smoke'n

[chessy56]

An earlier post on feed pipe nut torque went a bit off topic, so I'm starting a new thread on tail pipe smoke on a '01 LB7. After posting my BR and PW numbers, it began to appear that my injectors weren't in as bad of shape as I may have thought- despite the heavy smell of diesel which still is in my exhaust and the truck still smokes with greater frequency. There was a suggestion that my smoke may be related to something other than injectors.

A few months back, at around 340K miles, I had a set of head gaskets replaced and the heads were machined, with new valve guides and a valve job performed by a local performance shop. My local dealership did the balance of the work. I am now noticing that my oil level appears to be dropping- between a half to a full quart in ~600 miles (nearly all of which is highway miles @ about 60mph). I'll check the level immediately after allowing the engine to idle for a couple of minutes, then notice the oil level being down ~1-2 squares on the dipper. I'll add nearly a qt of Rotella T6 synth and check the level again immediately after allowing the engine to run for a couple of minutes- all better, until a week later. The last 2 weeks now, I've noticed the oil level as being low. In better than 300K miles (previous to the head gasket job), I've NEVER added oil beyond a filter change at 4K and an oil/filter change at 8K.

Do I have oil seeping past the valve guides? Oil leaking into the manifold? This appears to be way more oil consumption than I've had ever and quite possibly the source of my tail pipe smoke!

Comments?

[DmaxMaverick]

Try a different oil brand. In my experience, and many reported here, Rotella seems to have the highest level of consumption, when consumption is an issue.

[Kennedy]

Balance rates are over rated IMHO. You can have a perfectly good running engine with low balance rates and bad injectors which is likely your case.


As an example if you have a +15 it could be a plugged/stuck injector OR it could be a bad cylinder.

The just Dmax doesn't typically smoke and burn oil. I suppose you probably could make it burn oil, but I think you'd have to really bake it to get the tension out of the rings.

More likely you have a case of the drips which has become quite common with the LB7 injectors.

[chessy56]

I'm due for my oil/filter change interval. I can try running the Delvac synthetic instead to see what happens. I should know in a couple of weeks if the oil level drops. Odd, I've been running the T6 for years with the only oil I've added to any extent being at the 4K filter change interval. The service mgr at my dealership is at a loss. Will report back after changing to the Delvac and running it for a couple of weeks.

At least with the dipper appearing low, it would seem I'm not "making oil".

[DmaxMaverick]

It may be worthwhile to have an oil analysis done. It you do have a drippy injector, the fuel content in the oil should show elevated levels. It will also show if your change intervals are within a good range, otherwise.

[chessy56]

I agree. I've been having more frequent oil analysis done as of late and they are usually fairly normal. The last one taken (6K after the heads were serviced) showed an increase in iron (45ppm vs. 7 or less). Perhaps expected being that the heads were removed/serviced. That was Delvac synthetic. I'll pull another sample this weekend.

[Kennedy]

Maybe "seep" would be more appropriate term.

[rapidoxidationman]

I agree. I've been having more frequent oil analysis done as of late and they are usually fairly normal. The last one taken (6K after the heads were serviced) showed an increase in iron (45ppm vs. 7 or less). Perhaps expected being that the heads were removed/serviced. That was Delvac synthetic. I'll pull another sample this weekend.

Aren't the heads on these things aluminum?

[chessy56]

Heads are aluminum, but I believe the entire valve train is steel. 45ppm may not sound like much, but compared to readings that were 4, 5 or 7ppm over that past several oil samples, it's a flag that something's changed. If this number continues to climb, I'll suspect additional wear that may be a sign of something detrimental. But if it drops back down to previous levels, then I probably won't be too concerned. We'll see what we get after the next analysis.

[chessy56]

Changed oil/filter, but checked oil level beforehand after another 600 miles- didn't see a drop in oil level this time. Something changed- don't know what caused the oil drop the previous 2 weeks. Anyway, after another 600 miles since the oil change (this time, using Mobil One synthetic), no drop in oil level. So far, so good.

