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post #111 of 174 (permalink) Old 01-06-2018, 04:14 AM
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@codycool55 and @Strassenkreuzer :

I suggest to first check the camshaft … before worrying about the details of changing it. There are quite a few more details worth considering than the ones mentioned in this thread so far.

And don‘t worry about the "“non-shiny" yellow edges“ mentioned in post 110 ! … They‘re very normal and there's nothing wrong with them. On the cams they are areas the rocker arms never had contact with, and on the journals they are areas the bearings never had contact with.

And again, don‘t rashly follow suggestions to change the valve guides ! … (see what I said about them in posts 75, 100 and 109)

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post #112 of 174 (permalink) Old 01-07-2018, 05:47 PM
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Originally Posted by H.D. View Post
That‘s the right expression … ‘potentially‘ worn camshaft and rocker arm(s). The part beside the camshaft is one of the rocker arms (not a lifter).
So, before you try to find suitable replacement parts at junkyards, I recommend both of you to first check the installed camshaft.
Yes. When time permits, I'm going to remove the valve cover and see if I can get a good look at the camshaft—with emphasis on cylinder #1's lobes. Is there anything that can be done to make the oil dripper more effective? It's my understanding that this is the weakness that causes the premature wear on these lobes.


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There may be no need to do the valves or the valve guides, even with 200,000 miles or more on the clock. What should be done though, especially if it has never been done before, is the valve stem seals. (See also what I said in post 100)
I hope you're right. My concern is that with burning a quart or so of oil every several hundred miles, the engine suffers carbon build up from burning tiny amounts of oil that have leaked through the stem seals. This is why I regularly add either of LiquidMoly or Seafoam or Lucas upper engine fuel treatment. I guess my question is: How do you determine that valves need replacement without dismantling the entire upper part of the engine? Seems a bit of a catch-22 in that if you're going to the trouble of replacing the camshaft and rocker arms, wouldn't you do a valve inspection then—instead of buttoning everything up to see if the replaced camshaft and rocker arms along with stem seals solves the problem?


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Might be failing lifters. In that case I suggest to replace them when you replace the valve stem seals. They‘re not very expensive either. If you don‘t buy them at the MB dealership, I recommend the ones made by “INA“.
So just what is a "failing lifter"? If they're hydraulic, I can understand that perhaps the mechanism is worn and needs replacing because there are oil and springs involved. If they're not hydraulic, then how does a lifter wear out? And if one replaces one lifter, shouldn't I replace all twelve?


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You too? …

Thanks for the compliment about my 300CE … my wife, who actually doesn’t care so much about cars, kept me from selling it about 10 years ago … she loves cruising around with it.

That picture of the engine bay, btw, also shows something that you usually don‘t see there (the grey plastic cap below the arrow. It‘s part of an on-board CIS-E test device … something those who plan to keep their CIS-E cars for the longer term might want to consider. This link leads to more details about it:
https://www.benzworld.org/forums/w126...st-device.html
I'd love to own a fleet of 126s; I love these cars. Today a friend sent a pic of a 1991 420SEL for sale—with a mere 61,000 original miles on the clock, and I'd love to have it for the $14,500 they're asking. BUT...my 300 SE is more nostalgic, and I love the color. I budget permits, I'm going to have her painted this year. And the M103 is more economical than the 4.2L V-8 of that era. Essentially, the shorty 300SE is an easier 126 to maintain even if it lacks a few of the bells and whistles. And the '91 I found is black—which, while beautiful, is a bit too "limousine-esque" for me; I'd feel too self-conscious driving it. Nevertheless, one of these days I'll have my 300SE's valve cover repainted and get the entire engine bay properly cleaned and detailed.
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post #113 of 174 (permalink) Old 01-08-2018, 10:05 AM
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Originally Posted by Strassenkreuzer View Post
... with emphasis on cylinder #1's lobes. Is there anything that can be done to make the oil dripper more effective? It's my understanding that this is the weakness that causes the premature wear on these lobes. ...
There is something that can be done to keep it from becoming less effective … make sure that it doesn‘t get clogged by old dirty engine oil !

