6.5T smokes on start up

[keenee]

My 6.5T smokes on cold start-ups. Any one else?

[61_FL_Apache]

how many miles on it? what color smoke?

[scotts62]

Just a quick puff its valve seals.

[C20-67_N_MO]

Originally Posted by scotts62

Just a quick puff its valve seals.

I would have to agree.

[keenee]

271,500 mi When it is cold it runs rough and blows white smoke for up to 1 min. Have new glow plugs, and they are working.

[special-K]

Take your oil fill cap off and check for water in the oil. Check the dip stick. Is the coolant level staying up? Also,look for bubbles in the radiator with engine running. Gotta watch out for a bad head gasket. The last thing you want is hydolock. Do you hear gurgling from the passenger side under the hood when you shut it down?

[keenee]

Been doing this since I bought it 1 year ago. I guess it is a diesel thing no mechanical issues, no water in the oil, it is smoke not steam, the colder it is outside the longer it smokes. Just looking for someone else with a 6.5 diesel, or knowledge of this engine.

thanks for the replies.

[special-K]

You said white smoke,which means steam to me. I have a 6.5TD I bought new about 20 years ago,had a '95 for a few years,have an '85 Jimmy 6.2,had a '91 Suburban 6.2,and an '84 K30 6.2 was my first one I bought in the '80s when it was a few years old. I have been running these trucks since the '80s,so I know a little about them. I just don't know anything about yours. That's why I asked all those questions.
People suggested valve seals,but that would be bluish smoke from burnt oil getting into the combustion chambers. Since it is only when it's cold and only on cold starts and you say the glow plugs are new it may not be cycling the GPs long enough (controller). Or,maybe some connectors at the GPs are not making contact. You could have a few cold cylinders,which would cause the rough idle and smoke. Mine puff more like a little black smoke on cold starts,which is unburnt fuel due to cold cylinders and the fuel cranked through.
I was alluding to possible head gasket failure,not only based on the white smoke/rough idle when cold,but also based on the miles on your engine. These things run about 22:1 compression and that's a lot of pressure pushing for a lot of hours multiplied by the rpms your motor has turned. That,and the corrosive effect of coolant running through there for that long (miles and years) would make your head gaskets fairly well aged. My '92 has 280,000+ and last winter I had a head gasket let go. I fixed it and the motor is happy as ever. Definitely keep an eye on the coolant situation.

[keenee]

special-K sorry if i was a bit blunt. Thank you for the insight. I will keep an eye on a few things you mentioned. I never got around to changing the last 1 or 2 gp's behind the turbo mabee I need to do that. Ken

[special-K]

Yeah,those are a pain for sure. That could be the issue,which really isn't one. My Jimmy has one stuck that I broke my glow plug puller on. I just left it in there for now. 7 new ones will gitter done. It's a bit rough for a minute,then smooths right out.

[americanmusc1e]

well I always respect Special-K's advice, but I must say....

I'm not so easily convinced it's coolant.... although there is an easy way to tell.... unburnt diesel smoke is also white BUT it has a terrible smell and burns your eyes like crazy..... get a whiff of that smoke and if it smells sorta like your being fogged with diesel it's probably unburnt diesel

which could be caused by:

glowplugs not working.... or glowplug controller..... I think this is most likely especially considering that its worse when it gets colder

The pump timing is off..... You didn't say the year of your truck... most likely it has the Standyne DS4 electronically controlled pump.... not sure how they are timed though...

..... I guess I should shut up now.... I must say I have never owned a 6.5... I have seen them at the shop where I work and I have done alot of research because I am contemplating a swap into my 70 .... most of my knowledge comes from my dad owning two 12v Cummins trucks.... one of which we are having a similar smoking problem right now.... but it happens every (not hot) startup.....

[keenee]

americanmusc1e, yes it is unburnt diesel. It smells to high heaven, lol. My suburban is a 1996. I feel I need to look at the glow plugs and controller, a high idle kit or the possibility of air in the fuel lines.