Restoration of 6.9 #496

[McNuggets]

Hello everyone,

I'm a mechanical engineer from New York, recently moved to California. I've been enamored with Mercedes cars for as long as I can remember, and have many pleasant memories of riding around on the rear bench of my father's 350SL, and of learning to drive in the mighty 560SEL. A few weeks ago I bought my first project car, naturally choosing a 6.9 as a good starting place for the beginner . The details (and photos) in the listing were pretty sketchy, but from what I have seen on the car and the documentation that came with it, this was an early Euro spec model imported through Houston in 1986 as a grey market car. It was driven by an electrical engineer here in the SF bay area until 2002 when the seller bought it from a scrap yard. He failed to get it running, and after purchasing a new engine and transmission (??), he..... let it sit, for 18 years, until I bought it. I haven't registered it with the DMV yet (and am now far removed from the ten day window in which I was supposed to, oops) so I cannot get the data card from the classic center yet, but I am very interested in obtaining it. The title lists the model year as 1900, the import documentation lists 1976 and 1977, and the data plate near the radiator bears the leading digit "5." If it is a 1975 model, having proof will come in handy as the car would otherwise need to pass smog in California, which means I would need to restore the aftermarket closed-loop lambda control system retrofitted by the importer, to working condition.

The car is in pretty rough shape overall. The interior is totally dried out and crackles painfully when disturbed, the paint is sunblasted and there is some rust over the driver's door where a vinyl top once trapped rainwater, and there is forklift damage to the side skirts, floor pans, and trunk pan, but I believe the car was originally totalled by a failure in the fuel distributor. My thinking is based on the following facts:
1.) The airflow meter plate moves freely and does not feel like it is touching the control plunger at all.
2.) The car came with the fuel tank in the back seat, having been replaced by a red jerry can in the trunk.
3.) Removal of the valve covers brought forth the hideous stench of old gas.
4.) The engine, I was told by the seller, would turn over with the starter but not stay running.
Based on this I was pretty sure previous owner had flooded it while trying to fix something fuel related, and my attention turned to determining whether it had any bent rods, having recently finished a reading of Raueda1's horror story of an experience with a maladjusted fuel distributor last summer. What I have done so far is this:
0.) Bought missing 6.9 emblem on ebay as a good luck charm.
1.) Borescope inspection of cylinders via spark plug hole revealed the pistons were generally dirty and looked as though the engine had been running very rich, although some had VERY clean areas where fuel had pooled, dissolved these deposits, and evaporated.
2.) I sprayed PB blaster into the cylinders, and blew them out with compressed air to be sure there was no solid debris lurking
3.) I turned the engine over with a breaker bar and 50mm socket at the crank pulley, for two laps of the timing chain and found no problems
4.) I tuned the engine over with a new battery, and measured compression. The workshop manual says to do this with a warm engine but that's not really an option for me. Overall, readings looked good. In Bar and in order 1-8 they measured 10.5, 11.5, 10, 11.5, 11.5, 9.5, 10, 10. Cylinder 6 is a bit low, but the gauge I used was rented from O'Reilly's and was coming unscrewed all the time. Minimum spec is 8.5 Bar, and all cylinders should be within 1.5 Bar of each other. The camshafts are mostly clean, and the oiler tubes are at least dribbling oil onto each lobe (I replaced the oil, but did not bleed air out as the manual suggests, as the engine does not run yet). I feel good enough about this result to proceed, which brings me to today.

What do I do now, w116.org? I am planning to remove the retrofitted lambda control system until I can get the car running. I've ordered a rebuild kit for the FD as well as the WUR, and plan to get these components working on the bench before shelling out for new injectors and trying to start the engine for real. There is a lot to do, and I've already written a wall of text in this post. I plan to update this thread as I make progress over the next few months or years. I look forward to writing back and forth to you all, and to learn as much as I can about these cars, as we appreciate an excellent series of top-class autobahn cruisers together!

- Nuggies

[john erbe]

Good luck with project. Im up here in Vallejo. May be able to help out with some extra parts Ive got laying around. PM me if interested.

[daantjie]

Welcome to the house of fun   Indeed here you will find a lot of help, if not a place to come and cry in your beer every now and then

Yes KJET needs super clean fuel to be happy, so the fact that there has been some shenanigans in the fuel system by the previous owner apparently is not a good sign.  If the car sat for a long time and the guy/gal tried to start it with a gunked up fuel system then you will need to clean it out properly.  Sounds like you are on this path already, so, carry on

Fresh oil is a must yes, also the fact that you are getting oil to the top end with cranking bodes well too.  The bottom end of these engines is hella stout, so a bent rod is unlikely I would say, but of course not impossible as Dave (raueda1) found out...