I did send in another oil sample for analysis: Although the iron level is still a bit high (58ppm- used to be 10 or less), there was no fuel/water/coolant in the oil. So, while there's still smoke at the tail pipe, apparently the injectors haven't gotten so bad that I'm making any oil yet. Still wondering about the iron content- slight as it might seem.

[chessy56]

Over the last 2 weeks and about 1K - 1.2K miles, my oil is again down 2 marks on the dipper- and this is after changing to Mobil 1 5w-40 synth. I am noticing an increase in tail pipe smoke and am beginning to think this is partially seeping from one or more injectors (as Kennedy had mentioned) and also from oil? But how would the oil be getting into the cylinders?

Up until the 340K mark (at which point the head gaskets were replaced, with new valve guides and surface ground heads), I haven't ever had to add oil between oil/filter change intervals. At this rate, I'm guessing I'll go through about a gallon of oil (+/-) every 2500 miles or so! Seems a bit much to me. Any thoughts before I take this engine back to the dealership which did the work?

[DmaxMaverick]

That's quite a bit of oil loss. I don't think a valve guide, alone, would allow that much. Perhaps if they were all passing oil, but what's the chance of that? Add to that, the chance of valve guides leaking oil into the intake or exhaust is much less likely on a turbo Diesel. Not much off idle, the intake and exhaust are pressurized well beyond the static oil pressure around the guides, and much more likely to have intake and exhaust gasses passing into the valve cover. So, that doesn't leave many opportunities for oil to be passing, one way or another, to the exhaust.

Cylinders and rings. Well, can't say much about that until compression and leak-down tests are done. It's possible, but still, that's a lot of oil loss, and more than a cylinder would pass, typically. Add to that again, pressurized intake and exhaust, making it much less likely. A large cylinder leak would show itself at the crankcase vent tube, and would probably be quite messy. If you aren't seeing significant oil dripping from the tube, cylinder blow-by is probably not an issue.

Turbo. I'd have a closer look. A spindle seal leak will pass oil into the intake and/or exhaust. The oil pressure should always be more than the gas pressures on either side of the turbo, and more so at idle or minimal load (no boost). A leak into the intake would just burn during combustion, and may not smoke, at all. A leak into the turbine, however, would be smoky, and has a potential to pass a lot of oil. A leak into the compressor would certainly show a mess. That's the easiest to check. Just disconnect one of the hose connections between the compressor and CAC. If that's clean, then you'll have to get a look after the turbine. This isn't real difficult, and the simplest place is the downpipe. The V-clamp is easily accessed through the passenger/right side wheel well, with the wheel and liner removed. If it's there, you should find excessive coking (and perhaps some grime) inside the pipe.

[chessy56]

By "V clamp", I'll assume you are talking about the pipe clamp that connects the exhaust pipe (which runs down and under the passenger side of the cab) to the pipe which comes down behind the right side of the engine- which I'll further assume is what you refer to as the "down pipe". If you (or anyone) can confirm/deny, that would be great. (I've been told I've got a leak there, as I can hear what appears to be a 'knocking noise' at lower RPMs and it began after the head gaskets were replaced.)

If oily and crusty looking, then I take it I'd need to either replace or rebuilt the turbo? I'll be checking this and the CAC pipes this weekend. Thanks for the tips...
Gary

[DmaxMaverick]

By "V clamp", I'll assume you are talking about the pipe clamp that connects the exhaust pipe (which runs down and under the passenger side of the cab) to the pipe which comes down behind the right side of the engine- which I'll further assume is what you refer to as the "down pipe". If you (or anyone) can confirm/deny, that would be great. (I've been told I've got a leak there, as I can hear what appears to be a 'knocking noise' at lower RPMs and it began after the head gaskets were replaced.)

Correct. Down pipe and V-clamp. If you take loose the exhaust pipe hangers, the pipe will fall away and twist enough to see well inside. While you're there, check the mounting tab on the down pipe above the clamp. If it hasn't been repaired (welded), it may be cracked. Low RPM knocking is probably not an exhaust leak. It could be a cracked tab, or a real knock in that area. Exhaust "knock" sounds will usually be around the manifold, turbine or wastegate housing.


