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Restoration of 6.9 #496

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

daantjie

Ugh ja that ring gear is toasty :o  big job to replace.  On the 6.9 you have to pull the engine and trans which in itself is no walk in the park.  Best to bang out other jobbies while it's out.  Bon chance ;)
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Quote from: daantjie on 27 March 2021, 08:57 PM
Ugh ja that ring gear is toasty :o  big job to replace.  On the 6.9 you have to pull the engine and trans which in itself is no walk in the park.  Best to bang out other jobbies while it's out.  Bon chance ;)
Yes, spot on.  Prepare yourself for some soul searching on how much work you want to do when engine is out.  It's such a great opportunity to do jobs you'd probably never consider otherwise! 

Anyway, if you do pull the engine make sure that your engine hoist is HUGE.  It's not just a question of weight.  The boom needs to surprisingly long or you'll eventually get stuck.  Also get a good, heavy duty leveling arm.  The cheap ones with small threads (such as Harbor Freight) will wear out surprisingly fast.  With the right equipment pulling the engine really isn't as bad as you'd expect, though it is laborious.  With undersized or cheap-o equipment there's a very high risk of something very bad happening.  Don't ask me how it know this.   ::)
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

McNuggets

Some updates since last time: I moved across town to a house with 2 driveways, into one of which I had my car towed. I didn't touch it for a few months, but recently have started working toward engine removal. I took off a lot of the easy stuff plus the ac compressor, which was tricky. I got it out without removing the RH engine mount like they do in the book, but their way is probably easiest with how little room you get otherwise. I bought some flare nut wrenches because I was worried about rounding AC and oil/hydraulic line connections with the adjustables, but can tell I will soon also be buying extensions, swivel joints, impact sockets, crows foot wrenches, etc as I suspect they would really ease working on this engine.

I haven't decided what I will do while the engine is out besides the ring gear but there's no shortage of good candidates ;D There is a long list of work that I would be silly not to do with this opportunity. Looking at the age and condition of the parts on this car is making me anxious, and the closer I look the more I want to replace. I am realizing the best would be to just set about replacing all the usual suspects in the suspension, driveline, and brakes before trying to drive it despite how slowly I am moving. I think I am in for a long and expensive period of working on smaller assemblies before I can really see the big picture but I am ok with that because it should make for a great feeling car, albeit not a looker.

To this end I am considering buying an air compressor for blasting, sanding, painting, pressure testing, tools, etc. Does anyone have a setup like this?

Nuggies

Flogrates

Air compressors are so handy, just make sure you get a big enough one

rumb

For sandblasting and painting you would really want @17 cfm compressor.  Yes thats big but you need that much air flow to do the job.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

McNuggets

I got the engine out today! I had forgotten the three sump oil hoses and the engine dampers. Lifting it out was not difficult, just go slow and try not to damage anything. I had the crane off to the passenger side slightly, which meant the exhaust manifold rubbed against the strut tower on that side, but it's not like I damaged a concours paintjob... Based on Dave's prior work in these threads: https://forum.w116.org/mechanicals/oil-sump-hose-specs/ https://forum.w116.org/mechanicals/6-9-oil-tank-hoses-and-related-issues/ I decided to cut through my hoses with a hacksaw rather than try to disconnect them with no blowtorch and the engine still in the car. I also cut the oil line from the engine to the oil pressure gauge in the instrument cluster (the fitting would not unscrew without also twisting the hardline to which it is affixed at the rear of the engine, no room for counterhold), and the diagnostic sensor on the crankshaft, which I thought was a vacuum line but does enclose two (severed) wires. Next time I do this I will remove the crank pulley beforehand. I didn't this time, and my AC condenser has flattened fins from the pulley and various hoses I did not tie out of the way.

The only real hiccup was the load-leveler I used to pitch the engine up/down. This is the ubiquitous harbor freight 2 ton model. Even with liberal and repeated application of graphite lube, the screw stripped while I was trying to pitch the engine down so that the transmission would clear the radiator support. I am lucky it only froze in place instead of letting the engine slide down the rest of the screw. They used a regular machine screw thread instead of an acme thread, which sprinkled its shavings onto my air metering plate, eek! I have got the engine+trans on a wooden crib for now, while I plan my next move.