You can also run a quart of ATF in a full tank of gas as a detergent, many folks do this routinely to keep the fuel system happy.

You will likely need to overhaul the shock mounted fuel delivery package at the back of the car too.  All those parts are still readily available and cheap (ish).  Change all the hoses too, this is an area ripe for a Car - B - Q

Cheers and good luck!  Also post some pics of this bad boy

[rumb]

Welcome,  Your tale sounds familiar probably not too different than mine, including the forklift damages.   Sounds like you are on the right track getting the fuel system cleaned out and rebuilt first.

What is the VIN, you can then calculate the year of mfg.  MB of that vintage were often titled the year first sold. The datacard will have the actual birth date on it. Edit: 496 was the 22nd car built in 1976.

Post photos! including the lamba system as I have not ever seen an aftermarket one on a 6.9.  Most often they have EGR system added for EPA.

Check out Federal emissions exemptions. Here in Colo that then allowed state exemption. 

https://www.epa.gov/sites/production/files/2020-07/documents/form3520-1-2020-07-secured-enabled.pdf

Code E, vehicle older than 21 years old will original equipment. (you would want to remove all mods to meet this.)

[raueda1]

Welcome, welcome, sounds like you got a fun little project going!  Sitting 18 years isn't kind to the car and ensures that things are stuck with varnish, gum, sediment, etc etc.  You can safely assume that things are stuck, blocked, etc.

For sure, renew all the rubber bits on the tank and rear fuel module.  Absolutely essential.  I'd take out the tank, replace the tank sieve and clean that out too while things are disconnected.  Otherwise you'll have fuel delivery gremlins forever.  You might as well just replace the injectors too.  They aren't very expensive and new ones will just remove another source of problems.  As for FD and WUR, sounds like you know you'll need a pressure gauge kit.  I wouldn't even bother trying to start the car till they're rebuilt and you're confident that the pressures are right.  Get a primary pressure regulator rebuild kit too.  It will include the teeny washers for setting primary pressure among other things.  PM me if you're doing the FD rebuild yourself, I have some useful info on that.  Finally, inspect all the rubber air and vacuum hoses and fittings carefully.  If they're stiff just replace.  Vacuum leaks wil cause all kinds of undiagnosable problems and drive you crazy.

The old M100 board has an excellent Bosch K-jet diagnosis manual.  It's super, super helpful.  It would be great to add to the tech docs list here but I don't know how and it's too big to email.  Anyway, if you can get your hands on that it goes through all the steps of getting the fuel system working right.

Good luck!  Take your time and enjoy it.  We'll enjoy hearing about it as much as you enjoy doing it, so keep posting.  Cheers,

[daantjie]

Another topic you need to address would be coolant of course.  I would also just go ahead and change the thermostat as well.

Do not try and drain the block via the drain plugs at this point.  Just drain the radiator, expansion tank and the hoses as much as you can.  Then fill with Zerex G-05 Coolant (Valvoline) diluted 50/50 with distilled water.  The 6.9 water pump needs to be a babied  as much as you can and coolant changes are cheap insurance, they are pricey and hard to change out, so preventative maintenance is key.

Cheers

[raueda1]

Another topic you need to address would be coolant of course.  I would also just go ahead and change the thermostat as well.

Do not try and drain the block via the drain plugs at this point.  Just drain the radiator, expansion tank and the hoses as much as you can.  Then fill with Zerex G-05 Coolant (Valvoline) diluted 50/50 with distilled water.  The 6.9 water pump needs to be a babied  as much as you can and coolant changes are cheap insurance, they are pricey and hard to change out, so preventative maintenance is key.

Cheers

Yeah, great point.  FWIW, I had my radiator flushed/boiled out.  The shop did a flow test and said that it was about 30% blocked by deposits!  I wasn't having overheating problems but it runs cooler now and the system holds the temp much better.

[Jed]

Pictures Please!

Inside and out!

[Randys01]

Welcome to Looney Tunes.
...at last you will be pitting all your engineering skills against the dark forces..........lol!!
...........good luck......make sure you exhaust the Tech info/search function to bring yourself up to speed.

You will find different folk on this site have different "sweet spot" knowledge.  Between the lot of us,  we could get a Renault 750 sorted?!!

[McNuggets]

I wrote out a longer summary of the car's status but one of the photos I attached was too small, and the page deleted what I had written Anyway, some of you had asked for pictures of the car and right now what photos I have are in a jumbled heap in google drive, in apple's silly .HEIC format. I've attached a few small photos to this post, and will try to get hold of a small digital camera for the future.

