Question On Oil Smoke
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Pro
Joined: Apr 2001
Posts: 663
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From: Omaha, Ne GO BIG RED
Question On Oil Smoke
Ok, a buddy and I were having a discussion after seeing a guy in a parking lot start up an older beater car and it having a puff of blue smoke come out of the exhaust. I was theorizing it was more likely a valve guide or top-end component since the vehicle was warm. We came to the conclusion that we couldn't really tell for sure unless we knew what happened when the vehicle was cold.
So here is the theory we decided on, please let me know whether it seems like a fair one or not.
-If your vehicle puffs blue oil smoke when you start it when it is cold, it is more likely to be a ring, from oil seepage while resting.
-if your vehicle puffs blue oil smoke when it is warm (been driven, parked, restarted), but NOT when it is cold (start in the morning), it may be more likely to be a valve guide or upper end component, not necessarily a ring.
What is the consensus? He had a vehicle that wouldn't smoke in the morning, but if he went out to lunch where he drove it for 15 minutes or so, parked for 30, then went out to start, it would smoke.
I know, a lot to think about early in the morning....
So here is the theory we decided on, please let me know whether it seems like a fair one or not.
-If your vehicle puffs blue oil smoke when you start it when it is cold, it is more likely to be a ring, from oil seepage while resting.
-if your vehicle puffs blue oil smoke when it is warm (been driven, parked, restarted), but NOT when it is cold (start in the morning), it may be more likely to be a valve guide or upper end component, not necessarily a ring.
What is the consensus? He had a vehicle that wouldn't smoke in the morning, but if he went out to lunch where he drove it for 15 minutes or so, parked for 30, then went out to start, it would smoke.
I know, a lot to think about early in the morning....
Le Mans Master
Joined: Mar 2001
Posts: 9,464
Likes: 1
From: Modesto CA
Re: Question On Oil Smoke (86Coupe)
I would think it would be always a valve guide if it puffed smoke on startup. It just does it less when it's warm, because the valve seals are warm and expanded.
Racer
Joined: Apr 2003
Posts: 280
Likes: 0
From: edmonton ab
Re: Question On Oil Smoke (AGENT 86)
Smoke on start up cold or hot = valve seals and guides
Smoke while driving= rings
Smoke while driving= rings
Team Owner
Joined: Jan 2003
Posts: 20,324
Likes: 250
From: Summerland B.C. Canada
Re: Question On Oil Smoke (vettek50)
Smoke on start up cold or hot = valve seals and guides
Smoke while driving= rings
AGENT86, nice pic of your car....i agree with your comment above.. :cheers: . what the weather like in summerland? if good making trip that way next week.. :auto:
Smoke while driving= rings
AGENT86, nice pic of your car....i agree with your comment above.. :cheers: . what the weather like in summerland? if good making trip that way next week.. :auto:
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Question On Oil Smoke (86Coupe)
If your vehicle puffs blue oil smoke when you start it when it is cold, it is more likely to be a ring, from oil seepage while resting.
-if your vehicle puffs blue oil smoke when it is warm (been driven, parked, restarted), but NOT when it is cold (start in the morning), it may be more likely to be a valve guide or upper end component, not necessarily a ring.
-if your vehicle puffs blue oil smoke when it is warm (been driven, parked, restarted), but NOT when it is cold (start in the morning), it may be more likely to be a valve guide or upper end component, not necessarily a ring.
[Modified by BBA, 7:22 AM 8/5/2003]
Team Owner
Joined: Jan 2003
Posts: 20,324
Likes: 250
From: Summerland B.C. Canada
Re: Question On Oil Smoke (BBA)
That is pretty accurate. Valve guide seals will not make it smoke on cold startup. If it smokes on cold startup, it will likely smoke all the time because the rings are shot.
[Modified by BBA, 7:22 AM 8/5/2003]
[Modified by BBA, 7:22 AM 8/5/2003]
Park hot car,oil leaks past seals into combustion chamber.
Start cold car with oil in chamber=puff of blue smoke.
My oil doesn't run uphill past 3 rings and waite there till i start it up :D
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Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Question On Oil Smoke (AGENT 86)
Ok...with the cat converter on my car, it would not smoke on start up ever.
When I took it off, it smoked on startup ONLY WHEN HOT!
I replaced valve guide seals, no more smoking on hot starts.
If yours is smoking on COLD starts, you have oil or fuel richness problems and the cats not being hot enough to filter it/burn it off right off.
I can tell you if you have bad valve seals, enough oil can pour through them when the motor is first shut off and it can make way too much smoke for the cat to handle, but by the time the engine is cold, the oil will all have drained back past the rings: No oil is there when you do the cold start and no smoke.
So, unless you have total seal or other gapless piston rings, if your car smokes when cold, I dont think simply replacing valve guide seals will fix it.
[Modified by BBA, 7:35 PM 8/5/2003]
[Modified by BBA, 7:38 PM 8/5/2003]
When I took it off, it smoked on startup ONLY WHEN HOT!
I replaced valve guide seals, no more smoking on hot starts.
If yours is smoking on COLD starts, you have oil or fuel richness problems and the cats not being hot enough to filter it/burn it off right off.
I can tell you if you have bad valve seals, enough oil can pour through them when the motor is first shut off and it can make way too much smoke for the cat to handle, but by the time the engine is cold, the oil will all have drained back past the rings: No oil is there when you do the cold start and no smoke.
So, unless you have total seal or other gapless piston rings, if your car smokes when cold, I dont think simply replacing valve guide seals will fix it.
[Modified by BBA, 7:35 PM 8/5/2003]
[Modified by BBA, 7:38 PM 8/5/2003]
