smoke - The 1947 - Present Chevrolet & GMC Truck Message Board Network

my70chevyc10 · 08-14-2007, 12:51 AM

Help..... i have grayish white smoke coming from exhaust and i dont know what from. Oil is full and water is full please help

chipflyer · 08-14-2007, 12:56 AM

If its an auto trans and it is smoking badly it is probably the transmission modulator valve sucking trans fluid up the vacuum line and burning it. Disconnect the vacuum line and see if it stops smoking.

Jeff

my70chevyc10 · 08-14-2007, 01:14 AM

its a 350 with a 3 on the tree

ChevLoRay · 08-14-2007, 10:48 AM

Back in the day, we were told that bluish smoke was oil. White smoke was water and that was it. If it smoked on startup but cleared up after a few moments, it was probably valve stems causing the oil to settle on top of the pistons. Using a set of Studebaker umbrella seals on the stems was the cure that we were given. Coolant that found its way into the combustion process would cause white smoke, that was actually steam. Cracked blocks, leaking head gaskets, cracked heads were all possible sources. Grey smoke....fuel issues? Does the smoke have a specific odor? Usually, in my experience, fuel burning issues caused my truck exhaust to burn my eyes. Running really rich. Changed carbs and cured that problem. My Lexus has a brief puff of smoke on startup, but I'm not worried about that. My truck has blowby and the only cure for that is gonna cost me....rebuild or replace.

70gmcjimmy · 08-14-2007, 10:31 PM

I had a similar situation little over a year ago with my 72 C2500. White smoke out of the left bank. Pulled the spark plugs and a trickle of liquid came out #7 hole. Tasted it and yup, antifreeze. Had to be a head gasket leak.The coolant in the radiator had not dropped noticably. It doesnt take much to create a lot of smoke. I had built the motor in 1986, and that damm head gasket only made it 20 years! Oh well, replaced them and no more smoke.

Any way thats my guess---DAC

68gmsee · 08-14-2007, 10:56 PM

If the engine is otherwise in good shape and you're suddenly burning a whitish smoke. It's more than like condensation of some sort. Either water from the radiator or moisture accumulating in the exhaust.

Put your hand by the exhaust (careful not to burn yourself of course) and let the exhaust condense in you hand. You can usually detect the odor of anitfreeze, xmission fluid or other.

I also agree as was mentioned that oil burns a bluish color, gas a gray, dark gray or black and water whitish color.

08-14-2007, 12:51 AM	#1
my70chevyc10 Registered User Join Date: Jul 2007 Location: Covina Calif Posts: 172	smoke Help..... i have grayish white smoke coming from exhaust and i dont know what from. Oil is full and water is full please help

08-14-2007, 12:56 AM	#2
chipflyer Registered User Join Date: May 2004 Location: Topeka, Ks Posts: 2,293	Re: smoke If its an auto trans and it is smoking badly it is probably the transmission modulator valve sucking trans fluid up the vacuum line and burning it. Disconnect the vacuum line and see if it stops smoking. Jeff __________________ I'm not a pessimist, I'm just optimistic that bad things are going to happen. 1971 Cheyenne Super K10 - tilt, cruise, air, am/fm, tow hooks, factory buckets! 1986 Jeep J10 pickup, - 5.3L Vortec with 4L60e and NP241.

08-14-2007, 01:14 AM	#3
my70chevyc10 Registered User Join Date: Jul 2007 Location: Covina Calif Posts: 172	Re: smoke its a 350 with a 3 on the tree

08-14-2007, 10:48 AM	#4
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: smoke Back in the day, we were told that bluish smoke was oil. White smoke was water and that was it. If it smoked on startup but cleared up after a few moments, it was probably valve stems causing the oil to settle on top of the pistons. Using a set of Studebaker umbrella seals on the stems was the cure that we were given. Coolant that found its way into the combustion process would cause white smoke, that was actually steam. Cracked blocks, leaking head gaskets, cracked heads were all possible sources. Grey smoke....fuel issues? Does the smoke have a specific odor? Usually, in my experience, fuel burning issues caused my truck exhaust to burn my eyes. Running really rich. Changed carbs and cured that problem. My Lexus has a brief puff of smoke on startup, but I'm not worried about that. My truck has blowby and the only cure for that is gonna cost me....rebuild or replace. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

08-14-2007, 10:31 PM	#5
70gmcjimmy GMCDAC Join Date: Apr 2006 Location: Rapid City, SD Posts: 837	Re: smoke I had a similar situation little over a year ago with my 72 C2500. White smoke out of the left bank. Pulled the spark plugs and a trickle of liquid came out #7 hole. Tasted it and yup, antifreeze. Had to be a head gasket leak.The coolant in the radiator had not dropped noticably. It doesnt take much to create a lot of smoke. I had built the motor in 1986, and that damm head gasket only made it 20 years! Oh well, replaced them and no more smoke. Any way thats my guess---DAC __________________ 1970 GMC K5 Jimmy Custom 4X4 Mom's driver from 1971 to 2001!! Under rebuild! 1972 GMC C2500 Pickup owned since 1979 Needs a rest and refurbish! 1955 GMC 100 2nd design driven almost daily! Rest In Peace Mom. "Dolly" 7/15/23 - 5/18/09 GMC driver for 30 years!

08-14-2007, 10:56 PM	#6
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: smoke If the engine is otherwise in good shape and you're suddenly burning a whitish smoke. It's more than like condensation of some sort. Either water from the radiator or moisture accumulating in the exhaust. Put your hand by the exhaust (careful not to burn yourself of course) and let the exhaust condense in you hand. You can usually detect the odor of anitfreeze, xmission fluid or other. I also agree as was mentioned that oil burns a bluish color, gas a gray, dark gray or black and water whitish color.



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