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  #1  
Old 05-24-2016, 04:49 PM
multi string slinger
 
Join Date: Jan 2014
Location: Los Angeles, CA United States
Posts: 113
Fuel delivery related shaking

Hi folks,

I ve been trying to get to the bottom of my incessant shaking OM617 Non-Turbo 300D (1978).

Pretty much everything in the fuel delivery system has been gone through, valve adjustment, new OFV spring and injector rebuild from Greazzer, new filters, fuel system cleaner, diesel purge, new hand primer pump etc.

My car revs really nicely and has decent power compared to other W123s I ve driven. I did notice recently that some days it shakes less and the engine sounds "better" at idle, other days it rocks the whole car, the hood and there is an obvious knock. The power/performance difference in both cases is negligible. Just the idle is much worse in the latter.

Is there a reason why with the same tank of diesel (I use HPR - which makes it run much better than regular diesel) it has such varying idle performance? My mounts are relatively new and Phoenix/Lemfoerder.

I m suspecting that my fuel delivery system has some inconsistencies that are affecting idle performance from day to day.

I recently found a video by a fellow forum members of his car after a delivery valve change. It seemed to have gotten rid of his shaking. I m wondering if old delivery valves can cause inconsistent idling.

What else in your opinions can cause this?

Your ideas are sincerely appreciated.

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  #2  
Old 05-24-2016, 07:02 PM
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Join Date: Oct 2012
Posts: 5,924
One helpful member mentioned putting a piece of clear fuel line in the fuel return. That way if say air entering is a variable or system drain back because of worn lift pump valves you will see air in the fuel.

There should be nothing more than solid fuel in that line at all times. Air has more effect on idle than at any other operational point on these engines. If you have no overflow into that line also fuel pressure may be low. If the valve made a difference when installed it probably has good enough fuel pressure. It should still overflow though and I assume the major fuel filter is not ancient.
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  #3  
Old 05-24-2016, 08:11 PM
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Location: Washington D.C.
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Where do you get new delivery valves? Dealership? Anyone have experience with this. I'm kinda on the same boat and wondering what to replace. I'd like to tackle the delivery valve route to solve rough idle
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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
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Last edited by brownrice78; 05-24-2016 at 08:46 PM.
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  #4  
Old 05-25-2016, 04:03 AM
multi string slinger
 
Join Date: Jan 2014
Location: Los Angeles, CA United States
Posts: 113
hi barry12345 - Thanks. By "return" in this case, are you referring to the individual return lines from each injector?
If so, I used to have clear ones in the past and there was always a little air bubble that hovered around the bend in the lines. I think that suggested there was no additional air coming in or going out ? Am I assuming wrong? Or does that suggest that there was active air moving? Either way, I replaced those not too long ago with the braided ones when I got the injectors from Greazzer. So I cant see anything anymore.

the lines from IP to the large spin-on filter are dark with age (see video below) and I cant see whats going on in them. Did you mean these guys?

Here is a video of the shaking

https://www.youtube.com/watch?v=YFf2zr1SSQU

As you can hear, the engine sounds nice and once the revs are up, its awesome. Unfortunately I do a lot of city driving and spend a lot of time at low revs or idle, stop lights/traffic. I love my car but I am just tired of the shaking.

----

brownrice78 - Good luck friend! I ve looked everywhere. My last hope is to ask the dealer - it will most likely be a sad and ridiculous dollar amount so I fear, this might be something I will just have to live with....or get a newer gas Mercedes
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  #5  
Old 05-25-2016, 04:36 AM
cho's Avatar
cho cho is offline
diesel power
 
Join Date: Dec 2011
Location: Europe
Posts: 934
dv's

Quote:
Originally Posted by guyonabuffalo View Post

I recently found a video by a fellow forum members of his car after a delivery valve change. It seemed to have gotten rid of his shaking. I m wondering if old delivery valves can cause inconsistent idling.
if the guy mentioned is Eaton, my advice to him worked,...it may not be
applicable for you...but if you are having serious and most violent shakes after a good highway run and then stop and idle.. I'm most certain that your problem IS worn delivery valves.

the thing is,.. over here in Europe dealer does not have any available
only Bosch can supply those...quite pricey as I remember...30 bucks per piece or so.... sometimes it is much easier to source dv's from another good runnin IP.... if you are scared of IP swap all together....

for the p/n of dv's search my old threads here on PP ....


cheers

ChO


..
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Last edited by cho; 05-26-2016 at 03:21 AM. Reason: typo
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  #6  
Old 05-25-2016, 06:45 AM
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Join Date: Dec 2012
Location: Albuquerque, NM
Posts: 173
rack damper?

Your delivery valves may indeed be contributing to the problem, but why not start with fixing/adjusting the things that are easiest/cheapest first?

Have you tried adjusting the rack damper? Lots of info on the web.