If oily and crusty looking, then I take it I'd need to either replace or rebuilt the turbo? I'll be checking this and the CAC pipes this weekend. Thanks for the tips...
Gary

There will be some flaky soot build-up in the pipe, which is normal. If oil has been getting into it, then burned on the pipe, it will look much different, more like an exhaust port on a well-used 2-cycle engine (like a chain saw or weed wacker).

[chessy56]

Thanks for the tips. The dealership checked out this "knocking" I referred to and the tech told me he could feel the exhaust leaking from around the seal (clamp). He recommended sanding the mating surfaces a bit and using some of that red hi-temp RTV stuff. Sounded a bit weird, but I was willing to give it a try. I'll look for any cracks as well.

BTW: Having never pulled the turbo off of one of these, what might I expect to get into time-wise? Hopefully, I won't have to drop the tranny or anything like that.

I can only imagine that if this is a leaker, it'll eventually get worse- so continuing to dump oil into it would be a waste of $$. I've got a local reputable diesel shop that can either rebuild these or, exchange them for about a grand.
Gary

[DmaxMaverick]

Try not to lose focus. The goal here is to find your source of the smoke. What's discussed here is merely possibilities. We can't see what you, or your mechanic, sees. If you have a leak at the down pipe coupling, it's something to address, but has nothing to do with your initial concern. It's on the low/no pressure side of the system, and is minor, if it exists. There's a reason there's no gasket there. It isn't necessary, even if it leaks a little. Unless it's really bad, a little soot will plug it up in a very short period. Sanding the mating surfaces isn't going to gain anything. It leaks, or it doesn't. If it leaks, after a long period of time, something has broken. If you need RTV, something is broken.

You don't have to drop the tranny to R/R the turbo, but it takes some time. Not difficult, but it is time consuming. One step at a time.

[chessy56]

OK- here's what I've got: No oil or oily film from the CAC or the interconnecting hoses. Separated the front exhaust pipe from the down pipe- soot and nothing but soot. Was able to get to the turbine blades from the front (removed the air intake hose, post filter)- turbine spins freely w/o any rubbing type noises. Checked oil after 550 miles (since topping off last weekend)- down 1 mark/square on the dipper. Added a little less than a pint (estimated). Still, I go back to virtually zero oil consumption prior to the head gaskets being replaced (and heads rebuilt) to my current consumption. What could have led to this? A cylinder goes bad all of a sudden?

The crankcase vent tube was referred to earlier- If I'm correct, this would be the tube that interconnects the 2 upper valve covers, drains into a collector mounted behind the alternator and finally, drains out of a hose running down the right side of the engine. Yes, it's kind of wet and oily down there, but I never notice any spots/drips under the vehicle. I was poking around regarding the crankcase vent and ran across a post from 2005 in response to a question on an '02 LB7 and oil dripping from this tube. One reply mentioned "the oil drainback becomes clogged in the oil seperator and it runs out of breather pipe". Does this make sense and if so, might this be a variable to consider? (Remember, it is after running the engine briefly in the morning, shutting it off and then checking my oil. If I check the oil before starting up the engine, oil level appears normal.)

(Digressing slightly- the exhaust leak I was informed of appears to be the result of erosion of the downpipe's flange- there are 2 small sections in which the flange surface is only 1/3 its original width.)

Given the smoke I'm seeing from the tail pipe (continuously "heavy" if viewed at night with headlights behind me) and the smell of fuel, I'm inclined to proceed with injector replacement. If I can get past the tail pipe smoke and resolve my oil consumption, I'd be inclined to keep the vehicle for a few more miles. Otherwise, I might be better off cutting my losses here and look for a replacement, given the wetness I'm seeing around the tranny harness/NSBU switch and the loss of fluid around the tail shaft of my transfer case. Eventually, this ride is going to need some additional work ($$$).

Any other thoughts on the above and the oil loss?

[Kennedy]

Valve guides/seals?

We seldom "rebuild" heads for head gasket jobs. Usually just a skim cut and wash.

