IP element question
IP element question
05-29-2020, 12:58 PM
#1
Long time reader, first time poster.
Having an unusual issue with my om616 and suspect an equally unusual cause.
As you have far more experience tearing down pumps than perhaps anyone, I'm wondering if anyone has ever encountered an internally leaking fuel element.
There must be a seal, o-ring or other that prevents fuel from entering the IP cam area.
How does this area work?
Difficult finding info on what goes on in there.
Hey gang,
Long time reader, first time poster.
Having an unusual issue with my om616 and suspect an equally unusual cause.
As you have far more experience tearing down pumps than perhaps anyone, I'm wondering if anyone has ever encountered an internally leaking fuel element.
There must be a seal, o-ring or other that prevents fuel from entering the IP cam area.
How does this area work?
Difficult finding info on what goes on in there.
05-29-2020, 01:07 PM
#2
(05-29-2020, 12:58 PM)Shern Hey gang,Are you talking about the area in between the plunger and barrel? There is no seal or o-ring there, they are machined to high tolerances and honed. When reassembling the pump, Bosch recommends that the elements are installed, the pump submerged in test oil, and compressed air fed in at pressure while the operator watches for bubbles. Hypothetically, if poor quality fuel was run for a long time I suppose the inside of the barrel could wear out, but I don't think it's likely. Have you found fuel inside the pump housing? Depending on what year you have, it either has its own oil, or it has oil fed from the engine and returned to the engine. You can see the rebuilding instructions and everything else for the MW-pump here: https://archive.org/details/MWpump and if you have an M-pump, it will be somewhere in here: https://archive.org/details/warchive . What makes you suspect the fuel elements?
Long time reader, first time poster.
Having an unusual issue with my om616 and suspect an equally unusual cause.
As you have far more experience tearing down pumps than perhaps anyone, I'm wondering if anyone has ever encountered an internally leaking fuel element.
There must be a seal, o-ring or other that prevents fuel from entering the IP cam area.
How does this area work?
Difficult finding info on what goes on in there.
(05-29-2020, 12:58 PM)Shern Hey gang,Are you talking about the area in between the plunger and barrel? There is no seal or o-ring there, they are machined to high tolerances and honed. When reassembling the pump, Bosch recommends that the elements are installed, the pump submerged in test oil, and compressed air fed in at pressure while the operator watches for bubbles. Hypothetically, if poor quality fuel was run for a long time I suppose the inside of the barrel could wear out, but I don't think it's likely. Have you found fuel inside the pump housing? Depending on what year you have, it either has its own oil, or it has oil fed from the engine and returned to the engine. You can see the rebuilding instructions and everything else for the MW-pump here: https://archive.org/details/MWpump and if you have an M-pump, it will be somewhere in here: https://archive.org/details/warchive . What makes you suspect the fuel elements?
Long time reader, first time poster.
Having an unusual issue with my om616 and suspect an equally unusual cause.
As you have far more experience tearing down pumps than perhaps anyone, I'm wondering if anyone has ever encountered an internally leaking fuel element.
There must be a seal, o-ring or other that prevents fuel from entering the IP cam area.
How does this area work?
Difficult finding info on what goes on in there.
05-29-2020, 01:27 PM
#3
I'm trying to account for a fuel drain back issue.
In short, the fuel level in the clear IP return line drops after shutdown.
About an inch or two within the hour and about 4-5 inches over night. No further beyond that point regardless of time.
Important to note that bubbles are not rising, the fuel level itself is dropping.
If I pinch off the inlet line before the prefilter, I still get a drop overnight.
If I pinch off the inlet and return line (thus isolating the fuel circuit), I don't get a drop, but I do get air in the system and have a harder time starting.
I have three possible suspects...
1.) the o-ring in the lift pump is allowing latent fuel pressure to force diesel into the engine oil of the IP.
2.)The valves in the lift pump are not seating properly allowing some kind of drain back (this doesn't really track though with the pinched off line)
3.) fuel is draining out of the IP somehow.
Basically, it has to be going somewhere.
There's a peachpart post on the subject.
Copy that, thank you. FYI it's an 81 240D with an MW pump. The oil is supplied by the engine.
I'm trying to account for a fuel drain back issue.
In short, the fuel level in the clear IP return line drops after shutdown.
