SMOKE ON COLD START

[bigcontender]

My 96 6.5 96k miles is blowing bluish smoke on the first start up in the morning. Dosen't smoke after its run for 2 minutes or so, does smoke slightly after sitting for 8 hours. GM dealer replaced the PCV valve 4 weeks ago and it quit smoking for about a week, then it came back as bad as ever. Back to the dealer this week and they checked pump, glow plugs etc and said it's a diesel and you're not driving it far daily enough to get it warmed up. Said somthing about oil lying in the heads getting blow in by the turbo on cold start. Basically they said to live with it. Truck dosen't seem to be losing any oil, I use rotella synthetic changed every 5000 miles. Do't know but I'm readdy to trade it, can't park it in the garage anymore and winter is coming in upstate NY. Any tips?

[William Fullington]

Blue smoke usually indicates oil bieng burned off. Getting past the piston rings and burned up in the cylinders possibly. Check your turbo seals and check if there is excessive oil in the intake manifold.

Hopefully others have something to offer.


Originally posted by bigcontender:
My 96 6.5 96k miles is blowing bluish smoke on the first start up in the morning. Dosen't smoke after its run for 2 minutes or so, does smoke slightly after sitting for 8 hours. GM dealer replaced the PCV valve 4 weeks ago and it quit smoking for about a week, then it came back as bad as ever. Back to the dealer this week and they checked pump, glow plugs etc and said it's a diesel and you're not driving it far daily enough to get it warmed up. Said somthing about oil lying in the heads getting blow in by the turbo on cold start. Basically they said to live with it. Truck dosen't seem to be losing any oil, I use rotella synthetic changed every 5000 miles. Do't know but I'm readdy to trade it, can't park it in the garage anymore and winter is coming in upstate NY. Any tips?

[20050420|7|006071|000022|69.19.2.78]

how is your timing chain? when the timimng chain is slock it wil effect your valve`s and pumptiming

[twaddle]

It can be difficult to determine if the cause is oil or fuel when you get excess smoke on initial start up going just by the color of it even to the experianced eye.
Funny how the new PCV seemed to cure it for a week then the fault returnded. Is the PCV at fault? Can you get another one to try?
Has the dealer actually seen the smoke to see what he thinks?

If there is no oil loss then it may be something else ie glow plug fault, have the injectors ever been overhauled?

Check the simple things first, are all the glow plugs ok, is there any excessive crankcase pressure? Check the crankcase pressure by removing the oil filler cap and feel for pressure, watch out for your fingers on the fan blades when doing this check.

Let us know what you find.

Regards

Jim Twaddle
Biggar, Scotland

[Kennedy]

Bluish smoke at startup is not necessarily a sign of a problem. A fresh set of hot glow plugs can help minimize the smoke and quicken the clean up.

It is often mistakenly blamed on oil burning when it is actually just diesel (an oil) burning poorly just like a farm tractor or semi when cold and under no load...

[ 11-14-2005, 12:43 PM: Message edited by: kennedy ]

[Kidd]

JK is right, Diesels often blow blue smoke on a cold start. My farm tractors do for quite a while. Worst engine I ever saw was a 3208 Cat.. until you put it under load would smoke forever.

K.D.

[moondoggie]

Good Day!

I've found (limited experience- twice) white smoke on start-up to be retarded timing.

How much oil does it consume?

PCV? I thought diesels got a CDR (Crankcase Depression Regulator), not a PCV. Hmmm...

Blessings!

[William Fullington]

learn something new every day. apparently i was wrong. thanks.

[bigcontender]

Thanks I will be look into several of the suggested items. Injectors have never been overhauled, pump was replaced on warentee ~ 6 months ago. Blue smoke is rather new and quite excessive on cold start especally below 30 deg F. It's been to the gm dealer 3 times for this complaint in the last 6 wks. I have the feeling they are just blowing me off. Think I will try anouther PVC valve. Don't know but I'm very disapointed with GM and what is otherwise a very nice truck.

[Tough Guy]

I would check the glow controller first, then the glow plugs themselves...I use fuel additive every fill up and that seems to make a big difference for my 6.5L

Chris

[Kennedy]

If I ran enough glow time on my '96 even with the 18:1 CR it would start exceptionally clean. Glow plug heat is the key issue here...

[bigcontender]

How do I chaeck the glow controller? Is the timing adjustible?
Thanks

[moondoggie]

Good Day!