FP

daantjie

Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

Quote from: McNuggets on 19 September 2021, 10:09 PM
I got the engine out today! I had forgotten the three sump oil hoses and the engine dampers. Lifting it out was not difficult, just go slow and try not to damage anything. I had the crane off to the passenger side slightly, which meant the exhaust manifold rubbed against the strut tower on that side, but it's not like I damaged a concours paintjob... Based on Dave's prior work in these threads: https://forum.w116.org/mechanicals/oil-sump-hose-specs/ https://forum.w116.org/mechanicals/6-9-oil-tank-hoses-and-related-issues/ I decided to cut through my hoses with a hacksaw rather than try to disconnect them with no blowtorch and the engine still in the car. I also cut the oil line from the engine to the oil pressure gauge in the instrument cluster (the fitting would not unscrew without also twisting the hardline to which it is affixed at the rear of the engine, no room for counterhold), and the diagnostic sensor on the crankshaft, which I thought was a vacuum line but does enclose two (severed) wires. Next time I do this I will remove the crank pulley beforehand. I didn't this time, and my AC condenser has flattened fins from the pulley and various hoses I did not tie out of the way.

The only real hiccup was the load-leveler I used to pitch the engine up/down. This is the ubiquitous harbor freight 2 ton model. Even with liberal and repeated application of graphite lube, the screw stripped while I was trying to pitch the engine down so that the transmission would clear the radiator support. I am lucky it only froze in place instead of letting the engine slide down the rest of the screw. They used a regular machine screw thread instead of an acme thread, which sprinkled its shavings onto my air metering plate, eek! I have got the engine+trans on a wooden crib for now, while I plan my next move.

FP
Nice work!  Good move cutting the oil pressure tube instead of trying to remove the fitting, inevitably breaking it and finding a replacement (don't ask how I know this).  Anyway, I used that same damn load leveler.  Anticipation of stripping the threads made me a nervous wreck.  Happily mine survived long enough for me to complete the job, then I threw it away.   My conclusion:  avoid Harbor Freight for mission-critical equipment. Keep us informed on progress!  It's more fun reading about somebody else doing it than doing it yourself!  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

rumb

Yes, those engines are big and heavy! It's quite satisfying to see the engine out of the car.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

daantjie

Quote from: rumb on 22 September 2021, 04:21 PM
Yes, those engines are big and heavy!

I recall a number of 750 lbs for the motor alone, indeed "lightweight baby!" as Ronny Coleman would say:

https://www.youtube.com/watch?v=aRz0QZc8TDE

Daniel
1977 450 SEL 6.9 - Astralsilber

McNuggets

Oh look at that, it's been another six months! I have at most three months left on my current premises for doing serious work on my car and will try to rush to have it driveable by the end of the summer. I am not sure yet where I will live next, and cannot seem get out of the habit of moving every year or so. In the meantime, I have been buying tools like it's going out of style. I have fixed up an air compressor (new belt, head gaskets, cleaned valve plate, new start+run caps, cleaned motor internals, adjusted centrifugal switch, pressure tested tank) which should be capable of about 12scfm. Its bores are pretty smooth and it looks like it had been run in a very dusty environment, but a cylinder hone costs as much as I paid for the thing... I will leave it alone for now. I've also now got a sandblasting cabinet, a filter/regulator, some hoses, and some air tools courtesy of craigslist, friends, harbor freight, and mcmaster-carr. I scored an unused parts washer from a guy who was restoring an MG but have not bought solvent for it yet.

I have also bought an old BMW motorcycle, which needed some attention too. This is my first bike and so far I absolutely love it. It looks a bit ratty because the last guy started chopping it to make a cafe racer but mechanically it is sound. I relined the gas tank, rebuilt the carburetors, fixed some electrical mistakes, changed all fluids, and registered it. Compared to the car, it is a primitive machine.

