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  #1  
Old 11-10-2009, 12:27 AM
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another possible cause of rough idle

I was talking to my mechanic today while he was working on my service truck. I brought up the rough idle on my 616 and told him I had turned the barrel on my third cylinder delivery valve slightly and the idle smoothed out. He told me that through the life of the car the injection lines are removed , loosened, and tightened.

many mechanics will bump the wrench with their palm , causing the barrel to move around and change the fuel delivery rate . This causes unbalanced cylinders and rough idle. Pulling the pump and bench testing is the only way to get it back in factory specs. Its more common on the barrels with the clamps than ours with the 2 bolts but he has seen it. When breaking loose the lines he recommended using a back up wrench as not to pull or push on the barrel. One more possibility after checking everything else first.
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Old 11-10-2009, 01:52 AM
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I suppose it is possible but, if you put any 25 year old Fuel Injection Pump on the Test Stand it would expect something to be out of spec on it.

There is a lot of parts to wear and a lot to get out of time (each Element is Drip Timed to each lobe if the IP Camshaft with a Degree Wheel or they do the same thing but with a Dial Indicator to measure the stroke of the plunger).

As a Fuel Injection Pump wears the Fuel Delivery quantity and timing to the IP Camshaft become more erratic. And, delivered Fuel quantities decrease slightly.

The exception might be if something in the Governor that could cause excess Fuel delivery. But, this is more often a problem with Pneumatic Governors when the Diaphragm gets stiff.
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Old 11-10-2009, 10:28 AM
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I went and searched barrel adjustment lots of good threads. The video that cervan put on you tube is what got me checking in the first place. The hold down screws were snug but not what I would call tight. I used a thermo gun on my exhaust and matched temp as close as I could to remaining cylinders.

Bosch manual shows the barrels can be changed or removed in the field on the car. It tells you to mark barrel and mark pump housing. Not the shim underneath.....OOPS!!! Shims do move around. Then it tells how to use drip guage to get it back in specs.

Mechanic said on old cat dozers the injection pumps were such a PIA to remove they would rebuild them on the machine and get them close and good enough. Basically same pump as ours inline bosch . M,MW,and Cummins P pump are all in the same family s very similar.
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  #4  
Old 11-10-2009, 01:52 PM
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Quote:
Originally Posted by soothappens View Post
I went and searched barrel adjustment lots of good threads. The video that cervan put on you tube is what got me checking in the first place. The hold down screws were snug but not what I would call tight. I used a thermo gun on my exhaust and matched temp as close as I could to remaining cylinders.

Bosch manual shows the barrels can be changed or removed in the field on the car. It tells you to mark barrel and mark pump housing. Not the shim underneath.....OOPS!!! Shims do move around. Then it tells how to use drip guage to get it back in specs.

Mechanic said on old cat dozers the injection pumps were such a PIA to remove they would rebuild them on the machine and get them close and good enough. Basically same pump as ours inline bosch . M,MW,and Cummins P pump are all in the same family s very similar.

CAT Fuel Injection Pumps compared to a BOSCH Fuel Injection Pump about as much as a Gasoline Engine Compares to a Diesel Engine. They have a lot of the same parts but the parts are way different.

Some CAT Fuel Injection Systems in the Past were made to be replaced like that. The Fuel Injection Elements were calibrated at the Factory to put out the amount of Fuel Specified. On some you could use a depth Micrometer or Dial Indicator to set up the parts in the Main Fuel Injection Pump Housing.

If they did not take apart the whole Fuel Injection Pump and inspect the Bearings and Governor Parts and replace the worn ones they cannot say that they Rebuilt the Fuel Injection Pump in the Field.

When I worked in a Fuel Injection Shop and I was Calibrating a Fuel Injection Pump I was amazed how little movement it took of the Element Fuel Adjustment the make a big change in the amount of Fuel Quantity that the Elements delivered.

The other think is (this is related to your use of the Heat Gun ) that especially on a used Fuel Injection Pump getting the Idle fuel quantity. correct compared to the correct full load fuel is difficult. Because, at idle the Fuel Injection Pump turns slower and the Fuel has more time to leak past worn Plungers in the Elements. So often the idle fuel quantity is more erratic than the more important full load fuel quantity. The full load fuel quantity is the most important; an erratic idle is a nuisance but does no harm.

