M103 Rough idle and vacuum leak - Page 11 - Mercedes-Benz Forum
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post #101 of 174 (permalink) Old 12-29-2017, 03:18 PM Thread Starter
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These spark plugs are fairly new, I replaced them in August and have driven the car little since then. 500 miles or less would be my ballpark estimate.

Is there a particular brand of fuel additive you'd recommend? I've used SeaFoam in the past but it's been a while.

Between pins 1 & 2 the resistance is .2. The resistance goes to infinite just after the throttle linkage disengages from the wheel on the unit labeled s27/2 in the image attached to post 86. This corresponds to a slight depress of the gas pedal, maybe 1/8th of the full range of motion. s27/2 is the decel fuel shutoff switch or something like that, correct?
As for pins 3&2 I had infinite resistance regardless of throttle position. This proved true whether actuating the throttle with the gas pedal or manualing moving the linkage.

As for checking the camshaft, is there anything in particular I need to look for? Is removing the oil dripper absolutely necessary or just recomended? Where can I use that 27mm socket to turn the crankshaft and how would removing the sparkplugs make it easier? Is cleanliness a major concern? Most of the places I would be able to perform this are relatively dirty (farm garages or woodshops) and my engine has a lot of grease and grime on the exterior.
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post #102 of 174 (permalink) Old 12-30-2017, 09:39 AM
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... Is there a particular brand of fuel additive you'd recommend? I've used SeaFoam in the past but it's been a while. ...
I’m not familiar with injection system cleaning additives in the US market. It should be a petroleum-based product. I had good experience with “Injection Reiniger” from “Liqui Moly”.

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Originally Posted by codycool55 View Post
... Between pins 1 & 2 the resistance is .2. The resistance goes to infinite just after the throttle linkage disengages from the wheel on the unit labeled s27/2 in the image attached to post 86. This corresponds to a slight depress of the gas pedal, maybe 1/8th of the full range of motion. s27/2 is the decel fuel shutoff switch or something like that, correct? ...
That’s how it should be. But you should see the same resistance between terminal 13 & 2 at the ECU connector ! … I suggest to check the resistance there again and if you still measure what you reported in post 98 (4.97 Ω with the pedal depressed), measure again with the TPS connector disconnected.
The micro switch S27/2 does several things, but ECU terminal 13 is the input terminal for the closed-signal of the TPS (Throttle Posisiton Switch). S27/2 is supposed to open before the TPS opens, as you observed.

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... As for pins 3&2 I had infinite resistance regardless of throttle position. This proved true whether actuating the throttle with the gas pedal or manualing moving the linkage. ...
If you don’t see less than 1 Ω between pins 3 & 2 with the pedal completely depressed or with the throttle completely opened manually, there is a problem with the TPS’s WOT-signal, which is not relevant as for the symptoms you have reported so far and can be taken care of later.

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... As for checking the camshaft, is there anything in particular I need to look for? Is removing the oil dripper absolutely necessary or just recomended? Where can I use that 27mm socket to turn the crankshaft and how would removing the sparkplugs make it easier? Is cleanliness a major concern? Most of the places I would be able to perform this are relatively dirty (farm garages or woodshops) and my engine has a lot of grease and grime on the exterior.
If you can see any camshaft lobe that resembles the first one in the attached image with the oil dripper installed, then you have seen enough and don’t need to remove it.

The 27 mm socket is used on the head of the bolt that sits in the front end of the crankshaft (behind the fan). With the spark plugs removed there’s no compression, which reduces the torque required to turn the crankshaft significantly.
If turning the crankshaft manually is too much trouble under the given circumstances, you can also use the starter via ignition key. However, you should deactivate the ignition system to prevent the engine from firing. You can do that by disconnecting the coaxial CPS plug from port 2 of the ignition control unit (see attached image). It’s located on the left fender well.

As for cleanness … if the valve cover is dirty, clean it a little, so that no dirt gets into the valve train area when you remove it and when you put it back. If not too much dust is flying around in these farm garages or woodshops, it’s okay … and if chicken are running around there, keep ’em out of the engine bay while the valve cover is off. …

H.D.
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post #103 of 174 (permalink) Old 01-01-2018, 12:32 AM
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Looks like the cam I replaced 5 months ago. Happy to be rid of that one.
#1 intake (like shown in the photo is the first one to check.

