Does anyone have any idea why my OM617 begins to run extremely rough when hot
Does anyone have any idea why my OM617 begins to run extremely rough when hot
My car has a N/A om617 that has been turbocharged with a Holset HE221W and has the stock M-pump turned up to max. The car is as fast as I would expect it to be with the fueling I can get from the 5.5mm elements.
The thing is that it runs fine when cold but after it warms up real good (has reached max coolant temp for over 15 minutes) it starts to idle extremely rough like you can see the whole front end of the car shake around and this change in how it runs comes over quite suddenly. I can notice it getting a bit rough and after 2 minutes it's crazy rough.
Revving the engine smooths it out but not completely. It sounds like it's not running right on one of the cylinders. I have a straight pipe and the sound is like when you run a gas engine without 1 spark plug wire, doesn't sound like a 5 cylinder at all but in the higher rpms it seems to fire on that cylinder again at least partially.
I have just checked the valves again and set the clearance to what a 617A would use but it made no difference. Previously I checked the injectors and all were at stock N/A 115 bar
pressure and spray was good.
I haven't checked compression but don't see a reason for that being the issue in this case.
Opening any of the injector lines results in the engine somehow running even rougher and I can't spot which of the cylinders runs rough if it's related to a specific cylinder even.
I assume it can't be a fuel delivery issue to the pump because it can accelerate just fine without any issues expect that you can notice it's a tiny bit slower than when cold.
The only thing I can imagine causing this is something going wrong with an element or a delivery valve after the engine oil gets hot (M-pump uses engine oil for lubrication)
Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
I've heard of pouring cold water over the injection pump if it won't start when hot...similar thinking here maybe
(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
(07-30-2023, 01:13 PM)Alec300SD(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
Slow air incursion into fuel lines (prior to the injection pump) or from cavitation of fuel due to excess suction through clogged filters.
The accumulated air in the injection pump will eventually cause a stumble at idle.
Shine a light though the clear(ish) hard line going from the fuel filter outlet to the injection pump while the car is running.
If present, a small stream of random bubbles will increase in frequency when you raise the engine speed.
Usual culprit is the small rubber fuel hose on either side of the clear primary fuel filter and/or the clear primary fuel filter itself.
The best primary fuel filter I've found is the Hembuller (001 477 79 01) which has the brass inserts.
Best practice is to change both fuel hoses on either side of the primary fuel filter when it is replaced.
Thanks for the reply.
This would make sense. I've replaced all the fuel lines from the fuel tank to the injection pump and the fuel filter but there could still be something wrong.
I will check this soon.
(07-30-2023, 01:13 PM)Alec300SD(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
Slow air incursion into fuel lines (prior to the injection pump) or from cavitation of fuel due to excess suction through clogged filters.
The accumulated air in the injection pump will eventually cause a stumble at idle.
Shine a light though the clear(ish) hard line going from the fuel filter outlet to the injection pump while the car is running.
If present, a small stream of random bubbles will increase in frequency when you raise the engine speed.
Usual culprit is the small rubber fuel hose on either side of the clear primary fuel filter and/or the clear primary fuel filter itself.
The best primary fuel filter I've found is the Hembuller (001 477 79 01) which has the brass inserts.
Best practice is to change both fuel hoses on either side of the primary fuel filter when it is replaced.
Thanks for the reply.
This would make sense. I've replaced all the fuel lines from the fuel tank to the injection pump and the fuel filter but there could still be something wrong.
I will check this soon.
(07-30-2023, 01:13 PM)Alec300SD(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
Slow air incursion into fuel lines (prior to the injection pump) or from cavitation of fuel due to excess suction through clogged filters.
The accumulated air in the injection pump will eventually cause a stumble at idle.
Shine a light though the clear(ish) hard line going from the fuel filter outlet to the injection pump while the car is running.
If present, a small stream of random bubbles will increase in frequency when you raise the engine speed.
Usual culprit is the small rubber fuel hose on either side of the clear primary fuel filter and/or the clear primary fuel filter itself.
The best primary fuel filter I've found is the Hembuller (001 477 79 01) which has the brass inserts.