The current thing with the car: while trying to degrease the engine+trans I decided to just start taking parts off and labelling them. I think the way forward is to clean/blast/replace everything I can in the engine and suspension, then worry about the cosmetic stuff later. I need to get in the habit of spending time and money _regularly_ on this project soon, or the dream may die!

While trying to undo the inbus screws on the intake manifold, I broke the two foremost bolts as many of you warned me I would. If memory serves, this happens because they are close to the coolant passage and corrode in place. After rounding out the hex recess, I neatly drilled the bolt and tried an extractor. This sheared the head clean off on the passenger side. On the driver's side, I broke the tap socket I was using. I ordered a solid single-piece tap socket, which rounded out as it wasn't hardened. What the hell do I do now? My roommate suggested tapping the hole and using a left-hand threaded screw to try backing the bolts out. My propane torch can't be tipped over far enough to heat the head of the bolt without flaming out, as the liquid sloshes into the burner, so heating it is not an option for now.

I don't post often, but I do enjoy reading nearly everything that gets discussed on this website, how fun it is. Looking forward to a hopefully busy summer!

daantjie

https://m.youtube.com/watch?v=YqFLoq567zk

I quite like this guy  mostly he is into US muscle cars but he has tons of good info gleaned from many years of experience.
Daniel
1977 450 SEL 6.9 - Astralsilber

McNuggets

My bi-annual post is late! The car and engine sat more or less untouched all year from September '21 until September '22. I have tried waiting but the parts remain just as disassembled until I actually do something. Maybe I should try calling the car Christine for better results. I don't have a place to host images and for whatever reason the forum will let me upload images but still not attach them inline. I want them to last as long as the posts, so to the bottom they go. I have more photos and may post them in a trickle over the next few weeks.

In May, my friend and I removed the suspension leaving only the steering gear, torsion bars, and leveling valves in place. We started at the front of the car, separating the upper control arm from the body by removing the 19mm hex bolt and nut from inside the engine bay.

The brake hoses were simply cut since they will be replaced with new ones. The pad wear sensor cable passes through a protective metal tube. I couldn't figure out how to pull the cable back through the tube since the connector is too large, so instead I disconnected the tube from the brake dust shield and left it hanging there. Was this cable terminated after being passed through the tube or am I missing something?

Disconnecting the UCA from the sway bar is done by removing the 24mm bolt that threads into the end of the sway bar, and can only be done once the clamping screws on the sway bar have been backed off. We also separated the tie rod from the knuckle. At this point you can swing the knuckle out (pic 1) and get the ball joint press on the lower ball joint ("supporting joint" in the manual). I used a two-arm one since this joint is tough to remove from the LCA. Tighten the screw until you find yourself squinting, and then tap the screw with a hammer to pop the tapered stud of the ball joint out of the bore in the LCA (pic 2). I didn't catch what size the nut is for the ball joint and don't know if I saved it since the new ball joints from Lemförder come with a nut. I removed the upper ball joint ("guide joint") from the knuckle with the knuckle on the bench since I found that easier.

Removing the front strut was next, two 13mm hex bolts that secure the ball joint to the LCA and three sets of 10mm screws and nuts which hold the strut's top mount into its perch on the body. My top mounts are totally dried out. These are NLA everywhere I checked but I was able to find a supplier in Germany offering a rebuild service, provided your core is rebuildable: https://roland-merz-katalog.de/ersatzteile-mercedes-32-federn-und-aufhaengung Has anyone bought from Roland Merz before? They also offer the bumpstop for the front struts, which I need too. Definitely buy a selection of flare nut wrenches for working on this car, since you will very likely round the fittings on the hydraulic hoses if you do not.