The way this relates to the use of a Heat Gun to measure the Exhaust temp is that you need to do this while the Engine is under some sort of load. In big Engines they do the with a Pyrometer in each of the Exhaust Manifolds; sometime they Pyrometer port/s is built into the Cylinder head.

Last comment on CAT Fuel Injection Pumps. Despite the fact that some of that on some CAT Fuel Injection Pumps you were supposed to be able to replace the Elements without calibrating the Fuel Injection Pump. We used to Calibrate the ones that were small enough for our test stand to handle and quite a few of them were not within specs.
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  #5  
Old 11-10-2009, 08:30 PM
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Quote:
Originally Posted by Diesel911 View Post
CAT Fuel Injection Pumps compared to a BOSCH Fuel Injection Pump about as much as a Gasoline Engine Compares to a Diesel Engine. They have a lot of the same parts but the parts are way different.

Some CAT Fuel Injection Systems in the Past were made to be replaced like that. The Fuel Injection Elements were calibrated at the Factory to put out the amount of Fuel Specified. On some you could use a depth Micrometer or Dial Indicator to set up the parts in the Main Fuel Injection Pump Housing.

If they did not take apart the whole Fuel Injection Pump and inspect the Bearings and Governor Parts and replace the worn ones they cannot say that they Rebuilt the Fuel Injection Pump in the Field.

When I worked in a Fuel Injection Shop and I was Calibrating a Fuel Injection Pump I was amazed how little movement it took of the Element Fuel Adjustment the make a big change in the amount of Fuel Quantity that the Elements delivered.

The other think is (this is related to your use of the Heat Gun ) that especially on a used Fuel Injection Pump getting the Idle fuel quantity. correct compared to the correct full load fuel is difficult. Because, at idle the Fuel Injection Pump turns slower and the Fuel has more time to leak past worn Plungers in the Elements. So often the idle fuel quantity is more erratic than the more important full load fuel quantity. The full load fuel quantity is the most important; an erratic idle is a nuisance but does no harm.

The way this relates to the use of a Heat Gun to measure the Exhaust temp is that you need to do this while the Engine is under some sort of load. In big Engines they do the with a Pyrometer in each of the Exhaust Manifolds; sometime they Pyrometer port/s is built into the Cylinder head.

Last comment on CAT Fuel Injection Pumps. Despite the fact that some of that on some CAT Fuel Injection Pumps you were supposed to be able to replace the Elements without calibrating the Fuel Injection Pump. We used to Calibrate the ones that were small enough for our test stand to handle and quite a few of them were not within specs.

No more cat I promise . I specialize in hydraulics industrial and mobile.went to school for gassers. I drive diesels , and for five years I've been Trying to get this mercedes from A to B , key word trying. I have done everything in this forum checked and double checked clearances , injectors , pump timing ,head gasket .

The other day found a 21 page thread on 27mm releif spring and video from cervan on barrel adjust and ( good god that was a read ) taa daa ! this thing is smooth as glass at idle.

Also the powerband is amazing ,and went from 20mpg to 28-29. top end is higher and water temp stays right under 80C . just cant believe all that from so little.

In short forgive my ignorance I recently joined this forum (mainly because I havent a clue how these computers work...son set up account)I'm here to learn and knowledge from someone whos done it is what I need, so keep it coming !!!!!
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  #6  
Old 11-11-2009, 02:08 AM
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[QUOTE=soothappens;2336363]No more cat I promise . I specialize in hydraulics industrial and mobile.went to school for gassers. I drive diesels , and for five years I've been Trying to get this mercedes from A to B , key word trying. I have done everything in this forum checked and double checked clearances , injectors , pump timing ,head gasket .

The other day found a 21 page thread on 27mm releif spring and video from cervan on barrel adjust and ( good god that was a read ) taa daa ! this thing is smooth as glass at idle.

Also the powerband is amazing ,and went from 20mpg to 28-29. top end is higher and water temp stays right under 80C . just cant believe all that from so little.

