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  #61  
Old 06-15-2010, 12:32 PM
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If that is the case, why are we getting great fuel pressure when we just disconnect the lines by ip and crank the engine? Fuel delivery seems to be good. One of dad's friend said that the little swivel is stuck inside each injector except one because he might have receive water inside his fuel.
As odd as it sounds or impossible, that is the more likely cause. Because the injector pump is full of fuel and continues to get even on return line..

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  #62  
Old 06-15-2010, 05:19 PM
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Clamp the return line or close it temporarily. There is a chance the return relief valve totally failed open.

This way you would get pressure out that line when you pump with no noise of the relief valve squeeling. Some engines will still run with no actual fuel pressure in the base of the pump and some may not in my opinion.

It is still unlikely that something effecting so many elements in the injection pump failed. Still possible of course just unlikely. Your elements may be badly fuel starved if there is zero actual fuel pressure in the base of the injection pump.

You will do no harm by closing the return line off temporarily. The design of the lift pump makes this possible. This is still a long shot though as I would not expect the only element in the pump delivering to be the number three with no pressure.

Think about it though you are not reporting the squeeling of the relief valve nor is the hand primer building pressure to open the relief valve. Perhaps it is open all the time now..

Try the close off of the return valves line on the injection pump. It takes very little time. Not rocket science to do either. Even if it is not the issue it clears the relief valve as the culprit.
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  #63  
Old 06-16-2010, 10:29 AM
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so the relief valve is spring pressured and you think it just stuck? Fuel can unstuck it for good and bring it back to operating order temperately?

Lets say that's the problem, i still dont want to plug my return line every time i get done driving. It still needs a new injector pump right? unless i tare it apart and attempt to fix it which i dont want to waste time on. Let me know thanks.
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  #64  
Old 06-16-2010, 11:43 AM
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Originally Posted by KnightOwl View Post
so the relief valve is spring pressured and you think it just stuck? Fuel can unstuck it for good and bring it back to operating order temperately?

Lets say that's the problem, i still don't want to plug my return line every time i get done driving. It still needs a new injector pump right? unless i tare it apart and attempt to fix it which i don't want to waste time on. Let me know thanks.
If it is a bypass valve spring issue = you do NOT need an injection pump.
Read the following thread on how to fix this issue.

Fuel injection pump starvation with good a good lift pump
http://www.peachparts.com/shopforum/diesel-discussion/247039-fuel-injection-pump-starvation-good-lift-pump.html#post2133911
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  #65  
Old 06-16-2010, 12:29 PM
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That is starting to make more and more sense now. Where is this bolt located and do you have any removal pictures?
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  #66  
Old 06-16-2010, 01:04 PM
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That is starting to make more and more sense now. Where is this bolt located and do you have any removal pictures?
Look at the picture attached to post#1 in the following thread.
#200 in the picture is the bypass valve.
Location is between the injection pump and engine block.


Fuel injection pump starvation with good a good lift pump
http://www.peachparts.com/shopforum/showthread.php?p=2133911
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  #67  
Old 06-16-2010, 01:56 PM
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The closing off is the test to see if it is the problem. There is no way you should try to service the relief valve unless the engine starts to run with the return line closed. It may or may not be fine.

That is why you do the quick test and repair it only if found faulty.

Last edited by barry123400; 06-16-2010 at 02:09 PM.
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  #68  
Old 06-16-2010, 01:56 PM
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Thank you for the information!

One thing i noticed. The spring was at first pretty stiff to move. After pressing with a screw driver back and forth it seems to move more freely now.

However, a thing to note. I notice that the ball that you can see through the hole, it seems like the spring push's it PAST the hole (towards the end of the threaded bolt). If i stick a screw driver and push about 1/8" of a inch BACK, the ball covers the hole completely. Is this correct? Or is my spring pushes the ball too far? Maybe my spring expanded during a hot run?
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  #69  
Old 06-16-2010, 02:14 PM
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Close the line off and check for fuel supply improvement. You should not have taken the ball/spring apart until you did. Put it back on the car and close the line.

Since you already have you might try to establish if you feel the hand primer pump stiffening up and the relief valve making a noise. Still do the close off test if engine will not fuel. At kleast do an air pressure test to see if the vale is closed at say eight pounds pressure.

Otherwise you may go right over the issue if not careful.
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  #70  
Old 06-16-2010, 03:09 PM
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Originally Posted by KnightOwl View Post
Thank you for the information!

One thing i noticed. The spring was at first pretty stiff to move. After pressing with a screw driver back and forth it seems to move more freely now.

However, a thing to note. I notice that the ball that you can see through the hole, it seems like the spring pushes it PAST the hole (toward the end of the threaded bolt). If i stick a screw driver and push about 1/8" of a inch BACK, the ball covers the hole completely. Is this correct? Or is my spring pushes the ball too far? Maybe my spring expanded during a hot run?
The spring can NOT grow, only shorten = become weaker.
If you read the full thread, you know there are two types of valves:
* Repairable.
* Stamped (sealed).

What type do you have?
A picture of it would help.
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  #71  
Old 06-16-2010, 03:50 PM
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Notice how the ball is "pushed pass the hole" by like 1/8 of an inch.

I can take a better picture with camera if needed. Those are my cell phone pics.
Attached Thumbnails
1985 Mercedes 300d Engine died while driving-0616001245.jpg   1985 Mercedes 300d Engine died while driving-0616001245a.jpg  
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  #72  
Old 06-16-2010, 04:07 PM
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Answer

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Originally Posted by KnightOwl View Post
Notice how the ball is "pushed pass the hole" by like 1/8 of an inch.