Removing the lower control arms from the car was a bit trickier as the bolts had begun rusting together with the inner sleeves of the bushings. I bought an air hammer, which was a great help in pushing the long 24mm eccentric bolts out. Unscrew the 24mm nut first, and the nut only! I bent one of my eccentric bolts by trying to unscrew it with a pneumatic impact wrench which made it a bear to get out. I don't know how I would have done this with the engine in place. The front subframe tube is very easy to remove, two more 24mm bolts and nuts and it falls right out.

We then moved to the rear of the car. Lots to undo here: cut the service brake hoses, disconnect the parking brake cables, undo the flex disc at the differential input and push the prop shaft forward, separate the sway bar from the rest of the suspension linkage, and release the rear struts from the trailing arms. Now you can start on removal of the rear end. The manual dictates to remove the complete rear axle assembly with diff, trailing arms, etc all still together using a special jack attachment. I found that most of the weight of this assembly is about inline with the rear axle. If the limit stops on the subframe and trailing arms are still intact, you can support the diff with a jack and lower everything to the ground without it falling off, using your hand (or a friend's) to keep the forward  "tips" of the subframe level. This takes only light pressure and prevents the cv axles from excessive misalignment, very convenient. Careful not to damage the brake dust shields like I did... We first loosened the two 17mm screws which hold the small metal brackets between the subframe bushings and body to the body, then the large 24mm screw which passes through the center of the bushing into the body. On one side this was easy. On the other, the bolt had seized to the bushing so tightly that the rubber had to be sheared away by applying LOTS of torque. The bolt came out with the bushing sleeve and metal bracket permanently attached. Get the jack in position, undo the four 13mm screws which hold the rubberized diff mount to the frame floor, and lower away (pics 3, 4, 5)

With the jackstands where we placed them, we were now stuck. It was decided to remove the diff first since it is quite heavy and the cv axles were preventing removal of the complete assembly from beneath the car. Undo the axle bolt at each wheel (I have the later style 13mm head bolt with washer and spacer, yours might be different) and push the axle out of the hub. To get some more room, slide the diff off the jack onto a pile of cardboard. Next, do the four 19mm nuts and washers atop the subframe. Lift the subframe off of the four studs on the diff and pull the cardboard with the diff on it out from under car. Gawk at filthy diff (pic 6). There was now plenty of room to remove the trailing arms from the subframe (two pairs 24mm hex bolts and nuts) and drag all out laterally from beneath the car (pic 7, 8). Remove the rear HPF struts by undoing the hydraulic lines, and at the top by undoing the nuts from inside the trunk (if your fuel tank is already out, like mine) or from inside the car by removing the rear seat backrest. A period of 6 months' hibernation followed....

McNuggets

Planning a move to house #3 in November provided some motivation: I thought if I hurry I may be able to at least reassemble the suspension so the car can be towed to its third and final resting place. Wishful thinking but at least I've now got the ball rolling if not the car itself.

Anyway, I started stripping the control arms intent on replacing every moving part in the suspension. The front upper ball joint came out using the smaller lever-style ball joint press easily. Remember to put something between the press and the stud of the ball joint if you need to reuse the joint. My new upper control arms came with ball joints so this was not important.

On to the lower control arms: the three-piece bearing assembly cannot be pushed through from one side. The manual (33-530) states ominously "The remover and installer required for repairing the lower control arm consists of 12 parts." I took a tip from another forum member and sawed off the forward thrust bearing, which allows you to beat the rest of the parts out with a hammer (pics 9, 10). These are bonafide plain bearings and would allow the arm to rotate without any spring force returning them to ride height. The rear bushings consist of a central steel tube, a layer of rubber, and 2-piece outer steel sleeve. The rubber was perished and the outer sleeve corroded in place. Trying to push the bushing out by the tube sheared the rubber, leaving it and the outer sleeve stuck in the control arm. I used a punch against the flange of the sleeve and separated it from the control arm. The two clamshell halves of the sleeve came out easily this way (pics 11, 12). I pressed the bushings out of the front subframe too, this was pretty easy.