You can also temporarily replace the cigar hose with a segment of clear vinyl hose to check for air in the fuel. The cigar hose is also supposed to absorb pulsations from the fuel pump and you can see a new one expanding and contracting when the engine idles. Maybe your cigar hose is old and hard?

Have you tried a diesel purge?
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  #7  
Old 05-25-2016, 11:16 AM
Diesel Preferred
 
Join Date: Oct 2007
Location: Charleston SC
Posts: 2,788
Time for a Lubromoly Diesel Purge treatment. I think Napa carries it. Perform on a hot engine, disconnect the suction and discharge fuel lines in the engine bay and run the pure diesel purge right through the engine until it is all consumed.

Edit: I see you list this, so ignore unless you (a) just dumped it into the fuel tank or (b) did this on a cold engine.

Next, I vote for rebuild of the delivery valves (if that applies to this IP). Generally a valve adjustment is the first step, and then after eliminating injectors as the source, the next most common thing would be a problem in the delivery valves. Diesel purge may fix it, if not then I'd rebuild them.

I know on later 123 and 124 cars, the delivery valves have a copper washer and a spring inside, and both can be replaced. Later models also have O-rings that can leak, but I think your car does not have O-rings?
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/s/
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'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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  #8  
Old 05-25-2016, 12:34 PM
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Quote:
Originally Posted by guyonabuffalo View Post
hi barry12345 - Thanks. By "return" in this case, are you referring to the individual return lines from each injector?
If so, I used to have clear ones in the past and there was always a little air bubble that hovered around the bend in the lines. I think that suggested there was no additional air coming in or going out ? Am I assuming wrong? Or does that suggest that there was active air moving? Either way, I replaced those not too long ago with the braided ones when I got the injectors from Greazzer. So I cant see anything anymore.

the lines from IP to the large spin-on filter are dark with age (see video below) and I cant see whats going on in them. Did you mean these guys?

Here is a video of the shaking

https://www.youtube.com/watch?v=YFf2zr1SSQU

As you can hear, the engine sounds nice and once the revs are up, its awesome. Unfortunately I do a lot of city driving and spend a lot of time at low revs or idle, stop lights/traffic. I love my car but I am just tired of the shaking.



----

brownrice78 - Good luck friend! I ve looked everywhere. My last hope is to ask the dealer - it will most likely be a sad and ridiculous dollar amount so I fear, this might be something I will just have to live with....or get a newer gas Mercedes
The fuel return line I meant is the main one and there is only one return line off of the relief valve on the injection pump. Just my opinion but you should make certain you are not processing air into the fuel when the engine is running rough before moving on.

No from every indication I have seen so far you do not have to live with it. Do you have any ideal of how long this engine has been running on other than straight diesel fuel? Fortunately like my 77 300d the injection pump you have is not in demand like the turbo engine pump is.

These cars are not scrapped out because their injection pumps are bad usually. Even though you have not done a compression check since the car idles normal sometimes it is a reasonable assumption that the compression of the engine is probably not the issue.

I have a few simple rules when buying a used in line injection pump. Take it off a vehicle that still has fuel in the fuel system. Try to get one off of a salvage car that does not look to be beaten to death by milage. Living in a rustbelt makes this pretty simple in many areas.

A typical thing you noticed was the engine runs better and less rough at idle when not using diesel fuel. So in the case of your car if it where mine. I would make positive that there is no air when running rough. Get a cheap used pump and sub it. If it cures the problem fine. If not you have a good pump to sell if you want or need the money.

My approach is based on a couple of things. Easier on the head and the cheapest way to get past an expensive possibly suspect component. Most the time it is not the injection pump is certain. Yet at times it still will be. It also would take me much more than fifty dollars worth of time to do all the tests to absolutely verify the injection pump is the issue in your case. If your car where mine I probably would be running those tests already. Or subbing in a pump if I lived in an area where one was easily found cheap enough. Also my policy is to never install an old in line injection pump that has been sitting around dry of fuel.

I also like simple tests. If you have a pretty normal idle when the engine is cold. Take the car for a drive until you have the rough idle. Go back home and feed a small stream of water onto the injection pump with a garden hose.. If a much better idle results in a minute or so you may have one or more worn elements in the injection pump. Another old test is to run the engine on straight vegetable oil from a can. If no rough idle occurs once again it is probably a worn pump element situation. You have to allow enough run time to get rid of your current fuel in the filter remember for this test. As the fuel heats up in the injection pump the viscosity of it thins out. Marginal elements stop pumping the fuel as well then. Sometimes not even reaching the pop off pressure of the injector nozzles. Your cooling of the injection pump will increase the fuel viscosity enough that marginal elements can raise the pressure back up again.

Last edited by barry12345; 05-25-2016 at 02:48 PM.
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  #9  
Old 05-25-2016, 01:42 PM
multi string slinger
 
Join Date: Jan 2014
Location: Los Angeles, CA United States
Posts: 113
Thanks for all your suggestions.