This is a perfect opportunity to caution against the seemingly logic idea of enlarging the oil dripper holes. That affects the oil pressure and can severely reduce the oil flow through the bearings (crankshaft, connecting rods, camshaft, rocker arms). … Baaaad idea !!

The main cause for the premature wear is actually a quality problem with the inductively hardened surface of the lobes … or more precisely, with the hardening process in the camshaft production line. With a little luck your camshaft is still okay, even with 200,000 miles or more on the clock … if you‘re less fortunate you have worn lobes (even with very frequent oil changes).

A quick answer to the question why the intake cam lobes are usually hit hardest is: they are hit harder … LOL … has to do with the camshaft‘s direction of rotation.

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Originally Posted by Strassenkreuzer View Post
... How do you determine that valves need replacement without dismantling the entire upper part of the engine? ...
When I replace valve stem seals I grab the valve shaft with my fingers … with the piston of the respective cyclinder sitting high enough to prevent the valve from falling so deep that the valve stem completely disappears into the valve guide … and feel how it sits in the guide. And I visually check the part of the valve stem that moves in and out of the guide during operation. … Then I compare these impressions with the intended future of the engine/car. … If you have never done that, I suggest to have it done by an experienced and trustable mechanic.

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Originally Posted by Strassenkreuzer View Post
... So just what is a "failing lifter"? If they're hydraulic, I can understand that perhaps the mechanism is worn and needs replacing because there are oil and springs involved. If they're not hydraulic, then how does a lifter wear out? And if one replaces one lifter, shouldn't I replace all twelve? ...
They work hydraulically and they fail hydraulically if their mechanism wears. If you hear a suspicious ticking sound coming from the valve train area (when the engine is cold) I suggest to replace all 12 lifters when you replace the valve stem seals.

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post #114 of 174 (permalink) Old 01-09-2018, 07:00 AM
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I found problems on my m103 after removing the valve cover to replace the gasket seal . On removal I saw lots of old black paint that had come from in side the valve cover .This is the remainder of the spray paint from new .The spray job is done on a jig and if the spray gun is set to low you get lots of over spray get inside the valve cover . This over time will find its way down into the cam shaft and rockers immersed in the oil .So if your in the stage of replacing the valve cover gasket seal , do a good job removing the old paint bubbles inside the valve cover .Clean out both holes in the valve cover for the breathers ,these holes alone can if not kept open cause problems in the breathing system . Paint a thick oil on the inside of the valve cover .Replace the valve cover with a new gasket seal from mb without sealant bolts set to 10nm .Hope this helps .
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post #115 of 174 (permalink) Old 01-11-2018, 09:41 AM
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ADMINS, any way to get "MB Engine Forums"? Too much good info spread across at least two forums as it is.

H.D., As I have only been introduced to your posts today, and have only had the time to read a few, I wonder if you have spent much time on the bottom end. My M103 and the one I bought at the junkyard both had enough bottom end wear to cause my oil consumption, which can slowly foul the O2 sensor leading to problems x,y,z..... With your systematic approach, I wonder where you place the bottom end in your list of things to check.

All, H.D. mentions checking the play of the AFM in an earlier post. The focus seemed to go to adjusting the height of the plate and its exact position in the aluminum body, but I didn't see enough stress placed on making sure the plunger in the middle of the FD was NOT depressed while the motor idles. Here is what I posted to the peachparts forum back in 2011 as an update to the head and CIS-E rebuild:

"My rich idle was the result of the fuel distributor’s plunger extending too far down onto the roller on the flapper. Adjusting the position of the roller with the 3 mm CO screw did not work for me. I could get the idle mixture correct but then something else went wrong: bad throttle response, hard restarts, surging idle, high RPM idle, etc. The rich idle could have been the result of the flapper spring fatiguing over time as well. Who knows? Bottom line, adjusting the plunger (moving it up into the distributor) about half a turn allowed the other parts of the fuel system to work as designed."
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post #116 of 174 (permalink) Old 01-11-2018, 02:53 PM
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... H.D., ... I wonder if you have spent much time on the bottom end.
From ‘83 to ‘84 I spent 8 hours a day on almost nothing but the M103‘s bottom & top end … LOL

