Another possibility for causing lower power: EGR is failed in the open position, feeding exhaust gasses back into the intake, so there is not enough oxygen to burn the fuel. Engine will produce smoke and have low power.

Perhaps the nozzles were already replaced at some point. Or there's some other confounding factor. Interesting.

I guess I'd inspect them at 80K and see how they tested out. But I might wait until 100K? Hard to say.

I'm looking forward to getting my cruise control working again. I guess your cruise control isn't vacuum-powered, which mine is. Also interesting.

Henry

Sluggish Performance
 

Yes, the tube and valve *must* have zero resistance when you blow through them, remove both and clean with purple de greaser cut 50/50 with tap water, be careful to not drop the two small & thin copper crush washers on the banjo bolt at the rear end of the intake manifold nor the hard to reach sheet metal screws holding the valve to the firewall .

Once this is all done, the plastic pipes to the ALDA from the valve go: top one to the ALDA, bottom one to the intake manifold, yes it makes a difference .

All done ? good ~ now with the engine fully warmed up and hot, apply vacuum to the EGR valve's nipple, the engine *must* stumble as the vacuum is applied and smooth out as the vacuum is released .

It's very common for these EGR valves to stick part way open, they're easy to clean using a tooth brush and the same purple degreaser and water mix....

Unless you have a sink in the garage be VERY CAREFUL about making sure SWMBO is gone long enough for you to do serious cleaning of the kitchen / washroom sink after you're all done, YOU HAVE BEEN WARNED.

It might be. The vaccum issues are hard to figure. Sometimes the door locking works, other times not. Sometimes the engine will turn off right away, other times not. The cruise control mostly works well, I should amend that. About once a half hour it will suddenly cut out completely. As if you just took your foot off the pedal. I've gotten in the habit of being ready to use the foot immediately, is quicker than resetting the CC, but it will reset and work again just fine until the next drop off. I can only guess it suddenly loses vacuum in those episodes.

I haven't yet mentioned that another issue is my ignition key/st. wheel lock going south. One day I had a bit of trouble with the key, didn't think to immediatly pull the cylinder, that night I suffered the dreaded paperweight/key won't turn sydrome. I was in WA state, in a parking lot, with my mother. I called her an UBER, and started looking hard at what to do. Decided to tow, AAA asked what's up, and then said their policy is to first send a locksmith. Dude did his best, no dummy, had one of those vibrator thingies. Could not get it to turn. None of it sounded good, me 750 miles from my shop. It occured to me that Home Depot was still open, I figured that to buy a batt powered Makita angle grinder to destroy the st. wheel lock would be cheaper than paying a locksmith $500 (WAG) to pull it out. And I'd still have the tool.

Saints be praised, I pulled it off. Will install new stuff soon. The punchline is, for the brief spell I've driven it since, I hooked my mighty vac up to the igntion shut down line. Oh man, that engine shuts off right now when I squeeze the handle. I've GOT to improve vacuum.

Car sounds like it needs just a detailed mainteance run. An assortment of the usual suspects. Time more than money.

Estimate a day or twos time to lubricate everything after the essential issues are dealt with. It is well worth the effort in my opinion. It also can bond the car to you. So may things return to what they were like when new.

You got caught by the magic ignition tumbler. Any sensation of it becoming an issue at all. Members should replace it right away. They are too well known to cause real grief otherwise.

On you car it's done by a servo motor that's right next to the power steering pump. And cutting out is a sign of cruise ecu going bad (bad caps and cold solder joints I have a diy link if you want)



On a W123 with OM617a an engine driven vacuum pump does:
1. engine shutoff
2. brakes
3. central locking (no separate electric pump like in a w126)
4. automatic transmission shifting (VCV simulates vacuum so it's like in a gas engine)
5. egr
6. climate control pods


so as you see there is a huge potential for leaks


If you test your vacuum pump by itself it should be making minimum 15 inches of vacuum


I would start by testing other systems with a mityvac

Holy crap I was kicking myself hard. I knew that a dead tumbers were a big problem. I just didn't think it would happen that fast. I had my Makita 18 volt screwgun with me - two batts. So buying the grinder w/o batts wasn't too steep. I've been around tools long enough to know that grind/cutting (those .048 thick carborundum wheels) works a lot better on hardened steel that drill bits, hacksaw, etc. Trying to drill out the tumblers struck me as way tough. Would need a good corded drill and parhaps diamond bits. One bad move and you scar up your dash. Grinding from underneath wasn't easy, a couple of times I thought I was at a dead end but it worked.