I can take a better picture with camera if needed. Those are my cell phone pics.
You have the * Stamped (sealed) unit.

You options:
* Find the older style that you can repair.
* Replace it with a new one.

MB# 0000747284
Diesel fuel return valve/banjo bolt, back of injection pump by engine block, at nylon return line going to fuel filter housing.

At this moment (March-12-2009), I have verified five new units remaining in north America.

Application list:

OM615. 910, 911, 912, 913, 914, 915, 916, 917, 919, 930, 932, 936, 937, 938, 939, 940, 941, 942, 943, 944, 963, 970

OM616. 911, 912, 913, 914, 915, 916, 917, 930, 932 933, 934, 936, 937, 938, 939, 940, 960, 961, 963

OM617. 910, 912, 931, 932, 933, 950, 951, 952

OM621. 912, 913, 915, 916, 918, 919, 930, 931, 932

NOTE:
You should replace the banjo bolt/valve seal rings at this time.

Two of the following
Item Number: 007603012111
Main Category: MERCEDES BENZ
Description: SEAL RING, BANJO WASHER
Weight: 0.02
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  #73  
Old 06-17-2010, 11:44 AM
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thanks. as for those washers, i need 2 of them as they are the same for each right?
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  #74  
Old 06-17-2010, 12:19 PM
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Yes

Quote:
Originally Posted by KnightOwl View Post
thanks. as for those washers, i need 2 of them as they are the same for each right?
two..
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  #75  
Old 06-17-2010, 12:36 PM
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Quote:
Originally Posted by KnightOwl View Post
thanks. as for those washers, i need 2 of them as they are the same for each right?
I thought annealing the copper washers sometimes restores them enough for reuse when diifficult to source. Any opinions? This applies to hard to find ones that these are not. Even volkswagon dealers probably stock these.

Since you observed manipulating the relief valve spring and ball loosened it up it may have just been gunked up. Anyways there are many available from the salvage yards still that are the adjustable type. Flush and soak that valve with laquer thinner to remove any gunk.

Reading the thread on the relief valve is time consuming but worthwhile. It is an important part of the fuel supply system.

Also your injection pump could benifit perhaps by a good flushing if that much gunk was present in the relief valve. Of course at a later date after you get the engine running.

If my suspicions are correct a manual cleaning of the delivery valve seats might be in order as well as an injector check at some point if the car is worth it. There is no reason not to suspect the delivery valves especially might have experienced the gunking up as well to some extent if the relief valve was affected.

Depends on how the car runs or does not when the pressure is restored in the base of the injection pump. Thats again if it is certain the pressure was missing. You could have had some remaining pressure with a seriously gunked up delivery valves for example. The relief line could provide some restriction especially with a good quantity of fuel on board to enable this.

I was going to direct you towards the delivery valves in the injection pump if the test for the relief valve failed. No choice if only the number three element was producing output in my opinion. With low to non existant fuel supply pressure it should have been the number one element producing a little more likely than the number three.

That was bothering me and still is. The only hope by me was that your powers of observation or some variable might explain it. The delivery valves cleaning is managable by the individual at least if it comes to it.

I am about ready to start a thread on the importance of having clean proper sealing delivery valves. Plus many other posters inputs into what to expect in general if they are not clean and sealing well. There will be non sealing to various degrees to expect I think. We are fortunate that flow errosion does not seem to be a factor with the actual valves and seats. Or it has never been reported to my knowledge that is very limited of course.

We will have to develop a test where we input some air pressure into each injector line. Or a spare injector line installed in each individual injection pump element port one at a time so it is easily accessed to apply air pressure. With the crank rotation set at established points for each line.

That opens up the input port for the individual element under test. If the valve passes too much air or in fact any the delivery valve is not sealing properly. I suspect we wil have to work out some method like a fluid held in a loop between the air supply and the element as an indicator of any air flow. This should be cheap and accurate.

Kind of a leakdown test for delivery valves I think. Unless someone else has a better ideal. These cars are old and some people especially that burn other than diesel fuel should be aware of what is required.

There were just too many injection pumps being changed out that I suspected just had gunked up delivery valves. Most people assumed it was just totalled element bore problems instead. Again this applies primarily to wvo users.

It of course was possible but few if any ever checked the state of the delivery valves by test before changing the injection pump. Thats if anyone did to my knowledge.

My motavation is simple. As time goes on there will be fewer and fewer good used injection pumps around. We want to see them available for cases where the need is real as they are expensive otherwise.

Has anyone not wondered why a non producing injection pump sent to a pump shop does not come back with new elements usually? Or it is my belief right or wrong they do not. It takes so little time and equipment to do a delivery valve test if the need is indicated. Or it may be an intelligent to do this type of check when trying to get an old 123 running the best it can.

I am slowly trying over time to format a good tune up sequece or if you wish a methology to cheaply check out the few systems on these engines competently ourselves as time moves along. This is in my opinion the least I can contribute to a good site.

During the evalution process other members contribute ideals that lead to refinements and new areas to critically examine with time. Plus my original posted thrust long ago to remove the black box feelings of certain components in the system decreases by most of us part time self repairing types.


Last edited by barry123400; 06-17-2010 at 02:17 PM.
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