Smoke at startup
Nov 22, 2011 | 04:26 PM
#21
Thread Starter
Staging Lane
Joined: Nov 2011
Posts: 58
Likes: 0
I assume this means my problem is probably not valve seals.
Can you tell me why you had me do this test? PCV?
Last edited by Junkyard Dog; Nov 22, 2011 at 05:04 PM.
Nov 23, 2011 | 06:40 AM
#23
Thread Starter
Staging Lane
Joined: Nov 2011
Posts: 58
Likes: 0
2005 GMC Yukon with 4.8
Google brought me to this forum, and I see that I have a common problem. Smoke pours out of the tailpipe at start up and then disappears after I am about 1/8 of a mile down the road. The tailpipe is black.
I have confirmed that there is no PCV valve (this is a 2005, so there is just the orifice that they started installing in 2004). This is on the driver's side.
I have seen the suggestion of a catch can.
I noted also that there appears to be a tube that goes from the passenger side valve cover to right behind the throttle body at the front of the intake manifold. Couldn't the engine be sucking oil from there just as easily as from the PCV (or orifice)?
For what it's worth, I had this same problem about 8-9 months ago, for about 3 weeks, and then it went away on its own. Now it is back. This is why I do not think it is my valve seals or guides, even though I just turned 200,000 miles. Two weeks ago the engine did not use a drop of oil, then one morning I turn it on and cover the driveway in smoke and use a quart every 100-200 miles!
Suggestions and advice are welcome.
I am considering right now a pressure and leakdown test and perhaps two catchcans (one for each valve cover tube).
Google brought me here for my smoking problem, but this forum already has me considering a cam, headers, Trick Flow ported heads, a 3,000 stall torque converter, lower gears, and maybe a supercharger or a turbo!
But let's get my smoking problem fixed first.
Google brought me to this forum, and I see that I have a common problem. Smoke pours out of the tailpipe at start up and then disappears after I am about 1/8 of a mile down the road. The tailpipe is black.
I have confirmed that there is no PCV valve (this is a 2005, so there is just the orifice that they started installing in 2004). This is on the driver's side.
I have seen the suggestion of a catch can.
I noted also that there appears to be a tube that goes from the passenger side valve cover to right behind the throttle body at the front of the intake manifold. Couldn't the engine be sucking oil from there just as easily as from the PCV (or orifice)?
For what it's worth, I had this same problem about 8-9 months ago, for about 3 weeks, and then it went away on its own. Now it is back. This is why I do not think it is my valve seals or guides, even though I just turned 200,000 miles. Two weeks ago the engine did not use a drop of oil, then one morning I turn it on and cover the driveway in smoke and use a quart every 100-200 miles!
Suggestions and advice are welcome.
I am considering right now a pressure and leakdown test and perhaps two catchcans (one for each valve cover tube).
Google brought me here for my smoking problem, but this forum already has me considering a cam, headers, Trick Flow ported heads, a 3,000 stall torque converter, lower gears, and maybe a supercharger or a turbo!
But let's get my smoking problem fixed first.
Nov 24, 2011 | 10:37 AM
#24
Thread Starter
Staging Lane
Joined: Nov 2011
Posts: 58
Likes: 0
I took off the driver's side valve cover. The tube at the back of the valve cover (which takes the place of a PCV valve on earlier models) has brown oil in it. I do not know whether this is normal.
When I turn over the valve cover, there is a baffle that runs the length of the valve cover, and I do not see a way to disassemble it for cleaning.
Just spray seafoam cleaner in it wherever I can and hope for the best?
Suggestions?
When I turn over the valve cover, there is a baffle that runs the length of the valve cover, and I do not see a way to disassemble it for cleaning.
Just spray seafoam cleaner in it wherever I can and hope for the best?
Suggestions?
Nov 24, 2011 | 11:18 AM
#25
It sounds like valve seals to me but if you suspect your pcv system, cap the intake fittings and install some breathers. If the problem persists then I would perform a leakdown and if that checks out you know you need to throw some stem seals in it. Its not that bad of a job.
Nov 24, 2011 | 11:52 AM
#27
Thread Starter
Staging Lane
Joined: Nov 2011
Posts: 58
Likes: 0
Nov 24, 2011 | 12:02 PM
#28
My 5.3 starting having a random misfire @ 173k on cyl 1 and 3 and used lots of oil, drove it till 175k before replacing it, cylinder 1 & 3 both had broken piston rings. The amount of oil in the intake was crazy, oil was dripping from the intake when I took it off.
With the new engine I used the older style valve cover and got rid of the hose to the valve cover and switched to the LS6 valley cover w/ PCV
I cant find a close up of the LS6 valley cover, on the valley cover you can just barely make out the pcv tube.
With the new engine I used the older style valve cover and got rid of the hose to the valve cover and switched to the LS6 valley cover w/ PCV
I cant find a close up of the LS6 valley cover, on the valley cover you can just barely make out the pcv tube.
Nov 24, 2011 | 01:01 PM
#29
Burning oil on startup sounds like bad valve stem seals and/or worn valve guides. Pull your plugs and see if they have a lot of black carbon or oily buildup. If one or more is black, then that is probably the cylinder(s). It doesn't take much oil to cause that blue puff at startup. If it seems worse the longer it sits, I would say that that is the cause. I've seen it lots.
You'll have to remove the valve spring and give the valve a wobble. If it's loose then the guide is worn. If it's tight then you should be able to get away with changing the seal.
You'll have to remove the valve spring and give the valve a wobble. If it's loose then the guide is worn. If it's tight then you should be able to get away with changing the seal.