Best practice is to change both fuel hoses on either side of the primary fuel filter when it is replaced.
You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
(07-30-2023, 01:13 PM)Alec300SD(07-29-2023, 06:32 PM)Echo575 Please suggest anything that I could try to find the problem. This has been an issue for a long time and I want to get it fixed.
Slow air incursion into fuel lines (prior to the injection pump) or from cavitation of fuel due to excess suction through clogged filters.
The accumulated air in the injection pump will eventually cause a stumble at idle.
Shine a light though the clear(ish) hard line going from the fuel filter outlet to the injection pump while the car is running.
If present, a small stream of random bubbles will increase in frequency when you raise the engine speed.
Usual culprit is the small rubber fuel hose on either side of the clear primary fuel filter and/or the clear primary fuel filter itself.
The best primary fuel filter I've found is the Hembuller (001 477 79 01) which has the brass inserts.
Best practice is to change both fuel hoses on either side of the primary fuel filter when it is replaced.
You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
(07-31-2023, 07:10 PM)Alec300SD(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
Just supply fuel from a clean plasic bottle (mini fuel tank) that bypasses the metal feed line from the main fuel tank.
If the bubbles are absent with the mini fuel tank, the problem is aft of the lift pump.
The lift pumps tend to leak air at the old stlye primer pump handle.
The rubber seal on the piston/handle dries out.
The hollow bolt on the fuel filter head seals with an upper aluminum crush washer and a lower rubber o-ring on the "01"
fuel filter head (6150920108) or 2 o-rings on the later "02" fuel filter head (6150920208).
If these seals are inadequate, air can be introduced fom the small bleed hole on top of the fuel filter head.
Hairline cracks on the clear(ish) hard lines tend to happen near the transition into the barbed fittings.
The aluminum crush washers on the banjo fittings can let air leak in.
Any fuel unions that were disturbed previously are also suspect as possible air incursion points.
As mentioned before, the rubber fuel hoses on either side of the primary fuel filter can leak.
The test is to see if they leak is to try and rotate them by firmly twisting them by hand.
If they do rotate, they will leak air.
(07-31-2023, 07:10 PM)Alec300SD(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
Just supply fuel from a clean plasic bottle (mini fuel tank) that bypasses the metal feed line from the main fuel tank.
If the bubbles are absent with the mini fuel tank, the problem is aft of the lift pump.
The lift pumps tend to leak air at the old stlye primer pump handle.
The rubber seal on the piston/handle dries out.
The hollow bolt on the fuel filter head seals with an upper aluminum crush washer and a lower rubber o-ring on the "01"
fuel filter head (6150920108) or 2 o-rings on the later "02" fuel filter head (6150920208).
If these seals are inadequate, air can be introduced fom the small bleed hole on top of the fuel filter head.
Hairline cracks on the clear(ish) hard lines tend to happen near the transition into the barbed fittings.
The aluminum crush washers on the banjo fittings can let air leak in.
Any fuel unions that were disturbed previously are also suspect as possible air incursion points.
As mentioned before, the rubber fuel hoses on either side of the primary fuel filter can leak.
The test is to see if they leak is to try and rotate them by firmly twisting them by hand.
If they do rotate, they will leak air.
(07-31-2023, 07:10 PM)Alec300SD(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
Just supply fuel from a clean plasic bottle (mini fuel tank) that bypasses the metal feed line from the main fuel tank.
If the bubbles are absent with the mini fuel tank, the problem is aft of the lift pump.
The lift pumps tend to leak air at the old stlye primer pump handle.
The rubber seal on the piston/handle dries out.
The hollow bolt on the fuel filter head seals with an upper aluminum crush washer and a lower rubber o-ring on the "01"
fuel filter head (6150920108) or 2 o-rings on the later "02" fuel filter head (6150920208).
If these seals are inadequate, air can be introduced fom the small bleed hole on top of the fuel filter head.
Hairline cracks on the clear(ish) hard lines tend to happen near the transition into the barbed fittings.
The aluminum crush washers on the banjo fittings can let air leak in.
