Burst of blue smoke out the tailpipe when accelerating?

Most commonly that is due to oil running past the valve guide seals. That can be caused by oil that has been diluted with raw gas from a recent spark-related no-start condition, or some other problem that is causing the engine to use too much gas. It can also be caused by worn guide seals.

This guide can help us fix it

https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust

I'd start with an oil change. If the problem continues, especially at the mileage you listed, consider switching to one viscosity rating higher. Thicker oil will have less tendency to sneak past the seals.

HI and thanks for using 2CarPros.

Most likely the cause is bad valve seals. I attached a picture below. If you locate number 3 in picture 1, it is the seal that I am referring to. Now, each valve stem has one. To check them requires removal of the valve covers so you can see them.

To replace the seals, the valve springs need removed. There are different ways of doing it, but the flat rate (labor time) calls for 6.6 hours to do both sides which doesn't include parts.

Here are the directions for removal of the spring. The seal is installed once the spring is off.

____________________________

REMOVAL

Picture 2

1. Remove the cylinder head cover See: Valve Cover > Removal and Replacement > Cylinder Head Cover - Removal.
2. Using Valve Spring Compressor 10102 (2), remove the rocker arms and the hydraulic lash adjusters.
3. Remove the spark plug for the cylinder the valve spring and seal are to be removed from.
4. Apply shop air to the cylinder to hold the valves in place when the spring is removed

NOTE: All eight valve springs and seals are removed in the same manner; this procedure only covers one valve seal and valve spring.

5. Using Valve Spring Compressor 10102, compress the valve spring.

NOTE: It may be necessary to tap the top of the valve spring to loosen the spring retainers locks enough to be removed.

6. Remove the two spring retainer lock halves.

NOTE: the valve spring is under tension use care when releasing the valve spring compressor.

7. Remove the valve spring compressor.
8. Remove the spring retainer, and the spring.
9. Remove the valve stem seal.

_____________________________________________________

Install

INSTALLATION

Picture 3

1. Coat the valve stem with clean engine oil and install the valve stem seal. Make sure the seal is fully seated and that the garter spring at the top of the seal is intact.
2. Install the spring (6) and the spring retainer (2).
3. Using Valve Spring Compressor 10102, compress the spring and install the two valve spring retainer halves.
4. Release the valve spring compressor and make sure the two spring retainer halves and the spring retainer are fully seated.
5. Position the hydraulic lash adjusters and rocker arms.
6. Install the cylinder head cover See: Valve Cover > Removal and Replacement > Cylinder Head Cover - Installation.
7. Install spark plugs and plug wires.

Let me know if this helps or if you have other questions. Please keep in mind, this is a theory at this point, but I feel confident that is the problem.

Take care,
Joe

You are very welcome. Did it take care of the problem you were having?

Joe

It sounds like the engine is just getting tired and will require a rebuild in the future. As for the smoke you are seeing it is more then likely the valve stem seals. So what you can try it to add Lucas Oil Stabilizer to each oil change. This will not hurt anything at worst it won't help which you will know the oil change you add it. Hope this buy's you some time. You could also look to your local salvage or wrecking yards for a low mileage engine to put your truck too when money permits. Thanks and let me know how it goes.

Hi,

Often times, an engine vacuum leak can cause a stalling issue. The blue smoke has me concerned, however. That is normally an indication that the engine is burning oil. Does it smoke all the time or only when you place it in gear? When placed in gear, does it just stall or does the vehicle lurch forward?

Here is a link you may find of interest. It explains the most common causes of a stall at idle.

https://www.2carpros.com/articles/stall-at-idle

Also, here is a link that shows how to check for vacuum leaks:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know exactly what is happening. Also, let me know if you are able to keep it running by lightly pressing the throttle when you shift.

Take care,
Joe

Hello,

The old slant 6 wow. Those motors are bomb proof, you don't see many of them around anymore. The cars rotted out from around them, lol. As for your stalling with the new carburetor. There's a good chance it needs to be adjusted properly. Was it put on by a shop with an older person. The younger techs don't really get taught to much about carburetor mixture adjustments these days also in those years the manufacturers started putting all kinds of emissions stuff on them and they were kind of new at it. Does it have a lot of vacuum lines on it or do you have one that's still basic? Adjusting them is a little tricky and is best done with an exhaust analyser hooked up to it. The factory setting only get you so close. People mess with the timing to offset the carburetor adjustments too. Your probably looking at something like that. Let me know which carburetor you put on it and I can get the basic settings and you can check that first then make sure the timing is set correctly afterwards. The blue smoke is oil burning with an old motor like that it could be a number of things, warn rings or valve seals among them. Have you done a compression test on it yet?
Let me know,
Tom