Bosch Injectors: Durmax vs. Cummins

[Archive]

The Duramax has been plagued with injector problems. I saw it posted that Bosch has had to replace 60,000 defective injectors for GM.



Anyone know anything definitive? Forum posts by Duramax owners confirm injector problems and a backlog in replacement injectors.



Doesn't Bosch make the injectors for Cummins? Why have these worked so much better than the ones they made for GM?

 

[Vaughn MacKenzie]

Two reasons I have heard, TCSF. First the Bosch units are made to Cummins' specs, and secondly (probably most important reason) the filtration performance on GM trucks is pretty poor compared to the Fleetguard unit on the Ram trucks. I think ours filter to 5-10ppm whereas GM was like 20ppm if I recall correctly.



Vaughn

 

[Buffalo]

Hi, Vaughn. I have two friends with Duramaxes and they are actively looking for fuel systems with pumps and filtering capabilities down to 2 microns. Aparently, it's a serious issue with the GM product. I've called Fleetguard and Cummins and was told that Fleetguard filters to 10 microns and that is good enough. Even talked to a Bosch repair facility in Las Vegas and was told that filtering less than 10 microns is not an issue. I've got to admit that 2 microns sounds better than 10 microns. You seem to have some pretty good connections. Do You have any thoughts about the filteration issue and any products that look good. Thanks for Your input. Joe F.

 

[JoeBioDiesel]

There is also a difference in design. The Duramax injectors require about 2000 watts to open them. the Cummins design uses some of the high pressure fuel to help open the injector. The Cummins injectors are under much less stress, even though they run similar pressures as the Duramax. Simple idea. I don't know why the others are not designed like that.

Joe

 

[Archive]

Thanks for the help. From the reports I've read, the Duramax injectors leak, and since the plumbing is underneath the valve covers, the diesel gets into the crankcase. The most the owners get done under warranty is injector replacement. I guess the Duramax is very cleverly designed since GM doesn't consider that they need replacement after running on a diesel and engine oil blend of lubricant.



Call me stupid since I don't design engines, but injector plumbing is bound to leak on some percentage of owners, so why put it where the diesel fuel can get into the engine lube? Ford did the same thing with the new 6. 0 Powerstroke.

 

[rbattelle]

Check out the pics in this thread. Shows how the injectors have equalized pressure on each side of the plunger, so very little energy is required to move them.

 

[JakeGMCHD]

The Duramax filter is suppose to be 2 micron but it only filters down to 5 micron well. Many of the owners have added true 2 micron filters from Racor or Cat. This still has not corrected the problem with the injectors. Other factors are causing the injectors to fail. GM has said Bosch had some material problems with some of the injectors. GM has also extended the warranty for most of the 2001 & 2002 owners to 7years/200K miles.

 

[Yo Hoot]

There is also a difference in design. The Duramax injectors require about 2000 watts to open them. the Cummins design uses some of the high pressure fuel to help open the injector. The Cummins injectors are under much less stress, even though they run similar pressures as the Duramax. Simple idea. I don't know why the others are not designed like that.

Joe

That's not true. The Dmax injectors work on the same principle, using pressure to open, not the full force of the solenoid. All the solenoid does is open a small port which relieves pressure above the valve allowing the pintle to lift itself. I believe the core of the Cummins injectors are almost the same as the DMax ones. The are Bosch injectors... Cummins or Dmax

 

[Yo Hoot]

Thanks for the help. From the reports I've read, the Duramax injectors leak, and since the plumbing is underneath the valve covers, the diesel gets into the crankcase. The most the owners get done under warranty is injector replacement. I guess the Duramax is very cleverly designed since GM doesn't consider that they need replacement after running on a diesel and engine oil blend of lubricant.



Call me stupid since I don't design engines, but injector plumbing is bound to leak on some percentage of owners, so why put it where the diesel fuel can get into the engine lube? Ford did the same thing with the new 6. 0 Powerstroke.