Happy new Year!
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post #104 of 174 (permalink) Old 01-04-2018, 09:46 AM Thread Starter
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Tank 1 of fuel + additive is under way!

Rechecked, and the value is 5.02 k ohm with the throttle depressed fully (or otherwise depressed.) If I take off the TPS the value is at 5.02k ohm regardless of throttle position. These test regarding throttle position have all been done with engine at or close to ambient temperature, which has been below 40 F.

Just to make sure I understand what I'm looking at.. the wear is the recessed surface on the cam correct? I've attached an image circling what I think we're talking about.

So now that I've had some time to drive the car after adjusting the duty cycle the main symptom I'm still having 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. Theres a sweet spot just slightly before max throttle. Some additional (most likely unrelated to this discussion) are the heat stops working about around 60-70 mph and no cruise control. The lack of cruise has been an issue for a while, but the heat is relatively new, but I haven't drove the car much in the winter so I could be wrong. Again I don't believe these are relevant to this discussion and I'm not necessarily asking for the solution, just thought I'd throw them out there in case they actually are relevant
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post #105 of 174 (permalink) Old 01-04-2018, 03:07 PM
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... Just to make sure I understand what I'm looking at.. the wear is the recessed surface on the cam correct? I've attached an image circling what I think we're talking about. ...
Correct.

Your resistance measurements match the cold engine‘s behavior you describe. … I‘ll come back to that and the other things tomorrow … it‘s already midnight here.

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post #106 of 174 (permalink) Old 01-04-2018, 09:36 PM
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If you can see any camshaft lobe that resembles the first one in the attached image with the oil dripper installed, then you have seen enough and don’t need to remove it.
So it seems like @codycool55 and I have M103s with potentially worn camshafts. That's a bummer, because I have no idea how to take one out of a junkyard engine even were I able to find one. If I have mine replaced, I'm going to have to put a big dent in my wallet because I'll get the valves and the valve stem seals done at the same time. Cha-ching. In the meantime, though, the camshaft pic from @H.D. left me wondering which of these cams is worn. So I attached a pic that asks that question. I also assume that the #1 cylinder's intake valve is the most susceptible—for reasons that have to do with the oil dripper?

When I cold start the engine and it occasionally taps very loudly until the oil is pumped up into the valve train—usually after sitting for days or weeks—what exactly am I hearing? It strikes me as much louder than a valve whacking its seat, so is it the lifter that's kind of whacking the cam lobe as it spins around? When I hear that sound it makes me sad, because—grab your Kleenex—I kind of anthropomorphize things like car engines, and I feel like it's wounded when it makes sounds like that. Makes me cringe. I know—you're probably gagging right about now.
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post #107 of 174 (permalink) Old 01-04-2018, 09:56 PM
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Note: The picture shows the engine bay of my 300CE. Your engine bay looks a little different, but the regeneration valve should look the same.
All I can say here is wow. Wow. Wow. Wow. LOOK at that engine bay. @H.D. , I have but one word: Respect! That car is immaculate. And here I thought I keep my cars spiffy. I can't hold a candle to this. Well done, sir!
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post #108 of 174 (permalink) Old 01-05-2018, 01:49 PM
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... Rechecked, and the value is 5.02 k ohm with the throttle depressed fully (or otherwise depressed.) If I take off the TPS the value is at 5.02k ohm regardless of throttle position. ...
According to the resistance between pins 1 & 2 of the TPS connector you reported in post 101 the TPS provides correct “throttle closed“ / “throttle opened“ signals.
But these 5 kΩ you measure between the CIS-ECU terminals 13 & 2 while the TPS is disconnected (or while the TPS is connected and the throttle opened) point to a connection between these two terminals that should not be there, and which prevents the ECU from correctly detecting the TPS‘s “throttle opened“ signal.

During the warm-up phase and depending on the load the engine requires “acceleration enrichments“ of the fuel/air mixture. … But without a proper “throttle opened“ signal getting to the ECU (represented by infinite resistance between 13 & 2) that function is deactivated … which leads to the symptoms you describe (“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 doesn‘t have to be a direct connection between the two wires of terminal 13 & 2. Since terminal 2 is connected to engine ground, the wire of terminal 13 might have a (5 kΩ) connection to engine ground via some other path. I suggest to start the search by checking the resistance between terminal 13 and all other terminals of the ECU connector, with the TPS connector disconnected !

