Lowering the fuse box down for inspection turned out to be a bit more of a project than I expected:  The B pillar cover, threshold plate, air suspension and hood release assembly, and the carpet in the foot well had to be removed to access the two bolts securing the fuse panel.  But it was worth the effort and piece of mind to know there is nothing that is at risk of burning or catching fire.

And finally, I took a closer look at the shifter bushings I need.  My parts guy gave me two to try, but I don’t think they’re right.  I can’t quite understand what holds the bushing and linkage to the shift lever.  There is no place for a clip of any kind, and the EPC doesn’t show anything.  Anyone have any ideas?  You can see the stub the linkage hangs on here:

I’ve been thinking about buying some short jack stands to support the car so I could climb under it.  Today I used a solution the worked very well, and seems more secure.  I took the cut 2x10s I had ready when we picked up the car and stacked them under the frame rail on each side of the front of the car.  When the car’s suspension is pumped it, the boards fit under without the need for a jack.  After the car sinks down a bit, it sits on the boards.  Removing them is easy, just connect the compressor and raise up the car.  I’ll have to cut more boards for the rear of the car when it comes time to drop the fuel tank.

Things to do… or?

I was digging through the paperwork found in the glove box of the 300SEL.  Tucked in with all the original manuals was this piece of paper:

It appears to be a list of issues with the car, perhaps written for a mechanic to review.  With some luck, these repairs will have already been performed.  Nothing is of a really any major concern except for the heater fan not working.  This is a major job to repair, and its often one of the first things I check when inspecting these cars for the first time.  Other complains point to issues with the warm up thermostat on the injection pump, perhaps.  The tires are shot no matter what, the exhaust is home to mice, and the AC is the least of my concerns.

Driving the W116

This week I’ve enjoyed driving my 1979 300SD everyday while we’re down one car with my wife’s E320 in the body shop.  This car only sees a few thousand miles a year, and goes into winter storage when the weather turns cold.  But when I do drive it, I drive it a lot.  Weekend trips to the shore, or the occasional daily commute.  Long highway trips are good for the car, allowing everything to get up to running temperature.

Using the car for daily transportation gives you a great appreciation of how well engineered it is.  The car is one of the earlier 300SDs produced, with a 110hp 5 cylinder turbo diesel and automatic transmission that starts in second gear from a stop.  (Later cars had 120hp and a first gear start.)  The result is a relaxed driving experience, but more than enough power is available to keep up with modern traffic.  The car has excellent passing power in top gear on the highway, pulling from 70 to 80mph without much effort.  Pressing the accelerator to the floor from a start yields a kickdown into first and somewhat more spirited acceleration, and some help getting up steep grades.

Everything works on this car, which really adds to the joy of driving it.  The climate control does an excellent job keeping the cabin comfortable in weather like this… mid 70s, humid.  It mixes just a bit of warm air with the air conditioner to keep things dry and cool.  The vacuum operated cruise control holds your speed nicely on the highway.  Ride and handling, as well as the brakes, are excellent.  If you choose, it can be driven quite aggressively and fly through the curves.  The occasional rain shower has been no problem, its very confident on slippery roads as well.

Additional pictures of this lovely car can be found here.

Some discovery work

I spent a few hours after work today taking a deeper look at the car to determine its general condition.  I started by pulling the spark plugs and having a look… all were consistently carbon’ed up.  I then pulled the valve cover to have a look at the valvetrain.  I was quite impressed!

Everything looked quite nice, still covered with a thin film of oil.  There was still some oil pooled up in the tops of the head bolts making me wonder just how long ago this engine was last run.  I’d have expected sitting for over two decades would have dried things up a bit more.  The cam and rockers all looked good with little or no wear.  When I first saw the car, I thought I saw some fine metal shaving covering the cam.  Now that I’ve had a good look, I can see there are a few shiny shavings on the cam I can’t really explain, but its so little I’m not alarmed at this point.  Although its probably overkill, I poured a bit of a mixture of brake fluid and acetone into each cylinder to help free up any rings that might be sticking.

Next, I moved onto cleaning up the interior a bit.  There were several vintage plastic bags and random bits all over the interior.  The carpet cleaned up very nicely with just a vacuuming for now.  There were lots of small shells and other organic bits that were most likely leftover by mice that once lived in the car.  Surprisingly, there was no damage to the carpet.

Since I knew there had been mice in the car, I decided to pull apart the dashboard to inspect the wiring.  I removed the instrument cluster, radio, speaker, ash tray, and glove box.  As I suspected, there was a collection of paper and plastic bits just behind the instrument cluster.  A careful inspection of the wiring turned up a few chewed up wires running to the headlight switch.  It shouldn’t be a major issue to correct, but needs to be done before a battery is connected to the car again.  In addition, the speaker wires were broken and mostly missing.  It seems these wires are made of something far more delicious than the other wiring in the car!

I’ll have to go over the car again once more very carefully before connecting the battery.  The only other damage the mice caused were chewing through the line running to the oil pressure gauge, the top of one cooling hose.  The oil pressure line is quite a cheap part new from Mercedes, and all the hoses need to be replaced anyway.

The next step will be to get some oil in the cylinders and see if the engine will turn by hand.

Lean to the left

So, it seems the air suspension isn’t looking so good now that it’s been under pressure and up and down a few times.. The left rear bag is now leaking pretty badly which brings the rest of the car down after a short time. The right front side keeps some air in the bag much longer, resulting in the car sitting at a funny angle.

This is a bit disappointing, but I knew the suspension would need some serious work at one point anyway. Hopefully I’ll still be able to raise up the car to make it easier to work on as necessary for now. An added bonus would be if the engine’s compressor can keep up with the leak to make some very short test drives when the time comes.


Still standing, 48 hours later

This morning I was very pleased to find the car had only fallen an inch or two in the front after sitting for two days.  This is very promising for the air suspension, especially since it was only filled with a small compressor.

I ran out to the home disappointment and picked up a portable compressor capable of 175psi.  Since I’ll be doing quite a bit of work to the car before I have the engine running, I wanted to have a appropriate tool to keep the car level while I work.

I connected the new compressor and the car raised up to a normal height.  I had the air suspension lever inside the car set to the locking position, so I decided to see what would happen if switched to the “high” setting.  The car immediately rose even higher!  So far, I’m quite happy with this car.