Great info, thanks. I really want to get on top of the vacuum issues, I just needed to get to greater priorities.

What you say about the CC makes sense. The vacuum is too inconsistent to operate the CC as well as it works. I would like that DIY link. Won't get to it for a while. If it went completely south I'd proably get to it quicker. :)

diagnostics:

https://sites.google.com/site/mbcruisecontrolrepair/home/diagnostics/1982-1995-electric-servo-cruise-control-diagnostics

repair of a cruise amp (half way through the first post is your model):

http://www.peachparts.com/shopforum/tech-help/313824-how-cruise-control-amp-repair-14-pin.html

same guy can also do it for you. his new website:

Cruise Control Repair

Vacuum "Fun" ~
 

(it's never fun)

However, it's do - able, I spent some time to - day diagnosing the leaky HVAC in my '82 240D, before I started I bought some 3.5MM silicone vacuum hose from Pelican Parts and replaced most of the short straight bits I touched .

It turned out to be the trunk lock actuator so I disconnected it and plugged the yellow plastic pipes and the door locks all work fine gain, I'll place an order for the actuator, supposedly it's in stock now .

Do the little basics first and you're car will run and work better making you happier as you go along peaking and tweaking it......

Here are mine. Your description of cupped, concave nozzles caught my eye. Mine don't seem to have any of that, but these are the first MB injectors I've seen. What do you think?

https://i.postimg.cc/Rh02j1Sx/IMG-3401-2.jpg

https://i.postimg.cc/zG95KQJb/IMG-3402-2.jpg

https://i.postimg.cc/d19YMtGr/IMG-3403-2.jpg

It’s really hard to tell by looking. They look normal but you need to pop them if you really want to check them. I thought your Vietnamese mechanic “checked” them already? Checked should mean popping them on a tester and looking at the spray pattern.

Ive read over your posts and you haven’t mentioned checking out your fuel tank strainer and your two fuel filters. Sorry if I missed it. If you haven’t you need to check and replace filters. This is a must when acquiring one of these diesels without a maintenance history. Top end power issues scream fuel filters to me.

I got my 300d with low power. It was really neglected. It was different though, it was weak off the line but had good top end power. I did all the basics boost line, valves, fuel filters, timing, rack damper adjustment, linkage adjustment, cleaned sticky turbo, removed clogged trap oxidizer. It seemed everything gave it some power back. Now it is a pleasure to drive and drives normally.

Then after all that, I tested my injectors. They were perfect and I put them right back.

Mine were definitely worse looking. It's kinda hard to see from the lighting. My fingernail would easily get stuck on the lip of the cupping. Now that you have them out, pop-test them. If only you were in Atlanta, I'd lend you my pop tester.

-Henry

He did test them, I called him, he said he has a machine for it, his English is fairly good but he doesn't use some of the terms that others use. When I told him I was thinking about getting them tested he said to bring them in as long as I have them out, he'll show me. Will do that in the next couple of days.

Oh man, rust. I was having huge trouble with the primary filter clogging up in short order. I was taking them out almost every day to clean them with WD-40. Probably other ways to do it. I bought about 4 or 5 before I realized I could clean them out. I also replaced the secondary filter.

I finally took the tank out and cleaned it. Used purple degreaser, acid, pea gravel. I think I did it about 95% effective, if I did it over I might have done a few things better but it was a huge improvement. I put in another new secondary filter. I had a thread about maybe putting in a new tank. Here's the post after I pulled it.

I've done a few other things as well. New oil cooler lines. THAT was a tough job. One of the existing was leaking, not a small leak. My Mechanic, Ky, spotted a badly worn fan clutch, put in a new one. If you're ever in a bind in the Bay Area: Ky's Auto Repair, Redwood City, south of SF, north of Palo Alto.

Thanks! Nah, Atlanta's a bit far. :D

I hitchhiked through Georgia in Dec. '73. Camped out at a rest stop. Maybe the starriest night I ever saw.