That's why they re-designed the 04 Dmax engine and put the injectors and plumbing on the outside and called it the LLY



#ad

 

[JoeBioDiesel]

"That's not true. The Dmax injectors work on the same principle, using pressure to open, not the full force of the solenoid. All the solenoid does is open a small port which relieves pressure above the valve allowing the pintle to lift itself. I believe the core of the Cummins injectors are almost the same as the DMax ones. The are Bosch injectors... Cummins or Dmax"





The fact remains that the Duramax injectors require about 2000 Watts to open, where the Cummins requires a fraction of that.



Joe

 

[tractorface]

"Do You have any thoughts about the filteration issue and any products that look good. Thanks for Your input. Joe F. "



I have a Fass with a 2 Micron filter on my truck. Filter is a very stout Hydraulic filter.

Hope this helps

 

[Archive]

"That's not true. The Dmax injectors work on the same principle, using pressure to open, not the full force of the solenoid. All the solenoid does is open a small port which relieves pressure above the valve allowing the pintle to lift itself. I believe the core of the Cummins injectors are almost the same as the DMax ones. The are Bosch injectors... Cummins or Dmax"





The fact remains that the Duramax injectors require about 2000 Watts to open, where the Cummins requires a fraction of that.



Joe

That's a awful lot of electricity! The same amount of juice would be used by 20 one hundred watt bulbs or two 1,000 watt electrical heaters.



Maybe your source of this info misprinted one to many zeros. The number defies common sense. At 12 volts, the wiring would have to be very thick since 2000 watts divided by 12 volts is 166 amperes! This sounds like starting motor amperage, and you'd need starting motor cables.

 

[nickleinonen]

This sounds like starting motor amperage, and you'd need starting motor cables

your starter is peaking at something like 600-750amps at load, then settles down to 400-500 amps...



are you sure the injectors are running at 12v? i remember reading somewhere that the voltage going to the injectors is 48v or 96v... higher voltage will allow thinner gauge cables to be used

 

[Archive]

600 amps x 24 volts = 14,400 watts



8 injectors x 2,000 watts = 16,000 watts.



If the 2,000 watt number is true, those 8 Duramax injectors are using more power than is used by the starter at peak load. That exceeds the capacity of any charging system using one alternator, maybe even two. The batteries would be discharged.



Something doesn't add up. This fails the common sense test. My guess is that an extra zero snuck into this number somehow. Or that 2,000 watts is the total draw for all eight injectors.

 

[JoeBioDiesel]

90 volts, as produced by the fuel injection control module (FICM) at 20 amps. That's why the Duramax runs fuel through it to cool it off. Also remember that the power is only needed for a fraction of time, and the consumption is not continuous. No mistake in the numbers. The 6. 0 Powerstroke runs 48 volts at 20 amps as well.



Joe

 

[Archive]

If the injection event takes place over only a few degrees of crank rotation out of 720 then that current may used as little as one-hundreth of the time compared to continuous use. This would bring power consumption down to reasonable levels, say, 160 watts or so.



Running the fuel through the injection module sounds interesting, especially if there's a short in the module and it starts burning. I wonder if this is done on the Cummins?

 

[rbattelle]

Running the fuel through the injection module sounds interesting, especially if there's a short in the module and it starts burning. I wonder if this is done on the Cummins?

It's not. Good point about the short in the module!

 

[Archive]

Thinking a little further, a component combining electrical wiring with high pressure fuel plumbing would be complicated, and might help explain the high number of premature injector leaks.

 

[Big_Daddy_T]

I think the 7. 3 ran closer to 90v.

 

[CJ8Rockcrawler]

Running the fuel through the injection module sounds interesting, especially if there's a short in the module and it starts burning. I wonder if this is done on the Cummins?

This is really know different than the idea of having an electronic fuel pump in the fuel tank that is cooled by the fuel... something very common on a gasser (and apparently on the 05 diesel rams as well). I would be far more concerned running gasoline as a coolant than diesel... There have been very few issues with the gassers, I would not expect any with the diesel trucks in this instance either.



Kyle