W126 Benz Oil Spec and Other Questions

[Citroënbender]

Time and WD-40 prevailed; as I slammed the door in disgust at 3PM today the arm suddenly dislodged. That’s 21 hours under massive tension. I think it would have been dangerous to attempt out of the chassis as you could then only get the preload with an impact and they aren’t generally best friends with puller threads.

I set the steering centre position with my modified stop bolt, it showed up the lash in the input side - whether it’s wear in the worm, the ball guides, insufficient preload - whatever, it was disappointing. Similarly, setting the output shaft preload was a bit futile because the torque was highest about 60° either side of centre, then fell away as centre was approached.

Pitman arm is back on for keeps (I hope!) and I took the contentious step of applying a little Würth CU-800 to the shaft splines. If nothing else it will help keep moisture out.

Drained PAS fluid looked suspiciously like Dexron, and smelled like it. I’m going to see if D-II or D-III are widely accepted as suitable.

In chasing suspension fluid over the counter, I tried EAI first - no dice - but they suggested Silver Star Spares. Can’t seem to avoid dealing with them! Tomorrow I’m chasing a few copper washers that are needed for accumulator replacement, and prepping the coolant transfer pipe for re-painting after rain spoiled its topcoat last time. At this rate, oil change may happen Sunday…

Also a snippet of shop humour, my occasional colleague wondered aloud who made the ETC bulbs as they never blow - would nail the headlight globe market if they tried. And we discussed whether Würth might sell “ABS & Airbag Tape” being a thin matte black tape one applied to cover a persistent fault light for the purpose of passing registration.

[Citroënbender]

Not impressed right now; got a no-start condition, not even catching on ether spray. As I crank, it almost catches but won’t fire. It’s like a weak spark - are the coils or ignition drivers known to be iffy? Have made no adjustments to engine operation other than screwing the white-beige plastic headed idle air screw (not mixture screw) into the stop then back out to count turns - it’s about 1.6 turns out.

Can’t believe how much dirt is still on the motor, even during reassembling the bits I moved to clean, I’ve repeatedly got black hands.

[Citroënbender]

Cleaned the plugs, off he went. Now to give it an Italian tune-up tonight!

[Citroënbender]

Next road test completed, I added a bottle of fuel system cleaner at owner’s request and topped off the tank ($100!)…

Steering is slightly improved, it helps subconsciously to now have the wheel level. Haven’t done the spheres yet, I think that will assist further. Can hear what sounds like diff noise, a bit of lash in the rear as well. 1-2 up shift on light/medium throttle is inclined to harshness or thumping.

Car would not hold itself at speed up a steepish hill - fell steadily from 60 down to about 40. Either the bores are stuffed (lack of compression) or something else is quite out of whack. Hot idle remains too high (~1200 in P/N). Although the broken part of throttle linkage was replaced, it still feels stiff, unnaturally so.

Either the temperature gauge is unreliable, the thermostat stuck or missing, or the viscous fan locked on - indicated temperature approached a steady state and remained there. Cabin heat controls work OK. The dash lighting rheostat seems to do nothing. After an hour of driving at speeds ranging from 40 to 90, no odd smells from the motor, no apparent fluid leaks - so this much is definitely a positive.

[Franco Cozzo]

German Star in Reservoir here in Melbourne are a large Mercedes wrecker and also new parts distributor.

https://german-star.com.au/

They've got a workshop attached to their wrecking yard as well as a parts operation, could be worth a call if you need some hard to find stuff for that nightmare

With your lack of mumbo up hill, what's the fuel pressure like? Can you get a gauge on it? Usually with fuel pressure issues you'll get an intermittent dying in the *** that only occurs with load or heavy right foot.

It'll start, idle, drive around town fine but die in the *** up a decent hill or if you decide to do traffic light grand prix and coincide with fuel pressure dropping.

[Citroënbender]

I’ll check all the dumb stuff first; bear in mind the car has been serviced by specialists so nothing odd is out of the question. It’s also forty years old and has an EGR on thermo-vacuum control; got to be a possibility the intake tract is loaded with gritty, filthy accretions.

What would be nice is a free opinion (drive test) of someone who knows these systems well and can just say after a minute or three “Yep, definitely your <insert component>”. It didn’t feel like loss of fuelling when it struggled, there was no pinging. I’ve been really reluctant to poke at the system while so many fringe items are in the mix. Once suspension and steering are sorted is probably when I’ll feel brave enough.