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Originally Posted by KJZ78701 View Post
... My M103 and the one I bought at the junkyard both had enough bottom end wear to cause my oil consumption, which can slowly foul the O2 sensor leading to problems x,y,z..... With your systematic approach, I wonder where you place the bottom end in your list of things to check. ...
Oil consumption can, of course, foul the o2 sensor … (see what I said in post 30).
According to my experiences with the M103 (after it came off the production line ) oil consumption is much more often caused by hardened valve stem seals than by bottom end wear. Since they can relatively easily be replaced (with the head installed) I suggest to replace the valve stem seals first … certainly if they have never been replaced.

As for oil loss, the M103 is equipped with something that here in Germany is often called “Sollsiffstelle“ (“predetermined drooling point“) … LOL … It‘s often wrongly diagnosed as “head gasket failure“, but it‘s only a failure of the much easier to fix upper front cover sealing.

Quote:
Originally Posted by KJZ78701 View Post
... All, H.D. mentions checking the play of the AFM in an earlier post. The focus seemed to go to adjusting the height of the plate and its exact position in the aluminum body, but I didn't see enough stress placed on making sure the plunger in the middle of the FD was NOT depressed while the motor idles. ...
Did you read posts 39, 41, 45, 49, 52, 82, 84, 86 and 91 ?

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... The rich idle could have been the result of the flapper spring fatiguing over time as well. ...
On the M103 the AFM does not have a flapper spring, it has a counterweight. … See what I said about the movability / resistance of the AFM up from post 39 !

In order to not confuse the OP, I think it‘s best to do one step at a time. A few problems on this car have been fixed during this thread. The remaining problem (at this point) is:

“a lack of power before the car heats up. The engine seems very bogged down, and if I fully depress the gas pedal this gets worse.“


It‘s evident (since post 108) that the CIS-ECU does not receive a proper signal that is necessary for acceleration enrichment. So, IMHO, that should definitely be taken care of first. … And if that does not completely fix this remaining problem, I haven‘t cancelled the EHA on my list of suspects yet. …

H.D.
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post #117 of 174 (permalink) Old 01-12-2018, 04:38 AM
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Cody, The following is to H.D. I am hoping that he can teach me something as well.

>>Did you read posts 39, 41, 45, 49, 52, 82, 84, 86 and 91 ?<<

Habe ich. Sogar ein paar Mal.

>>Originally Posted by codycool55 Post 51
... Checking the zero position now I notice when I depress the meter slightly, (just before the resistance from the CP kicks in) the gap disappears, and both sides appear to sit within the "rim." ...
and H.D. replies in Post 52:
Sounds correct.<<


That Cody did not really understand this, you did have to ask several times, tells me that it could have been one of many items that was lost. You will note that I stated, "but I didn't see enough stress placed on making sure the plunger in the middle of the FD was NOT depressed while the motor idles."

As I did all of my tuning back in 2010 and 2011, I didn't remember it all that well. Once I reread my posts quite a bit came back, including the importance of the flapper not applying pressure to the plunger in the FD while the motor was at idle. It seemed to me that your tests with Cody were sometimes engine off and sometimes engine running. The AFM flapper tests seem like the former. Perhaps you could clarify?

As I recall there was a spring in there somewhere, perhaps in the FD above the plunger. Regardless, there was a reason for me to believe that nobody had ever been inside my AFM or FD or EHA (can't remember now what that was), and that lead me to believe that as these systems and parts age, they fall away from the original spec.

I love your approach, but I found that with my car, I needed to do it iteratively. I also decided to work from what I thought was the most important side, fuel delivery (the injectors) back. I pulled all of the injectors, checked their crack pressures, also found a bunch of hard seals needing love, and then checked the flow of all together. This is perhaps not a sight that would sit well with you, as the FD assembly was unbolted from the flapper assembly and the injectors and lines were up in the air with plastic bottles under all of the injectors. So, perhaps ugly, but very illustrative. Here is what I posted seven years ago.