In short forgive my ignorance I recently joined this forum (mainly because I havent a clue how these computers work...son set up account)I'm here to learn and knowledge from someone whos done it is what I need, so keep it coming !!!!![/QUOTE]

In the Factory Service Manual there is a test for the Fuel Supply Pump System and the Overflow Valve Pressure.
Before you tweaked the Overflow Valve spring did the test show that it was not up to pressure?
I am not saying this to be an Axx but I am guessing that the pressure test on the Overflow Valve was not done.

As far a ignorance goes I am here to learn also; and I help when I can.

In my case I lucked out while I was going to Tradeschool learnig Diesel Mechanics I got a job in a Fuel Injection Shop and ended up working there for 5 years. (We also did other things besides Fuel Injection.)
But, getting back to your origional Post and my Post #4 people; Mechanics are going to tell you all kinds of stuff. The only way to weed out what is resonable and what is not is to understand how stuff works and how all that stuff works together.

I am going to go back to the use of that Heat Gun to measure the Exhaust Temp as a way to set your Fuel Injection Pump.
What are the list of things that would have an effect on your Exhaust temp?

If I put a brand new Fuel Injection Pump on my well used 84 300D I would not expect my Exhaust temps to all be the same (even though the Fuel Injection Pump is within specs) because of those other factors a differance in Cylinder Compression between Cylinders being one of them.

It would not make sense (to me) to adjust my Fuel Injection Pump Fuel quanity so that all my Exhausts had the same temp when it could be the difference in compression causing the temp differance.

So if another Mechanic told me that you should set up you Fuel Injection Pump that way I would not do it.
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Last edited by Diesel911; 11-11-2009 at 02:35 AM.
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  #7  
Old 11-11-2009, 10:53 AM
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[QUOTE=Diesel911;2336638]
Quote:
Originally Posted by soothappens View Post
No more cat I promise . I specialize in hydraulics industrial and mobile.went to school for gassers. I drive diesels , and for five years I've been Trying to get this mercedes from A to B , key word trying. I have done everything in this forum checked and double checked clearances , injectors , pump timing ,head gasket .

The other day found a 21 page thread on 27mm releif spring and video from cervan on barrel adjust and ( good god that was a read ) taa daa ! this thing is smooth as glass at idle.

Also the powerband is amazing ,and went from 20mpg to 28-29. top end is higher and water temp stays right under 80C . just cant believe all that from so little.

In short forgive my ignorance I recently joined this forum (mainly because I havent a clue how these computers work...son set up account)I'm here to learn and knowledge from someone whos done it is what I need, so keep it coming !!!!![/QUOTE]

In the Factory Service Manual there is a test for the Fuel Supply Pump System and the Overflow Valve Pressure.
Before you tweaked the Overflow Valve spring did the test show that it was not up to pressure?
I am not saying this to be an Axx but I am guessing that the pressure test on the Overflow Valve was not done.

As far a ignorance goes I am here to learn also; and I help when I can.

In my case I lucked out while I was going to Tradeschool learnig Diesel Mechanics I got a job in a Fuel Injection Shop and ended up working there for 5 years. (We also did other things besides Fuel Injection.)
But, getting back to your origional Post and my Post #4 people; Mechanics are going to tell you all kinds of stuff. The only way to weed out what is resonable and what is not is to understand how stuff works and how all that stuff works together.

I am going to go back to the use of that Heat Gun to measure the Exhaust Temp as a way to set your Fuel Injection Pump.
What are the list of things that would have an effect on your Exhaust temp?

If I put a brand new Fuel Injection Pump on my well used 84 300D I would not expect my Exhaust temps to all be the same (even though the Fuel Injection Pump is within specs) because of those other factors a differance in Cylinder Compression between Cylinders being one of them.

It would not make sense (to me) to adjust my Fuel Injection Pump Fuel quanity so that all my Exhausts had the same temp when it could be the difference in compression causing the temp differance.

So if another Mechanic told me that you should set up you Fuel Injection Pump that way I would not do it.
Appreciate the comeback. As far as the spring I found the thread on possible low pressure ,and figured what the hell I checked everything else. I seen an attachment from benz manual calling for 27mm , my spring was almost a quarter inch shy stretched spring as per attachment and tested.

Idle was improved slightly also started better. I had plumbed a spare cummins electric pump in line before the manual one on the engine a long time ago as fail safe . (thought manual was at end of life ,and a plus if wife runs out of fuel) I flip on this pump and idle would smooth out , top end power would increase = problem somewhere .

