Author Topic: Restoration of 6.9 #496  (Read 834 times)

raueda1

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Re: Restoration of 6.9 #496
« Reply #15 on: 24 August 2020, 07:28 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:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

john erbe

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Re: Restoration of 6.9 #496
« Reply #16 on: 24 August 2020, 03:28 PM »
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

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Re: Restoration of 6.9 #496
« Reply #17 on: 24 August 2020, 08:17 PM »
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

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Re: Restoration of 6.9 #496
« Reply #18 on: 25 August 2020, 10:21 AM »

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

raueda1

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Re: Restoration of 6.9 #496
« Reply #19 on: 25 August 2020, 11:59 AM »

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:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Jed

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Re: Restoration of 6.9 #496
« Reply #20 on: 25 August 2020, 03:39 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!?
1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

raueda1

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Re: Restoration of 6.9 #496
« Reply #21 on: 25 August 2020, 05:48 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:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

slfan

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Re: Restoration of 6.9 #496
« Reply #22 on: 26 August 2020, 02:18 AM »

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

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Re: Restoration of 6.9 #496
« Reply #23 on: 26 October 2020, 07:17 PM »
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

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Re: Restoration of 6.9 #496
« Reply #24 on: 26 October 2020, 07:34 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
Daniel
1977 450 SEL 6.9 - Astralsilber

BCK1963

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Re: Restoration of 6.9 #496
« Reply #25 on: 27 October 2020, 12:05 AM »
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

floyd111

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Re: Restoration of 6.9 #496
« Reply #26 on: 27 October 2020, 05:40 AM »
Have you found all the parts (numbers) you needed till now?

raueda1

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Re: Restoration of 6.9 #496
« Reply #27 on: 27 October 2020, 04:39 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:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0