Your 96 doesn't have a glow plug controller, just a glow plug relay that's run by the PCM. Do a search - some folks have extended the glow time by putting a switch in the PCM coolant temp circuit (yeah, there's two: one for the PCM, one for the gauge). If memory serves (& it often doesn't), they open this circuit with the switch before turning the key on, which tells the PCM it's 300 below zero or something, so you get a really long glow time. Right after it starts, they flip the switch again, & the PCM knows actual coolant temp. (Don't install such a switch based on what I wrote - go find where the folks that have actually done this have written it up. For example, I wouldn't consider doing this unless you were absolutely certain you had AC 60G's or JK's glow plugs in all holes; there's certainly other things you should know B4 doing this. ;) )

I'd still like to know how much oil you're using... :confused:

Blessings! :D

[bigcontender]

Truck is not using any oil. I checked it tonight 4 mos after the last oil change and it's just barely (less than a 1/16") below the normal dots.
So I remaine totally confused: using no oil but smoked like a bug zapper when it's cold.

[moondoggie]

Good Day!

The bizarre thing is that your smoke is blue, which is generally oil consumption. Every 6.2/6.5 I've owned used/uses ~ 1 qt/2000 miles of oil, & they NEVER make blue smoke.

White/grey smoke, especially at start-up, can be slightly retarded timing. Both my truck & Sub do this for a few seconds at start-up, longer as it gets colder. Down to 30F or so, it's a second or two; at -30F, it can last 30 seconds. (Yeah, I know, this could be fixed, but there's no budget.)

When I replaced the IP on my 82, it smoked white until it was FULLY warmed up. I had it timed, & that went away. I took notice that they said the timing was retarded, probably because of the high miles on this engine & the timing chain probably being a little longer than when it was mfg. When my daughter's 89 did the same thing, I gambled & advanced the timing a little by the marks on the IP - maybe 1/16"? The white smoke at start-up went away, & it still hardly rattles. ;)

Blessings!

[Kennedy]

Once again, color is a matter of perception, and a bluish tinge is quite common on a cold diesel engine. My 2005 will emit bluish smoke when cold, especially on fast idle.

A 6.5 that smokes like this simply needs more heat. Best is to do plugs first and look to manually extend the glow time with a simple plow solenoid if need be.

[bigcontender]

Thanks I'll look into ordering a set of glow plugs and changing them. Sounds like a winter project after hunting season.

[Jake]

Interesting thread guys. I am having some severe smoking with my 1996 K2500 Suburban as well. I have less than 1,000 miles on a new Peninsular 6.5 engine. With the 18:1 compression ratio I expected it to be a little harder to start, but the smoke has been incredible. I had the dealer check that all the glow plugs are good and receiving the proper voltage.

The guys at Peninsular are sending me a manual glow plug switch/solenoid. Hopefully, by extending the glow plug cycle I can get the cylinders warm enough to fire and run smoothly. Right now, with the rough starts and smoke, I can't see across the street to pull out of the driveway. It's THAT bad...

Jake
96 K2500 Suburban 6.5TD

[Jim@CFT]

Jake, I too have fought blue smoke on start up since installing the 18:1 pistons over 2 years ago. I have discovered several issues:

1. Watch using extended glow plug times, it will burn out glow plugs and get you chasing a never ending circle of long glow plug times burns out plugs yield more smoke, so more glow plug time, more plugs burn out, etc.

2. Check the electrical connection to the glow plugs and make sure it isn't rusted, especially the #7 cylinder (driver's side rear). GM partno 2965478 is the replacement end.

3. Pump timing also effects the start up, although if your electronic pump is timed between factory and the -1.94 advance, you should be fine.

4. I've used Kennedy's Quick, Autolite 1110, and AC Delco 60G glow plugs. Kennedy's did seem to help the situation, however I had other problems at the time that masked their true effectiveness.

5. If the truck runs good once warmed up and your not using noticeable amounts of oil, then keep looking for the small, little problems like one burnt glow plug or a bad electrical connection to the glow plugs, weak batteries, timing is off, worn contacts in the glow plug controller, or extending the glow plug time to 20 secs.

6. I don't remember if it was posted or not, but to check the glow plugs, get a test light from the local auto parts store, connect it to a POSITIVE battery post, DISCONNECT one glow plug, tough the probe to engine ground and verify the bulb comes on, then touch the probe to the electrical connection on the glow plug. If the bulb lights then glow is good, if it doesn't, it dead. This simple test has never failed me.

Good Luck and patience!

[jspringator]

Does the smoke really hurt anything? Mine smokes only when cold, and always starts even when cold outside. I know I may have a glow plug or two out because there is a slight miss for 2-3 seconds when starting a very cold engine. If it ain't broke...

[Robyn]

My 94 with 258K on it has 3 glow plugs that are not working and are the ones that are tough to get at under the turbo. Now I really dont care much but it smokes enough to kill off a swamp full
of mosquitoes on start up. After a few minutes it picks up all the other cylinders and is real clean and runs great getting about 18 mpg Hwy and 16 city.
Blue smoke can be cleaned up as mentioned by a better set of plugs and also if your injector nozzle pop pressure and spray patern are going south they will smoke cold too. Having good top condition nozzles with good spray along with good heat in the plugs will most likely solve your issue.