Any fuel unions that were disturbed previously are also suspect as possible air incursion points.
As mentioned before, the rubber fuel hoses on either side of the primary fuel filter can leak.
The test is to see if they leak is to try and rotate them by firmly twisting them by hand.
If they do rotate, they will leak air.
(07-31-2023, 07:10 PM)Alec300SD(07-30-2023, 03:29 PM)Echo575 You were right there is a lot of bubbles coming from the pump return line. Air bubbles are entering from the injection pump fuel pump on the side. Not sure if from fuel pump being broken or fuel line issue before pump.Easy to tell if the air incusion is between the lift pump and the fuel tank.
I'm surprised it runs because there is a constant stream of small bubbles and a few larger ones now and then and from my previous experience, any air causes the engine to shut off.
Just supply fuel from a clean plasic bottle (mini fuel tank) that bypasses the metal feed line from the main fuel tank.
If the bubbles are absent with the mini fuel tank, the problem is aft of the lift pump.
The lift pumps tend to leak air at the old stlye primer pump handle.
The rubber seal on the piston/handle dries out.
The hollow bolt on the fuel filter head seals with an upper aluminum crush washer and a lower rubber o-ring on the "01"
fuel filter head (6150920108) or 2 o-rings on the later "02" fuel filter head (6150920208).
If these seals are inadequate, air can be introduced fom the small bleed hole on top of the fuel filter head.
Hairline cracks on the clear(ish) hard lines tend to happen near the transition into the barbed fittings.
The aluminum crush washers on the banjo fittings can let air leak in.
Any fuel unions that were disturbed previously are also suspect as possible air incursion points.
As mentioned before, the rubber fuel hoses on either side of the primary fuel filter can leak.
The test is to see if they leak is to try and rotate them by firmly twisting them by hand.
If they do rotate, they will leak air.
I would suggest problem is in the pump. Smooth idle until warm, if cold weather, shake may take several hrs. to start.
Engine had dead miss, traced to #4 cyl. idle only. removed delivery valve lapped all parts, reinstalled miss gone .
Shake did return after several weeks, not as bad ,miss has never returned been several yrs.
(08-11-2023, 01:56 PM)Hercules I would suggest problem is in the pump. Smooth idle until warm, if cold weather, shake may take several hrs. to start.
Engine had dead miss, traced to #4 cyl. idle only. removed delivery valve lapped all parts, reinstalled miss gone .
Shake did return after several weeks, not as bad ,miss has never returned been several yrs.
(08-11-2023, 01:56 PM)Hercules I would suggest problem is in the pump. Smooth idle until warm, if cold weather, shake may take several hrs. to start.
Engine had dead miss, traced to #4 cyl. idle only. removed delivery valve lapped all parts, reinstalled miss gone .
Shake did return after several weeks, not as bad ,miss has never returned been several yrs.
I'm having something similar on may daily with an EDC pump . Starts fine, runs nice, warms up and does the shake . Nothing serious, but not mercedes-like .
It also had a smoking problem under full load and high RPM but that seems to have cleared up by changing the fuel pressure bolt on the pump .
(08-14-2023, 03:06 AM)Niko I'm having something similar on may daily with an EDC pump . Starts fine, runs nice, warms up and does the shake . Nothing serious, but not mercedes-like .
It also had a smoking problem under full load and high RPM but that seems to have cleared up by changing the fuel pressure bolt on the pump .
(08-14-2023, 03:06 AM)Niko I'm having something similar on may daily with an EDC pump . Starts fine, runs nice, warms up and does the shake . Nothing serious, but not mercedes-like .
It also had a smoking problem under full load and high RPM but that seems to have cleared up by changing the fuel pressure bolt on the pump .
(08-18-2023, 01:26 AM)Niko Any idea which oil is a better additive for diesel ? The debate was between two stroke oil and ATF, and somewhere I came across the statement that one improves the burn and reduces ash .
(08-18-2023, 01:26 AM)Niko Any idea which oil is a better additive for diesel ? The debate was between two stroke oil and ATF, and somewhere I came across the statement that one improves the burn and reduces ash .