It really bothers me when I seen posts from new folks like you (5) who make time to do a thorough write up of your situation, then get no replies.

As I’ve said before, I fear many old timers here have moved on to new rides and the ones who are still around are beginning to weary of answering the same questions, over and over...

Where was I?

Oh yea, starting with possible “fuel in oil” search this forum for “oil spot” test which will give an indication if that problem persists.

Also, search is your friend (on this forum or Google) with many suggestions and tests that are fairly straightforward.

Hope I haven’t insulted your intelligence, but in the current state of our forum, I’m afraid DIY is the order of the day .

Best

 

Hi stevewaclo - I appreciate the reply.

Yes, search is good and I have used it quite a bit. But I haven't found anything that seems to fit these symptoms (after CP3 replacement) - and to be honest looking through search results threads gets tedious quickly. I like to think forums have those that don't mind repeating them selves or pointing to something specific where they answered the question previously - but I guess like you said most of those folks have moved on.

The more I think about it the more I think I didn't need to change the CP3 and that my leak is probably at one of the high pressure line to injector connections. I know if it is an injector I would replace those lines at the same time so I am probably going to replace them first and see if the code P1093 returns or not. On the high pressure side there aren't that many places to leak and get fuel in the crankcase. I haven't had time to do the paper towel test (no, seriously) but will when we get back from vacation on Monday.

Thanks again

 

Thanks for your understanding.

Let us know about results of the paper towel test and we’ll speculate further.

 

So via the paper towel test diesel is in the crank case again. I'll be ordering new high pressure lines and see what that does.

 

Thinking out loud...always dangerous.

The most common issue of fuel in oil I read about here is trouble with return line fittings and that would obviously not throw the P1093 since those lines are just low pressure plumbing, directing unused fuel back to the tank. On the other hand, high return rates, due to failure of the return ball/seat inside one or more injectors might disrupt rail pressure, but would not fill your crankcase with diesel.

Early in the production run, LB7 injectors had metallurgical problems that resulted in cracked and leaking bodies, but I believe all of those injectors are long gone from the gene pool.

Regarding your thoughts about replacing HP lines, if you look closely at your engine you will see those lines from the common rail to each injector are external to the valve covers and any fuel leak there would result in diesel escaping the system (and a P1093) and soaking the top of the engine, but not getting under the upper valve cover and into the crankcase.

Something else I should mention in regard to replacing those lines. If you look at the HP connection atop each injector you will notice there is a small gap around the nut and the line. That gap accumulates water and then rust and when the line is removed, all that debris inevitably falls into the top of the injector, where there is a screen (for all the good it does) and is impossible to remove without injector tear-down. Since most folks who have dived that far into their engine are there to R&R injectors, the junk doesn’t matter, since the old injectors become cores.

In your case, that rust is going to be there (unless someone sealed around the aforementioned gap) and you know where it’s going to end up. :frown2:

Back to bad HP lines, there should be external diesel somewhere if one failed, but again I haven’t read of that often, although the connection to the injector has been known to leak. But again, where are signs of external diesel and how is it getting past the seal around the injector and upper valve cover?

Any failure of HP lines should be identifiable by using tissue or somesuch to absorb any leaking fluid.

I don’t need to remind you, but I will, high pressure diesel is DANGEROUS so check with utmost caution.

Well, I’m afraid I’m not being much help here and sure wish someone else would join the conversation.

Only thing that comes to mind is maybe you do have a cracked body (as unlikely as that would seem) but you said the engine is running fine. (???)

There are inexpensive apps for iOS and Android that can be loaded to a smart smart phone and, with a comm device in your OBD2 port, read balance rates (plus lots of other useful 411) and would tell you if a cracked injector is bleeding off rail pressure. TECH2 is what the big kids use in shops, but very $$$.

Finally, you mentioned that “...since March...” towing performance is degraded. Other symptoms?

C’mon gang, help this guy out!

Best

 

Wow! - thanks for the comprehensive and thoughtful reply.

So I guess I don't know or understand how the high pressure line connects to the injector. It looks like the connection is well below the upper valve cover even though the nut is outside so if that connection is bad the fuel would spray down at the injector or fan out but still be contained by the valve cover. I am thinking I could blow that space you mentioned out with compressed air before loosening. I am in Norcal east of the bay area which means low humidity etc. so maybe there isn't that much rust.

I have Torque on my phone and have checked the idle balance rates and they are all very close together. Although I have read lots of contradictory info on what they should actually be and what is good or bad - but since they are low and consistent from one to another and there are no other injector symptoms I think they are good - oh and only have 30k miles. Is there any other app that can do more I should look into?