Back to 21 page thread. Found video on cyl balance (adjustment of injection quantity ) read training manual quote : "changing the amount of fuel delivered by the MW and P pump simply requires turning the flange sleeve that rotates the plunger in the barrel. after loosening the two nuts movement of the sleeve is possible around the plunger up to a max of 10 degrees" Easy right ? Next sentence "the pump is then run on the TEST STAND until each pumping unit has been adjusted to *factory specs* end quote.

I have noticed since I bought this car that one barrel has been more toward the retard position #3 thus the first one I tried. It smoothed the idle and the engine perked up. I then rotated the barrel listening to idle while my other arm was on valve cover and fender wall. when engine and fender stopped vibrating I locked it down.

Not technical or factory by no means , but it runs good now. I was frustrated enough that pick and pull was going to get a call. While I have countless tools to adjust hydraulics , I have nothing to diagnose this diesel. Tools and training are costly 600 to test pump alone . In comes the diesel mechanic who's first suggestion was pulling the pump and testing.
Alternative was the heat gun . He said it will never be exact until pump is pulled.

Butterfly affect I know . But it received a second life and you guys received another user .

Thanks
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Old 11-11-2009, 11:51 AM
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[QUOTE=soothappens;2336782]
Quote:
Originally Posted by Diesel911 View Post

Appreciate the comeback. As far as the spring I found the thread on possible low pressure ,and figured what the hell I checked everything else. I seen an attachment from benz manual calling for 27mm , my spring was almost a quarter inch shy stretched spring as per attachment and tested.

Idle was improved slightly also started better. I had plumbed a spare cummins electric pump in line before the manual one on the engine a long time ago as fail safe . (thought manual was at end of life ,and a plus if wife runs out of fuel) I flip on this pump and idle would smooth out , top end power would increase = problem somewhere .

Back to 21 page thread. Found video on cyl balance (adjustment of injection quantity ) read training manual quote : "changing the amount of fuel delivered by the MW and P pump simply requires turning the flange sleeve that rotates the plunger in the barrel. after loosening the two nuts movement of the sleeve is possible around the plunger up to a max of 10 degrees" Easy right ? Next sentence "the pump is then run on the TEST STAND until each pumping unit has been adjusted to *factory specs* end quote.

I have noticed since I bought this car that one barrel has been more toward the retard position #3 thus the first one I tried. It smoothed the idle and the engine perked up. I then rotated the barrel listening to idle while my other arm was on valve cover and fender wall. when engine and fender stopped vibrating I locked it down.

Not technical or factory by no means , but it runs good now. I was frustrated enough that pick and pull was going to get a call. While I have countless tools to adjust hydraulics , I have nothing to diagnose this diesel. Tools and training are costly 600 to test pump alone . In comes the diesel mechanic who's first suggestion was pulling the pump and testing.
Alternative was the heat gun . He said it will never be exact until pump is pulled.

Butterfly affect I know . But it received a second life and you guys received another user .

Thanks
Your last post makes more sense to me now. I can see why you suspected something in the Fuel Supply System.

As you most likely have read on the Threads rebuilding the Fuel Supply Pump is extremely easy. The Valve Kit the sell here is aroudn $10 and you would need to scrounge up a 5mmx1.5 mm cross section O-ring (I found a local BMW Dealer that sells the O-ring but had to special order; they clame it will be here today; won't know if the other forum member gave the right size of the O-ring until I see it.).
Besides the Plastic Valaves, springs, and the )-ring the only thing that goes wrong is that I have seen the Piston Spring Break and the Piston get scored up by dirt or rust and stuck by the same items.

Concerning the Fuel Injection Pump when they are calibrated the Full Load Fuel quanity balance per cylinder takes pressedence over the idle Fuel quanity. A poor idle causes no damage.

The reason for this more applies to Trucks or Engines that operate alot close to full load is that over time a Cylinder that is getting more fuel at Full Load can actually cause the Crankshaft to Fail.

I have also seen a Detroit Diesel 71 Series V6 where the Fuel Rod Linkage that went to one bank of Cylinders was worn and the other bank of 3 Cylinders got more fuel and carried more of the load.

