Notes from beyond the Dark Side - PeachParts Mercedes-Benz Forum

ctaylor738 · #1 12-14-2006, 11:34 AM

If it's OK with you guys, I will open this thread, and update it as I work on the S500 Coupe. Normally this would not belong here, but it might be of interest to see how the cars have evolved, and to those who are considering the purchase of a newer car.

So last night was brake pads. Parts were not so bad - $134 for pads and sensors. But my first challenge was lifting the car. There is no single point to jack the car up in front, so I resorted to a SUV floor jack under four very convenient rubber lift points, stuck a jackstand under a frame piece, and did one wheel at a time. This worked well enough, but the size of the car forced me into some cramped and poorly lighted areas to do the rear brakes.

The brakes themselves are conventional and look a lot like 123 brakes. The front calipers have four pistons each, the rears two. The front have one sensor on the outside pad. Only the right rear brake has a sensor. Replacing the pads was straightforward. The only annoyance was that the fluid reservoir is covered with a large plastic piece that runs across the firewall and has amazingly inconvenient screws to remove for access.

Book time for the pads is 1.8 hours, and I ended up at about 3.

So tonight I will start on the oil tubes which involves removing the valve covers and, apparently, the ignition coils and fuel pipes.

cth350 · #2 12-14-2006, 08:43 PM

cool shoes. Now, for pictures of what's under the hood. Tracking the evolution of the engineering principles, not to mention bean counting is a fun armchair exercise.

What kind of convolutions are present in the suspension system. It's hydraulic, right? -CTH

ctaylor738 · #3 12-15-2006, 07:38 PM

Last night I took on the first serious engine work - replacing the oil tubes in an effort to eliminate a ticking valve and low oil pressure. There are 16 of these that move oil across the heads. They have a seal on one end that blows out, resulting in the ticking and pressure loss. See the first picture for their location (the black cigar shapes) and a shot of the head with the covers off. Note the recessed spark plug and the electronic injectors on the top of the head.

The second picture shows the culprit - #5 on the left side. Where you see the hole in the end should be solid.

When you replace the tubes, you need to loosen all the cam bearing caps, because they hold the tubes in place. You also remove the cam guides, which are plastic contraptions that straddle the chain between the sprockets. If you do this repair, they shoud be replaced because they are very brittle and break if you don't have the special tool to remove them. Picture #3 shows the new guide installed on the left side.

With the cam bearing caps torqued at 12 nm and the guides installed, you put the cam covers back on, then install the coils. See Pictures #4 and #5 for a shot of the coils installed, and a picture of a coil. No more distributor or coil wires.

Then all that is left is to put the coil covers on, then install the air cleaner assembly.

This repair worked out really well. Oil pressure is increased by about .5 bar at idle, and ticking and other engine noise is gone. Power is up and smoothness increased because the valve timing is better, being controlled by oil pressure.

Cost was $333.77 for the oil tubes (16x$15.08), valve cover gaskets, and new breather hoses, plus $42.53 for the cam guides.

There were no difficult-to-reach bolts or fittings in this repair. The AllData instructions and illustrations were quite good. Anyone with 116 or 117 experience could do this job without difficulty.

Next up - investigating the clunk in the rear end when going over any sort of bump.

wbain5280 · #4 12-16-2006, 12:40 AM

Thanks Chuck. I've often wondered wht MB makes such an unreliable engine part. After all, it can possibly cause engine damage. On the other hand, an owner could sell a perfectly good car to one of us thinking the engine is going bad and all it needs is oil tubes.

cth350 · #5 12-16-2006, 10:23 AM

Ah, now the light bulb clicks on for me. On a lark, I purchased a bunch of used ignition parts from ebay from various people. A few coils from this guy, ignition modules from somebody else. Nothing over 10 bucks mostly, just to have a stash of parts. My goal? (other than to waste money on ebay fees?) Coming up with a modern ignition system for a not-so modern benz.

I got a few coils with those long spikes on the "bottom" (I didn't know which end was "up"). I haven't gotten as far as figuring out what things I need vs what I've collected so far. Picture fitting those coils on top of the plugs for a 6.3. That would be ridiculous; like walking around with pencils sticking out of your ears. However, an M110 motor might like them just fine.

Thx -CTH

300SDog · #6 12-17-2006, 12:31 AM

Thats individual ignition coil components per spark plug? I'm impressed with what appears to be self-adjusting valve lifters, doing away with rocker arms. Looks like a pretty good "parts car" you've got there Chuck..... And have heard somewhere that thermostats from the mid 90's are choice upgrade for 4.5's

Tomguy · #7 12-17-2006, 12:57 AM

That spark plug coil thing looks a lot like the ones on the 300m. I dont want to know how much it'd cost to replace all 6

Nevermind all 8 of yours!

ctaylor738 · #8 12-17-2006, 11:05 AM

There is a huge amount of griping about the oil tubes. I don't understand why they were made that way. It would be simple to make it as one piec and not seal the end. And why are the replacement parts not improved?

The coils are painful - $75 apiece. And they do fail. But that seems reasonable compared to $324 for the fuel injectors.

ctaylor738 · #9 12-17-2006, 01:39 PM

One of the reasons I wanted a newer car was to learn about the diagnostics available under OBD. 1996 was the first year that OBD-II was available. I looked at code scanners that started at $950, then at PC-based stuff that was much less expensive. I selected the BR-3 adapter from these folks:

http://www.obddiagnostics.com

What you get is an adapter that runs between a serial port and the car's OBD2 connector, then you download the software from their web site. Cost was $83 plus $5 postage.

