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Discussion Starter #1
I would like to start off with apologizing if this is in the wrong section, i am new here :)

So couple of issues or concerns about my 6.6L LMM, for starters its my first winter with a diesel so i am not sure what is right and not right with a diesel in the cold or really in general. So, for starters in the summer i would be driving and if i do a slow enough but hard enough acceleration that it doesn't shift it will blow a little bit of black smoke until i let off (not allot of smoke). rarely i would get a Fuel rail system pressure too low (engine power reduced) code i would clear it no issues, most of the time by the time i would fill up again it would stop doing it. seems to happen significantly less when the fuel filter has been replaced.

Next is during the winter. Right now it is -16 degrees Celsius (or 3 degrees Fahrenheit for you Americans :p) without the windchill. Upon startup it blows white smoke until it is warmed up, is this normal? (I did have it plugged in the coolant return lines wasn't too warm but glow plugs didn't run so it wasn't cold either) then i did notice that today when i backed up to a snow bank after letting it run for like 10 mns there the snow had not allot of black but there was a little but of black on the snow. don't know if this is normal or not but it also smokes white when it is below 0 degrees Celsius. Oil was just replaced before winter (less than 4k ago) mid summer the thermostats where replaced. All of fluids are at proper levels.

Lastly, charging system. Didn't pay much attention to it before but i just replaced the batteries and i put fairly larger batteries than stock in there with higher cold cranking amps, and i have noticed that normally upon start up the charging system doesn't come on or at least it is lower for the first bit (not at 14 more like 12.4/5 maybe a bit higher) and it then goes up slowly when it does. Could this be the truck letting the batteries warm up a bit before charging them or is it because they are bigger so it doesn't need to come on until its used a bit.. i haven't tested them in warm weather to know if they do the same thing or not since i replaced them this winter, so was just wondering that that could be.

Thank you in advance !

Truck is a 2008 GMC Sierra SLE Crew Cab 2500HD 6.6L Duramax with the LMM and has just under 400 thousand KM on it.
 

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Short answer, all sounds normal, don't worry.

Cold exhaust white smoke is mostly condensation at that temp

Voltage is probably showing glow plug activity when cold, sounds normal, my lmm does the same

Black smoke sounds normal on deleted truck. might be on stock as well. Possible some of the smoke is from the turbo vains transitioning when you apply throttle, perhaps they are getting sluggish?
 

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Like what ‘corneredge’ mentioned pretty normal.
Voltage when starting cold you have the glow plugs and grid heater (if you still have it) drawing power for several seconds then they shut down your volts go back to normal.

Cold fuel can do strange things, are you using a fuel additive with anti-gel, if not you might consider doing this.
Are you turning the key on and waiting several seconds to start it at least until that little squiggly glow plug light goes out ?

I’ve found in cold temps like your dealing with to turn the key on wait a additional 10-15 seconds before you start the engine helps a little.

You might also consider checking the “Fuel Injector Balance Rates”, by what my diesel shops mentioned to me years ago that this is something that’s a good idea at least every 6 months to check.
 

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Discussion Starter #4
Like what ‘corneredge’ mentioned pretty normal.
Voltage when starting cold you have the glow plugs and grid heater (if you still have it) drawing power for several seconds then they shut down your volts go back to normal.

Cold fuel can do strange things, are you using a fuel additive with anti-gel, if not you might consider doing this.
Are you turning the key on and waiting several seconds to start it at least until that little squiggly glow plug light goes out ?

I’ve found in cold temps like your dealing with to turn the key on wait a additional 10-15 seconds before you start the engine helps a little.

You might also consider checking the “Fuel Injector Balance Rates”, by what my diesel shops mentioned to me years ago that this is something that’s a good idea at least every 6 months to check.
Short answer, all sounds normal, don't worry.

Cold exhaust white smoke is mostly condensation at that temp

Voltage is probably showing glow plug activity when cold, sounds normal, my lmm does the same

Black smoke sounds normal on deleted truck. might be on stock as well. Possible some of the smoke is from the turbo vains transitioning when you apply throttle, perhaps they are getting sluggish?

Thank you both! voltage is a relief :) No, the truck is not deleted (At least not yet lol:))) as for starting, i wasn't aware anything was happening if the glow plugs weren't running (no glow plug light since the block was plugged in), anything else was happening ill have to keep that in mind. The truck is completely stock so if it came with a grid heater its still there. As for the anti-gel, i have some on my shelf, i might use it if it continues to be as cold as it did, but today it warmed up a little bit.