About an inch or two within the hour and about 4-5 inches over night. No further beyond that point regardless of time.
Important to note that bubbles are not rising, the fuel level itself is dropping.
If I pinch off the inlet line before the prefilter, I still get a drop overnight.
If I pinch off the inlet and return line (thus isolating the fuel circuit), I don't get a drop, but I do get air in the system and have a harder time starting.
I have three possible suspects...
1.) the o-ring in the lift pump is allowing latent fuel pressure to force diesel into the engine oil of the IP.
2.)The valves in the lift pump are not seating properly allowing some kind of drain back (this doesn't really track though with the pinched off line)
3.) fuel is draining out of the IP somehow.
Basically, it has to be going somewhere.
There's a peachpart post on the subject.
05-29-2020, 03:06 PM
#4
(05-29-2020, 01:27 PM)Shern Copy that, thank you. FYI it's an 81 240D with an MW pump. The oil is supplied by the engine.I read through it a few times over there and couldn't think of much. In the MW-pump collection on archive.org I linked in my earlier reply, there are testing instructions and rebuild instructions for the lift pump (RP/K22MW22) which might help, as you can test the pressures of the pump.
I'm trying to account for a fuel drain back issue.
In short, the fuel level in the clear IP return line drops after shutdown.
About an inch or two within the hour and about 4-5 inches over night. No further beyond that point regardless of time.
Important to note that bubbles are not rising, the fuel level itself is dropping.
If I pinch off the inlet line before the prefilter, I still get a drop overnight.
If I pinch off the inlet and return line (thus isolating the fuel circuit), I don't get a drop, but I do get air in the system and have a harder time starting.
I have three possible suspects...
1.) the o-ring in the lift pump is allowing latent fuel pressure to force diesel into the engine oil of the IP.
2.)The valves in the lift pump are not seating properly allowing some kind of drain back (this doesn't really track though with the pinched off line)
3.) fuel is draining out of the IP somehow.
Basically, it has to be going somewhere.
There's a peachpart post on the subject.
This post was last modified: 05-29-2020, 03:06 PM by nastala.
(05-29-2020, 01:27 PM)Shern Copy that, thank you. FYI it's an 81 240D with an MW pump. The oil is supplied by the engine.I read through it a few times over there and couldn't think of much. In the MW-pump collection on archive.org I linked in my earlier reply, there are testing instructions and rebuild instructions for the lift pump (RP/K22MW22) which might help, as you can test the pressures of the pump.
I'm trying to account for a fuel drain back issue.
In short, the fuel level in the clear IP return line drops after shutdown.
About an inch or two within the hour and about 4-5 inches over night. No further beyond that point regardless of time.
Important to note that bubbles are not rising, the fuel level itself is dropping.
If I pinch off the inlet line before the prefilter, I still get a drop overnight.
If I pinch off the inlet and return line (thus isolating the fuel circuit), I don't get a drop, but I do get air in the system and have a harder time starting.
I have three possible suspects...
1.) the o-ring in the lift pump is allowing latent fuel pressure to force diesel into the engine oil of the IP.
2.)The valves in the lift pump are not seating properly allowing some kind of drain back (this doesn't really track though with the pinched off line)
3.) fuel is draining out of the IP somehow.
Basically, it has to be going somewhere.
There's a peachpart post on the subject.
05-29-2020, 04:44 PM
#5
I've committed to re-rebuilding the pump again. It should only take a few hours and then I can hopefully eliminate that as a cause.
Have you ever heard of one of these newer style bosch primers leaking air but not fuel?
05-29-2020, 05:06 PM
#6
(05-29-2020, 04:44 PM)Shern I appreciate you taking the time.I've never seen one leak, nor have I seen anyone say it leaks. I have diagrams of the old style of primer pump, but not the new one.
I've committed to re-rebuilding the pump again. It should only take a few hours and then I can hopefully eliminate that as a cause.
Have you ever heard of one of these newer style bosch primers leaking air but not fuel?
(05-29-2020, 04:44 PM)Shern I appreciate you taking the time.I've never seen one leak, nor have I seen anyone say it leaks. I have diagrams of the old style of primer pump, but not the new one.
I've committed to re-rebuilding the pump again. It should only take a few hours and then I can hopefully eliminate that as a cause.
Have you ever heard of one of these newer style bosch primers leaking air but not fuel?
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