To do this I pulled the fuel distributor (no wires connected) off the base (three Torx bolts-watch out for the o-ring around the plunger when you pull the distributor off the base) and put plastic water bottles over each injector. I weighed the bottles empty since I did not have seven (cold start injector-CSI) that matched and wrote the empty weights on the bottles. I then ran wires directly from a battery near the rear wheel to both pumps. I ran the pumps for about a minute as I pushed the plunger all the way up into the distributor (WOT). Wide Open Throttle

After removing the bottles and getting the fuel weights, the first run gave the following results.
60 – 65 – 68 – 62 – 64 – 72 with nothing from the CSI - 0

I then removed the cap screw on the bottom of the fuel distributor corresponding to injector 6 and turned the exposed set screw IN one turn and then recapped. Performing nearly the same flow test as above, but this time varying the amount that the plunger was pushed in (simulating varying throttle position), I got the following results.
70 – 75 – 79 – 72 – 73 – 66 (0 CSI) That told me that varied or fully depressed, the flows stayed about the same (relative).
Three runs later and a ¼ turn here and an 1/8 turn there (NEVER touching #4) I ended up with the following results after a longer run (plunger fully depressed since WOT was a bigger issue for me to match than idle).
123 – 122 – 123 – 121 – 123 – 121


Note the 20% difference between injectors 1 and 6 after the first test. Like Cody, I was chasing my tail for a while until I balanced the flow, then I was able to get meaningful results adjusting the EHA and the CO and the FD plunger.

Here was my follow up:

If I had to do it again on a running car I would:

-Make notes of fuel economy, idle mixture and fuel pressures at the top and bottom of the distributor (there are removable plugs on the top and bottom where you can attach your FP gauge) before I took anything apart. I would also remove the air filter and make a note of the position of the flapper when it just contacts the fuel distributor’s (FD's) plunger with the motor just turned off (residual fuel pressure in the distributor). This is a feel thing and a magnet helps to lift the flapper so you can let it drop just until you feel the point of greater resistance. Now mark that point on the aluminum housing around the flapper. Start the car and see if the flapper has moved down past the mark. If so, measure the drop. The ratio of flapper movement to plunger movement is 7 to 1. If I read the specs correctly, there should be from 0.1 to 2 mm of free play at the flapper at idle. That means 0.014 to 0.29 mm at the roller/plunger which you really can’t measure, but you can “feel”. Point is that the flapper should NOT push the roller into the plunger at idle. I do not know the thread pitch of the screw on the plunger but I assume it is a 1.0 mm pitch. If the flapper moves down 7 mm at idle from the resistance point you felt with the car off then you need to turn the plunger screw IN just over one turn. More likely you will need less. While you have it all taken apart, check the injectors for flow with plunger all the way out (idle) and all the way in and then adjust flow of up to five of the six injectors until all are matched. The min spec is 4-6 cc/min but suggested is 6.0 – 6.6 cc/min. A cc of water is a gram. Fuel is about 75% less massive, so 4.5 – 5 grams of fuel per minute is your target if you use a scale and plastic water bottles as I did. I flowed mine for three minutes at idle and was over the spec. Also check flow rates with the plunger pressed all the way in. There are two specs here: 100 – 109 cc/min (75 – 82 grams/min) and 140 cc/min. The 140 is a max. I just got the idle numbers in spec and then used the high flow to more precisely match the injectors. Since I removed the fuel distributor from the flapper assembly while flow matching I had no way to know how far the flapper was depressing the plunger so I could not check the “full” numbers. I saw mid 80 grams per minute with the plunger completely pressed into the distributor, so I concluded the fuel distributor was okay.

-Check the resistances of the air temp and water temp sensors at the computer’s connector. If out of spec (or more likely completely open or closed circuits), fix. Check the O2 sensor on the bench with a volt meter and torch.

-Put it all back together and go back to your notes. The differential pressure should be 3 – 4.5 Bar (difference between pressures at the top and bottom of the fuel distributor). If you are out of spec, remove the EHA and adjust the small Allen behind the cap screw. Be careful here. The lower pressure changes as the car warms up, so make notes of the ranges you see. If you can’t start the car after the EHA adjustment, you will need to adjust the idle/CO screw. If you turned the EHA CW a ¼ turn you will need to turn the idle/CO screw about ½ turn CCW, or the other way and twice as much (roughly). Careful again. If you had to go CCW on the EHA and CW on the idle/CO too much you will/might have allowed the flapper roller to contact the FD’s plunger at idle….meaning another adjustment to the plunger screw, sorry it all comes apart again.