As for the truck's performance the reduced towing power was just on the long grade leaving Pismo on 101 - slowed to about 45 when I could hit 55-65 when it wasn't throwing the code. After that climb there isn't much to climb the rest of the way home and it did fine cruising at +65 and I think I actually got a little better mileage (?) that trip. I am pulling a 35 ft 5th wheel that weighs about 11K. The truck is bone stock except for the lift pump I put on trying to mitigate the need for a CP3 I thought I needed.

It starts, idles, and drives fine or what I consider normal with no smoke. I have owned the truck about 6 years and put +30K miles on it with no problems beyond glow plugs until now.

Cheers

 

Just remembered I did replace the belt driven vacuum pump too - so not quite as trouble free as I said above.

 

You are correct!

Been a while since I did my injectors and I forgot how the HP lines connect to the injectors :frown2:.

As you can see from the first photo, the connection to the injector is long and does indeed extend down through the seal on the upper valve cover.

The next photo shows injectors as seen going into the upper valve cover, HP lines on. Notice the gap between the tubing and the fitting where water collects.

Another photo of the injectors peeking through the upper valve cover, with HP lines off.

The last photo shows my concern about rust buildup in the HP connector and as you can see, it falls into the top of the injector when the line is removed. Many folks arriving at this moment think the rust is the source of their problems, but it is not on top of the injector until the line is removed. Left alone, it stays out of harms way.

And the junk in the picture is only what is visible to the eye. Remember, our fuel filters are sub-10 micron for a reason, and I’m afraid there is no way to keep that mess out of the injector once the line is disconnected. 'dunno;

I fear replacing just HP lines may ruin any injectors that are functional.

Excellent you have discovered Torque and read your balance rates. Unfortunately, without knowing return rates, balance rates may not tell the whole story since they only tell you the difference between injectors. In other words, the Fuel Injection Control Module (FICM) may be maxing out the pulse width (“on” time) of every injector and BR’s would be in spec and close to each other.

But in your case, that would mean every injector is dripping instead of shutting off and your engine would be hazing up a storm at idle! And unless you have injectors stuck wide open (and with similar BR’s, it would have to be every one!). Also, a stuck open injector can be a disaster due to hydro-lock of a piston, as well as fuel in oil.

Arghhh 'dunno;'dunno;'dunno;.

This is just not making sense.

One final thought, there is a seal in the CP3 which can fail and leak fuel into the oil. But why the code!? Does that seal, if defective, compromise rail pressure? I’ll let you check that out.

I’m going to bed...

 

Regarding your last comment about the CP3 seal - recall that I replaced the CP3 because of the P1093 and had read the seal could leak which would explain the fuel in the oil. But since it is new (reman) and has the exact same symptoms I am very doubtful the CP3 is the culprit. I went ahead and ordered replacement high pressure lines and valve cover seals. When I take off the first one I will learn a lot about how viable changing them out without doing the injectors will be. I will post how that goes if there aren't any other thoughts from the community.

Cheers

 

Thanks for your gentle correction.

Occasionally I find myself babbling on in multiple posts and fail to make sure I have my facts straight about the one I am responding to .

Sure wish I knew what has become of regulars here, who’s sage advice in the past has always been welcome and productive.

Where did everyone go?

Hello!!!

Best

 

If you don't have a lift pump and you haven't rebuilt or replaced the fuel filter head, I'd do that first. My truck started losing power and fuel pressure under heavy load. It also started losing prime shortly thereafter if it sat for a day or more. I rebuilt the filter head and did the CAT filter mod and it was cured. Apparently it was sucking in a lot of air. You can always insert some clear tubing in the low pressure supply line to check visually.

 

I put in a lift pump when I first started getting the P1093 - didn't help. I also rebuilt the filter head right after I bought the truck due to leaking at the pump. More stuff has gone wrong than I first remembered above. But overall its been very reliable.

 

OK - I changed out the high pressure lines on one side yesterday - I now understand what stevewaclo was saying about water getting down inside and the rust - seems like a no-brainer to put some silicone there when installing the lines. I probably should have stopped after the first one but hadn't figured out yet that if a line was leaking at the connection diesel would shoot out the top all over the engine - at least that is what I am thinking now. I am amazed at how many mistakes I make a day.

Anyways, it has to be an injector, right? There is nowhere else for high pressure to bleed into the engine, right?

 

Well, I waited for someone else to weigh in on your post, but it appears that is not to be...

“Bueller, Bueller...?”

Regarding rust and sealant at the HP line connections, as I observed before, most people who remove those fittings are all-in on injector R&R so I suppose the primary reason to use sealant is to preserve the lines for reuse. Frankly, if I was that far into such a $$$ job, the cost of new lines would be an essential element.

I’m concerned that, due to the microscopic aspect of the rust particles you introduced into your injectors, they are all likely trashed. Recall my comments on our sub-10 micron filtration system.

And I am inclined to believe, since all other sources of diesel in your oil have been eliminated, the only remaining options would seem to be problems with the return lines or a cracked injector body, as unlikely as the latter would seem.

