News:

The ORG
Truly Independent and Unbiased!

Main Menu

Restoration of 6.9 #496

Started by McNuggets, 16 August 2020, 06:23 PM

raueda1

Quote from: daantjie on 24 August 2020, 07:46 AM
Interesting to note the decal on the dash knob for height control showing the 3x settings,  I have never seen this, wonder if it's stock ???
I noticed that too.  Not stock, I think.  My impression is that early cars had round knob, and this is an early car, to be sure.
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

john erbe

Regarding emissions, here in CA anything manufactured after '74 has to be smog tested and at a shop that's "Star Rated". Bottom line dont take off any emissions controls.

Jed

Quote from: raueda1 on 24 August 2020, 09:28 AM
Quote from: daantjie on 24 August 2020, 07:46 AM
Interesting to note the decal on the dash knob for height control showing the 3x settings,  I have never seen this, wonder if it's stock ???
I noticed that too.  Not stock, I think.  My impression is that early cars had round knob, and this is an early car, to be sure.

Yeah, never seen that sticker before either. Has anyone seen that sticker before?

.Also never seen or heard of a round knob? 
1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

daantjie


The only round pull knobs I've seen is on the W126.
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Quote from: daantjie on 25 August 2020, 12:21 PM

The only round pull knobs I've seen is on the W126.
Here it is.  Maybe from a W126?  But there it is.  My car a few other oddities.  Rumb says the straps behind the seats are some kind of lumbar support.  Whatever they are, Ido know this:  they don't work and you practically never see them.  My WUR is also flipped 90deg so tubes are more-or-less straight, not bent.  The bottom line is that these cars seem to have been more minor variants than we'll ever know.

To OP:  sorry for steering you wrong on removing smog stuff.
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Jed

Very interesting dave! What is your build number? #484 which is my 76 6.9 has a square knob. Maybe they just installed whatever they had laying around in the early days!?
1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

raueda1

Quote from: Jed on 25 August 2020, 05:39 PM
Very interesting dave! What is your build number? #484 which is my 76 6.9 has a square knob. Maybe they just installed whatever they had laying around in the early days!?
Yeah, this stuff is bizzare.  Mine is #923 - early but not as early as yours.  We'll never know!
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

slfan


When restoring my 6.9, I thought I had lost the suspension knob and after looking-up the part number in the EPC ordered one from the Classic Center.  The one I received was also round.  Therefore, I believe this round knob is an updated replacement from the W126.
1978 - 450SEL 6.9 - 3170
1978 - 450SEL 6.9 "Parts Car" - 2973

McNuggets

Hi everyone, it has been a little while now and I've had a trickier time balancing this project with my day job than I wanted. I've been getting really anxious about how much is still to be done and how uncertain the state of the engine is so I did the natural thing, and rushed the job :D I disassembled the FD, freed the stuck piston, reassembled (no sealant between the halves, really cutting corners), stripped half the case screws, tested it, and it leaked like a sieve. I took it apart again, saw that I had split the lower oring on the cylinder assembly, lapped the casting halves to 3000 grit on a surface plate, reassembled with split oring still in place, stripped the rest of the case screws trying to torque them up to 70in-lbf (I got this torque spec from a third party, are proper Bosch manuals available?), tested, and it seemed to be OK. The damaged oring separates the lower chambers of the FD from a void space in the casting whichseems to be vented to the return line. No leaks as far as I could tell, but I only bench tested it for maybe a half hour. Fuel delivery for each cylinder should be tested with the injectors installed and firing into soda bottles which I had saved up, but I am impatient so I observed the eight open ports filling with fuel as I depressed the airflow meter plate and decided the variation from cylinder-to-cylinder was at least not grotesquely huge, and that that was good enough for now. One more nagging problem: system pressure drops from 5.2 bar to about 2.6 bar instantly. I'm not sure how I will tell if this is a bad check valve in my original pump, or if I screwed up the pressure regulator assembly in the FD somehow but given all the mickey-mouse things I did to the FD I wouldn't be surprised if my problem is there.

I disassembled the WUR into its pieces, including pressing out the steel fuel cell, bimetallic strip mount, and plug by the vacuum diaphragm. I am not sure whether or not I ruined a perfectly good calibration doing this, but I suspect the WUR on my car was adjusted to suit the oddball closed-loop lambda control that was installed during federalization, so I committed to re-calibrating it early on. Pressing the steel part out was a real pain, after soaking it in penetrating oil I needed to use a lighter (I don't have a torch and I live in a rental house with fire sprinklers all over the place) to heat the body and reef on the vice to move it at all. Then came reassembly. Here I again tried to cheat and simply reassemble with new seals, but I found that the control pressure was pinned at system pressure when I tried testing it. That is to say, the WUR was bleeding off zero fuel from the top port of the FD. I think this happened because I used too much copper grease when replacing the little hat on the inside of the WUR which presses against the steel diaphragm. On the second disassembly of the WUR I found the inside reeked of fuel, so I lapped the cell halves on the surface plate until they were as shiny as the FD and made sure the bolts which hold the two halves of the cell together were Very Tight. The instructions I used for the WUR came from k-jet.biz where I had bought the seal kit. Those instructions mention only a single steel diaphragm in the WUR, but my car had two: one with an eccentric hole near the middle, and one plain. The one with the hole was originally placed "above" the plain one in the sandwich, touching the inlet and outlet ports on the cell, so I put it back together that way. I have no idea what it's for, has anyone run into this? This time, the WUR seemed to at least establish a lower control pressure of around 1.2 bar, and not leak any fuel.

