Blue fog on startup
Thread Starter
Instructor
Joined: Jan 2003
Posts: 188
Likes: 2
From: Flowermound Tx
Blue fog on startup
Hi guys,
been a LONG time since I've been here. Been firing up the 74 454 with 68k miles every 2-3 months for the past 4 years while working on various components. It has always blown a bit of blue smoke on startup but now it seems to be a relatively consistent fog when I let it run for 20 minutes. After the first 2-3 it clears but there is still a thin emission of smoke. The engine has never had any work done to it and has always run like a champ. Is it possible that the valve seals are finally starting to go ? I had the another 74 big block with the same mileage 25 years ago. The previous owner had done a valve job on it and said seals were a common problem on bigblocks after 50k. What do you all think ? I'm going to do a compression test on it when I get time but I was wondering if it would be worth it at this point to take the heads in for a 3 angle valve job ? Anyone have a ballpark as to how much that might run ?
Thanks for your help!!
been a LONG time since I've been here. Been firing up the 74 454 with 68k miles every 2-3 months for the past 4 years while working on various components. It has always blown a bit of blue smoke on startup but now it seems to be a relatively consistent fog when I let it run for 20 minutes. After the first 2-3 it clears but there is still a thin emission of smoke. The engine has never had any work done to it and has always run like a champ. Is it possible that the valve seals are finally starting to go ? I had the another 74 big block with the same mileage 25 years ago. The previous owner had done a valve job on it and said seals were a common problem on bigblocks after 50k. What do you all think ? I'm going to do a compression test on it when I get time but I was wondering if it would be worth it at this point to take the heads in for a 3 angle valve job ? Anyone have a ballpark as to how much that might run ?
Thanks for your help!!
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
I would say that valve seals are probably at least part of the problem. What color is the exhaust after warm up. BTW, it is always a good idea to drive these cars for at least a half hour or so periodically as opposed to just letting them idle. Short run times are harmful. 
Racer
Joined: Jan 2008
Posts: 386
Likes: 0
From: macks creek mo
I would say that valve seals are probably at least part of the problem. What color is the exhaust after warm up. BTW, it is always a good idea to drive these cars for at least a half hour or so periodically as opposed to just letting them idle. Short run times are harmful.
Melting Slicks
Joined: May 2005
Posts: 2,826
Likes: 3
From: Tennessee
I agree with the valve stem seals. Does it stop smoking after letting it run for a bit? I had a car that had the same issue. Only smoked on startup and occasionally at a stop light.
oops...just re-read the post and saw it conitnues to smoke but I still believe it is the valve stem seals.
Richard
oops...just re-read the post and saw it conitnues to smoke but I still believe it is the valve stem seals.
Richard
Last edited by rj8806; Jan 28, 2008 at 11:26 AM.
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
Hi guys,
been a LONG time since I've been here. Been firing up the 74 454 with 68k miles every 2-3 months for the past 4 years while working on various components. It has always blown a bit of blue smoke on startup but now it seems to be a relatively consistent fog when I let it run for 20 minutes. After the first 2-3 it clears but there is still a thin emission of smoke. The engine has never had any work done to it and has always run like a champ. Is it possible that the valve seals are finally starting to go ? I had the another 74 big block with the same mileage 25 years ago. The previous owner had done a valve job on it and said seals were a common problem on bigblocks after 50k. What do you all think ? I'm going to do a compression test on it when I get time but I was wondering if it would be worth it at this point to take the heads in for a 3 angle valve job ? Anyone have a ballpark as to how much that might run ?
Thanks for your help!!
been a LONG time since I've been here. Been firing up the 74 454 with 68k miles every 2-3 months for the past 4 years while working on various components. It has always blown a bit of blue smoke on startup but now it seems to be a relatively consistent fog when I let it run for 20 minutes. After the first 2-3 it clears but there is still a thin emission of smoke. The engine has never had any work done to it and has always run like a champ. Is it possible that the valve seals are finally starting to go ? I had the another 74 big block with the same mileage 25 years ago. The previous owner had done a valve job on it and said seals were a common problem on bigblocks after 50k. What do you all think ? I'm going to do a compression test on it when I get time but I was wondering if it would be worth it at this point to take the heads in for a 3 angle valve job ? Anyone have a ballpark as to how much that might run ?
Thanks for your help!!
Jim
Thread Starter
Instructor
Joined: Jan 2003
Posts: 188
Likes: 2
From: Flowermound Tx
Thanks for the replies. The smoke is gray with a hint of blue at startup. After 2-3 mins it turns to a mostly gray cloud. It alternates between very little smoke and puffs of gray.