I'll take them to my buddy, pretty sure that's the sort of device he has. Will get a kick out of seeing it. He wants to keep me happy. If I ever get rich and famous I'm going to have him put in new seals on my SDL tranny. He wants to do it. Says he can stop all the leaks. Might do it myself someday. Whoa, big job.

Do not waste the opportunity to inspect the glow plugs heating up with the injectors out. The tips should get really hot visually. If they do I would not put in a new set. As you would have no ideal on most acquisitions of the time they have been in service. They could have been replaced not that many miles ago for example. Also have a look for possible carbon buildup in the pre chambers. Many of the aquisitions have not seen highway service for years.

Of note was one poster on this thread mentioned that every thing he did seemed to make some difference. I have advocated going through the fuel system at least partially on any new acquisition for years. How extensive depends on your 0-60 times for the version you have.

At a minumim enough to reduce the chances of an issue while away from home. It is usually very cheap to do yourself. All my versions of 123s are on the faster side of most other similar ones I have driven. Especially the 240ds.

I have another bone to examine as well. I expect these engines to light off as soon as they start to turn over. If they do not something is not right. In reasonable temperatures of course. If they will not do this they are going to be harder to start in cold weather if you need that ability.

A road breakdown can be expected to become ever more expensive to deal with. Every year. Many mechanics have no working experience on these engines. Plus there are other factors that can impact the situation. You want to reduce the probability as much as you can yourself. Doing it all cost less than all the components of just one road breakdown. When far from home.

We are also driving cars that a wait for parts of even just a secondary filter or belt can take time. Mind things like your lift pump is bad. To me it is simply preventative maintenance on antique vehicles.

Our 77 N/A 300d even is not too bad for what it is. The 84 300d has passing ability like a gas car. Or at least feels that way to me. It does so well in that area I am almost positive that the whole system must be functioning like new. I call it just making certain that all components of the system are working well. Not a true restoration .Expected Zero to sixty times are well documented in the archives on each version.

I love going up to Berkeley and seeing all the diesel Benzes driving around. I used to live across from Fat Apples...uhm 30 years ago.

Good luck with the search. I was amazed at getting my 300d back to making power. It wasn’t any one thing that was robbing power. It was half a dozen things each eating a few HP and once I went through it all it finally ran properly.

Putting a boost gauge (just a T, some hose and a cheap air gauge) on my ALDL line gave me an idea just how much boost I was getting. I had a lot of goo on the inlet side of my turbo.

Is that something that needs attention?

Speaking of goo, I pulled the ALDA line from the manifold, that was on advice from this one:

Oh man, not sure I'd call it soot, but it was black and residue like, that's certain.

https://i.postimg.cc/FR2bR5dD/IMG-3404.jpg

I got the right size drill bit (loose fit) and cleaned the junk out of the long skinny part, then used WD-40 and brake cleaner to clean the rest and the line as well. Blew compressed air through it. Good thing I found that. My fix of the other broken line probably wouldn't have gone so good.

One thing I wonder about is the little relay hub where the lines converge. Tonight, to take off the manifold banjo bolt I took the hub/junction off the firewall as I couldn't see where that hose hooked in. I noticed an electric line coming off of it. I'm curious just what goes on in that little hub thingy.

Overboost Protection Valve
 

That's the one we've been telling you to clean out, it must not have any resistance to being blown through .

Get the proper de greaser, not brake clean and drill bits .

that's overboost protection valve.


if it gets continuity through the pressure sensor on the intake manifold it then vents this line to atmosphere therefore limiting fuel by not sending pressure to ALDA

I used mostly WD-40 as that tiny nozzle was good for getting into the plastic line as well as the end of the part in the photo I'm guessing the two pieces together are the banjo bolt. I got into it pretty good. I had clean solvent coming off it at the end. The brake cleaner was a brief thing to finish.

I blew compressed air through the various pieces to remove any WD-40 residue before hitting it with the brake cleaner. It's good.

It's near rocket science to me at this point. It sure seems like an electric line leading from it. Not sure what that's doing.

Overboost Protection Valve
 

It's open until it gets an electric signal fro a pressure switch on the intake manifold, then it opens and dumps the boost pressure to atmosphere, why it's important to properly connect the plastic lines .

This is the first time I've had injectors off of one of these motors. Looked like a fair amount of carbon buildup down in there but what do I know.

