OK so I've got a 2003 Chevy Duramax with about 135 K miles and it now has blue to dark smoke when starting or at idle. I don't see smoke at road speeds unless I really punch it. So now my question... A RV park owner noticed the exhaust when I pulled in to dump and asked if I had replaced the fuel filter as he noticed the blue exhaust. We have replaced it several times and WONDERING if there is anything like a tune up or other measures that can correct this issue. I get good milage and not other adverse effects with this truck. I just assumed this is what happens when a truck gets this many miles on it or can this be corrected?I see the big 18 wheelers who blow smoke so was not too concernend but would like to know if a tune up or something can be done to restore my Chevy to not do the smoke thing. Any thoughts.

Don't overlook valve guide seals letting crankcase oil seep into the combustion chamber. I may be wrong in this theory applying to Diesels but that is what we look for in gas motors. I had the blue smoke coming from my gas car and replacing the valve stem seals cured it.

Check your exhaust piping, you can get that condition if you have crossover pipe small leak prior to turbo inlet. Don't know if that is your problem but worth a look, especially if your still running on original 10 year old exhaust piping

At 135k it shouldn't smoke. Thats just broke in. Does the dipstick show oil missing?

If its a light smoke like hazing it could be injectors try an additive to see if it changes, or try getting diesel from another source

My guess would be to check injectors. Early model duramax engines had issues with the injectors.

Diesel exhaust smoke | Good Sam Community

13 Replies

ib516
Explorer II
Aug 26, 2013
IF the smoke is visible when the engine is up to operating temp, and mostly at idle, and is greyish in color...

I'm going to say you are about to buy ~$5000 worth of injectors & labor.
Dave_H_M
Explorer II
Aug 25, 2013
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45Ricochet
Explorer
Aug 25, 2013
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KD4UPL
Explorer II
Aug 25, 2013
As much as I love my Duramax engines I must admit the LB7 had serious injector issues. Have yours ever been changed? Many trucks are on their 2nd or even third set at 135K miles.
As for the smoke being normal, maybe on a really high mileage engine. Yours is not. My '05 has over 160K and doesn't smoke.
Turtle_n_Peeps
Explorer
Aug 25, 2013
64thunderbolt wrote:
I'll go with inj. Might want to take off the oil cap when idling to see if theres excessive blowby.

Your in for about a 5 grand bill. LB7 injector problems. Check your oil for fuel before you hose your whole engine.

To confirm this, check the return rates and smell the smoke coming out of the exhaust. If it smells fuelly it's an injector problem.
64thunderbolt
Explorer II
Aug 25, 2013
I'll go with inj. Might want to take off the oil cap when idling to see if theres excessive blowby.
coolbreeze01
Explorer
Aug 25, 2013
Could be a dirty air filter..........
powderman426
Explorer
Aug 25, 2013
gmc6000 wrote:
My guess would be to check injectors. Early model duramax engines had issues with the injectors.

Thats why I asked if oil level was down. If it's injector the oil level Will show full.
gmc6000
Explorer
Aug 25, 2013
My guess would be to check injectors. Early model duramax engines had issues with the injectors.
MARK_VANDERBENT
Explorer
Aug 25, 2013
If its a light smoke like hazing it could be injectors try an additive to see if it changes, or try getting diesel from another source