The result was that the 3 load bearing Cylinders got deeply scored and 1 Cylinder Liner Cracked. The other bank looked absolutely normal.

On a Car Engine it does not matter so much because the Engine is not under a Full load unless you are towing something heavy at high speeds.
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Last edited by Diesel911; 11-11-2009 at 12:02 PM.
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Old 11-11-2009, 08:33 PM
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[QUOTE=Diesel911;2336815]
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Originally Posted by soothappens View Post

Your last post makes more sense to me now. I can see why you suspected something in the Fuel Supply System.

As you most likely have read on the Threads rebuilding the Fuel Supply Pump is extremely easy. The Valve Kit the sell here is aroudn $10 and you would need to scrounge up a 5mmx1.5 mm cross section O-ring (I found a local BMW Dealer that sells the O-ring but had to special order; they clame it will be here today; won't know if the other forum member gave the right size of the O-ring until I see it.).
Besides the Plastic Valaves, springs, and the )-ring the only thing that goes wrong is that I have seen the Piston Spring Break and the Piston get scored up by dirt or rust and stuck by the same items.

Concerning the Fuel Injection Pump when they are calibrated the Full Load Fuel quanity balance per cylinder takes pressedence over the idle Fuel quanity. A poor idle causes no damage.

The reason for this more applies to Trucks or Engines that operate alot close to full load is that over time a Cylinder that is getting more fuel at Full Load can actually cause the Crankshaft to Fail.

I have also seen a Detroit Diesel 71 Series V6 where the Fuel Rod Linkage that went to one bank of Cylinders was worn and the other bank of 3 Cylinders got more fuel and carried more of the load.

The result was that the 3 load bearing Cylinders got deeply scored and 1 Cylinder Liner Cracked. The other bank looked absolutely normal.

On a Car Engine it does not matter so much because the Engine is not under a Full load unless you are towing something heavy at high speeds.

Yeah the pump has crossed my mind especially reading about the rust found in another members . I still have the old style primer in it , the only thing is it looks newer than anything else on the engine . Since I adjusted # 3 last problem I have is Fuel it seems. Hows that go if it aint broke fix it until it is !

The crank thing has been in the back of my mind and then you went and posted it , I thought my mind was just over thinking this thing. same theroy I had example would be 3 people hitting it with a hammer and 1 with a sledge.

It does seem to run up to speed good now and I use all the rpms without the car shaking when I get there. I'll check into the oring thing I have boxes of them and always got my buddys hyd shop to pick it up.

Thanks !

Last edited by soothappens; 11-11-2009 at 11:31 PM.
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Old 11-12-2009, 01:05 AM
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[QUOTE=soothappens;2337206]
Quote:
Originally Posted by Diesel911 View Post


Yeah the pump has crossed my mind especially reading about the rust found in another members . I still have the old style primer in it , the only thing is it looks newer than anything else on the engine . Since I adjusted # 3 last problem I have is Fuel it seems. Hows that go if it aint broke fix it until it is !

The crank thing has been in the back of my mind and then you went and posted it , I thought my mind was just over thinking this thing. same theroy I had example would be 3 people hitting it with a hammer and 1 with a sledge.

It does seem to run up to speed good now and I use all the rpms without the car shaking when I get there. I'll check into the oring thing I have boxes of them and always got my buddys hyd shop to pick it up.

Thanks !
I do not think in a Diesel Car it would ever be under a load Enough to Brake a Crankshaft under the conditions I was speaking of.

And, besides being under near Max load a lot consider the amount of Hours/Miles a Truck puts on in a short period of time.
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Old 11-12-2009, 10:07 AM
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[QUOTE=Diesel911;2337450]
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I do not think in a Diesel Car it would ever be under a load Enough to Brake a Crankshaft under the conditions I was speaking of.

And, besides being under near Max load a lot consider the amount of Hours/Miles a Truck puts on in a short period of time.

Point taken. Thanks for helping me sleep again!! Using the car as a field service truck right now, gonna pull the lift pump/primer and check it as soon as it stops its double duty.

06' f650 with cummins 5.9 160,000miles ecm failure lift pumps galore injectors hydroboost etc etc etc!!!!! Thats for a different forum though !

Thanks for all the help I'll post what i find on lift pump.
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