Even though it's low miles, pretty sure it was mostly city miles. So just as many startups as a car with say 400k and lot of highway miles. I've already ordered the glow plugs, a little over $60. If I'm going to take them out and ream them (have a reamer on the way) I may as well put new ones in. Would be interesting to test them though.

On my departed 300SD, a buddy of mine with two 123 617s back then, about 12 years ago, told me that I could take the cap off the ALDA and turn it, I forget which direction, to get more power. He clamed it was adjusted to a conservative position for emissions control or something. So, MB gods forgive me, I did it and did seem to get more power. I've since read of course of the danger in doing that. Not planning to do it now, at least not without knowing more.

Over Boosting
 

Yes, just so .

A -little- bit more boost is, for me, a good thing .

Others remove the overboost protection and crank the boost up to 20" then complain about crappy German cars when the engine begins to smoke and rattle....

The adjuster on the ALDA is very sensitive ~ a 1/16 turn is a lot .

You are learning fast. So your self confidence will rise. This could evolve into quite a long interesting thread for many.

I get great personal satisfaction for bringing things back to what they were. So many of these cars need a real dose of it. I also found over the years that wives in general do not seem to mind us doing it.

I also think it is mentally healthful for the individual in most situations. This I suspect has something to do with the sense of accomplishment.

Thanks. I've been wrenching on various cars for a long time and it's sort of amazing how little I know. I'm pretty good on brakes.

To the present, never a dull moment. I got my shipment from Pelican today and the glow plug heat shields have a larger hole than the ones that came out:

https://i.postimg.cc/ZnwCHGZm/IMG-3410.jpg

Slightly different OD as well. The new ones:

.797; .394 (ID)

The old ones:

.811; .282

Both are .106 thick.

The Trouble With Learning :
 

Is that you mostly discover how little you actually know...... :rolleyes: .

The good part is : as you learn and grasp how it all works you can share the knowledge freely and learn ever more....

Nothing quite beats the feeling of a good running machine you fixed with your own two hands .

I know that one pretty well. My first E30 was my favorite car ever, at least up til that time. Not as fast as some of the Bimmers, but plenty fast enough and just a great feel. I got 450k out of that one, got it at 214K. Helped that the PO was a Bimmer fanatic , took it to an expensive indie garage every 6 months. Good God, the new parts in that car. I had service records a quarter inch thick. I welded 4 CATs into it, put in new intake manifold gaskets (biatch of a job), added E36 injectors (noticeable power boost), new clutch and driveline (heaviest tranny I ever pulled, even compared to trucks), new rear bearings, rear tranny bushing, control arms, 3 racks, too much to go into. Would have been nutty to pay someone for all that work.

I just makes no economic sense to farm out a lot of work on older cars. Todays costs of doing so outweighs buying a much better car to start with. Of the same type.

Since I do not repair cars for a living. I find most jobs both relaxing and enjoyable. You do have to have enough tools though.. I never had any issue with buying tools .

Usually the first job you did with them basically paid for them in comparison to farming the work out. You normally keep them for your lifetime after and seldom wear them out. As you are not using them continually.

I realize they can be expensive retail today. Yet there are other sources as well. In the early spring I go to a few yard sales. Usually I already own most the tools being sold. Yet there are places that have various tools that I find useful for almost nothing on the dollar.

Especially tools that I may use very seldom. So cannot reasonably justify buying them at retail. Various supplies or consumables also frequently appear. Prices are frequently negotiable as people want the items gone.

Those heat shields don't look interchangible.

Good Tools
 

Yes, having the proper tools that are configured as you like them is critical, too many modern 'mechanics' these days are just parts changers with little concept of how things work or the bigger picture .

I was in a huge junkyar yesterday, they used to always have multiple W123 & W126's. nary a one yesterday but, they did have a table covered with old tools from the junkers, some were good quality, I found an American made Milton brand tire gauge that works, sweet .

I took my mechanic buddy Ky up on his offer to show me the injector test, vid below. He said he thought those shields would work. The larger hole models are close to 1/64" less in OD. All of the shields for sale at Pelican look to be that type. Not getting any luck on a web search regarding the difference. I dropped one of the old ones behind the pump, haven't looked for it yet, I understand it can be tough to find stuff there. I've read of guys reusing them, using a ball bearing and socket to flex them slightly. I think that was for these. Not sure how to do that.