[chessy56]

On this one, the valve guides were replaced. Unfortunately, this throws another variable into the mix; can't speak to seals being replaced, but it wouldn't make sense to replace the guides and not the seals (I'd have to inquire). But would oil be getting into the cylinders under an idle condition only? I don't see any tail pipe smoke much beyond idle (turbo's compressing air by then?). It doesn't spend a ton of time idling and ~pint (give/take) in 550 highway miles is a whole bunch more oil than I've ever consumed prior to the head job.

[Kennedy]

A blue white smoke at idle particularly worse when warm/hot has pretty typically been injector related. Not sure on the oil consumption thing. It shouldn't be pulling a bunch down the guides, but you never know what was used and how they were fit for stem to guide clearance.

[rapidoxidationman]

Would a PCV system gone awry cause the smoke? Maybe a bad pcv valve on one of the valve covers is allowing too much crankcase air to be pulled into the intake manifold?

[DmaxMaverick]

Would a PCV system gone awry cause the smoke? Maybe a bad pcv valve on one of the valve covers is allowing too much crankcase air to be pulled into the intake manifold?

No closed PCV system. Road draft tube.

[chessy56]

As JK mentioned, the smoke is now extremely heavy, with the engine hot and at idle. I see nothing once I'm up to traveling speed. Oil pressure appears normal. I've purchased the injectors and new feed tubes. That job will be starting soon.

As for the oil consumption, I may be all wet on this one and caused a false alarm-
According to one of the dealership techs, the proper method for checking the oil is to get the engine up to temperature, shut the engine off and allow it to sit for 5 minutes- THEN check the oil. Usually, I had been checking the oil using this method or, cold before starting the engine in the morning. For whatever reason, I recently changed the method I had been using, by starting the engine "cold" in the morning (to get the oil pressure up), allowing it to run for a minute or two, and then checking the oil. If the tech is correct, I've just created a false reading! My bad- probably have been over filling it lately.

I'll check the oil level using the method recommended by the tech for the next few weeks to see if there is any further loss noted. Sorry if I wasted your time!

[Kennedy]

I use the cold level check method. Temp not a huge concern so long as it has had adequate time for the oil to drain to pan.

[chessy56]

With the engine "cold", I can clearly see that my oil level is well above the limit and will have to have some drained after I'm done with the injector replacement.

I am noticing that the tips of my injectors are heavily caked with carbon. DMaxMav stated that I shouldn't be getting oil into the cylinders as they are pressurized by the turbo. So, then am I to believe they are that carboned from the fuel seeping past the needle/seat? Being that the injector tips are highly carboned, I'm wondering if my valves are experiencing the same buildup? (Just had the heads rebuilt a few months back with the head gasket change).

I've read on several web sites that Cefoam will help dissolve carbon buildup- so I'm wondering if it would help any if I dumped a can into the fuel once I get this truck back up and running? Or, perhaps som FPPF would help remove any carbon deposits?

Anyone with any experiences/observations on this?

[Kennedy]

I wouldn't expect any buildup on the intake valves as they are dry flow, and the exhaust valves generally run hot enough to remain clean.

Combustion efficiency could help the carbon as well as working the truck a bit. Regular use of FPPF should help-to a point.

I think the simplest solution is to start fresh with the injectors/lines and drive it.

[chessy56]

Been a while since I last visited the site- just an update:
The injectors were the problem. Despite the acceptable PW commands and balance rates, the smoke was indeed injectors- must have been seeping as JK suggested. I replaced them myself this time (with new pipes) and saved some $$$- no more smoke. Disassembly/reassembly not too big of an issue (about 8 hours each way)- but PITA when the dealership tech rounds out the cap screws on the valve covers to the point where vice grips are needed!!!

Not seeing a big issue with oil consumption either- false alarm on that one. No coolant/water/fuel in the oil based on lab test.

Still have a "ticking" noise from the right-hand side of the engine- and an exhaust leak around the down pipe to exit pipe connection. Flange of the down pipe is heavily eroded. Sealers and other such junk won't cure it and the erosion is too big to let soot build up plug it. Living with it.

Thanks for the help guys!