While waiting for FD and WUR rebuild kits to arrive, I removed them from the car, along with the 8 injector lines and the airflow meter. I set about looking at some of the vacuum connections on top of the engine, and decided I should replace or cap off as many as possible until I have a running engine. To that end, I've ordered 8 new injectors, 8 injector seals, the two U-shaped rubber hoses at the idle air control valve, the rubber seal between the airflow meter and throttle body, and the vacuum tubes between the WUR, ignition distributor, and intake manifold. I would like to remove the intake manifold entirely as it would allow me to clean the intake manifold, plenum, throttle body, and the inside of the vee, but doing so would mean needing to replace the eight rubber seals between the underside of the intake manifold and the plenum. For the 117 engines, genuine MB parts are available for about $8 each. EPC shows a different part number for the M100, 100-140-04-65, which I've found only in one or two places and which costs $70 each. Has anyone tried fitting the M117 seals to the M100? The photos look identical, but I cannot be sure of the diameter and I cannot compare a M117 seal to what's on the car without committing to this, or spending $70 on a single rubber seal. There's also the question of the intake manifold gaskets: can these be reused? I've found a complete set of NOS asbestos gaskets for 50 Euro, but I'd rather leave it all alone if the rubber parts are not known to leak air commonly, and if I need to spend hours scraping asbestos gaskets to do the job.

There's also a rubber Y hose that leads from the idle air control valve to the two cylinder banks. On the 4.5, I think this is P/N 116-090-01-82 but on the 6.9 the shape and orientation is slightly different. I can't find it in EPC, and the P/N molded into it (100-090-00-82?) brings up nothing in internet search. Does anyone know where this hose can be found? Mine is rock-hard and I want to replace it.

In one of the below pictures (I hope), you can see a piece of yellow plastic at the right of the FD. This is an extra fuel injector, which dumps fuel from the WUR control pressure port into the FD return port, allowing an ECU (which I've still not been able to find) to fine-tune the control pressure similarly to KE-Jet. There's also a Purolator brand charcoal canister haphazardly hose-clamped in place, which I want to replace with the boxy OEM style canister, if it will fit.

[raueda1]

Moving along!  Plenty to comment on.  But first, a point of clarity - is this a Euro car that was federalized more-or-less when imported?  If so I'd just get rid of all the USA smog stuff, whatever it is, and return to unmodified euro status.  Are there state regs preventing you from doing so?  This will make life a lot simpler.  Anyway, see bold insertions.

I wrote out a longer summary of the car's status but one of the photos I attached was too small, and the page deleted what I had written Anyway, some of you had asked for pictures of the car and right now what photos I have are in a jumbled heap in google drive, in apple's silly .HEIC format. I've attached a few small photos to this post, and will try to get hold of a small digital camera for the future.  Yes!  Pics are so helpful!

While waiting for FD and WUR rebuild kits to arrive,
PM or email me on FD rebuild.  The kit instructions (if any) are entirely inadequate.  Also, it's still far in the future, but you'll need to pick up a fuel pressure gauge kit if you don't have that already.

I removed them from the car, along with the 8 injector lines and the airflow meter. I set about looking at some of the vacuum connections on top of the engine, and decided I should replace or cap off as many as possible until I have a running engine.
This plays to the smog question.  All the vacuum connections do something - if they're capped off you won't have a running engine, or at least not a properly running engine.  Sooner or later they'll all need to be right.

To that end, I've ordered 8 new injectors, 8 injector seals, the two U-shaped rubber hoses at the idle air control valve, the rubber seal between the airflow meter and throttle body, and the vacuum tubes between the WUR, ignition distributor, and intake manifold. I would like to remove the intake manifold entirely as it would allow me to clean the intake manifold, plenum, throttle body, and the inside of the vee, but doing so would mean needing to replace the eight rubber seals between the underside of the intake manifold and the plenum. For the 117 engines, genuine MB parts are available for about $8 each. EPC shows a different part number for the M100, 100-140-04-65, which I've found only in one or two places and which costs $70 each. Has anyone tried fitting the M117 seals to the M100? The photos look identical, but I cannot be sure of the diameter and I cannot compare a M117 seal to what's on the car without committing to this, or spending $70 on a single rubber seal.
I tried and can confirm that they are not the same.  The M100 seals are indeed bigger.  But to my surprise mine weren't bad.  Yours may be OK too.  If you take it apart you'll be able to easily see how well they seal.  It's not at all impossible that they'll be OK.

