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Discussion Starter #1
I have a 95 E300D. My driveway slopes, which has been irrelevant until recently. When left parked facing uphill overnight, the car won't start (plenty of crank, but no fire). If I let the car roll to the flat street, it will start, but it takes awhile. If left facing downhill or on a flat surface, no worries.

I'm guessing that air is getting into the fuel lines, creating a gap that takes awhile to overcome. A lot of the fuel plumbing is hidden under the intake, so I haven't started tearing things apart to see. I thought I'd check the assembled wisdom to see if this is common, and if there is a recommended approach to fix. Some of the visible plumbing appears to be fairly thin plastic. It seems to me that if this si the case, that there may be an opportunity to replace some lines with something more robust.

I also have to confess that I'd be happier if the fuel pump could overcome this issue on a slope as well as on the flat. What are the odds that this is more about pumping uphill than leaky lines?

Thoughts?

Thanks,
Tom
 

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Hi Tom, this is clearly fuel related, and I've heard of this particular issue before with the OM606 engines. I believe this is associated with leaking o-rings at your fuel junctions on the pump and filter. The leaks allow air into the pump reservoir, which the mechanical pump then must try to displace even as new air enters. The o-rings are cheap and easy to replace, but unfortunately I think you need to remove the intake manifold in order to gain access. While you're in there, make sure the delivery valve seals on the top of the pump aren't also leaking. A little trickier to replace, but not difficult with the proper tool (617 589 01 09 00).

I've often thought about installing a little manually switched electric fuel pump in line with the main fuel supply, 'cause it usually takes a while for the engine to catch after fuel filter changes...not unlike what you're experiencing with your fuel "bleed-off" on slopes.
 

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Discussion Starter #3
Thanks!

Thanks, Zeitgeist! I've been saving additional action for a time when I have the whole weekend to take the manifold off, figure out what I'm doing, and put it back together. Since the car is new to me, I expect delays while I learn my way around the engine.

Thanks!
Tom
 

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Discussion Starter #4
Follow-up question:
Since 617 589 01 09 00 is a $55 tool, what are the odds that I will need to address the delivery valve seals while monkeying with the O-rings? I'd rather not take the car out of commission for a week waiting for the tool, nor do I want to spend the money on a tool that will not be used.

I seem to have a dilemma.
 

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Unless you see fuel weeping on the top of the injection pump, you can probably get by without doing the delivery valve seals...for now, but they will eventually need attention. They all do. That tool can be located for cheaper as a knock-off, but I can't remember who sells them. I think I paid something like $30. Since you're already getting into the fuel system, you might as well replace the primary and secondary fuel filters while you're at it.
 

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Discussion Starter #7
And a plea for a bit more clarification

Zeitgeist:

I sure appreciate the information you have given. I've been pondering my parts list. I'm thinking I may go ahead and do the delivery valve seals while I'm in there (if I can find a cheap enough splined socket). Maybe plumbing with some fresh Viton lines would be good where lines are stiff or cracking.

I don't want to lose sight of your original suggestion with regard to O-rings. I was looking at www.mercedescomplete.com. New main fuel filter looks to come with a couple of new O-rings. Pre-filter O-rings are separate. Apart from the O-rings on the valves, I see two O-rings and another seal on the injection pump:
- injection pump to crankcase O-ring
- vacuum stop box O-ring
- injection pump to block seal

Was your original suggestion to replace both of those IP O-rings, the two with the fuel filter, the one on the prefilter, and evaluate the delivery valve seals?

Thanks for your patience and help!
Tom
 

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Hi Tom, I'm suggesting that you replace all the o-rings you can while you've got the intake manifold off of there. If the top of the pump is dry, you can leave the delivery valves alone, but just be aware that they too will eventually fail.

I would strongly urge you to use viton for the fuel return lines that are a part of the injector and fuel filter circuit, if you're going to run any serious percentage of biodiesel.
 

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Discussion Starter #10
Next steps

I have not yet yanked the intake manifold to see what is really going on, but I've decided to go whole hog in following Zeitgeist's advice to replace any o-ring I can get at. In case anyone is following at home, and needs to cover similar territory, I'm finding parts info all over the place.

One poster found that Viton o-rings for the connections of the hard plastic fuel lines are available at McMaster. P/N 9464K44. In his case, the lines were OK, but the connections leaked.

Another poster was prepping for biodiesel use. He replaced the hard plastic lines with SAE J30R9 from an auto parts store. The injector return lines he replaced with 6 feet of Viton line, also from McMasters, P/N 5119K791 .

I found fuel filter, pre filter and pre filter o-ring at Redline.

My local MB dealer apparently can't figure out what is in the delivery valves in the injector pump, so I'm still looking for the delivery valve seals and crush washers. On the plus side, I think I found the splined socket for the delivery valves for about $32 at Impex. The price looks weird on the web at the moment, but I have an email indicating that it will be changed this week.

I think there are a couple other o-rings on the injector pump. I'm optimistic that my local dealer will have them. And I know I can find a torque wrench.

Good luck! And let me know if anyone has a source for the injector pump delivery valve seals and washers for a '95 E300D (OM606.910)

Tom
 

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Discussion Starter #11
Found a little more...

I stopped by my MB dealer today, and a different person at the parts counter spent a fair bit of time sifting through EPC to help me with the delivery valve seals. The system doesn't show detail on the delivery valves for the OM606.910 motor in my car. His recollection was that you had to look at a diagram from a different car/motor with the same pump. He had both the o-rings and copper washers in stock, so now all I need is the socket.

