Cause of blue smoke out of exhaust pipes?

[Rck68]

Hi All,

What could be the causes of blue smoke upon startup out of a 440’s exhaust pipes?

Is this a serious concern?

How can it be fixed?

 

[70chall440]

Valve guides/seals or rings. Least expensive is valve seals.

 

[Jerry Hall]

Possibility valve guide seals. How old is the build? How many miles on the engine? How is the oil pressure? It could be a lot of things. Rings, valve guide seals, are a couple of things that come to mind.

 

[andyf]

Yes, most likely bad valve seals. How old is the engine? If it is an original engine with cast iron heads then the oil seals are most likely as hard as a rock. That is, if they even exist at all. After 50 years they have probably disintegrated into dust and are in the oil pan.

 

[Rck68]

Not sure when it was rebuilt if it was at all lol runs pretty damn good though.

Oil pressure is holding at 40.

 

[dadsbee]

Where my money is betting! Easy place to start and change without pulling the heads.

 

[Rck68]

Where my money is betting! Easy place to start and change without pulling the heads.
View attachment 949071
View attachment 949076

Great, thanks for the pics as well!! I’ll do this.

Is that a tool to remove the springs? When I put the springs back, do these still have to be measured for height, or just put them back to their respective spots?

 

[dadsbee]

Pull the covers and just get a good flashlight and look in through the valve springs to see if your seals are cracked or broken in half just lying in there. If the seals are toast... you can stuff a rope in each cylinder and bring the piston up towards TDC and it will hold the valves in (cushioned by the rope). Valve compressor tool (about 20 bucks) will compress the spring so you can remove the valve spring keepers and then the springs. Change both valve seals and reinstall the springs, compress again and put the stem keepers back in place. Repeat for each cylinder. Simple as that if it has stock rockers...

While you have each spring off, give the valve stem a good tug in all directions as a "wobble test". If you can feel them move you may have more problems.

 

[Rck68]

Pull the covers and just get a good flashlight and look in through the valve springs to see if your seals are cracked or broken in half just lying in there. If the seals are toast... you can stuff a rope in each cylinder and bring the piston up towards TDC and it will hold the valves in (cushioned by the rope). Valve compressor tool (about 20 bucks) will compress the spring so you can remove the valve spring keepers and then the springs. Change both valve seals and reinstall the springs, compress again and put the stem keepers back in place. Repeat for each cylinder. Simple as that if it has stock rockers...

Alright thank you! I’ve never done this before. I believe it will have stock rockers though.

How much rope do I have to stuff in, and why does the Piston have to be at tdc?
To relieve pressure on springs?

I really have to put an engine together already. Been researching a lot!

 

[70chall440]

There are different ways to do this, I've never done the rope trick but I guess that would work but I would be more concerned about leaving some in the cylinders. The other method is to use an air compressor to put positive pressure in the cylinder to keep the valve from dropping into the cylinder. Spend some time watching YouTube videos and reading about how to do it before you try it. You do not want to drop a valve down into a cylinder, if you do it means the head has to come off, no you cannot rotate the engine to push the valve back up (in case you thought of doing that).

 

[dadsbee]

Why I use a rope and I don't see how you could leave any in the cylinder. Stuff some rope in, piston up and it holds the valves in place cushioned by the rope for zero damage. Air.. piston at bottom and you lose the air supply, then the valves go clink...

 

[70chall440]

Hey I am not hating on your technique, just have never tried it. As for the air technique, I also rotate the piston to the top. All that said, I would probably just pull the heads and do it on the bench.

 

[dadsbee]

Air and piston at the top? How do you keep the piston from going back down under the pressure you're putting on the cylinder? I do that for leak down on aircraft engines and you'd better have a damn good hold on the end of the prop.

 

[1 Wild R/T]

I just did a 383 out of a Dart, the seals were mostly gone entirely, I found them in the oil pick up tube....

 

[Hey-O]

If it's just at start up and just a second and stops and runs strong, drive it. As they all said, it's probably a valve guide seal. Easiest of all the possible fixes. A winter project.

 

[moparedtn]

If it's just at start up and just a second and stops and runs strong, drive it. As they all said, it's probably a valve guide seal. Easiest of all the possible fixes. A winter project.

Yep. If she's running good and just puffs when cold, I'd drive her and enjoy the ride - while planning for the
coming rebuild over the winter.

 

[66Satellite47]

To OP, valve guide seals are the likely cause. The tool shown in posts #6 & 11 works well with stock springs. The rope method really works, you need to hold the valve closed when removing the spring. I used about 6' of cotton cloths line, pull the spark plug, feed the rope in & turn the motor over by hand till the piston stops, compress the spring, remove the locks, install new seals, reverse process to re-install. I had cloths line, a lever style spring tool, spare rocker shaft, spare valve springs whenever I went to the strip. Changed many broken valve springs in the pits or staging lanes using this method. Won numerous races because I could change springs quickly.

 

[WP29440SE]

I just did mine too. I used a long bungie cord with one end cut off and a home made spring compressor. took about 2 hours.

 

[JimCoronette]

Why I use a rope and I don't see how you could leave any in the cylinder. Stuff some rope in, piston up and it holds the valves in place cushioned by the rope for zero damage. Air.. piston at bottom and you lose the air supply, then the valves go clink...
View attachment 949089 View attachment 949090

I've used the rope trick to tighten the crank bolt.
I love this idea for holding the valves up!

 

[Rck68]

To OP, valve guide seals are the likely cause. The tool shown in posts #6 & 11 works well with stock springs. The rope method really works, you need to hold the valve closed when removing the spring. I used about 6' of cotton cloths line, pull the spark plug, feed the rope in & turn the motor over by hand till the piston stops, compress the spring, remove the locks, install new seals, reverse process to re-install. I had cloths line, a lever style spring tool, spare rocker shaft, spare valve springs whenever I went to the strip. Changed many broken valve springs in the pits or staging lanes using this method. Won numerous races because I could change springs quickly.

That’s awesome! Thank you for your expertise!