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  #31  
Old 08-30-2013, 02:58 PM
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Just dribbled some heavy gear oil on the poppet cam shaft and there was an obvious drop in rpm with the motor running. Couldn't find any other leaks but it's now time to tear apart the governor (remove it from the IP) and see if the diaphragm is leaky.

EDIT: After disassembling the governor I found that the inboard side (engine side) of the shaft which rides in a bearing, had gotten some grit in via the very hardened rubber seal. The seals had basically turned into something like bakelite and although they are still intact, I know I could break them easily. The grit wandered around and narrowed the shaft by a few thousandths of an inch.



There's not really any option of repairing the shaft itself. Its probably garbage which I'll use in the future as a punch or something of the like. Now the question is, where do I get a replacement shaft? Or should I just take it to a machinist and have a piece of tool steel stock turned with the e-clip notches, the poppet cam locking screw and flats for the linkage arm?

I gently pulled out the diaphragm on the IP side just enough to shine a small LED light from the back side and there is at least one pinhole in the diaphragm.

Since it's a pinhole, is there any hope of repair? Silicone or something like that? I've read in another thread that someone may have tried repairing the diaphragm with some good silicone caulk but I'm not sure of the longevity of the repair. That dang cotter pin which holds it into the IP looks like a pain in the @$$ enough that I want to do this once and only once, so I'd rather find the new part and do it right the first time

So now that I know the diaphragm needs replacement along with the poppet shaft and seals, where the heck do I find these parts?

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Last edited by Phil_F_NM; 08-30-2013 at 05:48 PM.
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  #32  
Old 08-30-2013, 06:59 PM
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The diaphragm is connected to the rack and the ring will probably be stuck to the IP, so there is no fear the diaphragm will fall out.

The governor spring will fall out and the pre-load rings for the spring. There are probably a couple of them in there.
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  #33  
Old 08-30-2013, 07:06 PM
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Instead of hijacking the thread with multiple posts, I just edited my previous post to include the new information with a photo of half the problem.

The repair looks simple. Getting that cotter pin in to hold the diaphragm looks like the worst part but other than that, it's not a hard fix.

I just need to find a diaphragm, poppet shaft, rigid poppet "chamber" seal and some O-rings which will fit properly and not impede the turning of the poppet shaft.

Thanks for the guidance!

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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  #34  
Old 08-30-2013, 07:11 PM
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Quote:
Originally Posted by Phil_F_NM View Post
I gently pulled out the diaphragm on the IP side just enough to shine a small LED light from the back side and there is at least one pinhole in the diaphragm.

Since it's a pinhole, is there any hope of repair? Silicone or something like that? I've read in another thread that someone may have tried repairing the diaphragm with some good silicone caulk but I'm not sure of the longevity of the repair. That dang cotter pin which holds it into the IP looks like a pain in the @$$ enough that I want to do this once and only once, so I'd rather find the new part and do it right the first time

So now that I know the diaphragm needs replacement along with the poppet shaft and seals, where the heck do I find these parts?

Phil Forrest
Getting the pin out to remove the diaphragm is not that complicated. Getting in back in is more tricky. If you drop it, it can be fished out by means of a magnet on an antenna. You must also set the compensation path (described in the FSM), you need a micrometer dial for that.



And watch out for the parts in the diaphragm:



The diaphragm is double layer, so did you look straight through the diaphragm? I would just replace it, but perhaps a repair will work, but I'm knowledgeable about it.

The diaphragm is still obtainable I think. The poppet cam and axle are more complicated. The back cap including axle and cam used to be a (expensive) repair part sold by MB, but it is NLA nowadays I believe. Bosch also sold the parts (bearings, O rings and rings, axle) seperately, but they are also hard to find nowadays and I think the bearings are only sold in sets of ten. Sometimes you can find a diesel service which sells the back caps for cheap. Otherwise junkyards. Perhaps you can use generic bearings.
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  #35  
Old 08-30-2013, 07:27 PM
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Quote:
Originally Posted by Govert View Post
You must also set the compensation path (described in the FSM), you need a micrometer dial for that.

The diaphragm is double layer, so did you look straight through the diaphragm? I would just replace it, but perhaps a repair will work, but I'm knowledgeable about it.

The diaphragm is still obtainable I think. The poppet cam and axle are more complicated. The back cap including axle and cam used to be a (expensive) repair part sold by MB, but it is NLA nowadays I believe. Bosch also sold the parts (bearings, O rings and rings, axle) seperately, but they are also hard to find nowadays and I think the bearings are only sold in sets of ten. Sometimes you can find a diesel service which sells the back caps for cheap. Otherwise junkyards. Perhaps you can use generic bearings.
I didn't take the diaphragm all the way out yet but did shine light all the way through it so there's definitely a hole big enough on the IP side to allow a decent cone of light in to illuminate the pinhole on the governor side.

The bearings look fine. That shaft is the big problem unless I can find the part from a junkyard and it's also not toast. I'm thinking that having a piece of stainless machined down and drilled properly might be the cheapest route to go.

I also have to either find the proper gasket or make one out of rigid gasket material for the governor cap to poppet housing. Maybe a .5mm sheet of hard rubber can be cut to the proper dimensions to make the gasket.

I have a Benz dealer searching for the part but everyone is closed now so I have to wait till Tuesday (Monday is Labor Day holiday) to even hear anything back from anyone.

Till then I'm going to have to put everything back in so i can move my car so I don't incur a ton of parking tickets due to street sweeping. <--*--THIS* is the reason I have been asking for the last 6 months about a place to work on my car in a place to rent or maybe even a nearby driveway. Hopefully, I can get an answer by Tuesday and a part by the end of the week or else I'm going to have to figure out some long term storage solution.

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Last edited by Phil_F_NM; 08-30-2013 at 07:51 PM.
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  #36  
Old 09-03-2013, 08:12 PM
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Is there a gasket for around the diaphragm to seal it?
When I took the governor off, there was no seal on the back side of the diaphragm. Is there one on the front which needs to be replaced?
My genuine Mercedes IP diaphragm just arrived today and I want to get the car back up to snuff tomorrow if possible.

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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  #37  
Old 09-04-2013, 01:47 AM
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No, the outer ring of the diaphragm is the seal.
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  #38  
Old 09-04-2013, 02:20 AM
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When getting the diaphragm back into the IP, I have to set the compensation path? Won't it work by simply setting up the diaphragm using the exact same number of shims as in the old diaphragm?
I still haven't gotten a hold of a w115 / OM615 FSM and paying some of the ebay prices for a stained, yellowed, falling apart book seems ridiculous.

Phil Forrest
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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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  #39  
Old 09-04-2013, 02:36 AM
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Perhaps, but you are on your own if you do that. How bad it is just to put in the old shims I do not know.

For replacing the diaphragm and setting the compensation path, you can use the W123 FSM as well:

07.1 Diesel Injection System - OM616
Just use the chapters for the IP with pneumatic governor.
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  #40  
Old 09-04-2013, 02:55 AM
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Thanks for the link. I had been looking around in there for the pneumatic governed IP adjustments but couldn't find them.
Looks like I need 1.1mm of depth/travel. Doesn't matter since I don't have any compensating spacers anyway.
I'll keep my fingers crossed and hope it works.

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

Last edited by Phil_F_NM; 09-04-2013 at 12:14 PM.
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