There's also the question of the intake manifold gaskets: can these be reused? I've found a complete set of NOS asbestos gaskets for 50 Euro, but I'd rather leave it all alone if the rubber parts are not known to leak air commonly, and if I need to spend hours scraping asbestos gaskets to do the job.
I doubt that they can be reused, but maybe somebody else knows better.  Mine came off perfectly clean, not like the usual head gasket mess.  But....  The Classic Center has (or had) left and right gasket kits that are pretty reasonable.  They include head gasket, intake manifold gasket, valve cover gasket and other odds and ends (can't recall exactly what).  Email them, very very worthwhile.

There's also a rubber Y hose that leads from the idle air control valve to the two cylinder banks. On the 4.5, I think this is P/N 116-090-01-82 but on the 6.9 the shape and orientation is slightly different. I can't find it in EPC, and the P/N molded into it (100-090-00-82?) brings up nothing in internet search. Does anyone know where this hose can be found? Mine is rock-hard and I want to replace it.
Can't help with this at the moment. 

In one of the below pictures (I hope), you can see a piece of yellow plastic at the right of the FD. This is an extra fuel injector, which dumps fuel from the WUR control pressure port into the FD return port, allowing an ECU (which I've still not been able to find) to fine-tune the control pressure similarly to KE-Jet. There's also a Purolator brand charcoal canister haphazardly hose-clamped in place, which I want to replace with the boxy OEM style canister, if it will fit.
I've never seen that yellow thing before.  For sure, it's absolutely not something on a stock Euro engine.  Nor is there any kind of ECU whatsoever, at least on euro engines.  I'd dump all that stuff and return to stock.  Also, USA heads have a couple vacuum fittings, not sure where they go.  The euro heads don't have any such fittings and the casting has plugs instead.  It might be helpful to confirm that you've got euro heads.  Maybe others can comment further.

BTW, you seem to be digging into the whole thing here, which is certainly the right way IMO.  Out of laziness I kind of learned that the hard way.  Doing it piecemeal you can go nuts chasing issues.   Cheers,

[raueda1]

Another thought just occurred to me.  Should you decide to take off the intake manifold, there are a couple bolts that are close to or connected to the cooling passages.  Apparently these often freeze, as mine did, and so naturally the head shears off.  Now you've got a loose manifold that's impossible to remove cause there's still 10mm of bolt shaft sticking into the manifold preventing it from being lifted off.  Drilling it out is pretty ugly.  Lesson:  psychologically prepare yourself and be ready to deal with it if it happens.

[Alec300SD]

EPC shows a different part number for the M100, 100-140-04-65, which I've found only in one or two places and which costs $70 each. Has anyone tried fitting the M117 seals to the M100? The photos look identical, but I cannot be sure of the diameter and I cannot compare a M117 seal to what's on the car without committing to this, or spending $70 on a single rubber seal.

Lst price is $70, but you save a bit at online MB dealership parts webstores.
I've used mboemparts.com, shipping is reduced with promo code BENZWORLD2017.
https://www.mboemparts.com/oem-parts/mercedes-benz-connector-intake-manifold-1001400465

There's also a rubber Y hose that leads from the idle air control valve to the two cylinder banks. On the 4.5, I think this is P/N 116-090-01-82 but on the 6.9 the shape and orientation is slightly different. I can't find it in EPC, and the P/N molded into it (100-090-00-82?) brings up nothing in internet search. Does anyone know where this hose can be found? Mine is rock-hard and I want to replace it.

Adding the letter A can help in  parts searches.
A 100 090 00 82 shows up on the Russian EPC  as PANTS (between item 258 and item 265) but has been replaced by two parts: A 100 090 01 82
• +001 A 100 094 04 41.

Unfortunately, A 100 090 01 82 is a discontinued part as well.
A 100 094 04 41 has been superceeded by part number A 116 094 07 41.
A 116 094 07 41 is stlll available.

MB does remaufacture NLA parts if there is adequate demand:
http://www.peachparts.com/shopforum/4067363-post34.html

[PosedgeClk]

Another thought just occurred to me.  Should you decide to take off the intake manifold, there are a couple bolts that are close to or connected to the cooling passages.  Apparently these often freeze, as mine did, and so naturally the head shears off.  Now you've got a loose manifold that's impossible to remove cause there's still 10mm of bolt shaft sticking into the manifold preventing it from being lifted off.  Drilling it out is pretty ugly.  Lesson:  psychologically prepare yourself and be ready to deal with it if it happens.

Kroil and a torch go a long way.

[daantjie]

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