How would i check the Fuel Injector Balance Rates? Can i use a OBII Reader, i have one its not a abs one but it works for quite a bit.

Also, in the summer time when i start the truck cold and drive away for the first say 30 seconds or before i reach a speed i hear a loud fan noise and then it goes away, would this be the Grid Heater?

Thank you !!
 

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Fan noise is normal when engine is cold clutch is engaged, if it stops making this noise completely when cold before it warms up you might check out the fan clutch.
Being plugged in is probably why you don't see the glow plug light.
If your temps are below 30 degrees you really should consider using a additive with anti-gel every tank, not just once in a while.
In fact it'd be a good idea to always use a additive year round when it's warmer you won't need the anti-gel.
You won't hear the grid heater running you'll just notice the voltage lower until both the glow plugs and grid heater shut down.
 

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Discussion Starter #6
Fan noise is normal when engine is cold clutch is engaged, if it stops making this noise completely when cold before it warms up you might check out the fan clutch.
Being plugged in is probably why you don't see the glow plug light.
If your temps are below 30 degrees you really should consider using a additive with anti-gel every tank, not just once in a while.
In fact it'd be a good idea to always use a additive year round when it's warmer you won't need the anti-gel.
You won't hear the grid heater running you'll just notice the voltage lower until both the glow plugs and grid heater shut down.
Okay, that sounds good to me.

What additive would you recommend?
 

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Opening up Pandora’s box with that question.
Diesel Kleen in the White bottle for anti-gel.
For warmer climates Diesel Kleen in the silver bottle it has a little more cetane.
 

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Discussion Starter #8
Opening up Pandora’s box with that question.
Diesel Kleen in the White bottle for anti-gel.
For warmer climates Diesel Kleen in the silver bottle it has a little more cetane.
Alright. Thank you ! what about injector cleaners ? yes, no ? if yes which one ?

Also on the side note, i am looking at deleting my truck but not until the summer comes along so i am gathering up information for when i do it. Looking at going to a straight 5" from down pipe, deleting the EGR, should i completely remove the EGR or should i just use blocker plates, I've heard you get better performance and less stress is put on the engine by doing a delete rather a blocker plate. Is this true ? what tuning system should i go with ? EFI Live or something like a bullydog tuner? when it comes to which tunes i would like to run i want some form of towing tune, a more like city? tune kinda thing for casual driving, fuel economy, and maybe a performance tune but i don't want to have to build my tranny or anything (not yet anyway couple years away from this) so one that is kinda best of both worlds.. I also noticed in your signature a turbo break, is this a software or a new turbo that you have put in ? as well as the diy air box, what i that compared to a performance one ?

thank you !
 

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Diesel Kleen cleans injectors, LUCAS fuel treatment IMO also is a good injector cleaner.
DK has cetane boost.
I use both mixed on every tank since 2003.
Bully dog doesn’t support deleting emissions, very few if any canned tuners will these days.

You might re-evaluate your thoughts on 5” downpipe back exhaust.
At least consider keeping the stock cat, you’ll regret it when you have extreme drone and stinky exhaust if you get rid of the stock cat.
I did after 5 years and put my stock cat back on.
 

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Discussion Starter #10
Diesel Kleen cleans injectors, LUCAS fuel treatment IMO also is a good injector cleaner.
DK has cetane boost.
I use both mixed on every tank since 2003.
Bully dog doesn’t support deleting emissions, very few if any canned tuners will these days.

You might re-evaluate your thoughts on 5” downpipe back exhaust.
At least consider keeping the stock cat, you’ll regret it when you have extreme drone and stinky exhaust if you get rid of the stock cat.
I did after 5 years and put my stock cat back on.
So, if i get the 5" straight back from the downpipe, am i able to add the cat back in? because if i buy one with the cat in then i would have to buy a whole new exaust if i wanna remove it yes?

and who would you recommend to tune then ?
 

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I’ve explained this earlier to another member.

https://www.duramaxforum.com/forum/general-discussion/1004091-stock-cat-5-inch-downpipe-back.html

I’m pretty sure your front pipe with stock cat looks like the one in a picture in the thread post #8 the bottom pipe section.
Your downpipe is approx 3”, the factory cat front section that connects to the downpipe is 3 1/2”.