[Citroënbender]

A couple of WIP cleaning photos, dirty is August 19th and clean September 18th:

Starting to think the radiator has wrong cap fitted, as it has no signs of a leak in the cooling system but doesn’t pressurise. Perhaps a recovery type cap was used in error.

[Citroënbender]

Look ma, no kickdown. How could a Mercedes “specialist” send this out the door?

Discovered as I worked my way through the throttle linkage joints, all were dry/sticky to some extent. I removed the dead grease with brake cleaner or paint stripper depending on the location, reassembled with red Nulon grease (the one with PTFE in it). The throttle plate is binding, this needs further resolution and means the injection assembly will have to come off. Really didn’t want to do that.

[Citroënbender]

Accelerator pedal sorted, it had to be carefully re-bent in the vice but now aligns correctly with the pedal base and kickdown switch. Discovered the plastic pedal is actually broken, it’s supposed to be a single unit comprised of the “head” which attaches to the metal pedal structure, and the floor-fixed flat pedal element. It realigned well enough that it may work as separate elements. Action is really nice right to the final link.

I’m confused by the idle air controller. Which way does the airflow go - from the chamber under the fuel distribution head to somewhere back of the plenum, or the other way?

Found a broken vacuum line connector at the throttle body, decent size. And the throttle plate was binding because the stop screw was backed out past any usefulness and its lock nut loose.

Is the throttle supposed to be set to “almost lightproof closed” when cold, or a gauged clearance? All bar one very tiny vacuum port are above the plate. (All ports were checked for blockage and cleared where necessary.)

The plenum is pretty grimy, I think the EGR (inlet hole, centre of picture) is no longer working but it has done its crusty thing all right.

[Citroënbender]

More progress. Tonight I changed the rear spheres (accumulators as Mercedes call them). They were definitely dead, a good cupful of hydraulic oil trickled passively from each when unscrewed - if there was pressure behind the diaphragm, they’d either spray oil out when the unions were cracked enough - like the famous Citroën “douche verte” or give up barely a tablespoon of fluid if the system had returned to zero stored pressure.

Now I can feel every tired joint and bushing in the car, better, without the distraction of its rear end bouncing everywhere.

Quite a bit of lash in the diff, it’s noisy too. Also remarkably small for such a large car. One side seal is leaking, I wondered if the oil is mostly migrated out through there.

The other fluid giving issues at present is my choice of “whatever I had nearby” (that being Dex 3) in the power steering. It’s groaning!

[Citroënbender]

Some “OCD clean pr0n”.

…I can’t find a reliable number for torquing the nuts and centre bolts. Read 15 foot-pounds but that sounds way OTT. 15 inch-pounds maybe?

Not sure if this is of any use to you mate ?


https://www.woodsandbarclay.com/downloads

[Citroënbender]

Cheers, it’s the 300TD though, I don’t know how similar the motor is to borrow specs from it.

[GasoLane]

Have you got a VIN CB?

[Citroënbender]

Naturellement.

WOB12602222060823

[GasoLane]

Originally Posted by Citroënbender

Naturellement.

WOB12602222060823

Umm, possibly WDB?

[Citroënbender]

I’d say you’re right. Had used text scanning to capture it from a photo.

[Citroënbender]

…I’m waiting for the revelation something like where you tell me to double it, subtract five, divide by two, eat a square of chocolate, add one and then I’m back to the original VIN?

[GasoLane]

Originally Posted by Citroënbender

…I’m waiting for the revelation something like where you tell me to double it, subtract five, divide by two, eat a square of chocolate, add one and then I’m back to the original VIN?

Nooo, just trying to work my way through the WSM.

Still looking for Valve cover stuff but you could be right with your earlier number of 15ft/lbs going by these sump ones

[Citroënbender]

It’s still running pig-rich and got a miss.

Think a compression test is in order, and wondering if the last garage’s “adjust idle” was playing with the mixture (not air) screw.

[Franco Cozzo]

Originally Posted by Citroënbender

Some “OCD clean pr0n”.

image

…I can’t find a reliable number for torquing the nuts and centre bolts. Read 15 foot-pounds but that sounds way OTT. 15 inch-pounds maybe?

Tighten to FT

****en tight

Also how are you getting things that clean?

[Citroënbender]

Originally Posted by Franco Cozzo

Also how are you getting things that clean?

It’s spent 40 years coated in oil, remove the oil and it’s like new.

