smokin!?

jd75 · 03-12-2007, 06:41 AM

have a late 70's 350 motor and when running for more than 5 min. i pull the dip stick and smoke is pouring out. I recently replaced the oil pan seals and oil pump, they were in bad shape and the pump was full of hard chunks of what i guess was baked oil. no metal in the bottom of the pan and the motor still looked good from underneath. just put in a oil and temp gauge and the readings look ok, but the smoke has me scared of running it very long. the thing starts really good and sounds even better. Ive changed the oil a few times and next change am going to go to mobil 1 synthetic, but the oil is clean after every change. any advice is much appreciated!

Oldsmaniac · 03-12-2007, 12:44 PM

Is the PCV valve system working?...It evacuates the crankcase of unburned fuel and vapors......Excessive blowby from rings will also create this condition....maybe a compression test on each cylinder is in order...

soocutlass · 03-12-2007, 07:30 PM

I was thinking along the same thoughts as Oldsmaniac

keith6989 · 03-13-2007, 04:28 AM

Welcome to the forum, let us know how it fairs out for you, I am thinking along the lines of maniac too.

Oldsguy · 03-13-2007, 04:38 AM

You didn't say what you replaced the old oil with when you changed the pan gasket. I know you used oil, of course, and probably regular oil since you mentioned synthetic "next time" but did you use an additive or something that claims to clean out old engines? If you did, this could also be causing the smoke. Is it just some small vapors clinging to the dipstick, or is it a larger amount pouring out of the dipstick tube? Do you also get smoke from the oil fill tube in the front of the engine when you remove the cap as well? If yes, then how much? If it dissapates fairly quickly then the pcv system would be suspect as mentioned. If the vapors are just clinging to the stick then that is more charateristic of an old engine and I wouldn't worry too much. Those chunks in the pan were probably pieces of the old gasket, that cork material gets almost as hard as a rock when old. I would not recommend the expenditure of synthetic oil in an old un-rebuilt engine. My experience is that standard 10w30 or 10w40 works fine for an old engine. Especially for one that has not been rebuilt but many people disagree so you should do what you feel best. Finally, if you are getting a lot of smoke that does not dissapate quickly then you may be burning it. It could be worn rings as maniac mentioned and again, servicing the pcv system could help. Some old engines just smoke a lot. Does it overheat? What is the coolant temperature? If that is normal then I wouldn't worry, if it is high or the engine overheats then you MIGHT have some bearing failure but you said the engine sounds good and strong. Hard to say...Re-check your oil color and consistency, no sparkleys and no smell then you are ok.

jd75 · 03-13-2007, 06:54 AM

Thanks for the replies. I checked my pcv system and cleaned it. The smoke is gone, it was a large amount pouring out of the dipstick tube, but none from the oil fill tube. One more question, does anyone have diagrams of the hose routing for a q-jet? The numbers on mine are 17056259 0356 asc. All of the smog has been unhooked from what i can tell, but since these are vac carbs i wasnt sure if it was getting the right amount of vac. Thanks

soocutlass · 03-13-2007, 08:12 AM

Last year at the St Ingnace Michigan car show I bought an Oldsmobile cutlass 68-72 assemble manual with all the info for restoration. They are still around I recomend everyone to own one for instances like these

03-12-2007, 06:41 AM	#1 (permalink)
jd75 Member Join Date: Jan 2007 Posts: 25	smokin!? have a late 70's 350 motor and when running for more than 5 min. i pull the dip stick and smoke is pouring out. I recently replaced the oil pan seals and oil pump, they were in bad shape and the pump was full of hard chunks of what i guess was baked oil. no metal in the bottom of the pan and the motor still looked good from underneath. just put in a oil and temp gauge and the readings look ok, but the smoke has me scared of running it very long. the thing starts really good and sounds even better. Ive changed the oil a few times and next change am going to go to mobil 1 synthetic, but the oil is clean after every change. any advice is much appreciated!

03-13-2007, 04:28 AM	#4 (permalink)
keith6989 2Blue 55" Join Date: Dec 2006 Location: Nova Scotia, Canada Posts: 380	Welcome to the forum, let us know how it fairs out for you, I am thinking along the lines of maniac too. __________________ Robert 1955 Oldsmobile Super 88

03-13-2007, 04:38 AM	#5 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 3,167	You didn't say what you replaced the old oil with when you changed the pan gasket. I know you used oil, of course, and probably regular oil since you mentioned synthetic "next time" but did you use an additive or something that claims to clean out old engines? If you did, this could also be causing the smoke. Is it just some small vapors clinging to the dipstick, or is it a larger amount pouring out of the dipstick tube? Do you also get smoke from the oil fill tube in the front of the engine when you remove the cap as well? If yes, then how much? If it dissapates fairly quickly then the pcv system would be suspect as mentioned. If the vapors are just clinging to the stick then that is more charateristic of an old engine and I wouldn't worry too much. Those chunks in the pan were probably pieces of the old gasket, that cork material gets almost as hard as a rock when old. I would not recommend the expenditure of synthetic oil in an old un-rebuilt engine. My experience is that standard 10w30 or 10w40 works fine for an old engine. Especially for one that has not been rebuilt but many people disagree so you should do what you feel best. Finally, if you are getting a lot of smoke that does not dissapate quickly then you may be burning it. It could be worn rings as maniac mentioned and again, servicing the pcv system could help. Some old engines just smoke a lot. Does it overheat? What is the coolant temperature? If that is normal then I wouldn't worry, if it is high or the engine overheats then you MIGHT have some bearing failure but you said the engine sounds good and strong. Hard to say...Re-check your oil color and consistency, no sparkleys and no smell then you are ok. __________________ Dan '77 Cutlass Supreme '46 2 door

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03-12-2007, 12:44 PM	#2 (permalink)
Oldsmaniac Senior Member Join Date: Oct 2005 Location: NJ Posts: 430	Is the PCV valve system working?...It evacuates the crankcase of unburned fuel and vapors......Excessive blowby from rings will also create this condition....maybe a compression test on each cylinder is in order...

03-12-2007, 07:30 PM	#3 (permalink)
soocutlass Junior Member Join Date: Mar 2007 Posts: 15	I was thinking along the same thoughts as Oldsmaniac

03-13-2007, 06:54 AM	#6 (permalink)
jd75 Member Join Date: Jan 2007 Posts: 25	Thanks for the replies. I checked my pcv system and cleaned it. The smoke is gone, it was a large amount pouring out of the dipstick tube, but none from the oil fill tube. One more question, does anyone have diagrams of the hose routing for a q-jet? The numbers on mine are 17056259 0356 asc. All of the smog has been unhooked from what i can tell, but since these are vac carbs i wasnt sure if it was getting the right amount of vac. Thanks

03-13-2007, 08:12 AM	#7 (permalink)
soocutlass Junior Member Join Date: Mar 2007 Posts: 15	Last year at the St Ingnace Michigan car show I bought an Oldsmobile cutlass 68-72 assemble manual with all the info for restoration. They are still around I recomend everyone to own one for instances like these