The outlet of the stock cat is 4” same pipe.
Then you should have a 4 bolt flange cat like pictured, this is where you get another 4 bolt flange to bolt up to it with a 4” to 5” adapter to connect 5” if that’s what your dead set on using.

But I doubt you’ll find a delete pipe for your truck you’ll probably need to order exhaust for a 2005 Dmax cat back which all I’ve found so far is 4”.

This is what I did, one company offered delete pipes back in the day but at ridicules prices.
I put my own together.

Tuners are disappearing, not much to choose from anymore, maybe north of the USA boarder.
 

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Discussion Starter #12
Diesel Kleen cleans injectors, LUCAS fuel treatment IMO also is a good injector cleaner.
DK has cetane boost.
I use both mixed on every tank since 2003.
Bully dog doesn’t support deleting emissions, very few if any canned tuners will these days.

You might re-evaluate your thoughts on 5” downpipe back exhaust.
At least consider keeping the stock cat, you’ll regret it when you have extreme drone and stinky exhaust if you get rid of the stock cat.
I did after 5 years and put my stock cat back on.
I just removed the resonator in my truck and put on a 2" end cap, and the resonator box had a coating of oil in it. would this be an indicator of anything?
 

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Normal when you have the factory PCV.
Search doing the PCV re-route, many will do this mod, a few won’t they feel it’s a waist of time

I did after 6 months owning my truck 2008, well worth having one less preventive maintenance to do.
Stopping the PCV oil vapors going thru the entire intake system including the turbo and then thru the exhaust back thru the EGR then out, all burnt up.

No more possible turbo - Intercooler hose blowing off from oil soaked inside.
Check all clamps and keep them tight maybe removing the hoses and clean them up as a annual maintenance if your keeping the factory PCV.

When I removed my EGR 2013-2014 there was no oily sooty build-up inside, like it will be with the factory PCV.

What did you use for your 2” cap ?
If it’s a hardware rubber plumber cap keep a close eye on it as it will crack and deteriorate overtime, allowing dirt and debris to suck in.
Hardware rubber does not hold up well to the oily vapors and engines heat.

You need viton caps which is made to with-stand oil and high temps.
Or
Billet cap is what I used and put the resonator back on to keep the stock look.

Don't drop anything down that hole
 

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Discussion Starter #14
I’ve explained this earlier to another member.

https://www.duramaxforum.com/forum/general-discussion/1004091-stock-cat-5-inch-downpipe-back.html

I’m pretty sure your front pipe with stock cat looks like the one in a picture in the thread post #8 the bottom pipe section.
Your downpipe is approx 3”, the factory cat front section that connects to the downpipe is 3 1/2”.

The outlet of the stock cat is 4” same pipe.
Then you should have a 4 bolt flange cat like pictured, this is where you get another 4 bolt flange to bolt up to it with a 4” to 5” adapter to connect 5” if that’s what your dead set on using.

But I doubt you’ll find a delete pipe for your truck you’ll probably need to order exhaust for a 2005 Dmax cat back which all I’ve found so far is 4”.

This is what I did, one company offered delete pipes back in the day but at ridicules prices.
I put my own together.

Tuners are disappearing, not much to choose from anymore, maybe north of the USA boarder.
Normal when you have the factory PCV.
Search doing the PCV re-route, many will do this mod, a few won’t they feel it’s a waist of time

I did after 6 months owning my truck 2008, well worth having one less preventive maintenance to do.
Stopping the PCV oil vapors going thru the entire intake system including the turbo and then thru the exhaust back thru the EGR then out, all burnt up.

No more possible turbo - Intercooler hose blowing off from oil soaked inside.
Check all clamps and keep them tight maybe removing the hoses and clean them up as a annual maintenance if your keeping the factory PCV.

When I removed my EGR 2013-2014 there was no oily sooty build-up inside, like it will be with the factory PCV.

What did you use for your 2” cap ?
If it’s a hardware rubber plumber cap keep a close eye on it as it will crack and deteriorate overtime, allowing dirt and debris to suck in.
Hardware rubber does not hold up well to the oily vapors and engines heat.

You need viton caps which is made to with-stand oil and high temps.
Or
Billet cap is what I used and put the resonator back on to keep the stock look.

