Light Smoke

[onlychild]

My 2003 6.6 automatic has some light smoke coming from the exhaust. It only happens when the engine is hot and at an idle. I can't always see it. I'm a drag racer and I noticed it while stuck in a traffic jam on I-75 coming back from Atlanta. It wasn't overheating at idle and I was making sure I was a good distance back from the truck in front of me. My wife said, "Oh yeah, it's been doing that for a while." ?????????

I checked it out when I got home. Coolant was not low, it was ready for an oil change so I did that. Fuel mileage was usual 14 MPG average pulling a 7000 lb loaded race trailer. I measured the old oil quantity to see if we were "making" oil. Okay there. I let the old oil set in the clear jug I use to recycle to see if any coolant settled to the bottom. None there.

As we only had a few days before the next race I serviced the truck and set off for Baton Rouge. Same thing. Light puffy smoke coming from the exhaust at idle no extra oil or lost coolant. got the usual 14 MPG average over a 2000 mile tow.

As the new oil had 2K miles on it I sent it to Blackstone Labs where I send the oil from my racer. I'll try and post a PDF of the report here.

Yesterday I pressure checked the cooling system and it held pressure until I decided I'd let it set long enough. I released the pressure and let the truck run with the pressure gauge on it to see if it would build pressure. it didn't.

The truck has 98k miles on it. I've had it seven years and have put 42K on it. I got it from another racer who got it from another racer's estate. It came with one of those SuperChips tuner deals. I've got it on the "safe tow" setting. It has an Airaid air filter as that was on it. I don't have the stock filter assembly. It's been a dependable piece and has only required the usual upkeep like batteries, oil, tires, and filters.

Guys, this thing is driving me nuts and I have another race coming up soon.

[Mark Rinker]

My guess is you have one 'hanging' up a bit, not atomizing fuel well, and resulting in poor combustion in that cylinder and a trace of unburned fuel at the exhaust. Not uncommon at all, especially the earlier LB7s.

If it were my truck (and I did this many many times) I'd dump two quarts of ATF in the next tankful, run the tank to under 1/4 full, and then add a quart of ATF in the next two or three fill-ups after that.

If you aren't running a good additive with your fuel, you should be. Remember in 2003 we weren't pumping ULSD diesel yet and the extra lubricity can only help to extend the life of injectors. Howes (http://www.howeslube.com/)was my additive of choice.

[DmaxMaverick]

Dump the programmer, then start the diagnostic over. It may be something. Maybe not.

[Mark Rinker]

...and the Rotella.

Q: Do you add 1qt or more between changes?

If so, try Mobil Delvac and stop adding.

[More Power]

Do you know what the injector service history is for this truck?

Light smoke at idle is a common symptom of an injector issue. Like Mark mentioned, ATF might help. Worth a try.

Jim

[onlychild]

Sorry I've been late in replying. I build some race carbs on the side and I'm a bit behind. Like most mechanical problems this little issue couldn't have come at a worse time.

I usually will add 1/2 qt or so between oil changes. I have been using Rotella Synthetic for oil changes. I've had no injector issues. What I was mostly concerned about was head gasket issues and fuel leaks. That's why I went with the oil analysis first.

I'll try the ATF thing and see what happens. I'm getting the feeling that not using the truck all that much isn't helping. The truck has been sitting a lot as we've been rained out the last six weeks in a row.

Okay, as luck would have it my oldest son, as has his wife, has been a service writer at GM dealerships the last dozen years or so. Currently at a Caddy store. Would he be able to get the info I need as to history before I bought it? What specifically should I ask him for?

[DmaxMaverick]

Ask for a full VIN report. It'll have all the information they know about it.

[Kennedy]

Light smoke at idle is typically injectors on the LB7.

[onlychild]

Talked to the son this morning. Fuel filter and dash replacement TSOs. Both done by me. Nothing before 2006 including injectors. We couldn't talk long about this, he was really busy this morning.

[DIESEL/VETTE]

Does it hurt the engine if you drive it with the light smoke?

[mmiddle]

I drove mine quite a while until it started making oil. Injectors are not a big deal to change just a little time consuming. BUT as a warning.... READ MY POST TITTLED "LB7 GURU'S PLEASE HELP" Don't make the same mistakes. Admittedly the 3rd time appears to be the charm. about 800 miles now and no blue smoke;)
Don't fret, injectors fail and the LB7 seems to be a little above normal on the failure rate. If you love the truck it is worth 3k on the injectors.

[onlychild]

Okay, race season is over. I just got back from a race in LG (Lower Georgia). Got the usual trip mileage of 14.4 according to the DIC. Still smoking at idle after a couple of tanks of fuel and ATF. I've noticed that it doesn't start quite as quickly as it did.

Now it's time to fix the truck. I use the NAPA site to give me an idea how much parts will cost me for various items. Looks like Kennedy is the place for parts.

One of my fellow racers and I will do the injector change. So what do I need in total as far as parts go?

[More Power]

Okay, race season is over. I just got back from a race in LG (Lower Georgia). Got the usual trip mileage of 14.4 according to the DIC. Still smoking at idle after a couple of tanks of fuel and ATF. I've noticed that it doesn't start quite as quickly as it did.

Now it's time to fix the truck. I use the NAPA site to give me an idea how much parts will cost me for various items. Looks like Kennedy is the place for parts.

One of my fellow racers and I will do the injector change. So what do I need in total as far as parts go?

If you're buying from Kennedy, just have him assemble a kit for you. He knows what you'll need. Jim

[Kennedy]

I have the bulk of the parts needed listed on the same page in our web store. The only thing that you really need beyond this single page is silicone for the upper covers, and add ons like thermostats, dex/distilled, fuel filter etc.

From there I would highly recommend looking at preventive measures.

[onlychild]

Is there a warranty on those Bosch injectors?

[Kennedy]

Yes same as from a dealer be it Bosch, Chevrolet etc. 1 yr I believe. I've never had a claim on these and frankly don't know how they would handle it if they failed within a year. It does not happen unless outside circumstances like contaminated fuel etc.

[onlychild]

My race buddy called last night and told me the injectors were installed. He installed the eight Kennedy injectors and fuel lines. Two injector cups dislodged during installation. One was corroded and needed replacement. The other just needed O-ring replacement. The local NAPA store (owned by another racer pal) had the parts in stock.

I'll get all the details in church this morning and pick it up tomorrow. Just in time for me to go do my Federal jury duty in Tampa.

[Kennedy]

Corroded injector cup? I'd like to see this. They appear to be a pretty hi test stainless material.

[onlychild]

Let me see if I can get it tomorrow. I can post some pics then. Could be my hearing also.

[Kennedy]

They can get seriously stuck to the injector and get damaged by tools trying to remove. I've used gentle heat from propane torch with some success. We've never had to replace a cup except for those that we damaged with tools or that we punted and sent back with the core.

[onlychild]

The Kent Moore tool was used.

I've had the truck back a few days. No smoke and I've noticed a difference in fuel consumption already. It's quieter, too.

[onlychild]

Finally had a chance to take the truck to a race this weekend. Big difference in how it towed. There are a couple of hills about thirty miles from here where the truck would downshift while towing the trailer. This time it just pulled the hill.

Normally this trip nets me MPG in the area of 13.2 to 13.4. I got 14.4 this trip. We'll see how it runs on longer trips.