If I can find the o-rings in Viton locally before I tear things apart, I'll upgrade. If not, then I have bought some time. It looks like Viton o-rings for this are available here.

I also found a post that has info about the part numbers for these little doohickies. These numbers match my receipt today.
 

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For whatever reason, the delivery valve o-rings and washers don't seem to show up for the OM606 engines. But, they're the same as those found in the '87 300D/TD and '90 - '93 300D 2.5 turbo cars, so check those out as well. You'll need six of each
 

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Discussion Starter #13
Thanks! I found a guy at the parts counter that seems to be in on the secret. Now if MB would upgrade to Viton for their replacement parts...
 

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Discussion Starter #14
Finally found the time!

I finally got around to getting after the delivery valve seals. After 10.5 hours overnight, nose up on the driveway, it started perfectly. I declare complete victory!

Here is how it went:
The whole enchilada


The destination: Injection pump hiding under the intake manifold


It helps to have the washer bottle out of the way. There are two little pumps on the washer bottle. You can just pull them out of their grommets, and watch a geyser of washer fluid. After that, undo a wingnut, and flop it over the strut top with the coolant lines still attached.



The real work starts on the opposite side, have to remove the valve, EGR pipe and crossover


Here is a detailed look at how the mixer valve is connected


I thought it would be handy to have a reference for how the throttle linkages were connected. Please note the other ball joint on the under side. It was stubborn to reconnect.


I was very afraid of chunks falling into bad places, so I tried to cover gaping holes, especially the ones that would be open for the next 10 hours.


Hey! There is a valve under the cross over pipes. I just detached the bracket and ball joint and left the valve in place. I will clean pipes another time.


Hey! There is a valve under the intake manifold. I took this picture so I could reattach the vacuum lines later. There are also two electrical connectors.


Here is the routing for the crankcase ventilation.


Some of the rubber fittings that fit into the manifold were cracked. This would have been a good time to replace them all if I had planned ahead.


Here is the valve under the manifold after it is unhooked, and the manifold is off.


Sure looks different with out those huge aluminum pipes off.


Man, that glow plug harness housing is in the way! Just when we are getting to where we are going to do the work!


I don't recall if I was shaking with anger over the glow plug harness, or if I was just in a hurry. At any rate, you can get useful access to the delivery valves. I hope you remembered the splined socket.


Sadly, I have no clue what this connector goes to. I don't recall unhooking it, and the car runs with it loose. If you know what it is, and why I should reconnect it, please let me know.



That is it. Assembly is the reverse of disassembly.

Lessons learned:

* Might want to take this task on after the washer bottle is low. Mine was full. When I pulled the little valves it drained for a long time. I could do without the puddle.
* That valve on the underside of the back half of the intake manifold is an irritant. I figure I got all the hoses and wires back together correctly since it runs.
* I wish that I didn't have to unhook the crankcase ventilation tubes at the manifold in order to move a bracket in order to get to all the manifold bolts. One of the old rubber pieces broke off at the manifold. I haven't found the part in town, so I have at least one parts order to make.
* The last two Torx bolts on the intake manifold by the firewall are a bear to get to. You should have a u-joint for your ratchet.
* Those little ball joints don't always want to snap together very easily.
* Some days, a little cable claw tool is the handiest thing. I dropped more stuff on the belly pan!
* It is helpful to have a helper while setting the manifold back in place; it is always good to have an 18 year-old helper for some of the awkward reaching.
* It was useful to take pictures as I went. In fact, I should have taken more. I had at least one screw I had to puzzle over for a good bit.
* The glow plug harness housing is a pain to work around.
* It matters what order things are bolted back on. For example, don't start reattaching fuel lines until those little collars are back on. Also, get the EGR pipe in place before bolting the mixer valve bracket to the engine. Also, the cable doohickey from the passenger side that screws into the top of the plastic cover on the valve cover should be put in place before you bolt the mixer valve to the engine (even better if done before you put the mixer valve in place, but definitely before you bolt to the engine).
* 1995 was a long time ago, and there is a real good chance that some plastic or rubber parts will break while you are at this task. This includes plastic brackets for metal fuel line (it pays to cover the intake ports on the head!) and, most irritatingly, the rubber hoses that plug into the intake manifold as part of the crankcase ventilation system (did they really have to spread it across the whole manifold instead of dripping it into one spot?).
* If you are planning to replace fuel lines, be prepared for diesel to flow.
* Around here 5/16 ID SAE J30R9 fuel injection line is expensive ($9/ft). This will be relevant when I do more about replacing lines later.


Your mileage may vary. Contact me if you have specific questions.

Tom
 

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Tom, this is exactly why we try to encourage members to write up and take photos of repairs so that others can learn from our experiences.

Once again, many thanks.
 

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This is great Tom. I really appreciate the pics, 'cause I'm currently swapping a late model OM606 engine into my car, and I needed to see how the early OM606 throttle arrangement was configured.
 

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Discussion Starter #19
This is great Tom. I really appreciate the pics, 'cause I'm currently swapping a late model OM606 engine into my car, and I needed to see how the early OM606 throttle arrangement was configured.
Happy to help. You got me pointed at replacing the rubber bits back in September. I'm just slow to follow through. :)

I still have some other stuff to do, but successfully getting that manifold off and on unlocks a lot of possibilities.

Tom
 

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I had to order a new delivery valve holder and the dealer noticed that the "valve carrier 7g" is different on cylinder #1. Two through 6 were the same part number. Anybody ever notice any difference?
 
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