Don't drop anything down that hole
Alright, sorry for the late response, i have been in exams for the last week and am only replying now because i needed a break from studying. Yes i used a Hardware plumber cap, so thank you for the heads up to keep an eye on it ! it wont stay like that for long, as once my money starts flowing in after my exams i will be deleting and going to do that kind of stuff properly like getting a vition cap.

So, upcoming what i want to do is basically get the healthiest for the engine (no egr or dpf etc..) without making enough power to have to build the trans or diff's. I would like to for sure delete and tune, at the same time i would add a high flow air box and as for the exhaust set up i took a look at your other post as well and correct me if i am wrong but what i got out of it is that if i want to i am able to add the stock cat back in after the fact using adapters to adjust the sizing difference? So assuming this is correct, i think i want to know from actually hearing it my self how long the drone is (noises sometimes bother me sometimes don't, loud tires never has bothered me but if there is a dash rattle you can be rest assured that i am looking for that rattle as soon as im home to fix it) I like the deep rumble of an exhaust and from the little bit of research i have done i have found out that some people find that the 5" has a deeper rumble to it than the 4". Also the smell does not bother me at all, i cant smell things to begin with unless they're strong and i don't mind the smell of a diesel exhaust.

Also, should i use a blocker plate for egr or pull the whole thing ? Also, EFI live is the best tuning yes? what i want in the realm of tuning i don't know if it is possible or not but i would like a "on the fly" tune where well i am driving i can adjust it from say Eco to power or from tow to Eco for driving down the highway kinda thing and i want a powerful tune but nothing as i said before that is going to require me to build tranny or diff. So would this be EFI live then ? Lastly i was looking at a lift pump possibly benefits and disadvantages to this ?

Thank you ! :)
 

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The way I went about changing exhaust is different than what most will do, one piece at a time.
This way I’d know what actually helped and what didn’t.
I started with deleting only the restrictive stock muffler, this helped with lowering the EGT’s and shortening the regen time.
I eventually deleted the DPF leaving the stock frontpipe with cat, lower EGT’s and ran great, I ran this way for 5 years. :thumb

Then listening to all the bs claims on the forums about how much a 3” aftermarket down pipe will help, didn’t help with squat except for lighting up my wallet.
Then more bs claims of getting rid of the stock cat and go with a 4” front pipe will be a big plus, I went with the Diamond Eye Quiet tone 4” front pipe.
The plus was I had very annoying loud drone and very stinky exhaust, no noticeable gains/changes with power or EGT’s.

One concern I’d have is with 5” straight downpipe back, my 4” DE front pipe was only 5/8” from the trans lines, I ended up wrapping the exhaust.
The stock front pipe w cat back on has a 1 3/8” clearance from the trans lines.

Your going to do it the way you want, just be cautious on what really helps and what is BS mostly they spent the money and they want others to also spend more money because they did.
Human nature.

As far as not being concerned with having exhaust stink, the lawman behind you might and check your truck out.
And yes, the Dmax is very stinky deleted.
This always bugged me, my 03 Furd 6.0 was 4” straight piped no cat, the exhaust odor was about the same as my Dmax with stock cat.

A liftpump is always a good addition stock or modded.

EFI is best, but hard to come by, might have to go north of the boarder.

Something to ponder, good luck.
 

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Discussion Starter #16
The way I went about changing exhaust is different than what most will do, one piece at a time.
This way I’d know what actually helped and what didn’t.
I started with deleting only the restrictive stock muffler, this helped with lowering the EGT’s and shortening the regen time.
I eventually deleted the DPF leaving the stock frontpipe with cat, lower EGT’s and ran great, I ran this way for 5 years. :thumb

Then listening to all the bs claims on the forums about how much a 3” aftermarket down pipe will help, didn’t help with squat except for lighting up my wallet.
Then more bs claims of getting rid of the stock cat and go with a 4” front pipe will be a big plus, I went with the Diamond Eye Quiet tone 4” front pipe.
The plus was I had very annoying loud drone and very stinky exhaust, no noticeable gains/changes with power or EGT’s.

One concern I’d have is with 5” straight downpipe back, my 4” DE front pipe was only 5/8” from the trans lines, I ended up wrapping the exhaust.
The stock front pipe w cat back on has a 1 3/8” clearance from the trans lines.