Maxbumpo, I ve done numerous diesel purges in the past. The car idles relatively better for a week or two and then back to shaking. My injectors have been rebuilt recently. I ve been at this for quite a while now so I ve tried pretty much all the general items that could potentially lead to a shakey idle.

Greazzer did mention that there would be a slight lope. However; from my video you can clearly see that its more than just a slight lope.

This morning on the drive to work, it was much less shakey. This is exactly my problem, the inconsistency. I have drives that are relatively smooth but others where I feel like leaving the car and walking. On a hot afternoon, sitting in a hot car (no a/c) getting your teeth shaken out gets a little tiring.

Thank you all for your help. I will change the return lines to the filter with clear ones and check for air bubbles.

Will also call the local Bosch shop to see if they can get me delivery valves and copper washers.
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  #10  
Old 05-25-2016, 01:49 PM
oldsinner111's Avatar
lied to for years
 
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Location: Elizabethton, TN
Posts: 6,246
check tank and screen

Mine every once in a while plugs up.I connect air to line coming from tank,and blow out line.Be sure and removed fuel cap.I had my tank cleaned once before.
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  #11  
Old 05-25-2016, 04:03 PM
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Quote:
Originally Posted by guyonabuffalo View Post
Thanks for all your suggestions.

Maxbumpo, I ve done numerous diesel purges in the past. The car idles relatively better for a week or two and then back to shaking. My injectors have been rebuilt recently. I ve been at this for quite a while now so I ve tried pretty much all the general items that could potentially lead to a shakey idle.

Greazzer did mention that there would be a slight lope. However; from my video you can clearly see that its more than just a slight lope.

This morning on the drive to work, it was much less shakey. This is exactly my problem, the inconsistency. I have drives that are relatively smooth but others where I feel like leaving the car and walking. On a hot afternoon, sitting in a hot car (no a/c) getting your teeth shaken out gets a little tiring.

Thank you all for your help. I will change the return lines to the filter with clear ones and check for air bubbles.

Will also call the local Bosch shop to see if they can get me delivery valves and copper washers.
Was it a much colder day when you had a better idle? Hotter? Or just average? There almost has to be a variable at work here. Shakes like hell on a really hot day compared to a cooler one is more likely to be the injection pump. The injection pump temperature is usually much hotter and the fuel inside thinner as a result.

Only one line in the fuel return from the injection pump has to be clear. Why not buy a cheap used injection pump as it may provide a much cheaper source of delivery valves? it looks like you live in an area that the non turbo pumps used may be available easily and cheap enough. Remember again that in most areas there is no to little demand for the used non turbo pumps. Many of our members like myself tend to be thrifty individuals. Just a byproduct of being older and as they say old habits seem to die hard even after you have acquired a lot of money.

Then if the delivery valves from it are not the problem. You have a pump to install if the old pump has an element issue. Delivery valve problems are more likely to be constant than element problems are.

One correction. I noticed you replaced the injectors after you did several purge cleanings. Improvements lasting a few days are not uncommon with old injectors. . I will stop posting on your thread though rather than drive you crazy.

All four of my diesel engines run really well because they are simply afraid of me I suspect.
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  #12  
Old 05-25-2016, 04:30 PM
multi string slinger
 
Join Date: Jan 2014
Location: Los Angeles, CA United States
Posts: 113
Thanks Barry,

You might be right about the worn elements. My problem isnt constant, like I said it runs nice sometimes, idles and revs smooth etc. Rattles my jaw other times.

From what I ve read on this and other forums, element change is not an easy thing and requires a lot of specialized skill. I think I will look for one or two non-turbo pumps then just to try.

Thanks for all the help, your wisdom is greatly appreciated. Please continue posting, I m sure everyone appreciates it.
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  #13  
Old 05-25-2016, 04:46 PM
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If someone has not mentioned it previously Valve Adjustment.
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  #14  
Old 05-26-2016, 09:45 AM
Diesel Preferred
 
Join Date: Oct 2007
Location: Charleston SC
Posts: 2,788
Quote:
Originally Posted by Diesel911 View Post
If someone has not mentioned it previously Valve Adjustment.
I don't think that would make the idle get better and then worse, or respond to a Diesel Purge treatment, but I could be wrong. However, I do agree that it should be done because there may be many small things wrong that are contributing.

After the valve adjustment, I'd rebuild the delivery valves.
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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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  #15  
Old 05-26-2016, 07:13 PM
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What constitutes rebuilding the delivery valves? Do you just replace them and the copper washers? What about the springs?

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1983 300 Turbo-"Nora"
1983 240D Auto "Lucia"-slowest on earth-1st love
1985 300 Turbo-Blue Goose-slowly plucking parts

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