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... Some additional (most likely unrelated to this discussion) are the heat stops working about around 60-70 mph and no cruise control. ...
Regarding the not working heat … there might be a problem with the coolant circulating pump. Let‘s take care of the cruise control, and possibly other problems, later.

H.D.

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post #109 of 174 (permalink) Old 01-05-2018, 02:10 PM
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So it seems like @codycool55 and I have M103s with potentially worn camshafts. ...
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.

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... If I have mine replaced, I'm going to have to put a big dent in my wallet because I'll get the valves and the valve stem seals done at the same time. ...
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)

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... In the meantime, though, the camshaft pic from @H.D. left me wondering which of these cams is worn. So I attached a pic that asks that question. I also assume that the #1 cylinder's intake valve is the most susceptible—for reasons that have to do with the oil dripper? ...
Yes, that‘s the worn spot on the camshaft lobe … in this case the lobe for the first intake valve, which is the most susceptible, which may also have to do with the oil dripper. But also other lobes can be involved.

The spot on the rocker arm you point to in the pic is a spot that has never touched the camshaft lobe. The recessed spot further to the right is the worn spot. That spot and the spot on the camshaft lobe have worn each other.

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... When I cold start the engine and it occasionally taps very loudly until the oil is pumped up into the valve train—usually after sitting for days or weeks—what exactly am I hearing? ...
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“.

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... I kind of anthropomorphize things like car engines ...
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

H.D.

Last edited by H.D.; 01-08-2018 at 09:41 AM.
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post #110 of 174 (permalink) Old 01-05-2018, 02:34 PM
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Quote:
Originally Posted by Strassenkreuzer View Post
So it seems like @codycool55 and I have M103s with potentially worn camshafts. That's a bummer, because I have no idea how to take one out of a junkyard engine even were I able to find one. If I have mine replaced, I'm going to have to put a big dent in my wallet because I'll get the valves and the valve stem seals done at the same time. Cha-ching. In the meantime, though, the camshaft pic from @H.D. left me wondering which of these cams is worn. So I attached a pic that asks that question. I also assume that the #1 cylinder's intake valve is the most susceptible—for reasons that have to do with the oil dripper?

When I cold start the engine and it occasionally taps very loudly until the oil is pumped up into the valve train—usually after sitting for days or weeks—what exactly am I hearing? It strikes me as much louder than a valve whacking its seat, so is it the lifter that's kind of whacking the cam lobe as it spins around? When I hear that sound it makes me sad, because—grab your Kleenex—I kind of anthropomorphize things like car engines, and I feel like it's wounded when it makes sounds like that. Makes me cringe. I know—you're probably gagging right about now.
Yep, the lobe you point to is worn about 2mm or so and the matched rocker appears to be worn too. It should not have the dent on it. That combo probably shortchanges the valve opening more than 3 mm's. But all those lobes are starting to show some wear. A good cam does not have the "non-shiny" yellow edges. But of course the big problem is where the lobe has some serious metal missing.

Changing the cam and rockers is actually not that difficult (compared to pulling the head). What I did was to do it in steps. Find a donor car first, that is probably the most difficult part. With me, I was very fortune, my first visit to the JY and find the perfect donor. That was a year ago, I have not seen a car like that ever since after maybe a dozen trips to the JY for various small ticket items.

At the same time you need to take the v shaped washer that holds down the dripper at the point where the oil comes in from the head. I believe the problem is that there is some pressure loss at that joint because oil may seep out in certain conditons and there is not enough oil pressure to deliver a good flow at either ends of the pripper. Because the dripper oil inlet is off-set, number one cylinder is more vulnerable. At least this is what I'm told.

I do not believe doing the cam and guides together saves you that much money. Probably less than 2 hours of labor and if you replace the cams yourself that is free.

I was quoted $5K for the entire job. Pretty pricey.

Doing the cam yourself is less than $100 (An entire head with all the hardware is $69 at pick and pull)

Guide's will set you back $2000-$2500. Mostly labor
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