Where does this vac line go to stop rough idle? - PeachParts Mercedes-Benz Forum

DJNEWK2 · #1 02-13-2002, 08:24 AM

Hey guys!
Some background... I have an 86 560 SEL that has had a rough idle and slight shake lately...I changed out the plugs last night and she runs a bit smoother but when I took her out I still noticed the hesitation although she had more responsive accelleration.Of course when I called Autozone and Advance auto parts, they only wanted sell me plats and ensisted they were the best for my car (probably because they didn't have the bosch super coppers) although when I called prior to going they said they had the "stock" plugs for my car. Anyway, after explaining to the employees that my car never came with platinum plugs stock,I ended up at my buddy's independent MB shop (who was basically about to close shop but stayed open-thanks Rick!) and he sold me the coppers.
While I was there I heard hissing after we popped the hood to check my rotor (oh yea, his tech couldn't even get the cap off because it was so tight and we didn't want to strip the phillips screw-I've heard about that night mare from others and before the tech got a chance to make it a project to dislodge the screw, I told him to forget it because Rick was trying to close).Once I changed the plugs, I looked for the source of the hissing as the car ran and found that a vacuum line is not hooked to its "source" and if anyone could possibly tell me where this line goes to it would be appreciated. The part # is 001 140 20 60 and the vac line on one side goes to the top of the intake manifold and the other end has a vac line that goes down somewhere by the distributor but I couldn't find anything that it would connect to. What should this Themo vacuum valve connect to? TIA

stevebfl · #2 02-13-2002, 09:19 AM

The part number you give translates to what I think is the EGR amplifier item 90 in the drawing.

J.HIDALGO · #3 02-13-2002, 10:13 AM

You always go the extra mile!

DJNEWK2 · #4 02-13-2002, 10:54 AM

thanks but I was also wondering if you could "spoon feed the baby" and give me an idea what that sucker looks like and where it is? I'm wondering if I couldn't see it because I couldnt get the dist cap off...I could only hear hissing but can't find it. (What drawing are you refering to?) Of course I'm at work and the car's at home in the garage so I can't even go check it out. Also,would this even contribute to the rough idle? Yea you do go the extra mile dude, thanks

DJNEWK2 · #5 02-13-2002, 11:06 AM

okay NOW the drawing comes up...sorry I see it now- My only thing is that the little blue valve only has an elbow connector with a short vac line that only reaches as far as maybe the length of one's hand and couldn't possibly reach all the way over to the item 90...

stevebfl · #6 02-13-2002, 12:12 PM

The part number you gave 001 140 20 60 shows in the parts info as a part that I remember as being about 2in in diameter. It doesn't directly look like item 90, but item 90 is the graphical representation of the vacuum amp to the EGR which is what the picture in the parts info looks like.

Your descriptions sound more like one of the thermal valves item 79. The distances on the image aren't representative.

DJNEWK2 · #7 02-13-2002, 01:41 PM

that's exactly what it is, a thermo valve (blue/black in color and circular with two inlets) -vac line going to the intake manifold and the other connected to a short hard little white vac tube with an elbow vac line connector that goes down to the areas where the thermostat,water pump,etc is. Is the EGR valve anywhere in this area and should I connect this to it? I'm tempted to just plug it but want it to run right and its getting "personal". Sorry to bug you so much because I'm frustrated with this mess myself... your advice is really appreciated!!!!

stevebfl · #8 02-13-2002, 02:51 PM

The thermal valve is in the manifold. Did it have that number? The parts info shows the amp item 90 as the number you gave. If in error the info at least has us on the same system then the amplifier (item 90) should sit beside the distributor if I remember correctly. The diagram shows how it is plumbed. The EGR valve is on the left manifold and is represented in the diagram in about the right position (item 89).

JRJ · #9 02-13-2002, 08:19 PM

My vechile is an 82 380SL (euro). I have a similar intermittent rough cold start with low rpm and surging that resolves as the engine warms up. Once warm idling is smooth, but there is a slight hesitation with rpm drop when pressing the pedal lightly. Previously replaced warm up regulator, this decreased the loping idle. Disconnecting the electrical plug from the airsleeve boosts RPM to 1500 correctly. Stevebl posted a vacuum line diagram for the 560SL. Does anyone have a similar diagram for my car or the US equivalent that I may use for further troubleshooting. Any other suggestions to check on.

JRJ

DJNEWK2 · #10 02-14-2002, 08:30 AM

yep, that's the number...did you say the thermo valve is IN the manifold? It reads "themo valve" on the package I got from the dealer but assuming its the thermo valve with that part number.I also noticed that what looks like the item 89 in the diagram is right next to the right side (facing the car) of the spark plug wires and is not disconnected from its source...Do you think it would work if I put a T-connector and just call it a day? The only thing with that is the fact that whatever it is hissing will still hiss therfore losing vaccum "somewhere" I can't find...this is sooo frustrating and of course by the time I got in last night I didn't even get to check on her (but I do remember that the item 89 was connected). JRJ, my buddy did tell me about the airsleeve sometimes sticking and he tapped it with a "polyurethane" hammer just in case that was the case (that little sucker is like $300 here!) Once we did that and I got on the road, it didn't change and even when I got back home, I heard it doing what it was supposed to anyway... also Steve, is that diagram the same for the 560 SEL?

stevebfl · #11 02-14-2002, 10:48 AM

It is for a 1986 560SEL because that was what you asked for.

DJNEWK2 · #12 02-14-2002, 11:07 AM

then yes,that's what I needed...I just wondered because of the previous post of it being a 560 SL and wasn't sure if it was the same. I'll also try to get to that darn valve vac line issue today (pending the future wife can keep her hands off of me-he he). Waddaya think about me splitting the vac line from that item 89??

stevebfl · #13 02-14-2002, 12:33 PM

I wouldn't worry about what ran where until you find the leak. You definitely do not want the EGR valve openned when it shouldn't. You are better to have it not work at all. If the hiss you hear is a vacuum leak rather than the normal sound through the idle vale, then this WILL affect your running. We use a number of ways to find vacuum leaks, but in ones that we can hear (sort of) we use a stethescope without the end just an open tube to the earpiece. This allows you to search under and around areas that one's head can't fit.

DJNEWK2 · #14 02-15-2002, 08:13 AM

UPDATE:
I only had a few minutes (because I like probably a lot of the guys had to take the little lady out yesterday) while she got ready but anyway, I previously said that the valve had only two outlets (trying to work from memory) but after checking it out it actually has THREE outlets...Steve, you're right about both of the lines you described. One went to the item 89 (by the spark plugs-right side) and the other went to the top of the intake (which is plugged) but there is ONE MORE outlet and that one is the one I cannot locate the correct place to connect to its source. It has an elbow connector on both sides of a white colored "hard" line that reaches down toward the water pump area (and the elbow end down there does seem to have some minor dirt and expansion toward the end of it (like it was over something that would expand the tubing when installed-I hope that sounds right).Any ideas as two why this valve would need to have THREE inlets or could I plug it because the other two are connected (to the item 89 and the intake)? Thanks for all of the help so far Steve...

DJNEWK2 · #15 02-20-2002, 03:58 PM

another update:
problem solved and basically no rough idle...I cleaned my schematics sticker enough to actually read it

and don't know why I didn't look earlier. It seems that the vac line (white/yellow) did go underneath the intake where I heard the hissing and the others were fine as I traced them according to the schematics. So far she ran like a champ into work this morning and all I need to do now is continue with the stuff I was replacing anyway like the dist cap, rotor,etc... Whew! Next project is to locate some polyurethane suspension components to replace the rubber bushings. Thanks for the help Steve

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