So, anything in there that you might incorporate into your current approach to help people in the future?
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post #118 of 174 (permalink) Old 01-13-2018, 01:13 PM
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... So, anything in there that you might incorporate into your current approach to help people in the future?
On aging systems and also in case of FD refurbishment, the things you talk about in your post can, of course, be relevant. I've refurbished quite a few FD‘s over the years, never without checking their alibration afterwards. And in about half of these cases, I had to recalibrate them … and reused original EHA‘s often needed to be adjusted too.

For now I suggest to focus on the remaining problem of the OP‘s car … “lack of power before the car heats up“. And taking care of the matchingly missing, but necessary, proper signal to the CIS-ECU to activate acceleration enrichment (as confirmed in post 104) should be the next step, shouldn't it.

And, as I said, if that does not (completely) fix this remaining problem, I‘ll suggest specific EHA tests. And the results of these tests would determine the further approach … possibly including things you mentioned in your post.

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post #119 of 174 (permalink) Old 01-19-2018, 01:29 PM
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>>“lack of power before the car heats up“. And taking care of the matchingly missing, but necessary, proper signal to the CIS-ECU to activate acceleration enrichment (as confirmed in post 104) should be the next step, shouldn't it.<<

I am not sure. 5k ohms seems like an odd amount. 5M ohms maybe, which for all intents and purposes is an open circuit. When I go back to the original post, I see other signs that the engine is getting too much fuel. Stepping on the gas to start the car opens the micro switch, which, I believe, takes the car out of its start programming, which in most cases has fuel enrichment built in. i.e. cracking the throttle during start up actually supplies less fuel, which may have been why he was able to start the car that way. Note that I had to do just that, in fact, I put a little piece of vacuum hose under the micro switch to keep it open until I figured out that my FD was delivering too much fuel at idle and made what became the problem solving adjustment. No more micro switch always open band aide required.
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post #120 of 174 (permalink) Old 01-21-2018, 06:47 AM
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… I am not sure. 5k ohms seems like an odd amount. 5M ohms maybe, which for all intents and purposes is an open circuit. ...
See what I said in post 108 about that 5 kΩ connection to engine ground … and note that I mentioned “some other path“ !

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Originally Posted by KJZ78701 View Post
… When I go back to the original post, I see other signs that the engine is getting too much fuel. …
The original post is almost 2 ½ years old … there‘s been some change since then.

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… Stepping on the gas to start the car opens the micro switch, which, I believe, takes the car out of its start programming, which in most cases has fuel enrichment built in. i.e. cracking the throttle during start up actually supplies less fuel …
Please allow me to correct that. … The KE-Jetronic cold start program has fuel enrichment built in by default, not only in most cases. … And that is not switched off when the throttle, or the micro switch, is opened.

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… Once I reread my posts quite a bit came back, including the importance of the flapper not applying pressure to the plunger in the FD while the motor was at idle. …
Please allow me to correct that too. … The AFM / FD unit is designed in such a way that the “flapper“ does apply pressure to the CP (Control Plunger) when the engine is running at idle speed … by which the CP is slightly pushed up, thus slightly opening the metering slits.

If, while the motor is running at idle speed, the CP is not slightly pushed up by the roller of the air sensor lever, then because of (at least one of) the following reasons:
- the CP can not descend all the way to the set screw (e.g. due to contamination)
- the CP set screw is screwed in too far
- the CP or/and CP guide is/are (significantly) worn
- the metering slit o-rings are worn


You said “I love your approach“. … Since I‘m a little short of time, this is currently the only thread I‘m active in, and I‘m trying to keep it systematic and to prevent confusion … and I really think that, not least in view of the hint I gave with the first sentence above, waiting for the results of the test I suggested in post 108 (possibly followed by further test steps) is in order. …

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