Trembling with excitement, I quickly replaced the old fuel injectors and seals with my new ones, mounted FD and WUR back in their places in the engine bay, and attached the injector lines. I replaced some of the rubber intake pipes between the AFM, auxiliary air valve, and idle speed adjusting screw, and began trying to start the car. After much trial and error (fuel spraying from fittings I forgot to tighten in my haste directly into my friend's face for the second time this weekend, realizing after several attempts to start the car that I had long ago pulled the ignition trigger wire off the EZL, oil pouring out of the rocker covers because half the acorn nuts were missing when I got the car and the other half I forgot to tighten, etc etc etc) the car did start and run for about three seconds. YAY! I am elated!!! I have some photos and a recording of the three happiest seconds of my life on my cellphone, I will try to upload these tomorrow. I tried to start the car again, but no joy. I suspect the no-name battery I bought at O'Reilly's two months ago has gone flat with all the cranking from this and the earlier compression/oil system testing I did, but by then it was late on a Sunday night and I decided to leave it for another day. The next thing to do, of course, is worry about the corner-cutting I just did.... I suppose I will find out whether I am in for another disassembly/reassembly cycle this weekend when I try to dial in the WUR and get the car idling continuously. I seriously messed up the screws on the FD and will replace them with Torx heads instantly if I need to touch it again. Sorry for slinging this long rambling post with no pictures your way, I'll try to contain my excitement before I post again. It may have been only three seconds, but it sounds like a beefy machine  ;D

Nuggies

daantjie

I'm glad to see I'm not the only impatient one on the forum haha...
Take heed from fellow member Dave's ("raueda1")  shenanigans with hydro locking a cylinder, it can easily happen if your FD is dumping a lot if fuel into the chamber.  Hilarity will not ensue :o
Daniel
1977 450 SEL 6.9 - Astralsilber

BCK1963

The strap behind the front seat is indeed to adjust a lumbar support. Changing the tension of the strap modifies the bulge of the support behind the seat back. In modern cars that would be achieved by an air pump.

I have come across a sheme recently but currently am unable to find it. I will  post it if I can.

     Bernd
Bernd

1976 Merc 6.9  since 2013

floyd111

Have you found all the parts (numbers) you needed till now?

raueda1

Quote from: daantjie on 26 October 2020, 09:34 PM
I'm glad to see I'm not the only impatient one on the forum haha...
Take heed from fellow member Dave's ("raueda1")  shenanigans with hydro locking a cylinder, it can easily happen if your FD is dumping a lot if fuel into the chamber.  Hilarity will not ensue :o
^^^This!!  Sounds like major progress, but Daniel's right.  Don't fall into the trap of rushing.  I didn't fully appreciate how tiny mistake that just less than 2 seconds ended up ruining my engine.  Be the tortoise, not the hare.
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

Daniel
1977 450 SEL 6.9 - Astralsilber

McNuggets

Hello again, time sure does fly! Progress has been slow and unsteady owing to work, anxiety about the cost of buying parts, and lockdown depression. So, what has happened is:

Last November I had gotten the car to turn over and start, running for fully 3-4 seconds before stalling and becoming unable to restart. This turned out to be the ignition amplifier/EZL thing on the left fender, and may have been damaged because I cranked the engine over without spark plugs during the compression test. I forgot to unplug the green trigger lead from the amplifier, and probably blew out the transistor, oopsies. My multimeter is not great but the coil and ballast resistors were close to nominal. The voltage at numerous points in the resistor network was floating at battery voltage so I felt confident the problem was related to the amplifier not closing the circuit to ground so that the ballast resistors could establish their intended voltages for the coil. I bought a used one from a running car on Ebay for ~$75 and was back in business.

The next few runs, on the order of 15-20 minutes, allowed me to start warming the engine up a little, feel hot water flowing through the upper radiator hose, and burn off the oil that leaked onto the exhaust manifolds. I am sure my neighbors were thrilled to see a big cloud of smoke wafting out of the building: https://drive.google.com/file/d/1BqwdFfhPX3ukgAUhkemxMHIYLDUQcQPB/view?usp=sharing It sounded GOOD! I don't remember the suspension coming up, but I will need to fix one thing at a time if I ever want to get there. I wasn't able to dial in the WUR as thoroughly as I wanted and didn't write down what the control pressures were, so I'll have to put that off until such time as I can run it again.

Speaking of, the next item to give up the ghost was the starter motor. It would spin, but not engage the flywheel. I got discouraged, and let it sit for a while... Eventually, I gave up on hammering it in hopes it would stop binding and decided on removing and opening it. This was tricky, but with a set of cheap harbor freight offset wrenches and valuable advice gathered from posts on here, I got it out without removing the steering linkage. The bendix drive was stuck on the armature shaft to begin with, and I certainly sealed its fate with the hammer while trying to remove it, so I've bought a new one. I also bought a set of bushings and brushes. I have pictures of this process and couldn't find a post about it on here, maybe I will make one.

My attention then turned to the ring gear, which I had seen a couple of you replace due to excessive wear. Mine is pretty much hosed in my opinion, and I am worried that there is little sense in putting my rejuvenated starter motor (indeed, any starter motor) into mesh with this grisly piece of work (attached, can't figure out how to post pics in the text...)

I suspect this wear has to do with the extremely loose ignition lock, which makes it hard to engage/disengage the starter because there's no feeling left in it. What do you think? Right now, the available space I have ends right at the garage door so if this needs to be replaced I think I would like to move house so I can get more space. That would also allow me to buy John's engine before someone on CL snaps it up  ;)

I have since been to the DMV and confirmed the car will need to pass smog here in California, both at idle and on a treadmill. My cats are welded in, so if they are bad probably I will need a new exhaust system. I have seen Timevalve recommended by forum members, does anyone know if they make 6.9 exhausts with cats? What does a new exhaust cost?

I am sure I'm forgetting a few details, it has been much too long. With summer coming I would like to get on the road!!!!

Florian