Smoking engine

[09112]

Recently got my 48 Allis up and going. Initially, it ran very well with no smoke. Now, upon starting, it runs clean but when it warms up it starts blowing blue smoke at idle. Smoke disappears at half throttle. I've cleaned the oil bath filter and found a mud dauber nest. Thinking this was the problem, but it never improved. Any ideas?

 

[3Lfarms]

When was the oil last changed? A simple oil change may help free up any stuck oil control rings. It sounds like oil is getting past the rings, or the valve seals and/or guides are worn.
Switching to a thicker oil may help, but may not be good for it in cold weather.

 

[09112]

I am using 30 wt oil at the moment and have just recently changed it. The engine sat for some years in the weather but I did a valve job on it prior to firing it up. When I initially fired the engine with 10W40 it ran quite clean. I changed over to the 30 wt after running the engine for about three hours to get as much dirt out as possible. Perhaps I should add an engine cleaner and run for 15 minutes or so and change again. The oil was super black when I changed the first time. What baffles me is that it runs totally clean cold then smokes as it warms up. Perhaps it's the expansion of the block, thus allowing oil past the oil ring. I never tore the engine down prior to installation, just took the head off to see what it looked like. There was no sideway movement in the pistons so I just did a quick valve seat job and put the head back on. Unfortunately, I fear my lack of mechanical abilities is beginning to show. So here's what I'll do next: Add an engine cleaner into the oil, run for 15/20 minutes, change to 10W40 and add a good oil additive and see if that helps. Though the engine is 70 years old, I know the person I bought it from and the tractor was never used much and then only for light work, so I have some hope that it is still in pretty good shape. I'll get this done in the next couple days and post the results. Thanks for your comments.

 

[3Lfarms]

That is what I would do. Some old timers were pretty bad about using poor quality non detergent oils.
I would do as you suggest, but keep changing it with cheap Walmart brand oil until it stays clean through a few hours of use. Then change again with your preferred oil....although new Walmart Supertech oil is 1000 percent better than the oil that was available when the tractor was built. That should pretty well clean it out.

 

[Raspy]

Not sure how changing the oil, over and over is going to help. Was the engine severely carboned up in the upper cylinder head/rocker arm area and oil return passages through the block (assuming it is overhead valve)?

Make sure the breather is clear and not clogged up. You should see blowby freely coming out of it.

I'd say, get some good oil in it and work it. Get it up to temp and put a load on it for a while, to see if it improves.

I'm assuming it's a gas engine, but not sure. If so, the most likely reason for smoking when warm and idling is oil getting in through the intake valve guides. Did you put seals on them?

 

[09112]

Hi Raspy, My second lot of oil is still dirty after about four hours of total running. The first lot came out like tar. This lot is much better but still dirty and I will take advise from 3Lfarms and use walmart stuff until it runs clean, because at 50 bucks a pop my wife is getting a bit upset at the B. Now about the seals. This is the first time I have ever seriously looked inside an engine, however, in my 84 years I have picked up a few things through life itself. That said, I wouldn't know a seal from a walrus. When I went into the head I ensured that the valves were seated properly since a professional valve job had been done some years prior but the head had been stored in a box on the back porch for years. I then put it back like it came apart. However, now that the subject of seals has arisin I will see if there is such a thing that should be added. This should be a fairly simple job by the sound of it. The breather was cleaned and mud daubers removed. Really thought that would take care of the problem. Anyhow, it started as a project and what an experience I've had. Wouldn't change it for the world. Bye the Bye, every question I had on this project was answered by others on this site so a big thankyou goes out to everyone that helped me on my way.

 

[CodemanLivs]

Hi Raspy, My second lot of oil is still dirty after about four hours of total running. The first lot came out like tar. This lot is much better but still dirty and I will take advise from 3Lfarms and use walmart stuff until it runs clean, because at 50 bucks a pop my wife is getting a bit upset at the B. Now about the seals. This is the first time I have ever seriously looked inside an engine, however, in my 84 years I have picked up a few things through life itself. That said, I wouldn't know a seal from a walrus. When I went into the head I ensured that the valves were seated properly since a professional valve job had been done some years prior but the head had been stored in a box on the back porch for years. I then put it back like it came apart. However, now that the subject of seals has arisin I will see if there is such a thing that should be added. This should be a fairly simple job by the sound of it. The breather was cleaned and mud daubers removed. Really thought that would take care of the problem. Anyhow, it started as a project and what an experience I've had. Wouldn't change it for the world. Bye the Bye, every question I had on this project was answered by others on this site so a big thankyou goes out to everyone that helped me on my way.

This is a valve stem seal, it prevents oil from getting past the valve stem, which is what old seals will do and in turn cause blue smoke.

 

[CodemanLivs]

Don't mean to butt in, just trying to help. Not really sure how old this post is but ....

 

[IH3444]

If the head was stored in a box on the back porch for years, then finally installed. If the head was off for years, and the engine was stored in a barn or shed without the cylinders not being protected with a good film of grease then the cylinder walls can have a very fine rusted surface on them. Upon start up the cylinders then begin to once again seat into the piston rings, but with some very fine pitting due to the rust. This could be where your oil smoking problem is coming from. Many, many tiny pockets of oil trapped in the pitting.

 

[09112]

Don't mean to butt in, just trying to help. Not really sure how old this post is but ....View attachment 592932

This is the first time I"ve seen a valve seal and is something my head did not have when I removed the valves. Do all engines use seals? I looked them up on "yesterdays tractors" but only got engine rebuild kits on screen for everything BUT a B. Could these be ordered as a part number or by diameter of valve stem from a local auto parts store?