1. Solvent degreaser, agitated with bristle brush and hot rinsed
2. After drying and cooling, methylene chloride, agitated with brush, hot rinsed
3. Kenco degreaser solution, toothbrush/nail brush, liberal rinse (not allowing solution to dry on part)

I hate oil leaks, they’re unsociable to motorcyclists and damage the wishbone bushes in FWD transverse powered cars. Keeping the driveline clean is my way of identifying new leaks and their origin.

That's the spirit, you can lick the underside of my Merc and it's a diesel... well if that's ya thing i guess

[Citroënbender]

Hopefully the last big spend for now on this car, nearly AUD$750 with post from Pelican. Note they charge GST but it’s not shown (applied) until the last stages of checkout.

The best (chirpiest, can-do) “vibe” of all the parts providers has come from FCP Euro, but the most sincere replies from Pelican. RockAuto are more scripted; for the size of their business you’d expect it.

My interesting find for the week has been “aavpart.com” - looks like a sensibly priced option for DIY-ing the air valve rebuild. Before this discovery, I’d been thinking about adapting a universal heater tap with a choke cable. Second most interesting find was “Mechanics’ Tool Hire”. This may help sort the front lower ball joints more economically.

[Citroënbender]

Window escapades, only one goes up/down. Fortunately, the driver’s window. The other doors are debatably “hinged glass” in their fixed window state and therefore roadworthy for NSW. I dismantled a rear door in my aim of improvement.

Discovery 1: They’re apparently W123 door shells to the rear. Not sure if because it’s a fairly early W126 or just how they did it.

Discovery 2: The vacuum actuator for locking has had its shaft welded. I have no idea why, it’s not like this is a hard to find part or easily damaged.

Discovery 3: Window motors have a thermal cutout in them which fatigues with age, eventually not making contact.

Discovery 4: Broken slide clip on the regulator arm; it’s been replaced before and I think the pivot rivet peened too hard.

I’m going to bridge the dead thermal cutouts and replace with external Narva or Bussmann blade type 20A units soldered directly by the legs. Slide clips for the regulator arms are fortunately easy to get and not dear. Thinking I’ll re-grease the reduction drive as my sample was dried to a hard waxy consistency.

[Citroënbender]

Gives every impression of being snotted by a coarse hand, was probably cracked in the action of peening.

The regulator arm is ridiculously stiff, too - more Ancient Grease. Considering how I might loosen it up enduringly; thinking kerosene to start it moving, then trying to wick in some 90W.

Shame it’s not one of these, they come to bits much more comprehensively.

[Citroënbender]

A month later, near-stagnation. Too many things on the go, even for my frenetic interests.

Have nicknamed the car “Bunnings” because it’s a big green shed.

Today I made a wooden (thick ply) fixture to hold the regulator gearboxes level while drilling out their lid peening in the drill press. Thought I had a 3,5mm bit to prepare for tapping; alas not. The peening is being replaced by 8-32X1/2” UNC button head capscrews in stainless, as their pitch is marginally coarser than 4mm. I considered this desirable, given the gear case softness.

Also bought a tub of SuperPro silicone grease for $84, figuring it was a cheaper alternative to “Gleitpast” for the window sliders.

[Citroënbender]

Door check straps, not the greatest design for mounting in a fairly lightweight door shell. One could not be revived with fresh grease and repeated working, so a replacement was ordered.

To reduce the conspicuity of a new part, I painted the tongue of it per the originals in Thistle Green. Scuffed with a grey pad, then 2K wet-on-wet primer, basecoat and 2K clear. Fast hardener will slightly reduce the clear gloss as it catalyses. Although not shown, both sides were painted.

[Citroënbender]

Yummy, yummy. Dead chewy sweets in the nearside rear ashtray.

Discovered the puddle light housings are pretty much all cracked, looks like a common fault as they are sold in sets of four, new and genuine. A better “find” was the driver’s door internals being apparently faultless. I realise the regulator grease is probably dry and sticky but it’s the lesser of two evils to not disturb.

[Citroënbender]

This shoddy repair is shaping up to be a real pain.

The part which is supposed to be fixed rigidly to the door hinge post, is completely loose; it’s steadily stress-cracking its way through the sheetmetal. The rivets may have once done something but at present they are simply ornamental.

To investigate/repair I need to remove the handbrake, kick panel and cut away part of the insulation. To plug weld either the original stiffener or a stronger part onto the pillar, the door will need to be un-pinned. It really isn’t the greatest design.