Next were the front spindles. First I removed the brake calipers and steering knuckles. Early cars have wheel bearings pressed on to the spindles, luckily not mine. Pop off the grease cap, undo the locking screw, and back off the spindle nut (pic 13). Slide the hub and bearings off the spindle, leaving it bare. You can then easily remove the brake dust shield with three 5mm allen screws leaving the bare spindle (pic 14). The inner roller bearing cage and grease seal come out easily by hand.

With the hub off, it is very easy to remove the brake rotor, five 10mm allen screws with loctite. The hub should now only contain both outer bearing races, which are difficult to remove even with a suitable mandrel. I bought a large brass rod to use as a punch (McMaster 89225K52) which worked nicely. Large diameter (minimum 1"/25mm) is critical here, as the bearing race only protrudes a tiny bit from the inside of the hub. Use a soft metal to avoid marring the bearing seats. I also bought a 3/4" punch (3483A22) for other jobs, but couldn't get the bearing races out with it. I don't have any photos of the front, but the rear is similar and I did take pictures of that for illustration (pic 15). The first few taps are the hardest part, once the race begins to move out better purchase becomes available. It helps to pull the punch toward you as you strike it, to prevent it jumping off the race.

The last thing I did on the front was to pound out the lower ball joints. Googling around for advice, I saw a redneck method of burying the spindle upside down in the dirt to stabilize it and hopefully prevent it from bending. I was able to get both lower ball joints out without heat in a few minutes (pic 16). If I am lucky, I will be able to harvest two new growth spindles next spring!

McNuggets

The rear was more challenging. I took apart the parking brake cable and mechanism but there are no pictures and it's all an angry foul-mouthed blur in my memory. I have since bought the two special tools needed for attaching and removing the springs inside, namely, Hazet 4964-1 for the return spring and Hazet 2730 for the hold-down springs. Starting with the trailing arm (pic 17), I removed the brake caliper,  popped off the grease cap for the wheel carrier spindle off (there is a special tool but it is not necessary, use a large open end wrench and work your way around) and loosened the 24mm nut which holds the carrier spindle into the bearings in the trailing arm (pic 18). I also removed the two 13mm screws which hold the bearing cap for the starting torque compensation shackle to the caliper carrier. After that, just slide the trailing arm off.

With the wheel carrier assembly on the bench, I removed the inner snap ring and dust shield for the caliper carrier bearing (pic 19), then used a puller to remove the caliper carrier from the wheel carrier (pic 20). The 50mm socket you need for the crank pulley nut on the 6.9 works nicely for this purpose and it helps to use the brake disc as a stand of sorts. Note that the bearing is destroyed in doing this! You are pulling the inner race off the wheel carrier via the outer race of the bearing, bad news for the bearing. Once the caliper carrier is off, remove the outer snap ring (pic 21) and tap the bearing out with a punch (pic 22). The only marking on the bearing I could find is 361952 A, it is Mercedes part number 001 981 82 25. This part was like $400 at the time so I ordered a generic part number that I found on another forum, 3816-B-2RS-TVH. Now it is available through Mercedes for about $45. it's a sealed double-row ball bearing, just so that the caliper carrier can rotate a few degrees. I've never driven a car with this sort of anti-squat starting torque compensation, hopefully it works well for all the trouble the designers went to!

Next was removing the rear wheel bearing nut. This requires a special axle bearing groove nut socket, which has aftermarket options available. Part numbers I found during my search:

Mercedes 115 589 02 07 00
Mercedes 915 589 02 07 00
KLANN KL-0301
Baum Tools 915-0207
Sir Tools M0027
MMMM 4M-007

I Paid about $120 for mine (Baum), afterwards found them as cheap as $70. Good luck without one. The nut is deformed into two slots on the hub, and must be punched back out before loosening. Ensure the socket is fully inserted and flush with the nut. It takes a lot of torque to remove the nut and there are only four little tabs to apply it. That said, I used the impact wrench for this and the tool held up just fine (pic 23). I am not looking forward to re-torquing this joint. This will allow you to remove the hub from the wheel carrier (pic 24) and remove the bearing outer races with the trusty brass rod as shown earlier.