Your going to do it the way you want, just be cautious on what really helps and what is BS mostly they spent the money and they want others to also spend more money because they did.
Human nature.

As far as not being concerned with having exhaust stink, the lawman behind you might and check your truck out.
And yes, the Dmax is very stinky deleted.
This always bugged me, my 03 Furd 6.0 was 4” straight piped no cat, the exhaust odor was about the same as my Dmax with stock cat.

A liftpump is always a good addition stock or modded.

EFI is best, but hard to come by, might have to go north of the boarder.

Something to ponder, good luck.
Alright thank you ! Another note is i am from Canada so i don't know what kinda tuners lay here. i will consider doing the same method you did. I think this will be my last question, i don't think my truck has ever done a Regen tbh. Other than the high idle in the winter time i have never noticed the RPM to go up or fuel millage to go down. My truck does also at times smell thought this was just a exhaust leak somewhere. But i think it may explain the black smoke every once and a while? So is my DPF not working ? My EGR does make its noise when i shut the truck off so i am assuming it is working.. I should just get rid of the whole head ace to begin with lol..
 

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Monitor oil life once in a while to watch it drop quickly durning regen, if it’s actually going thru a regen.
Exhaust stink usually happens during regen.
With a normal working system, oil life usually drops about 1% every 80-90 miles, during a regen it can drop around 5%-10%.

Mileage won’t go down as quick as the oil life will during a regen.
My last regen was 10/2008, so I’m going by what memory I have left.

At least in Canada 🇨🇦 you don’t have the USA EPA all over your butt on emissions.
EFI MotorOps Canada.
 

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EGR block or delete 'dunno;, I started off blocking but wanted to get rid of the EGR cooler then eventually deleted using this in the link :thumb as far as I’m concerned, no issues since installed around 2013-2014.
https://sinisterdiesel.com/i-15883463-sinister-diesel-egr-delete-kit-for-2007-5-2010-gm-duramax-6-6l-lmm.html

Do NOT buy a copy cat they are real cheap and the quality is also real cheap on the block plate that bolts up to the up-pipe, buy only Sinister if you go this type lower cost delete.

All parts you remove you might try to keep stored somewhere, incase you ever sell or trade-in, they might want it back to stock.
 

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Discussion Starter #19
Monitor oil life once in a while to watch it drop quickly durning regen, if it’s actually going thru a regen.
Exhaust stink usually happens during regen.
With a normal working system, oil life usually drops about 1% every 80-90 miles, during a regen it can drop around 5%-10%.

Mileage won’t go down as quick as the oil life will during a regen.
My last regen was 10/2008, so I’m going by what memory I have left.

At least in Canada 🇨🇦 you don’t have the USA EPA all over your butt on emissions.
EFI MotorOps Canada.
EGR block or delete 'dunno;, I started off blocking but wanted to get rid of the EGR cooler then eventually deleted using this in the link :thumb as far as I’m concerned, no issues since installed around 2013-2014.
https://sinisterdiesel.com/i-15883463-sinister-diesel-egr-delete-kit-for-2007-5-2010-gm-duramax-6-6l-lmm.html

Do NOT buy a copy cat they are real cheap and the quality is also real cheap on the block plate that bolts up to the up-pipe, buy only Sinister if you go this type lower cost delete.

All parts you remove you might try to keep stored somewhere, incase you ever sell or trade-in, they might want it back to stock.
Perfect, Im probably going to go with a blocker plate and then down the road get rid of the egr all together, thanks for the heads up on keeping parts too !

as for the oil life going down during a regen i will watch it closer, but i don't think its ever really gone down faster then normal. So are there maybe any other ways of checking to see if it is even regening? I can smell it nearly every start up and sometimes when i come to a stop light.
 

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If you have a little raunchy exhaust smell working it way into your cab and it doesn’t happen all the time, then it’s probably going thru a regen at that time.
Regens only last about 20-30 minutes, if your on the highway during this time you’ll probably won’t notice the difference.

If you are able to monitor EGT’s they will go up about 175*-200* during regen, again on the highway you might not notice this especially when towing.

There’s been several that’s never notice except for maybe the additional strange exhaust smell during this time.

The oil life only drops quickly during the regen time.
Normal oil life drops about 1% every 80-90 miles, just check your oil life based on this.
If all of a sudden the % appeared to drop more then it went back to normal, it did a regen.
 
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