Keep us (me?) posted.

 

Although I think you made a good argument for not disturbing the HP lines early on I often need to do/see things for myself to learn the lesson.

I ordered new injectors and return lines (to go with my new HP lines) today. I am getting really good at stripping the driver's side stuff off the valve cover so I got a good jump on it last night. I will let you know how it goes. When I return my injector cores I will see if they can tell me if any were bad.

Thanks for hanging there with me.

Cheers

 

Glad to be of assistance!

Regarding checkout of your cores, I don’t believe you will learn anything from your seller, since I’m pretty sure cores are sent directly to rehab, where they are stripped down for cleaning and checking and then reassembled with any necessary replacements installed. Cores returned for warranty purposes are a different situation, of course.

You have my congratulations for tackling this job. Been over a year since I did mine (CA emissions) and unpleasant memories of slowly plowing through the engine are only beginning to fade. I kept a detailed notebook (4x6, 16 pages, one side) of every step, and bagged and tagged nearly everything I removed. I went backward through the notes upon reassembly. Guys who get the job done over a weekend are much admired but anyone who does this job, enters a special fellowship.

One tip which may be helpful was removal of the upper valve covers. Many use a pry bar and leverage, but I found alternating blows with a 5# sledge and a block of wood, quickly popped them loose. Also, no special tools for pulling injectors. Reattach an HP line and you should be able to twist and pull the Injection. If one or two refuse to come out, prying under the hold down clamp works well. Good 411 on YouTube.

Some owners replace all their injector cups, but only one of mine came out with the injector. Careful cleaning of the cup and the hole it fit into was fiddly, but not a big deal.

There are small, special washers on the return fittings that must be properly oriented prior to tightening or they will twist. I didn’t figure that out till the passenger side, so I was either fortunate or it doesn’t really matter, but obviously better to do it right.

You may want to search “tool no one should be without” here (maybe use advanced search and add my username) to learn of a rig you can set up to pressure test the return circuit before buttoning up the valve covers. Using care on assembly should suffice, but the rig is a positive, definitive test.

Best

 

I finished replacing all 8 injectors weekend of the 21st - nice looong project with lots of roadblocks to bulldoze through. The driver's side valve cover screws by the firewall were especially fun. And whoever did the job previously reused all the valve cover screws so the rest weren't always easy either. My truck has the CA emissions stuff so there is a lot more around the filter head and the EGR needs to be worked around - I loosened the 4 nuts/bolts by the firewall and removed the two studs and was able to prop it up enough to use a split fuel line socket I found on amazon. Anyway I am now intimately familiar with the plumbing past the fuel rails and know that my previous theory about the high pressure lines leaking was garbage - couldn't happen like I envisioned. I have a lift pump so there wasn't a big priming issue and it started on the 3rd try. Runs nice and smooth and no codes so I am thinking I did a decent job. No P1093 and no fuel in the oil. The exhaust smells more than I remember but that could just be me. The real tests will be measuring mpg and pulling my 10Klb trailer up a grade.

My last concern is the amount of time/miles I put on the truck with diesel in the oil. It was probably over a year and maybe as much as a couple thousand miles (oil dilution was something I just didn't see that much about it and thought it was a rare thing). I guess time will tell.

 

Welcome to the club!

There can’t be more than a few hundred (thousand?) shade tree types who have installed injectors in an LB7 and you are to be congratulated!

Welcome to the club:smile2::smile2::smile2:.

Reading your report brings back unpleasant memories of doing my injectors last summer and I also seemed to face roadblocks at every turn, from wonky connectors that wouldn’t release to fasteners (back side of EGR :frown2 that had to be conquered with The Force, since there was nothing to be seen.

Mine started on the third try too, and has been running great since.

Like you, I thought the exhaust smelled a bit stronger than it did at its best, but if that’s my only concern, so what'dunno;.

You went a long time with diesel in your oil, but Duramax have really stout internals and if oil pressure seems nominal, I believe the engine will endure. Not sure of any other symptoms of damage, but maybe a $25 used oil analysis from Blackstone (or equivalent) will set your mind at ease.

Again, take a bow!

 

Old thread, I know. But for any new Lb7 owners who have fuel in their oil - just proceed right to a write up about replacing the injectors. Do the HP lines. Get stainless ones. Put in a lift pump, don’t matter which one. FASS, Airdawg, Kennedy, ebay special cummins OEM replacement, w/e. Just put in a pump. Change your fuel filter. Unplug the injector harnesses for the first few cranks so you don’t dry fire the injectors while the air bleeds out of the lines. Enjoy the next 150k miles until you have to do it all again.

If you see metal shavings on the oil pan magnet, you might’ve waited too long. But worth a shot. If you see yellow metal shavings in your oil, you definitely waited too long so just skip the injectors and save your money for the rebuild you’re about to do.