I sure would like to take it for a drive but to make a long story short, I started the resto process backwards by replacing the exhaust. Then the rear bumper cracked so i removed it. Didn't know you had to drop the tank to get to the mounting studs. I spent months redoing the interior while trying to figure out how to attach the bumper without hacking off my brandnew exhaust & dropping the tank. Exhaust is still pristine, bumper is still AWOL, & I can't get the car inspected/licensed in Tx. without a rear bumper. I am slowly getting the nerve up to remove all of the above and finally finish what I started 2.5 years ago. I have resisted the urge to set it ablaze. I think my wife would like that though.
I appreciate any suggestions or comments. Laughing at my order of doing things is totally acceptable also.
Thanks
I sure would like to take it for a drive but to make a long story short, I started the resto process backwards by replacing the exhaust. Then the rear bumper cracked so i removed it. Didn't know you had to drop the tank to get to the mounting studs. I spent months redoing the interior while trying to figure out how to attach the bumper without hacking off my brandnew exhaust & dropping the tank. Exhaust is still pristine, bumper is still AWOL, & I can't get the car inspected/licensed in Tx. without a rear bumper. I am slowly getting the nerve up to remove all of the above and finally finish what I started 2.5 years ago. I have resisted the urge to set it ablaze. I think my wife would like that though.
I appreciate any suggestions or comments. Laughing at my order of doing things is totally acceptable also.
Thanks
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
Thanks for the replies. The smoke is gray with a hint of blue at startup. After 2-3 mins it turns to a mostly gray cloud. It alternates between very little smoke and puffs of gray.
I sure would like to take it for a drive but to make a long story short, I started the resto process backwards by replacing the exhaust. Then the rear bumper cracked so i removed it. Didn't know you had to drop the tank to get to the mounting studs. I spent months redoing the interior while trying to figure out how to attach the bumper without hacking off my brandnew exhaust & dropping the tank. Exhaust is still pristine, bumper is still AWOL, & I can't get the car inspected/licensed in Tx. without a rear bumper. I am slowly getting the nerve up to remove all of the above and finally finish what I started 2.5 years ago. I have resisted the urge to set it ablaze. I think my wife would like that though.
I appreciate any suggestions or comments. Laughing at my order of doing things is totally acceptable also.
Thanks
I sure would like to take it for a drive but to make a long story short, I started the resto process backwards by replacing the exhaust. Then the rear bumper cracked so i removed it. Didn't know you had to drop the tank to get to the mounting studs. I spent months redoing the interior while trying to figure out how to attach the bumper without hacking off my brandnew exhaust & dropping the tank. Exhaust is still pristine, bumper is still AWOL, & I can't get the car inspected/licensed in Tx. without a rear bumper. I am slowly getting the nerve up to remove all of the above and finally finish what I started 2.5 years ago. I have resisted the urge to set it ablaze. I think my wife would like that though.
I appreciate any suggestions or comments. Laughing at my order of doing things is totally acceptable also.
Thanks
FWIW I get the samething when I store mine. It clears up when i start driving it.
Change the gas....but if you are going to drop the tank do that first....
Melting Slicks
Joined: Aug 2004
Posts: 2,220
Likes: 6
From: www.Z16.org North/West Pennsylvania
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Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
1974, 68K miles, BBC never been into:
If Stock OE valve stem seals are truly +30 years old with ~ 68K miles ... they get hard, non-pliable & prone to cracking ... it's a safe bet they need replacement. Seems you're in no hurry so you might do this job yourself at minimal cost. Assuming valvesprings have same time-age ... I'd replace them also with std replacement type.
If Stock OE valve stem seals are truly +30 years old with ~ 68K miles ... they get hard, non-pliable & prone to cracking ... it's a safe bet they need replacement. Seems you're in no hurry so you might do this job yourself at minimal cost. Assuming valvesprings have same time-age ... I'd replace them also with std replacement type.
Drifting
Joined: Sep 2007
Posts: 1,572
Likes: 51
From: Wichita Kansas
Sounds like the valve seals and nothing more. However you should do a compression check (wet & dry) to confirm that the rings are good.
If the rings check good then pull the heads for rebuild and put them back on.
If the rings check good then pull the heads for rebuild and put them back on.
Intermediate
Joined: Jan 2008
Posts: 25
Likes: 0
From: El Toro California
i have a 66 427 its most likely the valve guides and possibly the piston rings depending on how it was driven previously.
but it would mostly be a valve guide.
if it smokes alot check your oil level to insure you dont run the motor dry.
that = expensive
but it would mostly be a valve guide.
if it smokes alot check your oil level to insure you dont run the motor dry.
that = expensive