At the end he put in a bad one to test, I was watching pretty close to make sure mine were a distinct bundle. Little bit hard to see the squirt.

https://www.youtube.com/watch?v=7uLxleMFcUc

Second vid is of the 350SD he's selling, the nicer of the two he has. He said he might as $9K for it. If I win the lottery... Might be fun.

https://www.youtube.com/watch?v=PyKfTc8fnF0

He has a couple of 617s he's saving to put into something, also a 616 attached to a 4 speed.

I have a soft spot for a 325iX. Capable snow machine

Hate the forward opening hood though.

This test is good enough. if your injectors pass then you don't need rebuilding.

Pop Testing Injectors
 

Wow, he's fast .

? What pressure did they all pop at ? .

Looked pretty low to me .

Didn't ask about that.

Never drove one of those. I heard mixed reports - extra weight and complexity. If I lived in a snowy region would be much different.

The hood got old in a hurry. First time I swapped the timing belt I took the hood off. And then, whoa, getting it back on is a PITA. I eventually had to rig up a way to hang it down from my garage door opening. I got to where I could do it with the hood in place but not fun.

The MBZ extra wide hood opening is like the polar opposite.

Injector Pop Testing
 

The pop off pressure is critical ~ so important in fact that I have the injectors in my 240D done by greazzer because he does them all to within 5 # of each other and this makes for a smooth running engine .

The good fine mist spray pattern is nice and important but smoking is caused more by low pop off pressure, I learned this from a fellow who use to be here who didn't ken the fine mist aspect of fuel injectors but had a nifty home brew rig that he used to set the injectors on my first 300CD (NA) to perfect pop off , he also used dental tools to ream the injector nozzles so they sprayed like tiny fire hoses, yet the car didn't smoke and started easily in 40 degree weather on 1/2 crank .

DO NOT DO THIS ! you need the fine mist spray pattern .

This is a delicate thing, your engine and fuel injection system ~ take the injectors to any Heavy Duty Diesel hp and they'll pop test them correctly and give you the exact pop off pressures .

So, too much ALDA boost can ruin an engine?

Put it all back together. Reamed the glow plug chambers, got quite a bit of carbon out, maybe not as much as Kent spoke of on some that he had done. As I still had the injectors out I used compressed air to blow it out, taking care to keep the cover over the pump well in place.

OMG, it runs a lot better. Huge difference. The turbo works now. I can't swear though that it's as perky as my departed '81 300SD. My mechanic thinks that the 300SD had a slightly better motor setup all in all. Seems unlikely somehow, I mean the engines are identical aren't they?

As luck would have it, we're in a cold spell now. 65 during daylight, 37 last night when I fired it up. Hadn't run in a few weeks and it started right up, this after bleeding the lines. It was about this temp during one of my lengthy difficult start experiences up in WA state in Dec.

Numerous smaller tasks ahead. The tach and clock don't work, the rear windows do a snap-snap noise at the end of close, got to adjust something, I did it once, I forget. One of the hood hinges is in bad shape, the hood open cable needs help. Most important I still need to get on top of the vacuum issues.

where I live in winter my 300SE can get dicey (single tire fire at stoplights, wheelspin at 30 mph etc...) and 325ix system is simpler than w124 4matic for example.



engine shutoff, transmission vacuum lines:


https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Engine/617/07_1-150.pdf


central locking:


https://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Chassis/80-900.pdf

Boost & ALDA
 

Boost and the ALDA are two different yet intertwined things ~ the turbocharger provides the boost pressure and the ALDA senses how much boost and applies more fuel to make use of that boost pressure .

You get more power, the engine gets *much* hotter and everything gets more wear .

Many heavy duty or Hot Rodded Diesels have Pyrometers (exhaust temperature gauges) to measure the cylinder heat so you don't melt the piston crowns....

I'm sure this doesn't answer your overall question, the smart thing is to give it a little bit more boost and if necessary (usually it's not) tweak the ALDA a 1/16th turn counter clockwise to richen it up .

Most of the time upping the boost from the factory 12 # or more often measured 8 ~ 10 # to 14 or 15 makes it run so much stronger there's no need to touch the ALDA .

More than 16 # boost is going to shorten the engine's life span no matter what any Diesel Nutter (oops, "Enthusiast" tells you .