D6T running rough, now won't start. Thinking HEUI pump.

[02Dmax]

Machine number KJL00898
Engine number THX14748
6700 hrs.

For the past few months this dozer will throw a fit now and then and it would cough, blow white smoke, maybe die, maybe just almost die. But they'd shut it off, let it sit for a few minutes and it'd be fine. Might run for another 40 hours before it did it again.

Recently it's gotten worse and the fits were becoming more common so they decided to address it. Yesterday when I started on it the machine was running slightly rough but not really missing. It was definitely low on power though. No codes, all vitals being watched through Cat ET checked out fine. I had my suspicions of #4 injector but couldn't prove to myself it was the problem.

I returned today to sort it out and it had to crank for 15 seconds or so to start. It ran for about 10 minutes then just died and now won't restart.

Actuation pressure while cranking is only showing 530 psi and I believe minimum is 800 to start.

Engine oil pressure is 35 psi and fuel pressure is 38 psi - both while cranking.

I confirmed all these pressures with manual gauges.

Is there anything else I should check before replacing the HEUI pump and all 6 injectors? It's at 6700 hrs which I've found to be close to the magic number for these C9's needing both.

Any input is appreciated.

 

[02Dmax]

Ok, I got it running again. After I looked closely at the injectors I noticed that #1 was dumping oil and none of the others were while cranking. I brought an injector with me this morning so installed it and it fired right up.

Now it's just dead on that cylinder because I don't have the matching trim file. Should the dealer supply me with that trim file?

 

[Nige]

If the injector was bought from the same dealer and you're a regular cusomer I think they should supply you with the Trim file.

One thing strikes me as strange though. The trim file simply fine tunes the injector output. AFAIK the injector shouldn't be "dead" until the trim file is installed because the ECM is not intelligent enough to know which specific injector it's hooked up to, only that its hooked up to an injector. IMHO it should be firing on that cylinder.

 

[Cmark]

+1 on what Nige said.

The correct trim file isn't necessary to make it run. Can't remember right now for the C9 but some injectors have the trim file on a CD supplied with the injector, others have a trim code stamped on the injector which you type straight into ET. Either way, you shouldn't need a dealer's help.

 

[dblaneyfan]

There is a procedure for checking the coil in the HEUI, basically drain/suction the oil out of the pump, then remove the top cover and inspect the coil for metal shavings. On our first failure we were able to remove the line going to the rail and catch some of the oil, found silver/metal in the oil, but that was the original pump design. Newer designs are supposed to avoid contaminating the system, or so I've been told.

 

[02Dmax]

I started it again and let it run for awhile and it came out of the miss.

I was like you guys, I didn't think it had to have the exact trim code to fire but it was the only thing I'd changed.

However, it still has a flutter when accelerating engine speed and is low on power.

No codes. The injectors (besides the one I put in today) are all original and so is the HEUI pump.

 

[Nige]

You really need to get ET on it and do a cylinder cutout test.

 

[02Dmax]

I did. They all cut out basically identical. All the solenoids are clicking during the solenoid test. They all seem to be releasing the same amount of oil while running.

This same outfit has a D6R that acted exactly like this at the same hours and I replaced the pump and all 6 injectors. It fixed it and hasn't had a problem since. It just rolled over 15,000 hrs.

 

[big ben]

Well sounds like you know what the outcome is going to be. Low HEUI pressure when cranking and now a miss. As mentioned pull the top cover and check the coil for fine metal. Also you should be able to run a HEUI pump test while its running with ET basically it tests the pump by stepping up the pressure. Monitor what the desired and actual pressures are while this is going on.

Make sure you clean the oil rail and cross drillings in the head when you are doing the clean out !!!

 

[02Dmax]

Thanks big ben.

Ya once I did my homework on these things I became super OCD when replacing the components. I clean everything with solvent, brake clean, and air. And a soft pipe cleaner - like brush where I can get it.

 

[Nige]

I did. They all cut out basically identical. All the solenoids are clicking during the solenoid test. They all seem to be releasing the same amount of oil while running.

all you did is to test the solenoids, not the operation of the injectors themselves. I mean to do a test where you cut out one or more cylinders at a time when the engine is running at low idle. On the 16-cylinder engines the test would cut out 11 cylinders and have it hitting on only 5. It puts so much load on the injectors that if one is dodgy it shows up straight away in the injection duration. So on a 6-cylinder I'd be cutting out at least 3 cylinders, maybe 4.

 

[02Dmax]

Sorry, I should've clarified. I also did a cutout test while it was running. I cut out 3 at a time then added a 4th to try and single one out. None of them stuck out as significantly worse than any of the others.

Yesterday I was leaning towards #4 because it was 50 degrees hotter at the exhaust than the nearest other port in temperature.

 

[02Dmax]

By the way, it would not stay running on any 2 cylinders. It would slowly drag down and die no matter what combination of cylinders I tried. Not sure if that's common or all the injectors are just that weak.

 

[Cmark]

This same outfit has a D6R that acted exactly like this at the same hours and I replaced the pump and all 6 injectors. It fixed it and hasn't had a problem since. It just rolled over 15,000 hrs.

Yes, I remember.

https://www.heavyequipmentforums.com/showthread.php?32468-CAT-D6R-w-C9-fluttering-under-load/page3

I bet you end up doing the same thing.

 

[02Dmax]

Yes, I remember.

I bet you end up doing the same thing.

That was actually yet a different machine but once again, same issue.

I gave the owner my opinion and he told me to go ahead so she'll be getting the works next week. Thanks guys.

 

[Mark250]

Hi 02Dmax, you posted a fuel pressure of 38 psi. seems a bit low to me remove the fuel pressure regulator at the back of the head. dismantle and inspect the check valve and screen. these check valves have given a bit of trouble over the years and have been updated a few times. Also the debris in the screen is a good indicator of failed pump bearings along with checking the coil in the pump as posted above
Mark

 

[02Dmax]

Hi 02Dmax, you posted a fuel pressure of 38 psi. seems a bit low to me remove the fuel pressure regulator at the back of the head. dismantle and inspect the check valve and screen. these check valves have given a bit of trouble over the years and have been updated a few times. Also the debris in the screen is a good indicator of failed pump bearings along with checking the coil in the pump as posted above
Mark

38 psi was while cranking. It's running up around 80 at a high idle.

 

[daterplant]

We had a similar problem on a D6T a new set of injectors was fitted, ran ok for a few hours then same thing running rough and misfiring. If you got access to Cat info check REHS3819 gives the procedure for troubleshooting and cleaning the oil rail system.
We found that the heui pump was worn sending contamination through the system and damaging the injectors, as mentioned above an updated pump is available which has a larger front bearing, you may also need a fitting kit which has pipes and fittings to suit the updated pump.