Howdy all,

I'm the proud owner of a 2003 Chevy Silverado Duramax Diesel which has been a faithful vehicle from the first day I own it. Now with 150000 + miles I've noticed whitish / bluish exhaust smoke when idling. There has been no drop in mpg...no drop in oil levels. No change in the trucks performance...I've change the oil and fuel filter every 7500 to 10,000 miles.

The truck has never been used to tow anything...but on a few occasions I have hauled heavy loads a few miles to the dump but the truck has never been under constant heavy load for very long.

I'm afraid to take it to the local Chevy dealership as I have caught them trying to do unneeded work or overcharging for required maintenance....I have no confidence in them at all!

So here's my question. Is there a test I can do to determine if the injectors are the problem or is there a reliable service company in Connecticut I can have test my truck...

I just don't have the time or money to waste on unnessary work!

Thanks!

 

Hi Willie, My 2003 just started smoking at idle last week. I just wanted to share what i have done. Had a new set of injectors courtesy of Gm at 29,000 miles, another new set at 120,000, same courtesy. Now at 155,000 smoke seems worse. Reading through the problems to see if i really need another set, or just one or two. Trying to get educated before i call the mechanic tomorrow for his inputs.

 

Personally wouldn't change just one or two, seems like everyone that does that is back in there shortly after.
Balance rates can be checked either at the dealer or by many handheld scanners, only one I know for sure is snap-on because that's what I used. There are also a lot of programmers/modules that will read this also.
Balance rates only tell half the story though. My balance rates weren't terrible at 3.5 on #7 but the return rates were way off. I knew I had problems because it smoked at idle and I could hear a knock starting.
There are tons of writeup on how to test return rates do a search and you will find them. Also search what programmers/scanners will read balance rates.


Sent from my DROIDX using Tapatalk 2

 

Hi Diesel wrench, Thanks for the reply. 42000 miles on a set of injectors seems a bit short. Had my repair miles off a little in my post. Getting old sucks. I will have them check return rates and pressures when it gets to the shop on monday.

 

try cleaning the injectors first before replacing them

How To: DIY - Injector cleaning - Chevy and GMC Duramax Diesel Forum

it is also good to run it hard for at least a little while. these engines are at their best under load

 

OK white smoke. White Smoke is caused by excessive fuel return. This is difficult to test on a Duramax. Most European models have a small hose to install a cc chamber test on. The duramax would require you to do this test with the engine running and the valve covers off. This would be quite messy. You need to know how much the fuel rate is in comparison to the other injectors. The return hoses hose removed and blocked and each individual injector would need the hose to the comparing CC bottle. the one with more return would be the one that is the problem. As much as I want to do all the testing myself and know which injector is the problem, The time you waste and the money you waste is not worth it.

Occasionally you can use a scan tool like Auto enginuity and check the balance rates. This will tell you something. Not really conclusive but if you have a injector that is over +-4 it may be the problem. Test it cold and hot. Look for the one that is consistently off. Drive it and check it again the next day. I have on on the left side that is reading -6 cold and -4 hot in drive. I am guessing it is the one that is returning fuel. Because the computer is sending less fuel to compensate for something. Because it is on the left side I am going to attempt to replace the one. But I would strongly suggest replacing all in most occasions. I just purchased one set for my ford and it is just too much money for me to do both right now.

Just go to Accurate diesel and order another set. I dont know about the ones on ebay for $1200. But the ones from Accurate for about $220 each are good quality.

If you have done the injectors on this truck you will know the job sucks especially on the right side. Just removing the valve cover and getting to the injectors is so much work to do it 2 times or 4 would be more work than it is worth to spend the 2 grand on a new set of injectors.

Can you imagine removing the valve cover and installing the pressure lines, hooking up return line to each injector and running the engine for a few minutes to get enough fuel to get a conclusive test.

Somebody should make a custom valve cover and return set up for this truck to be able to test these in a few minutes like the euro models. Now that would be trick.

 

There is a test for return rates, it tests each bank at a time. Not as specific as each injectors but it paints a better picture of what's going in inside.


Sent from my DROIDX using Tapatalk 2

 

i dont believe this is true. white smoke is unburned fuel or coolant. the returned fuel never sees the cylinder to make its way out the exhaust.

it is still likely to be an injector issue though. get us the balance rates in park/neutral and drive and engine fully warmed up. this will help in judging the health of the injectors.

test your oil too for diesel in it. white paper towel, drip some of the oil on it and watch if a ring around the drip forms. this will tell you if you have a leak or cracked injector under the valve covers.

also, how's your coolant. are you loosing any?

 

Hi Farnhamassoc, Thanks doing the oil drip now. Does not appear to be any fuel in the oil. Going in on Monday to run all those return rate tests. Not losing any coolant.

 

Mine had smoke at idle, smelled of fuel bad, but balance rates all were within specs, in park, neutral, drive, cold, hot didn't matter.
Return rates were off the chart though. If they are high it can mean a cracked body somewhere. It can wear in several places only some of which leaving fuel in your oil.
Mine had no fuel in the oil. Swapped injectors yesterday and all problems gone runs great now!

Sent from my DROIDX using Tapatalk 2