So I tried it out today. It works quite well. You get a nice graphic display of what is going on with the engine, as well as a log. You get RPM, temperature, vacuum, and a real-time read-out of O2 sensor voltage. And you get to see the trouble codes. There is a lot more that I need to explore, like how to get to the climate control, and transmission areas. I was glad to see that there were no engine codes reported!

Here is an excerpt from the log.

"BR Logfile"
#2006-12-17#
#1899-12-30 12:59:37#
0,3,0,"MIL indicator lamp is ON
Vehicle Reports 0 Codes stored."
0,7,0,""
7,109,0 " No trouble codes were received."
0,1,12," Engine RPM 1266 RPM"
0,1,17," Throttle Position Sensor (absolute) 2.7 %"
0,1,4," Calculated Engine Load Value 25.5 %"
0,1,5," Engine Coolant Temperature 79 degF 26 degC"
0,1,14," Ignition Timing Advance -7.0 deg"
0,1,11," Intake Manif. Pressure (absolute) 10.0 in.hg 34 kPaA"
0,1,15," Intake Air Temperature 70 degF 21 degC"
0,1,16," MAF sensor Air Flow Rate 1.0 lb/min 7.52 gm/s"
1,258,0,.015

kalpol · #10 12-17-2006, 04:32 PM

Quote:

Originally Posted by ctaylor738

One of the reasons I wanted a newer car was to learn about the diagnostics available under OBD. 1996 was the first year that OBD-II was available. I looked at code scanners that started at $950, then at PC-based stuff that was much less expensive. I selected the BR-3 adapter from these folks:

http://www.obddiagnostics.com

What you get is an adapter that runs between a serial port and the car's OBD2 connector, then you download the software from their web site. Cost was $83 plus $5 postage.

So I tried it out today. It works quite well. You get a nice graphic display of what is going on with the engine, as well as a log. You get RPM, temperature, vacuum, and a real-time read-out of O2 sensor voltage. And you get to see the trouble codes. There is a lot more that I need to explore, like how to get to the climate control, and transmission areas. I was glad to see that there were no engine codes reported!

Please keep us posted on this scanning software you speak of. I am pretty interested in it. HOw is the software? Buggy? easy to use? etc.?

cth350 · #11 12-18-2006, 08:57 PM

Looks like a great reason to buy a newer car. Nice toy. -CTH

ctaylor738 · #12 01-04-2007, 09:12 PM

Well, the Coupe did very well as the driver-of-choice for our twenty-something kids who were home for the holidays. My son especially liked it and fantasized that he was driving Tupac's car. But now it's time to get serious. I think that next up is to fix the clunk in the rear suspsension.

This is very new to me. The rear end has struts, which are sort of like hydraulic-filled shocks that control the ride height. But being filled with liquid, they don't compress and thus have no dampening. The dampening is handled by nitrogen-filled spheres (I am not making this up) called "actuators" that absord fluid when the strut is forced up by a bump. Apparently, these wear like shocks and need to be replaced at around 100k.

There is a great article on how this works, and how to replace the actuators.

http://v12uberalles.com/pressure_spheres.htm

So, I have the parts on order, and am set to return rear height to normal, get rid of the clunk, and improve ride and handling.

Tomguy · #13 01-04-2007, 09:27 PM

On my 300m I can read the OBD-II codes without a code reader. It's a (very) little-known fact that toggling the key on, then off 3 times (on, off, on, off, on) will print a readout of the codes. On older Chrysler OBD-I vehicles (like my Jeep) the CEL flashes to output the codes. On the 300M, it outputs it on the odometer. I had a P0700 for a while - now my car's in the shop with apparent transmission failure. I don't believe the dealer

Benzcrusher · #14 01-04-2007, 09:47 PM

The system is very similiar to the set-up on the w123 300TD as well as the w126 560SEL / SEC and special ordered w115 /w123 sedans.
The struts fail when they leak and are fairly durable. They are stupid expensive to replace with new ones ~$650 each. There a two types of rear struts as hydropneumatic front shocks were an option.
Be sure to flush and refill the system with the correct MB hydraulic fluid every year or so, no Walmart tractor fluid here.....
Unlike the earlier SLS system where the fluid had a dedicated pump the w140 uses a special PS/SLS pump. $$$$

I really like the 140 coupes, The first one I noticed, a 600, was parked at a hotel I was staying at in Phoenix in 1996...

nhdoc · #15 01-05-2007, 07:57 AM

Quote:

Originally Posted by ctaylor738

One of the reasons I wanted a newer car was to learn about the diagnostics available under OBD. 1996 was the first year that OBD-II was available. I looked at code scanners that started at $950, then at PC-based stuff that was much less expensive. I selected the BR-3 adapter from these folks:

http://www.obddiagnostics.com

What you get is an adapter that runs between a serial port and the car's OBD2 connector, then you download the software from their web site. Cost was $83 plus $5 postage.

I bought a similar OBD scanner for working on my '98 E300:
http://www.scantool.net/products/product_info.php?cPath=8_1&products_id=1
I found the "OBD Gauge" software on their site that allows it to work from a palm-pilot instead of a PC which is much more convenient for me. It retains most of the functionality of the PC software, though not all functions are available...still to read codes, clear CEL and check readings of major sensors it works fine.