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| W5YK Extreme Veteran Date registered: May 2006 Location: San Diego Vehicle(s): 2002 G500, Unimog U2450, Posts: 543  | Air Intake Manifold vacuum hose Posting this for reference - it might save someone some sweat. I couldn't find much when I googled this subject. My 2002 G500 has 150k miles on it, and some of the vacuum hoses at the front of the engine were starting to fall apart. The first clue I got was the Check Engine Light. After much head-scratching, I tracked it down to a crack in one of those vacuum lines that would sometimes leak and sometimes not leak. Very frustrating. After fixing that, ll was good for a few weeks, and the I got another CEL. That turned out to be a crack in the hose going from the bottom of the air intake manifold up to the switchover valve that swings the internal baffles in the manifold. so I figured that would be easy to replace. WRONG! It is not replaceable, and unless you know that, it will be difficult to figure it out. So my first tip is this - if you have the idea to change that hose, don't. Chop off the cracked piece and plumb in an extension. Here's how I screwed mine up; The place where the hose enters the bottom of the manifold is invisible and inaccessible unless you remove the manifold (don't do that). I felt around the area blind, and decided the hose must be sitting on a barb like all the other lines. So I pulled hard. It broke, right at the manifold. Big, big mistake. As in $2k. The hose is glued inside the manifold, and you cannot replace it without removing the manifold from the engine, cracking it open (bad idea), and even then it's difficult. Plan B is to buy a new manifold, which comes with the hose in place. Dumb design if you ask me, it means the life of the manifold is limited by a crappy perishable hose. When removing the old manifold, one of the secondary air valves broke. I also decided to replace all the rubber. It was nearly $2k at the dealership. Bonus was that I found quite a few other problems. Including a dead mouse under the manifold. (IMG_1961 (1).jpg) Attachments ----------------  IMG_1961 (1).jpg (121KB - 8 downloads) | |
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| fernweh Date registered: Apr 2006 Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa  | ||
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| DesertStar Expert Date registered: Apr 2006 Location: San Diego, CA USA Vehicle(s): 85-280GE/95-G320/08-G500 Posts: 2156 | ||
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hipine Date registered: Jul 2006 Location: US, CO, Bailey Vehicle(s): 460 1980 280GE w. 617A  | ||
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| AlanMcR Expert Date registered: Apr 2006 Location: US, CA, Los Altos Vehicle(s): G300DT E300DT 230SL Posts: 3500 | ||
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| DUTCH Administrator Doppelgänger Date registered: Apr 2006 Location: US, GA, Atlanta Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter Posts: 9963 | ||
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| fernweh Date registered: Apr 2006 Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa | ||
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| W5YK Extreme Veteran Date registered: May 2006 Location: San Diego Vehicle(s): 2002 G500, Unimog U2450, Posts: 543 | ||
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| W5YK Extreme Veteran Date registered: May 2006 Location: San Diego Vehicle(s): 2002 G500, Unimog U2450, Posts: 543 | RE: Air Intake Manifold vacuum hose Here is pic of the broken off hose. You don't get such a nice view when the manifold is on the engine, it is "up and under". If you crack the manifold open, you can't actually see into that rectangular part where the hose goes. But there is a barb about 30mm up inside, that seems to go into the top chamber, and the rectangular part is completely filled with RTV or something like that. So you could maybe push a hose onto the barb and seal it up, without cracking the manifold open. Maybe. Probably my best option once I broke the hose would have been to remove the manifold and ream out the RTV enough to push a barb into it. When the manifold is on the engine, you just can't do anything, you can just about feel where the hose is, but you couldn't do any repairs there. Looking at the hose that came off, I should have just left it alone, and spliced a new length onto it. The cracked part was at the other end. They all tend to crack at the end of the barb they are pushed onto. (IMG_1926.jpg) Attachments ---------------- IMG_1926.jpg (117KB - 14 downloads) | |
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| W5YK Extreme Veteran Date registered: May 2006 Location: San Diego Vehicle(s): 2002 G500, Unimog U2450, Posts: 543 | M113 Engine Air Intake Manifold G500 CL500 CLK500 E500 S500 SL500 ML500 CLS500 Here's some pics of the inside of the manifold. In the second photo you can just about see in the center the hole where the hose comes in. It goes about 30mm up into a tiny little barb on the other side of that little triangular plate. To get to the barb you would need to pull the internals apart, and they are glued together, so I'm not sure how you would do that. I tried to push the hose on from outside, and it is not possible. There is too much distance. I would not recommend cracking open the manifold to do a repair. It does not look possible. I assume there is something important about where this hose gets its vacuum from, or they would have just put it onto an external barb like all the other vacuum consumers. This hose supplies an actuator when the RPMs go over 3500, and I guess vacuum is in short supply at that speed so they have to get from the best spot. They must have had some reason for it, so I suspect you can't just hook this particular hose to one of the other barbs. Edited by W5YK 3/2/2012 11:09 PM (IMG_2052.jpg) (IMG_2053.jpg) Attachments ---------------- IMG_2052.jpg (161KB - 12 downloads) IMG_2053.jpg (167KB - 11 downloads) | |
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| nadd Expert Date registered: Apr 2006 Location: UAE, Dubai Vehicle(s): G500 2016 LHD, numerous Chevys Posts: 1285  | ||
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| Inkblotz Expert Date registered: Apr 2006 Location: Georgia Vehicle(s): 90 300GD "Thundering Turtle II", w/ 603A turbo Posts: 3186 | ||
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| W5YK Extreme Veteran Date registered: May 2006 Location: San Diego Vehicle(s): 2002 G500, Unimog U2450, Posts: 543 | ||
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| fernweh Date registered: Apr 2006 Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa | ||
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| nadd Expert Date registered: Apr 2006 Location: UAE, Dubai Vehicle(s): G500 2016 LHD, numerous Chevys Posts: 1285 | ||
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| fernweh Date registered: Apr 2006 Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa | ||
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| nadd Expert Date registered: Apr 2006 Location: UAE, Dubai Vehicle(s): G500 2016 LHD, numerous Chevys Posts: 1285 | ||
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| Roly Elite Veteran Date registered: Apr 2006 Location: Australia Vehicle(s): 1999 G500 Posts: 661 | RE: Air Intake Manifold vacuum hose The operation of the manifold is explaned a bit on the attached file. The actuator is controlled by the ECU with vacuum being supplied by the rubber hose. But the vacuum must vary as the different passages are opened and closed. I wonder how it is connected? Attachments ---------------- m113 intake manifold.pdf (195KB - 54 downloads) | |
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| fernweh Date registered: Apr 2006 Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa | RE: Air Intake Manifold vacuum hose Roly - 3/4/2012 11:45 AM The operation of the manifold is explaned a bit on the attached file. The actuator is controlled by the ECU with vacuum being supplied by the rubber hose. But the vacuum must vary as the different passages are opened and closed. I wonder how it is connected? Much cleaner manifold than Richard's....  I would think the closed position is achieved with the vacuum, so the ECU controls the RPM range via the solenoid and in the mid rpm range the vacuum is high to close the flaps. Karl Edited by fernweh 3/4/2012 5:16 PM | |
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| imjustdave Regular Date registered: Feb 2012 Location: Bonney Lake Washington USA Vehicle(s): 2004 G500, 2014 Audi Q7 TDI, 2006 Ram 3500. Posts: 77  | Re: Air Intake Manifold vacuum hose Has anyone come up with a solution for this? I have the dreaded broken line at this point  I think I'm going to be sick I assume the G is undriveable at this point. | |
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