Blue smoke from passenger side

[Jerry C.]

I changed the heads on my 1969 L71 and suddenly I'm seeing blue smoke from the one side only (passenger}. At first there was no smoke visible, now after ~30 KM I see this smoke. It is most noticeable when the car is idling. I would think that the piston rings are okay as there was no smoke when I had the other heads installed. Can the heat riser valve have anything to do with this? Thanks for any info.

[Terry D.]

Re: Blue smoke from passenger side

What heads did you put on? Are you sure the new heads are in good shape? Was a good valve job done on them, and the valve guides checked? Try doing a compression check on that side. Never heard of a heat riser causing that but I sure don't know everything, but did stay at a Holiday Inn once!

[Jerry C.]

Re: Blue smoke from passenger side

The heads are correct for the L71. They are suppose to be completely rebuilt. They were magnefluxed with all new components installed. I will do the compression check. Thanks for your reply, I'm new to this.

[William F.]

Re: Blue smoke from passenger side

were heads milled? If so, geometry between intake and heads can be off, causing poor gasket fit allowing oil to be sucked from under manifold into intake ports/combustion chamber. If heads weren't milled, could still be a bad intake gasket fit doing same thing as well as possibility of problem with valve guides/oil seals.

[Larry B.]

Re: Blue smoke from passenger side

Intake to head gasket can cause this problem but a bad valve guides can to. Look at the plugs on that side and see if you see any oil fouling on any cylinder.While the plugs are out run a leak down test and listen the PCV if you here air its going by the rings.Alot of times when you put on a good set of heads on a old bore ring combo the rings start to leak.

[William F.]

Re: Blue smoke from passenger side

Just asking, but if it's old rings, why is it smoking on only one side, as I understand it? Think either some of valve guides or valve oil seals done incorrectly or problem with intake to head gasket. Let us all know what the problem is when you find it since giving followup to solution to problems brought up in this forum will be helpful to other members if they encounter the same problem.

[Jerry C.]

Re: Blue smoke from passenger side

I will post the solution when I find out what it is. I took the car for a ride today and it seemed to be okay, no smoke. Later in the day I decided to start it up and the right side started to blow blue smoke again. I can see signs of oil at the tip of the passenger side exhaust.

[Edward J.]

Re: Blue smoke from passenger side

Jerry, I am with Larrys suggestion on removing the spark plugs, If they have been in there long enough time they should show signs of oil deposits on the tip or tips. This would be step one. Valve seals are generally a very common issue with older GM generation I engines.

[Jerry C.]

Re: Blue smoke from passenger side

I will remove the plugs and take a look at them to see what I find. I don't believe the piston seals are faulty because it did not have any blue smoke with the previous heads installed. I do believe it is either the valve stem seals or the intake manifold gasket. Is there an easy way to find out if the leak is from the valve stem seals or the intake manifold gasket?

[Tom L.]

Re: Blue smoke from passenger side

Had an oil consumption problem since I irst got my '72. I removed the intake hoping the gasket quit. Sadly the gasket was fine. What I found were puddles of oil on top of all the valves that were closed. Heads came off, new guides, valves, valve job, etc... I run it about 2-3k miles/year. The last two years I didn't burn a drop of oil. Hope your solution is easier but that's my story on this one. have fun!!

[Edward J.]

Re: Blue smoke from passenger side

I will remove the plugs and take a look at them to see what I find. I don't believe the piston seals are faulty because it did not have any blue smoke with the previous heads installed. I do believe it is either the valve stem seals or the intake manifold gasket. Is there an easy way to find out if the leak is from the valve stem seals or the intake manifold gasket?

Jerry, the only easy way is to remove the intake and look at the valves then when its a valve guide or seal you will see a oil trail running down the stems. I would wait until the plugs are out and this will tell you which cylinder or cylinders it is. If you have down such a job it not all that bad for a valve seal job.

[Jerry C.]

Re: Blue smoke from passenger side

The heads have just been installed and I don't have very many miles on the new heads. Probably less than 50 miles. So, what I will do is run it a little bit longer so that when I remove the plugs I will hopefully see something. In the meantime, I have checked the torque on a couple of intake manifold bolts and they seem to be loose. I think going through a heat cycle since I installed the new heads may have caused thing to change. I need to remove the valve cover to set the valve lash when the engine is up to temperature. At the same time I will check the torque on the head bolt, intake manifold and I will try to see if I can see any problems with any of the valve seals. Although I may not be able to see anything through the valve springs. I'm sure I will find out what it is and I will share it with everyone. Thanks to everyone for their support

[Jerry C.]

Re: Blue smoke from passenger side

Hi, Just wanted to let everyone know what the root cause of the blue smoke was. This morning I decided to work on the car to try to find out why the passenger side exhaust was blowing blue smoke. I removed the valve cover on the passenger side and right away I saw the problem.The push rod came out of the rocker arm on the exhaust valve at the front of the engine. I corrected this, put things back together, started the car and no more blue smoke. Thanks to everyone for their support and suggestions, great site!

[Richard M.]

Re: Blue smoke from passenger side

Jerry, Glad you found it, but.......Was the lash incorrect?(hopefully) Defective rocker locknut? Or cam lobe issue? Or a broken valve spring? Or ?

Knowing root cause could be very important later.

Rich

[Jerry C.]

Re: Blue smoke from passenger side

Hi Richard, I removed and checked the rocker, nut, pushrod and valve spring. They all looked okay. I believe the problem was with the valve lash. The car now runs a lot smoother with no blue smoke.